diff --git a/.gitignore b/.gitignore
index af7c9e4793ff..41c93c7bd84d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,4 +4,5 @@ deno.d.ts
 node_modules
 package.json
 package-lock.json
+yarn.lock
 .vscode
diff --git a/encoding/README.md b/encoding/README.md
index f03e80ba2515..550b10b36b42 100644
--- a/encoding/README.md
+++ b/encoding/README.md
@@ -217,3 +217,24 @@ const obj = {
 };
 const tomlString = stringify(obj);
 ```
+
+## YAML
+
+YAML parser / dumper for Deno
+
+Heavily inspired from [js-yaml]
+
+### Example
+
+See [`./yaml/example`](./yaml/example) folder and [js-yaml] repository.
+
+### :warning: Limitations
+
+- `binary` type is currently not stable
+- `function`, `regexp`, and `undefined` type are currently not supported
+
+# Basic usage
+
+TBD
+
+[js-yaml]: https://github.com/nodeca/js-yaml
diff --git a/encoding/test.ts b/encoding/test.ts
index c7a1c9716007..8cb2c5d4e3ad 100644
--- a/encoding/test.ts
+++ b/encoding/test.ts
@@ -2,3 +2,4 @@
 import "./hex_test.ts";
 import "./toml_test.ts";
 import "./csv_test.ts";
+import "./yaml_test.ts";
diff --git a/encoding/yaml.ts b/encoding/yaml.ts
new file mode 100644
index 000000000000..055edad72b23
--- /dev/null
+++ b/encoding/yaml.ts
@@ -0,0 +1,8 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+export * from "./yaml/parse.ts";
+export * from "./yaml/stringify.ts";
+export * from "./yaml/schema/mod.ts";
diff --git a/encoding/yaml/Mark.ts b/encoding/yaml/Mark.ts
new file mode 100644
index 000000000000..96c7ba8524a6
--- /dev/null
+++ b/encoding/yaml/Mark.ts
@@ -0,0 +1,76 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { repeat } from "./utils.ts";
+
+export class Mark {
+  constructor(
+    public name: string,
+    public buffer: string,
+    public position: number,
+    public line: number,
+    public column: number
+  ) {}
+
+  public getSnippet(indent = 4, maxLength = 75): string | null {
+    if (!this.buffer) return null;
+
+    let head = "";
+    let start = this.position;
+
+    while (
+      start > 0 &&
+      "\x00\r\n\x85\u2028\u2029".indexOf(this.buffer.charAt(start - 1)) === -1
+    ) {
+      start -= 1;
+      if (this.position - start > maxLength / 2 - 1) {
+        head = " ... ";
+        start += 5;
+        break;
+      }
+    }
+
+    let tail = "";
+    let end = this.position;
+
+    while (
+      end < this.buffer.length &&
+      "\x00\r\n\x85\u2028\u2029".indexOf(this.buffer.charAt(end)) === -1
+    ) {
+      end += 1;
+      if (end - this.position > maxLength / 2 - 1) {
+        tail = " ... ";
+        end -= 5;
+        break;
+      }
+    }
+
+    const snippet = this.buffer.slice(start, end);
+    return `${repeat(" ", indent)}${head}${snippet}${tail}\n${repeat(
+      " ",
+      indent + this.position - start + head.length
+    )}^`;
+  }
+
+  public toString(compact?: boolean): string {
+    let snippet,
+      where = "";
+
+    if (this.name) {
+      where += `in "${this.name}" `;
+    }
+
+    where += `at line ${this.line + 1}, column ${this.column + 1}`;
+
+    if (!compact) {
+      snippet = this.getSnippet();
+
+      if (snippet) {
+        where += `:\n${snippet}`;
+      }
+    }
+
+    return where;
+  }
+}
diff --git a/encoding/yaml/Schema.ts b/encoding/yaml/Schema.ts
new file mode 100644
index 000000000000..f43e5997fb02
--- /dev/null
+++ b/encoding/yaml/Schema.ts
@@ -0,0 +1,101 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { YAMLError } from "./error.ts";
+import { KindType, Type } from "./type.ts";
+import { ArrayObject, Any } from "./utils.ts";
+
+function compileList(
+  schema: Schema,
+  name: "implicit" | "explicit",
+  result: Type[]
+): Type[] {
+  const exclude: number[] = [];
+
+  for (const includedSchema of schema.include) {
+    result = compileList(includedSchema, name, result);
+  }
+
+  for (const currentType of schema[name]) {
+    for (
+      let previousIndex = 0;
+      previousIndex < result.length;
+      previousIndex++
+    ) {
+      const previousType = result[previousIndex];
+      if (
+        previousType.tag === currentType.tag &&
+        previousType.kind === currentType.kind
+      ) {
+        exclude.push(previousIndex);
+      }
+    }
+
+    result.push(currentType);
+  }
+
+  return result.filter((type, index): unknown => !exclude.includes(index));
+}
+
+export type TypeMap = { [k in KindType | "fallback"]: ArrayObject<Type> };
+function compileMap(...typesList: Type[][]): TypeMap {
+  const result: TypeMap = {
+    fallback: {},
+    mapping: {},
+    scalar: {},
+    sequence: {}
+  };
+
+  for (const types of typesList) {
+    for (const type of types) {
+      if (type.kind !== null) {
+        result[type.kind][type.tag] = result["fallback"][type.tag] = type;
+      }
+    }
+  }
+  return result;
+}
+
+export class Schema implements SchemaDefinition {
+  public static SCHEMA_DEFAULT?: Schema;
+
+  public implicit: Type[];
+  public explicit: Type[];
+  public include: Schema[];
+
+  public compiledImplicit: Type[];
+  public compiledExplicit: Type[];
+  public compiledTypeMap: TypeMap;
+
+  constructor(definition: SchemaDefinition) {
+    this.explicit = definition.explicit || [];
+    this.implicit = definition.implicit || [];
+    this.include = definition.include || [];
+
+    for (const type of this.implicit) {
+      if (type.loadKind && type.loadKind !== "scalar") {
+        throw new YAMLError(
+          // eslint-disable-next-line max-len
+          "There is a non-scalar type in the implicit list of a schema. Implicit resolving of such types is not supported."
+        );
+      }
+    }
+
+    this.compiledImplicit = compileList(this, "implicit", []);
+    this.compiledExplicit = compileList(this, "explicit", []);
+    this.compiledTypeMap = compileMap(
+      this.compiledImplicit,
+      this.compiledExplicit
+    );
+  }
+
+  public static create(): void {}
+}
+
+export interface SchemaDefinition {
+  implicit?: Any[];
+  explicit?: Type[];
+  include?: Schema[];
+}
diff --git a/encoding/yaml/State.ts b/encoding/yaml/State.ts
new file mode 100644
index 000000000000..3e20e5428b30
--- /dev/null
+++ b/encoding/yaml/State.ts
@@ -0,0 +1,11 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { SchemaDefinition } from "./schema.ts";
+import { DEFAULT_SCHEMA } from "./schema/mod.ts";
+
+export abstract class State {
+  constructor(public schema: SchemaDefinition = DEFAULT_SCHEMA) {}
+}
diff --git a/encoding/yaml/Type.ts b/encoding/yaml/Type.ts
new file mode 100644
index 000000000000..59030616eaf4
--- /dev/null
+++ b/encoding/yaml/Type.ts
@@ -0,0 +1,55 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { ArrayObject, Any } from "./utils.ts";
+
+export type KindType = "sequence" | "scalar" | "mapping";
+export type StyleVariant = "lowercase" | "uppercase" | "camelcase" | "decimal";
+export type RepresentFn = (data: Any, style?: StyleVariant) => Any;
+
+const DEFAULT_RESOLVE = (): boolean => true;
+const DEFAULT_CONSTRUCT = (data: Any): Any => data;
+
+interface TypeOptions {
+  kind: KindType;
+  resolve?: (data: Any) => boolean;
+  construct?: (data: string) => Any;
+  instanceOf?: Any;
+  predicate?: (data: object) => boolean;
+  represent?: RepresentFn | ArrayObject<RepresentFn>;
+  defaultStyle?: StyleVariant;
+  styleAliases?: ArrayObject;
+}
+
+function checkTagFormat(tag: string): string {
+  return tag;
+}
+
+export class Type {
+  public tag: string;
+  public kind: KindType | null = null;
+  public instanceOf: Any;
+  public predicate?: (data: object) => boolean;
+  public represent?: RepresentFn | ArrayObject<RepresentFn>;
+  public defaultStyle?: StyleVariant;
+  public styleAliases?: ArrayObject;
+  public loadKind?: KindType;
+
+  constructor(tag: string, options?: TypeOptions) {
+    this.tag = checkTagFormat(tag);
+    if (options) {
+      this.kind = options.kind;
+      this.resolve = options.resolve || DEFAULT_RESOLVE;
+      this.construct = options.construct || DEFAULT_CONSTRUCT;
+      this.instanceOf = options.instanceOf;
+      this.predicate = options.predicate;
+      this.represent = options.represent;
+      this.defaultStyle = options.defaultStyle;
+      this.styleAliases = options.styleAliases;
+    }
+  }
+  public resolve: (data?: Any) => boolean = (): boolean => true;
+  public construct: (data?: Any) => Any = (data): Any => data;
+}
diff --git a/encoding/yaml/__test__/00-units.js b/encoding/yaml/__test__/00-units.js
new file mode 100644
index 000000000000..fe8cfe1a3554
--- /dev/null
+++ b/encoding/yaml/__test__/00-units.js
@@ -0,0 +1,17 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var path = require('path');
+var fs   = require('fs');
+
+
+suite('Units', function () {
+  var directory = path.resolve(__dirname, 'units');
+
+  fs.readdirSync(directory).forEach(function (file) {
+    if (path.extname(file) === '.js') {
+      require(path.resolve(directory, file));
+    }
+  });
+});
diff --git a/encoding/yaml/__test__/10-loader.js b/encoding/yaml/__test__/10-loader.js
new file mode 100644
index 000000000000..a3088b052baf
--- /dev/null
+++ b/encoding/yaml/__test__/10-loader.js
@@ -0,0 +1,39 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var path   = require('path');
+var fs     = require('fs');
+var yaml   = require('../');
+
+var TEST_SCHEMA = require('./support/schema').TEST_SCHEMA;
+
+
+suite('Loader', function () {
+  var samplesDir = path.resolve(__dirname, 'samples-common');
+
+  fs.readdirSync(samplesDir).forEach(function (jsFile) {
+    if (path.extname(jsFile) !== '.js') return; // continue
+
+    var yamlFile = path.resolve(samplesDir, path.basename(jsFile, '.js') + '.yml');
+
+    test(path.basename(jsFile, '.js'), function () {
+      var expected = require(path.resolve(samplesDir, jsFile));
+      var actual   = [];
+
+      yaml.loadAll(fs.readFileSync(yamlFile, { encoding: 'utf8' }), function (doc) { actual.push(doc); }, {
+        filename: yamlFile,
+        schema: TEST_SCHEMA
+      });
+
+      if (actual.length === 1) actual = actual[0];
+
+      if (typeof expected === 'function') {
+        expected.call(this, actual);
+      } else {
+        assert.deepEqual(actual, expected);
+      }
+    });
+  });
+});
diff --git a/encoding/yaml/__test__/11-load-errors.js b/encoding/yaml/__test__/11-load-errors.js
new file mode 100644
index 000000000000..01f12494b4a1
--- /dev/null
+++ b/encoding/yaml/__test__/11-load-errors.js
@@ -0,0 +1,35 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var path   = require('path');
+var fs     = require('fs');
+var yaml   = require('../');
+
+var TEST_SCHEMA = require('./support/schema').TEST_SCHEMA;
+
+
+suite('Load errors', function () {
+  var samplesDir = path.resolve(__dirname, 'samples-load-errors');
+
+  fs.readdirSync(samplesDir).forEach(function (sampleName) {
+    var yamlFile = path.resolve(samplesDir, sampleName);
+
+    test(path.basename(sampleName, '.yml'), function () {
+      var yamlSource = fs.readFileSync(yamlFile, { encoding: 'utf8' });
+
+      assert.throws(function () {
+        yaml.loadAll(
+          yamlSource,
+          function () {},
+          {
+            filename: yamlFile,
+            schema: TEST_SCHEMA,
+            onWarning: function (e) { throw e; }
+          }
+        );
+      }, yaml.YAMLException, yamlFile);
+    });
+  });
+});
diff --git a/encoding/yaml/__test__/20-dumper.js b/encoding/yaml/__test__/20-dumper.js
new file mode 100644
index 000000000000..714dd232bdc9
--- /dev/null
+++ b/encoding/yaml/__test__/20-dumper.js
@@ -0,0 +1,32 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var path   = require('path');
+var fs     = require('fs');
+var yaml   = require('../');
+
+var TEST_SCHEMA = require('./support/schema').TEST_SCHEMA;
+
+
+suite('Dumper', function () {
+  var samplesDir = path.resolve(__dirname, 'samples-common');
+
+  fs.readdirSync(samplesDir).forEach(function (jsFile) {
+    if (path.extname(jsFile) !== '.js') return; // continue
+
+    test(path.basename(jsFile, '.js'), function () {
+      var sample       = require(path.resolve(samplesDir, jsFile));
+      var data         = typeof sample === 'function' ? sample.expected : sample,
+          serialized   = yaml.dump(data,       { schema: TEST_SCHEMA }),
+          deserialized = yaml.load(serialized, { schema: TEST_SCHEMA });
+
+      if (typeof sample === 'function') {
+        sample.call(this, deserialized);
+      } else {
+        assert.deepEqual(deserialized, sample);
+      }
+    });
+  });
+});
diff --git a/encoding/yaml/__test__/25-dumper-fuzzy.js b/encoding/yaml/__test__/25-dumper-fuzzy.js
new file mode 100644
index 000000000000..2f7adbc8649e
--- /dev/null
+++ b/encoding/yaml/__test__/25-dumper-fuzzy.js
@@ -0,0 +1,49 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var fc     = require('fast-check');
+var yaml   = require('../');
+
+// Generate valid YAML instances for yaml.safeDump
+var key = fc.string16bits();
+var values = [
+  key, fc.boolean(), fc.integer(), fc.double(),
+  fc.constantFrom(null, Number.NEGATIVE_INFINITY, Number.POSITIVE_INFINITY)
+];
+var yamlArbitrary = fc.object({ key: key, values: values });
+
+// Generate valid options for yaml.safeDump configuration
+var dumpOptionsArbitrary = fc.record({
+  skipInvalid: fc.boolean(),
+  sortKeys: fc.boolean(),
+  noRefs: fc.boolean(),
+  noCompatMode: fc.boolean(),
+  condenseFlow: fc.boolean(),
+  indent: fc.integer(1, 80),
+  flowLevel: fc.integer(-1, 10),
+  styles: fc.record({
+    '!!null': fc.constantFrom('lowercase', 'canonical', 'uppercase', 'camelcase'),
+    '!!int': fc.constantFrom('decimal', 'binary', 'octal', 'hexadecimal'),
+    '!!bool': fc.constantFrom('lowercase', 'uppercase', 'camelcase'),
+    '!!float': fc.constantFrom('lowercase', 'uppercase', 'camelcase')
+  }, { with_deleted_keys: true })
+}, { with_deleted_keys: true })
+  .map(function (instance) {
+    if (instance.condenseFlow === true && instance.flowLevel !== undefined) { instance.flowLevel = -1; }
+    return instance;
+  });
+
+suite('Properties', function () {
+  test('Load from dumped should be the original object', function () {
+    fc.assert(fc.property(
+      yamlArbitrary,
+      dumpOptionsArbitrary,
+      function (obj, dumpOptions) {
+        var yamlContent = yaml.safeDump(obj, dumpOptions);
+        assert.ok(typeof yamlContent === 'string');
+        assert.deepStrictEqual(yaml.safeLoad(yamlContent), obj);
+      }));
+  });
+});
diff --git a/encoding/yaml/__test__/30-issues.js b/encoding/yaml/__test__/30-issues.js
new file mode 100644
index 000000000000..a409cd43f47d
--- /dev/null
+++ b/encoding/yaml/__test__/30-issues.js
@@ -0,0 +1,17 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var path = require('path');
+var fs   = require('fs');
+
+
+suite('Issues', function () {
+  var issues = path.resolve(__dirname, 'issues');
+
+  fs.readdirSync(issues).forEach(function (file) {
+    if (path.extname(file) === '.js') {
+      require(path.resolve(issues, file));
+    }
+  });
+});
diff --git a/encoding/yaml/__test__/issues/0008.js b/encoding/yaml/__test__/issues/0008.js
new file mode 100644
index 000000000000..6c6b1effd8ec
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0008.js
@@ -0,0 +1,14 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Parse failed when no document start present', function () {
+  assert.doesNotThrow(function () {
+    yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0008.yml'), 'utf8'));
+  }, TypeError);
+});
diff --git a/encoding/yaml/__test__/issues/0008.yml b/encoding/yaml/__test__/issues/0008.yml
new file mode 100644
index 000000000000..ac9920457b18
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0008.yml
@@ -0,0 +1 @@
+foo: !!str bar
diff --git a/encoding/yaml/__test__/issues/0017.js b/encoding/yaml/__test__/issues/0017.js
new file mode 100644
index 000000000000..92b3c88ebe8e
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0017.js
@@ -0,0 +1,14 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Non-specific "!" tags should resolve to !!str', function () {
+  var data = yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0017.yml'), 'utf8'));
+
+  assert.strictEqual(typeof data, 'string');
+});
diff --git a/encoding/yaml/__test__/issues/0017.yml b/encoding/yaml/__test__/issues/0017.yml
new file mode 100644
index 000000000000..27ca721018fa
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0017.yml
@@ -0,0 +1 @@
+! 12
diff --git a/encoding/yaml/__test__/issues/0019.js b/encoding/yaml/__test__/issues/0019.js
new file mode 100644
index 000000000000..90e7f816f140
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0019.js
@@ -0,0 +1,15 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Timestamp parsing is one month off', function () {
+  var data = yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0019.yml'), 'utf8'));
+
+  // JS month starts with 0 (0 => Jan, 1 => Feb, ...)
+  assert.strictEqual(data.xmas.getTime(), Date.UTC(2011, 11, 24));
+});
diff --git a/encoding/yaml/__test__/issues/0019.yml b/encoding/yaml/__test__/issues/0019.yml
new file mode 100644
index 000000000000..79799fe98ccc
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0019.yml
@@ -0,0 +1,3 @@
+---
+xmas: 2011-12-24
+...
diff --git a/encoding/yaml/__test__/issues/0026.js b/encoding/yaml/__test__/issues/0026.js
new file mode 100644
index 000000000000..3172ec2182a5
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0026.js
@@ -0,0 +1,14 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('should convert new line into white space', function () {
+  var data = yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0026.yml'), 'utf8'));
+
+  assert.strictEqual(data.test, 'a b c\n');
+});
diff --git a/encoding/yaml/__test__/issues/0026.yml b/encoding/yaml/__test__/issues/0026.yml
new file mode 100644
index 000000000000..65d777e8ffcf
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0026.yml
@@ -0,0 +1,4 @@
+test: >
+  a
+  b
+  c
diff --git a/encoding/yaml/__test__/issues/0033.js b/encoding/yaml/__test__/issues/0033.js
new file mode 100644
index 000000000000..d3bd6768892e
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0033.js
@@ -0,0 +1,16 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('refactor compact variant of MarkedYAMLError.toString', function () {
+  var source = readFileSync(require('path').join(__dirname, '/0033.yml'), 'utf8');
+
+  assert.throws(function () {
+    yaml.safeLoad(source);
+  }, "require('issue-33.yml') should throw, but it does not");
+});
diff --git a/encoding/yaml/__test__/issues/0033.yml b/encoding/yaml/__test__/issues/0033.yml
new file mode 100644
index 000000000000..3eca41c9f1a8
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0033.yml
@@ -0,0 +1 @@
+foo: {bar} baz
diff --git a/encoding/yaml/__test__/issues/0046.js b/encoding/yaml/__test__/issues/0046.js
new file mode 100644
index 000000000000..f1e17365e58a
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0046.js
@@ -0,0 +1,29 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Timestamps are incorrectly parsed in local time', function () {
+  var data = yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0046.yml'), 'utf8')),
+      date1, date2;
+
+  date1 = data.date1; // date1: 2010-10-20T20:45:00Z
+  assert.strictEqual(date1.getUTCFullYear(), 2010, 'year');
+  assert.strictEqual(date1.getUTCMonth(), 9, 'month');
+  assert.strictEqual(date1.getUTCDate(), 20, 'date');
+  assert.strictEqual(date1.getUTCHours(), 20);
+  assert.strictEqual(date1.getUTCMinutes(), 45);
+  assert.strictEqual(date1.getUTCSeconds(), 0);
+
+  date2 = data.date2; // date2: 2010-10-20T20:45:00+0100
+  assert.strictEqual(date2.getUTCFullYear(), 2010, 'year');
+  assert.strictEqual(date2.getUTCMonth(), 9, 'month');
+  assert.strictEqual(date2.getUTCDate(), 20, 'date');
+  assert.strictEqual(date2.getUTCHours(), 19);
+  assert.strictEqual(date2.getUTCMinutes(), 45);
+  assert.strictEqual(date2.getUTCSeconds(), 0);
+});
diff --git a/encoding/yaml/__test__/issues/0046.yml b/encoding/yaml/__test__/issues/0046.yml
new file mode 100644
index 000000000000..fbe36bbee124
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0046.yml
@@ -0,0 +1,2 @@
+date1: 2010-10-20T20:45:00Z
+date2: 2010-10-20T20:45:00+01:00
diff --git a/encoding/yaml/__test__/issues/0054.js b/encoding/yaml/__test__/issues/0054.js
new file mode 100644
index 000000000000..46d000d32086
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0054.js
@@ -0,0 +1,29 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test("Incorrect utf-8 handling on require('file.yaml')", function () {
+  var data = yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0054.yml'), 'utf8')),
+      expected = '',
+      index;
+
+  //
+  // document is an array of 40 elements
+  // each element is a string of 100 `у` (Russian letter) chars
+  //
+  for (index = 0; index <= 100; index += 1) {
+    expected += 'у';
+  }
+
+  //
+  // make sure none of the strings were corrupted.
+  //
+  for (index = 0; index < 40; index += 1) {
+    assert.strictEqual(data[index], expected, ('Line ' + index + ' is corrupted'));
+  }
+});
diff --git a/encoding/yaml/__test__/issues/0054.yml b/encoding/yaml/__test__/issues/0054.yml
new file mode 100644
index 000000000000..a0c7a021bf86
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0054.yml
@@ -0,0 +1,41 @@
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
+- ууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууууу
diff --git a/encoding/yaml/__test__/issues/0063.js b/encoding/yaml/__test__/issues/0063.js
new file mode 100644
index 000000000000..6eb4e641ea9f
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0063.js
@@ -0,0 +1,24 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Invalid errors/warnings of invalid indentation on flow scalars', function () {
+  var sources = [
+    'text:\n    hello\n  world',   // plain style
+    "text:\n    'hello\n  world'", // single-quoted style
+    'text:\n    "hello\n  world"'  // double-quoted style
+  ];
+  var expected = { text: 'hello world' };
+
+  assert.doesNotThrow(function () { yaml.load(sources[0]); }, 'Throws on plain style');
+  assert.doesNotThrow(function () { yaml.load(sources[1]); }, 'Throws on single-quoted style');
+  assert.doesNotThrow(function () { yaml.load(sources[2]); }, 'Throws on double-quoted style');
+
+  assert.deepEqual(yaml.load(sources[0]), expected);
+  assert.deepEqual(yaml.load(sources[1]), expected);
+  assert.deepEqual(yaml.load(sources[2]), expected);
+});
diff --git a/encoding/yaml/__test__/issues/0064.js b/encoding/yaml/__test__/issues/0064.js
new file mode 100644
index 000000000000..f7b8590739bb
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0064.js
@@ -0,0 +1,14 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Wrong error message when yaml file contains tabs', function () {
+  assert.doesNotThrow(
+    function () { yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0064.yml'), 'utf8')); },
+    yaml.YAMLException);
+});
diff --git a/encoding/yaml/__test__/issues/0064.yml b/encoding/yaml/__test__/issues/0064.yml
new file mode 100644
index 000000000000..314140014f21
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0064.yml
@@ -0,0 +1 @@
+mapping: contains	tab
diff --git a/encoding/yaml/__test__/issues/0068.js b/encoding/yaml/__test__/issues/0068.js
new file mode 100644
index 000000000000..2e45c7d9aa17
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0068.js
@@ -0,0 +1,12 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Prevent adding unnecessary space character to end of a line within block collections', function () {
+  assert.strictEqual(yaml.dump({ data: [ 'foo', 'bar', 'baz' ] }), 'data:\n  - foo\n  - bar\n  - baz\n');
+  assert.strictEqual(yaml.dump({ foo: { bar: [ 'baz' ] } }),       'foo:\n  bar:\n    - baz\n');
+});
diff --git a/encoding/yaml/__test__/issues/0085.js b/encoding/yaml/__test__/issues/0085.js
new file mode 100644
index 000000000000..e9635e665215
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0085.js
@@ -0,0 +1,25 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+var DEPRECATED_BOOLEANS_SYNTAX = [
+  'y', 'Y', 'yes', 'Yes', 'YES', 'on', 'On', 'ON',
+  'n', 'N', 'no', 'No', 'NO', 'off', 'Off', 'OFF'
+];
+
+
+test('Dumper should take into account booleans syntax from YAML 1.0/1.1', function () {
+  DEPRECATED_BOOLEANS_SYNTAX.forEach(function (string) {
+    var dump = yaml.dump(string).trim();
+
+    assert(
+      ((dump === "'" + string + "'") || (dump === '"' + string + '"')),
+      ('"' + string + '" string is dumped without quoting; actual dump: ' + dump)
+    );
+  });
+});
+
diff --git a/encoding/yaml/__test__/issues/0092.js b/encoding/yaml/__test__/issues/0092.js
new file mode 100644
index 000000000000..cecfabddedc5
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0092.js
@@ -0,0 +1,13 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Invalid parse error on whitespace between quoted scalar keys and ":" symbol in mappings', function () {
+  assert.doesNotThrow(function () {
+    yaml.load('{ "field1" : "v1", "field2": "v2" }');
+  });
+});
diff --git a/encoding/yaml/__test__/issues/0093.js b/encoding/yaml/__test__/issues/0093.js
new file mode 100644
index 000000000000..71b321caad06
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0093.js
@@ -0,0 +1,16 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Unwanted line breaks in folded scalars', function () {
+  var data = yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0093.yml'), 'utf8'));
+
+  assert.strictEqual(data.first,  'a b\n  c\n  d\ne f\n');
+  assert.strictEqual(data.second, 'a b\n  c\n\n  d\ne f\n');
+  assert.strictEqual(data.third,  'a b\n\n  c\n  d\ne f\n');
+});
diff --git a/encoding/yaml/__test__/issues/0093.yml b/encoding/yaml/__test__/issues/0093.yml
new file mode 100644
index 000000000000..fc99568d6350
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0093.yml
@@ -0,0 +1,25 @@
+first: >
+  a
+  b
+    c
+    d
+  e
+  f
+
+second: >
+  a
+  b
+    c
+
+    d
+  e
+  f
+
+third: >
+  a
+  b
+
+    c
+    d
+  e
+  f
diff --git a/encoding/yaml/__test__/issues/0095.js b/encoding/yaml/__test__/issues/0095.js
new file mode 100644
index 000000000000..c75dc1047e24
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0095.js
@@ -0,0 +1,25 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Empty block scalars loaded wrong', function () {
+  assert.deepEqual(yaml.load('a: |\nb: .'),  { a: '', b: '.' });
+  assert.deepEqual(yaml.load('a: |+\nb: .'), { a: '', b: '.' });
+  assert.deepEqual(yaml.load('a: |-\nb: .'), { a: '', b: '.' });
+
+  assert.deepEqual(yaml.load('a: >\nb: .'),  { a: '', b: '.' });
+  assert.deepEqual(yaml.load('a: >+\nb: .'), { a: '', b: '.' });
+  assert.deepEqual(yaml.load('a: >-\nb: .'), { a: '', b: '.' });
+
+  assert.deepEqual(yaml.load('a: |\n\nb: .'),  { a: '',   b: '.' });
+  assert.deepEqual(yaml.load('a: |+\n\nb: .'), { a: '\n', b: '.' });
+  assert.deepEqual(yaml.load('a: |-\n\nb: .'), { a: '',   b: '.' });
+
+  assert.deepEqual(yaml.load('a: >\n\nb: .'),  { a: '',   b: '.' });
+  assert.deepEqual(yaml.load('a: >+\n\nb: .'), { a: '\n', b: '.' });
+  assert.deepEqual(yaml.load('a: >-\n\nb: .'), { a: '',   b: '.' });
+});
diff --git a/encoding/yaml/__test__/issues/0108.js b/encoding/yaml/__test__/issues/0108.js
new file mode 100644
index 000000000000..6de42035fa02
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0108.js
@@ -0,0 +1,13 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Literal scalars have an unwanted leading line break', function () {
+  assert.strictEqual(yaml.load('|\n  foobar\n'),            'foobar\n');
+  assert.strictEqual(yaml.load('|\n  hello\n  world\n'),      'hello\nworld\n');
+  assert.strictEqual(yaml.load('|\n  war never changes\n'), 'war never changes\n');
+});
diff --git a/encoding/yaml/__test__/issues/0110.js b/encoding/yaml/__test__/issues/0110.js
new file mode 100644
index 000000000000..a997450d1e2a
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0110.js
@@ -0,0 +1,29 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Circular and cross references', function () {
+  var source = {
+    a: { a: 1 },
+    b: [ 1, 2 ],
+    c: {},
+    d: []
+  };
+  source.crossObject = source.a;
+  source.crossArray = source.b;
+  source.c.circularObject = source;
+  source.d.push(source.d);
+  source.d.push(source);
+
+  var obtained = yaml.load(yaml.dump(source));
+
+  assert.strictEqual(obtained.crossObject, obtained.a);
+  assert.strictEqual(obtained.crossArray, obtained.b);
+  assert.strictEqual(obtained.c.circularObject, obtained);
+  assert.strictEqual(obtained.d[0], obtained.d);
+  assert.strictEqual(obtained.d[1], obtained);
+});
diff --git a/encoding/yaml/__test__/issues/0112.js b/encoding/yaml/__test__/issues/0112.js
new file mode 100644
index 000000000000..e2a83fa58370
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0112.js
@@ -0,0 +1,15 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Plain scalar "constructor" parsed as `null`', function () {
+  assert.strictEqual(yaml.load('constructor'),          'constructor');
+  assert.deepEqual(yaml.load('constructor: value'),     { constructor: 'value' });
+  assert.deepEqual(yaml.load('key: constructor'),       { key: 'constructor' });
+  assert.deepEqual(yaml.load('{ constructor: value }'), { constructor: 'value' });
+  assert.deepEqual(yaml.load('{ key: constructor }'),   { key: 'constructor' });
+});
diff --git a/encoding/yaml/__test__/issues/0117.js b/encoding/yaml/__test__/issues/0117.js
new file mode 100644
index 000000000000..3051ffcb0f2e
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0117.js
@@ -0,0 +1,11 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Negative zero loses the sign after dump', function () {
+  assert.strictEqual(yaml.dump(-0), '-0.0\n');
+});
diff --git a/encoding/yaml/__test__/issues/0123.js b/encoding/yaml/__test__/issues/0123.js
new file mode 100644
index 000000000000..c42825fb5188
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0123.js
@@ -0,0 +1,25 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('RegExps should be properly closed', function () {
+  assert.throws(function () { yaml.load('!!js/regexp /fo'); });
+  assert.throws(function () { yaml.load('!!js/regexp /fo/q'); });
+  assert.throws(function () { yaml.load('!!js/regexp /fo/giii'); });
+
+  // https://github.com/nodeca/js-yaml/issues/172
+  var regexp = yaml.load('!!js/regexp /fo/g/g');
+  assert.ok(regexp instanceof RegExp);
+  var regexpStr = regexp.toString();
+  // Accept the old (slightly incorrect) V8, as well as the new V8 result
+  // TODO: Remove when/if Node 0.12 and below is no longer supported.
+  if (regexpStr === '/fo/g/g') {
+    assert.strictEqual(regexpStr, '/fo/g/g');
+  } else {
+    assert.strictEqual(regexpStr, '/fo\\/g/g');
+  }
+});
diff --git a/encoding/yaml/__test__/issues/0144.js b/encoding/yaml/__test__/issues/0144.js
new file mode 100644
index 000000000000..85b5c4fb0d73
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0144.js
@@ -0,0 +1,11 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Infinite loop when attempting to parse multi-line scalar document that is not indented', function () {
+  assert.strictEqual(yaml.load('--- |\nfoo\n'), 'foo\n');
+});
diff --git a/encoding/yaml/__test__/issues/0154.js b/encoding/yaml/__test__/issues/0154.js
new file mode 100644
index 000000000000..9c941d7e868c
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0154.js
@@ -0,0 +1,14 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Indentation warning on empty lines within quoted scalars and flow collections', function () {
+  assert.doesNotThrow(function () { yaml.load("- 'hello\n\n  world'"); });
+  assert.doesNotThrow(function () { yaml.load('- "hello\n\n  world"'); });
+  assert.doesNotThrow(function () { yaml.load('- [hello,\n\n  world]'); });
+  assert.doesNotThrow(function () { yaml.load('- {hello: world,\n\n  foo: bar}'); });
+});
diff --git a/encoding/yaml/__test__/issues/0155.js b/encoding/yaml/__test__/issues/0155.js
new file mode 100644
index 000000000000..4df52ba0a80f
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0155.js
@@ -0,0 +1,11 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Named null', function () {
+  assert.deepEqual(yaml.load('---\ntest: !!null \nfoo: bar'), { test: null, foo: 'bar' });
+});
diff --git a/encoding/yaml/__test__/issues/0156.js b/encoding/yaml/__test__/issues/0156.js
new file mode 100644
index 000000000000..6b44ea7a6b3a
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0156.js
@@ -0,0 +1,21 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../lib/js-yaml');
+
+
+function SuccessSignal() {}
+
+var TestClassYaml = new yaml.Type('!test', {
+  kind: 'scalar',
+  resolve: function () { throw new SuccessSignal(); }
+});
+
+var TEST_SCHEMA = yaml.Schema.create([ TestClassYaml ]);
+
+
+test('Resolving of empty nodes are skipped in some cases', function () {
+  assert.throws(function () { yaml.load('- foo: !test\n- bar: baz', { schema: TEST_SCHEMA }); }, SuccessSignal);
+});
diff --git a/encoding/yaml/__test__/issues/0160.js b/encoding/yaml/__test__/issues/0160.js
new file mode 100644
index 000000000000..8511c79d7d62
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0160.js
@@ -0,0 +1,11 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+
+test('Correct encoding of UTF-16 surrogate pairs', function () {
+  assert.strictEqual(yaml.load('"\\U0001F431"'), '🐱');
+});
diff --git a/encoding/yaml/__test__/issues/0194.js b/encoding/yaml/__test__/issues/0194.js
new file mode 100644
index 000000000000..7a2c998fcd2b
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0194.js
@@ -0,0 +1,22 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Don\'t throw on warning', function () {
+  var src = readFileSync(require('path').join(__dirname, '/0194.yml'), 'utf8'),
+      warnings = [],
+      data;
+
+  data = yaml.safeLoad(src);
+
+  assert.deepEqual(data, { foo: { bar: true } });
+
+  yaml.safeLoad(src, { onWarning: function (e) { warnings.push(e); } });
+
+  assert.strictEqual(warnings.length, 1);
+});
diff --git a/encoding/yaml/__test__/issues/0194.yml b/encoding/yaml/__test__/issues/0194.yml
new file mode 100644
index 000000000000..6115793ab6d6
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0194.yml
@@ -0,0 +1,3 @@
+foo: {
+    bar: true
+}
diff --git a/encoding/yaml/__test__/issues/0203.js b/encoding/yaml/__test__/issues/0203.js
new file mode 100644
index 000000000000..868fa9d7396c
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0203.js
@@ -0,0 +1,14 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Don\'t throw on warning', function () {
+  var src = readFileSync(require('path').join(__dirname, '/0203.yml'), 'utf8');
+
+  assert.deepEqual(yaml.safeLoad(src), { test: '\n\nHello\nworld' });
+});
diff --git a/encoding/yaml/__test__/issues/0203.yml b/encoding/yaml/__test__/issues/0203.yml
new file mode 100644
index 000000000000..742d60824f92
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0203.yml
@@ -0,0 +1,5 @@
+test: |-
+
+
+  Hello
+  world
\ No newline at end of file
diff --git a/encoding/yaml/__test__/issues/0205.js b/encoding/yaml/__test__/issues/0205.js
new file mode 100644
index 000000000000..4bd5b3e40bff
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0205.js
@@ -0,0 +1,28 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Duplicated objects within array', function () {
+  var obj = { test: 'canary' };
+  var arrayWithRefs = [ obj, obj ];
+
+  var obtained = yaml.load(yaml.dump(arrayWithRefs));
+
+  assert.strictEqual(obtained[0].test, 'canary');
+  assert.strictEqual(obtained[0], obtained[1]);
+});
+
+test('Duplicated arrays within array', function () {
+  var array = [ 0, 1 ];
+  var arrayWithRefs = [ array, array ];
+
+  var obtained = yaml.load(yaml.dump(arrayWithRefs));
+
+  assert.strictEqual(obtained[0][0], 0);
+  assert.strictEqual(obtained[0][1], 1);
+  assert.strictEqual(obtained[0], obtained[1]);
+});
diff --git a/encoding/yaml/__test__/issues/0217.js b/encoding/yaml/__test__/issues/0217.js
new file mode 100644
index 000000000000..bdca3551be13
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0217.js
@@ -0,0 +1,117 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+// Simplistic check for folded style header at the end of the first line.
+function isFolded(s) {
+  return s.search(/^[^\n]*>[\-+]?\n/) !== -1;
+}
+
+// Runs one cycle of dump then load. Also checks that dumped result is folded.
+function loadAfterDump(input) {
+  var output = yaml.dump(input);
+  if (!isFolded(output)) {
+    assert.fail(output, '(first line should end with >-, >, or >+)',
+      'Test cannot continue: folded style was expected');
+  }
+  return yaml.load(output);
+}
+
+
+test('Folding Javascript functions preserves content', function () {
+  // Tests loading a function, then tests dumping and loading.
+  function assertFunctionPreserved(functionString, inputs, expectedOutputs, name) {
+    var f = yaml.load('!<tag:yaml.org,2002:js/function> "' + functionString + '"');
+    assert.strictEqual(typeof f, 'function', name + ' should be loaded as a function');
+
+    assert.deepEqual(inputs.map(f), expectedOutputs,
+      name + ' should be loaded correctly');
+
+    assert.deepEqual(inputs.map(loadAfterDump(f)), expectedOutputs,
+      name + ' should be dumped then loaded correctly');
+  }
+
+  // Backslash-escapes double quotes and newlines.
+  function escapeFnString(s) {
+    return s.replace(/"/g, '\\"').replace(/\n/g, '\\n');
+  }
+
+  var fnFactorial = escapeFnString(
+    'function factorial(start) {\n' +
+    '// Non-indented long line to trigger folding: throw new Error("bad fold"); throw new Error("bad fold");\n' +
+    '  var extra_long_string = "try to trick the dumper into creating a syntax error by folding this string";\n' +
+    '  var extra_long_string1 = "try to trick the dumper into creating a syntax error by folding this string";\n' +
+    'var extra_long_string2 = "this long string is fine to fold because it is not more-indented";\n' +
+    'function fac (n) {\n' +
+      'if (n <= 0) return 1; return n * fac(n-1); // here is a long line that can be safely folded\n' +
+    '}\n' +
+    'return fac(start);\n' +
+    '}\n');
+
+  var fnCollatz = escapeFnString(
+    'function collatz(start) {\n' +
+    '  var longString = "another long more-indented string that will cause a syntax error if folded";\n' +
+    'var result = [];\n' +
+    'function go(n) { result.push(n); return (n === 1) ? result : go(n % 2 === 0  ?  n / 2  :  3 * n + 1); }\n' +
+    'return go(start >= 1 ? Math.floor(start) : 1);\n' +
+    '}');
+
+  var fnRot13 = escapeFnString(
+    // single-line function.
+    // note the "{return" is so the line doesn't start with a space.
+    'function rot13(s) {return String.fromCharCode.apply(null, s.split("")' +
+    '.map(function (c) { return ((c.toLowerCase().charCodeAt(0) - 97) + 13) % 26 + 97; })); }'
+  );
+
+  assertFunctionPreserved(fnFactorial,
+    [ 0, 1, 2, 3,   5,    7,        12 ],
+    [ 1, 1, 2, 6, 120, 5040, 479001600 ],
+    'Factorial function');
+
+  assertFunctionPreserved(fnCollatz,
+    [ 6, 19 ],
+    [ [ 6, 3, 10, 5, 16, 8, 4, 2, 1 ],
+      [ 19, 58, 29, 88, 44, 22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1 ]
+    ], 'Hailstone sequence function');
+
+  assertFunctionPreserved(fnRot13,
+    [ 'nggnpxngqnja', 'orjnergurvqrfbsznepu' ],
+    [ 'attackatdawn', 'bewaretheidesofmarch' ],
+    'ROT13');
+});
+
+test('Folding long regular expressions preserves content', function () {
+  // Tests loading a regex, then tests dumping and loading.
+  function assertRegexPreserved(string, stringPattern) {
+    assert.strictEqual(string.search(stringPattern), 0,
+      'The test itself has errors: regex did not match its string');
+
+    var loadedRe = yaml.load('"key": !<tag:yaml.org,2002:js/regexp> /'
+      + stringPattern + '/').key;
+    assert.strictEqual(loadedRe.exec(string)[0], string,
+      'Loaded regex did not match the original string');
+
+    assert.strictEqual(
+      loadAfterDump({ key: new RegExp(stringPattern) }).key.exec(string)[0],
+      string,
+      'Dumping and loading did not preserve the regex');
+  }
+
+  var s1        =  'This is a very long regular expression. ' +
+    'It\'s so long that it is longer than 80 characters per line.';
+  var s1Pattern = '^This is a very long regular expression\\. ' +
+    'It\'s so long that it is longer than 80 characters per line\\.$';
+
+  assertRegexPreserved(s1, s1Pattern);
+});
+
+test('Strings are folded as usual', function () {
+  var doc = yaml.load('"key": |\n  It is just a very long string. It should be folded because the dumper ' +
+    'fold lines that are exceed limit in 80 characters per line.');
+  var dump = yaml.dump(doc);
+  assert(Math.max.apply(null, dump.split('\n').map(function (str) { return str.length; })) <= 80);
+});
diff --git a/encoding/yaml/__test__/issues/0220.js b/encoding/yaml/__test__/issues/0220.js
new file mode 100644
index 000000000000..9693b6ab4421
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0220.js
@@ -0,0 +1,15 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+
+test('Float type dumper should not miss dot', function () {
+  assert.strictEqual(5e-100.toString(10), '5e-100');
+  assert.strictEqual(0.5e-100.toString(10), '5e-101');
+
+  assert.strictEqual(yaml.dump(0.5e-100), '5.e-101\n');
+  assert.strictEqual(yaml.load(yaml.dump(5e-100)), 5e-100);
+});
diff --git a/encoding/yaml/__test__/issues/0221.js b/encoding/yaml/__test__/issues/0221.js
new file mode 100644
index 000000000000..46d71a1274fd
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0221.js
@@ -0,0 +1,12 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+
+test.skip('Block scalar chomping does not work on zero indent', function () {
+  assert.throws(function () { yaml.load('|-\nfoo\nbar'); }, yaml.YAMLException);
+  assert.deepEqual(yaml.dump('foo\nbar'), '|-\n  foo\nbar');
+});
diff --git a/encoding/yaml/__test__/issues/0235.js b/encoding/yaml/__test__/issues/0235.js
new file mode 100644
index 000000000000..be630872e70f
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0235.js
@@ -0,0 +1,15 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+test('Flow style does not dump with block literals.', function () {
+  assert.strictEqual(yaml.dump({ a: '\n' }, { flowLevel: 0 }), '{a: "\\n"}\n');
+});
+
+test('Ok to dump block-style literals when not yet flowing.', function () {
+  // cf. example 8.6 from the YAML 1.2 spec
+  assert.strictEqual(yaml.dump({ a: '\n' }, { flowLevel: 2 }), 'a: |+\n\n');
+});
diff --git a/encoding/yaml/__test__/issues/0243-basic.yml b/encoding/yaml/__test__/issues/0243-basic.yml
new file mode 100644
index 000000000000..ee98211d11b0
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0243-basic.yml
@@ -0,0 +1,15 @@
+a:
+  b: 1
+  c: 2
+d:
+  e: 3
+  f: 4
+duplicate: # 1
+  id: 1234
+  note: "this is the first one, so it won't raise an error"
+duplicate: # 2
+  id: 5678
+  note: "this is the second one, so it will raise an error, hopefully at the start of the key"
+g:
+  h: 5
+  i: 6
diff --git a/encoding/yaml/__test__/issues/0243-nested.yml b/encoding/yaml/__test__/issues/0243-nested.yml
new file mode 100644
index 000000000000..b24c33b18080
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0243-nested.yml
@@ -0,0 +1,15 @@
+a:
+  b: 1
+  c: 2
+d:
+  e: 3
+  f: 4
+  duplicate: # 1
+    id: 1234
+    note: "this is the first one, so it won't raise an error"
+  duplicate: # 2
+    id: 5678
+    note: "this is the second one, so it will raise an error, hopefully at the start of the key"
+g:
+  h: 5
+  i: 6
diff --git a/encoding/yaml/__test__/issues/0243.js b/encoding/yaml/__test__/issues/0243.js
new file mode 100644
index 000000000000..5d320dd104a2
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0243.js
@@ -0,0 +1,30 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Duplicated mapping key errors on top level throw at beginning of key', function () {
+  var src = readFileSync(require('path').join(__dirname, '/0243-basic.yml'), 'utf8');
+  var lines = src.split('\n');
+
+  try {
+    yaml.safeLoad(src);
+  } catch (e) {
+    assert.equal(lines[e.mark.line], 'duplicate: # 2');
+  }
+});
+
+test('Duplicated mapping key errors inside of mapping values throw at beginning of key', function () {
+  var src = readFileSync(require('path').join(__dirname, '/0243-nested.yml'), 'utf8');
+  var lines = src.split('\n');
+
+  try {
+    yaml.safeLoad(src);
+  } catch (e) {
+    assert.equal(lines[e.mark.line], '  duplicate: # 2');
+  }
+});
diff --git a/encoding/yaml/__test__/issues/0248-listener.js b/encoding/yaml/__test__/issues/0248-listener.js
new file mode 100644
index 000000000000..f8aa101c6d38
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0248-listener.js
@@ -0,0 +1,64 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+test('Listener informed on a very simple scalar.', function () {
+  var history = [];
+  function l(eventType, state) {
+    history.push([ eventType, state.position ]);
+  }
+
+  yaml.load('a_simple_scalar', { listener: l });
+
+  // 2 open events then 2 close events
+  assert.strictEqual(history.length, 4);
+  assert.strictEqual(history[0][0], 'open');
+  assert.strictEqual(history[1][0], 'open');
+  assert.strictEqual(history[2][0], 'close');
+  assert.strictEqual(history[3][0], 'close');
+  assert.strictEqual(history[0][1], 0);
+  assert.strictEqual(history[3][1], 16);
+});
+
+test('Listener informed on a map with a list.', function () {
+  var history = [];
+  function l(eventType, state) {
+    history.push([ eventType, state.position, state.result ]);
+  }
+
+  yaml.load('{ a: 1, b: [ 0, xyz ] }', { listener: l });
+
+  var i = -1;
+  assert.strictEqual(history[++i][0], 'open'); // doc
+  assert.strictEqual(history[++i][0], 'open'); // map
+
+  assert.strictEqual(history[++i][0], 'open'); // key
+  assert.strictEqual(history[++i][0], 'close');
+  assert.strictEqual(history[i][2], 'a');
+
+  assert.strictEqual(history[++i][0], 'open'); // a value
+  assert.strictEqual(history[++i][0], 'close');
+  assert.strictEqual(history[i][2], 1);
+
+  assert.strictEqual(history[++i][0], 'open'); // key
+  assert.strictEqual(history[++i][0], 'close');
+  assert.strictEqual(history[i][2], 'b');
+
+  assert.strictEqual(history[++i][0], 'open'); // b value (list)
+  assert.strictEqual(history[++i][0], 'open'); // item in list
+  assert.strictEqual(history[++i][0], 'close');
+  assert.strictEqual(history[i][2], 0);
+  assert.strictEqual(history[++i][0], 'open'); // item in list
+  assert.strictEqual(history[++i][0], 'close');
+
+  assert.strictEqual(history[++i][0], 'close'); // b value (list) end
+  assert.deepEqual(history[i][2], [ 0, 'xyz' ]);
+
+  assert.strictEqual(history[++i][0], 'close'); // map end
+  assert.strictEqual(history[++i][0], 'close'); // doc end
+
+  assert.strictEqual(history.length, ++i);
+});
diff --git a/encoding/yaml/__test__/issues/0266.js b/encoding/yaml/__test__/issues/0266.js
new file mode 100644
index 000000000000..f6abfedec698
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0266.js
@@ -0,0 +1,24 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+var DEPRECATED_BOOLEANS_SYNTAX = [
+  'y', 'Y', 'yes', 'Yes', 'YES', 'on', 'On', 'ON',
+  'n', 'N', 'no', 'No', 'NO', 'off', 'Off', 'OFF'
+];
+
+
+test('Dumper should not take into account booleans syntax from YAML 1.0/1.1 in noCompatMode', function () {
+  DEPRECATED_BOOLEANS_SYNTAX.forEach(function (string) {
+    var dump = yaml.dump(string, { noCompatMode: true }).trim();
+
+    assert(
+      (dump === string),
+      ('"' + string + '" string is not dumped as-is; actual dump: ' + dump)
+    );
+  });
+});
diff --git a/encoding/yaml/__test__/issues/0303.js b/encoding/yaml/__test__/issues/0303.js
new file mode 100644
index 000000000000..13df7fbe98ff
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0303.js
@@ -0,0 +1,13 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+test('Loader should not strip quotes before newlines', function () {
+  var with_space = yaml.load("'''foo'' '");
+  var with_newline = yaml.load("'''foo''\n'");
+  assert.strictEqual(with_space, "'foo' ");
+  assert.strictEqual(with_newline, "'foo' ");
+});
diff --git a/encoding/yaml/__test__/issues/0333.js b/encoding/yaml/__test__/issues/0333.js
new file mode 100644
index 000000000000..3b4b5bbc4ffd
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0333.js
@@ -0,0 +1,18 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('should allow cast integers as !!float', function () {
+  var data = yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0333.yml'), 'utf8'));
+
+  assert.deepEqual(data, {
+    negative: -1,
+    zero: 0,
+    positive: 23000
+  });
+});
diff --git a/encoding/yaml/__test__/issues/0333.yml b/encoding/yaml/__test__/issues/0333.yml
new file mode 100644
index 000000000000..6ff266236e12
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0333.yml
@@ -0,0 +1,3 @@
+negative: !!float -1
+zero: !!float 0
+positive: !!float 2.3e4
diff --git a/encoding/yaml/__test__/issues/0335.js b/encoding/yaml/__test__/issues/0335.js
new file mode 100644
index 000000000000..4e35b2023a62
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0335.js
@@ -0,0 +1,21 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Don\'t throw on warning', function () {
+  var src = readFileSync(require('path').join(__dirname, '/0335.yml'), 'utf8');
+
+  assert.deepEqual(yaml.safeLoad(src), {
+    not_num_1: '-_123',
+    not_num_2: '_123',
+    not_num_3: '123_',
+    not_num_4: '0b00_',
+    not_num_5: '0x00_',
+    not_num_6: '011_'
+  });
+});
diff --git a/encoding/yaml/__test__/issues/0335.yml b/encoding/yaml/__test__/issues/0335.yml
new file mode 100644
index 000000000000..a4b30b6c3c5e
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0335.yml
@@ -0,0 +1,6 @@
+not_num_1: -_123
+not_num_2: _123
+not_num_3: 123_
+not_num_4: 0b00_
+not_num_5: 0x00_
+not_num_6: 011_
diff --git a/encoding/yaml/__test__/issues/0342.js b/encoding/yaml/__test__/issues/0342.js
new file mode 100644
index 000000000000..651530c75c30
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0342.js
@@ -0,0 +1,62 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var simpleArray = [ 'a', 'b' ];
+var arrayOfSimpleObj = [ { a: 1 }, { b: 2 } ];
+var arrayOfObj = [ { a: 1, b: 'abc' }, { c: 'def', d: 2 } ];
+
+
+test('space should be added for array, regardless of indent', function () {
+  assert.deepEqual(
+    yaml.dump(simpleArray, { indent: 1 }),
+    '- a\n- b\n'
+  );
+  assert.deepEqual(
+    yaml.dump(simpleArray, { indent: 2 }),
+    '- a\n- b\n'
+  );
+  assert.deepEqual(
+    yaml.dump(simpleArray, { indent: 3 }),
+    '- a\n- b\n'
+  );
+  assert.deepEqual(
+    yaml.dump(simpleArray, { indent: 4 }),
+    '- a\n- b\n'
+  );
+});
+
+test('array of objects should not wrap at indentation of 2', function () {
+  assert.deepEqual(
+    yaml.dump(arrayOfSimpleObj, { indent: 2 }),
+    '- a: 1\n- b: 2\n'
+  );
+  assert.deepEqual(
+    yaml.dump(arrayOfObj, { indent: 2 }),
+    '- a: 1\n  b: abc\n- c: def\n  d: 2\n'
+  );
+});
+
+test('EOL space should not be added on array of objects at indentation of 3', function () {
+  assert.deepEqual(
+    yaml.dump(arrayOfSimpleObj, { indent: 3 }),
+    '-\n   a: 1\n-\n   b: 2\n'
+  );
+  assert.deepEqual(
+    yaml.dump(arrayOfObj, { indent: 3 }),
+    '-\n   a: 1\n   b: abc\n-\n   c: def\n   d: 2\n'
+  );
+});
+
+test('EOL space should not be added on array of objects at indentation of 4', function () {
+  assert.deepEqual(
+    yaml.dump(arrayOfSimpleObj, { indent: 4 }),
+    '-\n    a: 1\n-\n    b: 2\n'
+  );
+  assert.deepEqual(
+    yaml.dump(arrayOfObj, { indent: 4 }),
+    '-\n    a: 1\n    b: abc\n-\n    c: def\n    d: 2\n'
+  );
+});
diff --git a/encoding/yaml/__test__/issues/0346.js b/encoding/yaml/__test__/issues/0346.js
new file mode 100644
index 000000000000..e0179ff59a46
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0346.js
@@ -0,0 +1,27 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+
+test('should not emit spaces in arrays in flow mode between entries using condenseFlow: true', function () {
+  var array = [ 'a', 'b' ];
+  var dumpedArray = yaml.dump(array, { flowLevel: 0, indent: 0, condenseFlow: true });
+  assert.equal(
+    dumpedArray,
+    '[a,b]\n'
+  );
+  assert.deepEqual(yaml.load(dumpedArray), array);
+});
+
+test('should not emit spaces between key: value and quote keys using condenseFlow: true', function () {
+  var object = { a: { b: 'c' } };
+  var objectDump = yaml.dump(object, { flowLevel: 0, indent: 0, condenseFlow: true });
+  assert.equal(
+    objectDump,
+    '{"a":{"b":c}}\n'
+  );
+  assert.deepEqual(yaml.load(objectDump), object);
+});
diff --git a/encoding/yaml/__test__/issues/0350.js b/encoding/yaml/__test__/issues/0350.js
new file mode 100644
index 000000000000..7386fbced3a3
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0350.js
@@ -0,0 +1,14 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('should return parse docs from loadAll', function () {
+  var data = yaml.safeLoadAll(readFileSync(require('path').join(__dirname, '/0350.yml'), 'utf8'));
+
+  assert.deepEqual(data, [ { a: 1 }, { b: 2 } ]);
+});
diff --git a/encoding/yaml/__test__/issues/0350.yml b/encoding/yaml/__test__/issues/0350.yml
new file mode 100644
index 000000000000..d3f18ac45ba4
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0350.yml
@@ -0,0 +1,4 @@
+---
+a: 1
+---
+b: 2
diff --git a/encoding/yaml/__test__/issues/0351.js b/encoding/yaml/__test__/issues/0351.js
new file mode 100644
index 000000000000..5e956bdaf232
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0351.js
@@ -0,0 +1,18 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../..');
+var readFileSync = require('fs').readFileSync;
+
+
+test('should include the error message in the error stack', function () {
+  try {
+    yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0351.yml'), 'utf8'));
+  } catch (err) {
+    assert(err.stack.startsWith('YAMLException: end of the stream or a document separator is expected'));
+    return;
+  }
+  assert.fail(null, null, 'Expected an error to be thrown');
+});
diff --git a/encoding/yaml/__test__/issues/0351.yml b/encoding/yaml/__test__/issues/0351.yml
new file mode 100644
index 000000000000..8ab27b9aac66
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0351.yml
@@ -0,0 +1,4 @@
+# intentionally invalid yaml
+
+  foo: bar
+baz: qux
diff --git a/encoding/yaml/__test__/issues/0369.js b/encoding/yaml/__test__/issues/0369.js
new file mode 100644
index 000000000000..7a53003f2adf
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0369.js
@@ -0,0 +1,12 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+
+test('should dump astrals as codepoint', function () {
+  assert.deepEqual(yaml.safeDump('😀'), '"\\U0001F600"\n');
+  assert.deepEqual(yaml.safeLoad('"\\U0001F600"'), '😀');
+});
diff --git a/encoding/yaml/__test__/issues/0399.js b/encoding/yaml/__test__/issues/0399.js
new file mode 100644
index 000000000000..df28ad99d8a1
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0399.js
@@ -0,0 +1,20 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+
+test('should properly dump negative ints in different styles', function () {
+  var dump, src = { integer: -100 };
+
+  dump = yaml.dump(src, { styles: { '!!int': 'binary' } });
+  assert.deepEqual(yaml.safeLoad(dump), src);
+
+  dump = yaml.dump(src, { styles: { '!!int': 'octal' } });
+  assert.deepEqual(yaml.safeLoad(dump), src);
+
+  dump = yaml.dump(src, { styles: { '!!int': 'hex' } });
+  assert.deepEqual(yaml.safeLoad(dump), src);
+});
diff --git a/encoding/yaml/__test__/issues/0403.js b/encoding/yaml/__test__/issues/0403.js
new file mode 100644
index 000000000000..2b1362d566b7
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0403.js
@@ -0,0 +1,23 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+
+test('should properly dump leading newlines and spaces', function () {
+  var dump, src;
+
+  src = { str: '\n  a\nb' };
+  dump = yaml.dump(src);
+  assert.deepEqual(yaml.safeLoad(dump), src);
+
+  src = { str: '\n\n  a\nb' };
+  dump = yaml.dump(src);
+  assert.deepEqual(yaml.safeLoad(dump), src);
+
+  src = { str: '\n  a\nb' };
+  dump = yaml.dump(src, { indent: 10 });
+  assert.deepEqual(yaml.safeLoad(dump), src);
+});
diff --git a/encoding/yaml/__test__/issues/0432.js b/encoding/yaml/__test__/issues/0432.js
new file mode 100644
index 000000000000..ac525c9879c7
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0432.js
@@ -0,0 +1,19 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+
+test('should indent arrays an extra level by default', function () {
+  var output = yaml.safeDump({ array: [ 'a', 'b' ] });
+  var expected = 'array:\n  - a\n  - b\n';
+  assert.strictEqual(output, expected);
+});
+
+test('should not indent arrays an extra level when disabled', function () {
+  var output = yaml.safeDump({ array: [ 'a', 'b' ] }, { noArrayIndent: true });
+  var expected = 'array:\n- a\n- b\n';
+  assert.strictEqual(output, expected);
+});
diff --git a/encoding/yaml/__test__/issues/0468.js b/encoding/yaml/__test__/issues/0468.js
new file mode 100644
index 000000000000..ef13cda9b849
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0468.js
@@ -0,0 +1,30 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../..');
+
+test('should not indent arrays an extra level when disabled', function () {
+  /* eslint-disable max-len */
+  var output = yaml.dump(
+    [
+      {
+        a: 'a_val',
+        b: 'b_val'
+      },
+      {
+        a: 'a2_val',
+        items: [
+          {
+            a: 'a_a_val',
+            b: 'a_b_val'
+          }
+        ]
+      }
+    ],
+    { noArrayIndent: true }
+  );
+  var expected = '- a: a_val\n  b: b_val\n- a: a2_val\n  items:\n  - a: a_a_val\n    b: a_b_val\n';
+  assert.strictEqual(output, expected);
+});
diff --git a/encoding/yaml/__test__/issues/0475-case1.yml b/encoding/yaml/__test__/issues/0475-case1.yml
new file mode 100644
index 000000000000..29e78476f017
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0475-case1.yml
@@ -0,0 +1,117 @@
+? - - &id057
+      - &id055
+        - &id053
+          - &id051
+            - &id049
+              - &id047
+                - &id045
+                  - &id043
+                    - &id041
+                      - &id039
+                        - &id037
+                          - &id035
+                            - &id033
+                              - &id031
+                                - &id029
+                                  - &id027
+                                    - &id025
+                                      - &id023
+                                        - &id021
+                                          - &id019
+                                            - &id017
+                                              - &id015
+                                                - &id013
+                                                  - &id011
+                                                    - &id009
+                                                      - &id007
+                                                        - &id005
+                                                          - &id003
+                                                            - &id001 [lol]
+                                                            - &id002 [lol]
+                                                          - &id004
+                                                            - *id001
+                                                            - *id002
+                                                        - &id006
+                                                          - *id003
+                                                          - *id004
+                                                      - &id008
+                                                        - *id005
+                                                        - *id006
+                                                    - &id010
+                                                      - *id007
+                                                      - *id008
+                                                  - &id012
+                                                    - *id009
+                                                    - *id010
+                                                - &id014
+                                                  - *id011
+                                                  - *id012
+                                              - &id016
+                                                - *id013
+                                                - *id014
+                                            - &id018
+                                              - *id015
+                                              - *id016
+                                          - &id020
+                                            - *id017
+                                            - *id018
+                                        - &id022
+                                          - *id019
+                                          - *id020
+                                      - &id024
+                                        - *id021
+                                        - *id022
+                                    - &id026
+                                      - *id023
+                                      - *id024
+                                  - &id028
+                                    - *id025
+                                    - *id026
+                                - &id030
+                                  - *id027
+                                  - *id028
+                              - &id032
+                                - *id029
+                                - *id030
+                            - &id034
+                              - *id031
+                              - *id032
+                          - &id036
+                            - *id033
+                            - *id034
+                        - &id038
+                          - *id035
+                          - *id036
+                      - &id040
+                        - *id037
+                        - *id038
+                    - &id042
+                      - *id039
+                      - *id040
+                  - &id044
+                    - *id041
+                    - *id042
+                - &id046
+                  - *id043
+                  - *id044
+              - &id048
+                - *id045
+                - *id046
+            - &id050
+              - *id047
+              - *id048
+          - &id052
+            - *id049
+            - *id050
+        - &id054
+          - *id051
+          - *id052
+      - &id056
+        - *id053
+        - *id054
+    - &id058
+      - *id055
+      - *id056
+  - - *id057
+    - *id058
+: key
diff --git a/encoding/yaml/__test__/issues/0475-case2.yml b/encoding/yaml/__test__/issues/0475-case2.yml
new file mode 100644
index 000000000000..f5c69b535b21
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0475-case2.yml
@@ -0,0 +1,112 @@
+ - &id057
+   - &id055
+     - &id053
+       - &id051
+         - &id049
+           - &id047
+             - &id045
+               - &id043
+                 - &id041
+                   - &id039
+                     - &id037
+                       - &id035
+                         - &id033
+                           - &id031
+                             - &id029
+                               - &id027
+                                 - &id025
+                                   - &id023
+                                     - &id021
+                                       - &id019
+                                         - &id017
+                                           - &id015
+                                             - &id013
+                                               - &id011
+                                                 - &id009
+                                                   - &id007
+                                                     - &id005
+                                                       - &id003
+                                                         - &id001 [lol]
+                                                         - &id002 [lol]
+                                                       - &id004
+                                                         - *id001
+                                                         - *id002
+                                                     - &id006
+                                                       - *id003
+                                                       - *id004
+                                                   - &id008
+                                                     - *id005
+                                                     - *id006
+                                                 - &id010
+                                                   - *id007
+                                                   - *id008
+                                               - &id012
+                                                 - *id009
+                                                 - *id010
+                                             - &id014
+                                               - *id011
+                                               - *id012
+                                           - &id016
+                                             - *id013
+                                             - *id014
+                                         - &id018
+                                           - *id015
+                                           - *id016
+                                       - &id020
+                                         - *id017
+                                         - *id018
+                                     - &id022
+                                       - *id019
+                                       - *id020
+                                   - &id024
+                                     - *id021
+                                     - *id022
+                                 - &id026
+                                   - *id023
+                                   - *id024
+                               - &id028
+                                 - *id025
+                                 - *id026
+                             - &id030
+                               - *id027
+                               - *id028
+                           - &id032
+                             - *id029
+                             - *id030
+                         - &id034
+                           - *id031
+                           - *id032
+                       - &id036
+                         - *id033
+                         - *id034
+                     - &id038
+                       - *id035
+                       - *id036
+                   - &id040
+                     - *id037
+                     - *id038
+                 - &id042
+                   - *id039
+                   - *id040
+               - &id044
+                 - *id041
+                 - *id042
+             - &id046
+               - *id043
+               - *id044
+           - &id048
+             - *id045
+             - *id046
+         - &id050
+           - *id047
+           - *id048
+       - &id052
+         - *id049
+         - *id050
+     - &id054
+       - *id051
+       - *id052
+   - &id056
+     - *id053
+     - *id054
+ - *id057 : 1
diff --git a/encoding/yaml/__test__/issues/0475.js b/encoding/yaml/__test__/issues/0475.js
new file mode 100644
index 000000000000..8eb5afa50093
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0475.js
@@ -0,0 +1,28 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Should not allow nested arrays in map keys (explicit syntax)', function () {
+  try {
+    yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0475-case1.yml'), 'utf8'));
+  } catch (err) {
+    assert(err.stack.startsWith('YAMLException: nested arrays are not supported inside keys'));
+    return;
+  }
+  assert.fail(null, null, 'Expected an error to be thrown');
+});
+
+test('Should not allow nested arrays in map keys (implicit syntax)', function () {
+  try {
+    yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0475-case2.yml'), 'utf8'));
+  } catch (err) {
+    assert(err.stack.startsWith('YAMLException: nested arrays are not supported inside keys'));
+    return;
+  }
+  assert.fail(null, null, 'Expected an error to be thrown');
+});
diff --git a/encoding/yaml/__test__/issues/0480-date.yml b/encoding/yaml/__test__/issues/0480-date.yml
new file mode 100644
index 000000000000..3fcac6e08ea4
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0480-date.yml
@@ -0,0 +1 @@
+{ !<tag:yaml.org,2002:timestamp> '2019-04-05T12:00:43.467Z': 123 }
diff --git a/encoding/yaml/__test__/issues/0480-fn-array.yml b/encoding/yaml/__test__/issues/0480-fn-array.yml
new file mode 100644
index 000000000000..2e151bf5a172
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0480-fn-array.yml
@@ -0,0 +1,4 @@
+? [
+    123,
+    { toString: !<tag:yaml.org,2002:js/function> 'function (){throw new Error("code execution")}' }
+] : key
diff --git a/encoding/yaml/__test__/issues/0480-fn.yml b/encoding/yaml/__test__/issues/0480-fn.yml
new file mode 100644
index 000000000000..68412be544a1
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0480-fn.yml
@@ -0,0 +1 @@
+{ toString: !<tag:yaml.org,2002:js/function> 'function (){throw new Error("code execution")}' } : key
diff --git a/encoding/yaml/__test__/issues/0480-fn2.yml b/encoding/yaml/__test__/issues/0480-fn2.yml
new file mode 100644
index 000000000000..6efd250d141f
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0480-fn2.yml
@@ -0,0 +1 @@
+{ __proto__: { toString: !<tag:yaml.org,2002:js/function> 'function(){throw new Error("code execution")}' } } : key
diff --git a/encoding/yaml/__test__/issues/0480.js b/encoding/yaml/__test__/issues/0480.js
new file mode 100644
index 000000000000..b0e36381af97
--- /dev/null
+++ b/encoding/yaml/__test__/issues/0480.js
@@ -0,0 +1,35 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+var readFileSync = require('fs').readFileSync;
+
+
+test('Should not execute code when object with toString property is used as a key', function () {
+  var data = yaml.load(readFileSync(require('path').join(__dirname, '/0480-fn.yml'), 'utf8'));
+
+  assert.deepEqual(data, { '[object Object]': 'key' });
+});
+
+test('Should not execute code when object with __proto__ property is used as a key', function () {
+  var data = yaml.load(readFileSync(require('path').join(__dirname, '/0480-fn2.yml'), 'utf8'));
+
+  assert.deepEqual(data, { '[object Object]': 'key' });
+});
+
+test('Should not execute code when object inside array is used as a key', function () {
+  var data = yaml.load(readFileSync(require('path').join(__dirname, '/0480-fn-array.yml'), 'utf8'));
+
+  assert.deepEqual(data, { '123,[object Object]': 'key' });
+});
+
+// this test does not guarantee in any way proper handling of date objects,
+// it just keeps old behavior whenever possible
+test('Should leave non-plain objects as is', function () {
+  var data = yaml.load(readFileSync(require('path').join(__dirname, '/0480-date.yml'), 'utf8'));
+
+  assert.deepEqual(Object.keys(data).length, 1);
+  assert(/2019/.test(Object.keys(data)[0]));
+});
diff --git a/encoding/yaml/__test__/samples-common/construct-binary.js b/encoding/yaml/__test__/samples-common/construct-binary.js
new file mode 100644
index 000000000000..646d438b3d36
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-binary.js
@@ -0,0 +1,18 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+/*eslint-disable max-len*/
+
+// Support node 6.+ Buffer API when available
+function buffer(data, encoding) {
+  return Buffer.from ? Buffer.from(data, encoding) : new Buffer(data, encoding);
+}
+
+module.exports = {
+  canonical: buffer("GIF89a\x0c\x00\x0c\x00\x84\x00\x00\xff\xff\xf7\xf5\xf5\xee\xe9\xe9\xe5fff\x00\x00\x00\xe7\xe7\xe7^^^\xf3\xf3\xed\x8e\x8e\x8e\xe0\xe0\xe0\x9f\x9f\x9f\x93\x93\x93\xa7\xa7\xa7\x9e\x9e\x9eiiiccc\xa3\xa3\xa3\x84\x84\x84\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9!\xfe\x0eMade with GIMP\x00,\x00\x00\x00\x00\x0c\x00\x0c\x00\x00\x05,  \x8e\x810\x9e\xe3@\x14\xe8i\x10\xc4\xd1\x8a\x08\x1c\xcf\x80M$z\xef\xff0\x85p\xb8\xb01f\r\x1b\xce\x01\xc3\x01\x1e\x10' \x82\n\x01\x00;", 'binary'),
+
+  generic: buffer("GIF89a\x0c\x00\x0c\x00\x84\x00\x00\xff\xff\xf7\xf5\xf5\xee\xe9\xe9\xe5fff\x00\x00\x00\xe7\xe7\xe7^^^\xf3\xf3\xed\x8e\x8e\x8e\xe0\xe0\xe0\x9f\x9f\x9f\x93\x93\x93\xa7\xa7\xa7\x9e\x9e\x9eiiiccc\xa3\xa3\xa3\x84\x84\x84\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9\xff\xfe\xf9!\xfe\x0eMade with GIMP\x00,\x00\x00\x00\x00\x0c\x00\x0c\x00\x00\x05,  \x8e\x810\x9e\xe3@\x14\xe8i\x10\xc4\xd1\x8a\x08\x1c\xcf\x80M$z\xef\xff0\x85p\xb8\xb01f\r\x1b\xce\x01\xc3\x01\x1e\x10' \x82\n\x01\x00;", 'binary'),
+
+  description: 'The binary value above is a tiny arrow encoded as a gif image.'
+};
diff --git a/encoding/yaml/__test__/samples-common/construct-binary.yml b/encoding/yaml/__test__/samples-common/construct-binary.yml
new file mode 100644
index 000000000000..dcdb16f3b4ef
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-binary.yml
@@ -0,0 +1,12 @@
+canonical: !!binary "\
+ R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5\
+ OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/+\
+ +f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLC\
+ AgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs="
+generic: !!binary |
+ R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5
+ OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/+
+ +f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLC
+ AgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs=
+description:
+ The binary value above is a tiny arrow encoded as a gif image.
diff --git a/encoding/yaml/__test__/samples-common/construct-bool.js b/encoding/yaml/__test__/samples-common/construct-bool.js
new file mode 100644
index 000000000000..975088e23713
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-bool.js
@@ -0,0 +1,10 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  valid_true: [ true, true, true ],
+  valid_false: [ false, false, false ],
+  deprecated_true: [ 'y', 'Y', 'yes', 'Yes', 'YES', 'on', 'On', 'ON' ],
+  deprecated_false: [ 'n', 'N', 'no', 'No', 'NO', 'off', 'Off', 'OFF' ]
+};
diff --git a/encoding/yaml/__test__/samples-common/construct-bool.yml b/encoding/yaml/__test__/samples-common/construct-bool.yml
new file mode 100644
index 000000000000..2971e0a5194b
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-bool.yml
@@ -0,0 +1,33 @@
+# Valid notation. (YAML 1.2)
+#
+valid_true:
+  - true
+  - True
+  - TRUE
+
+valid_false:
+  - false
+  - False
+  - FALSE
+
+# Deprecated notation. (YAML 1.0/1.1)
+#
+deprecated_true:
+  - y
+  - Y
+  - yes
+  - Yes
+  - YES
+  - on
+  - On
+  - ON
+
+deprecated_false:
+  - n
+  - N
+  - no
+  - No
+  - NO
+  - off
+  - Off
+  - OFF
\ No newline at end of file
diff --git a/encoding/yaml/__test__/samples-common/construct-custom.js b/encoding/yaml/__test__/samples-common/construct-custom.js
new file mode 100644
index 000000000000..e02c1373064a
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-custom.js
@@ -0,0 +1,46 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var schema = require('../support/schema');
+
+var expected = [
+  new schema.Tag1({ x: 1 }),
+  new schema.Tag1({ x: 1, y: 2, z: 3 }),
+  new schema.Tag2({ x: 10 }),
+  new schema.Tag3({ x: 1 }),
+  new schema.Tag3({ x: 1, y: 2, z: 3 }),
+  new schema.Tag3({ x: 1, y: 2, z: 3 }),
+  new schema.Foo({ myParameter: 'foo', myAnotherParameter: [ 1, 2, 3 ] })
+];
+
+function testHandler(actual) {
+  assert.strictEqual(Object.prototype.toString.call(actual), '[object Array]');
+  assert.strictEqual(actual.length, 7);
+
+  assert.deepEqual(actual[0], expected[0]);
+  assert.strictEqual(Object.getPrototypeOf(actual[0]), Object.getPrototypeOf(expected[0]));
+
+  assert.deepEqual(actual[1], expected[1]);
+  assert.strictEqual(Object.getPrototypeOf(actual[1]), Object.getPrototypeOf(expected[1]));
+
+  assert.deepEqual(actual[2], expected[2]);
+  assert.strictEqual(Object.getPrototypeOf(actual[2]), Object.getPrototypeOf(expected[2]));
+
+  assert.deepEqual(actual[3], expected[3]);
+  assert.strictEqual(Object.getPrototypeOf(actual[3]), Object.getPrototypeOf(expected[3]));
+
+  assert.deepEqual(actual[4], expected[4]);
+  assert.strictEqual(Object.getPrototypeOf(actual[4]), Object.getPrototypeOf(expected[4]));
+
+  assert.deepEqual(actual[5], expected[5]);
+  assert.strictEqual(Object.getPrototypeOf(actual[5]), Object.getPrototypeOf(expected[5]));
+
+  assert.deepEqual(actual[6], expected[6]);
+  assert.strictEqual(Object.getPrototypeOf(actual[6]), Object.getPrototypeOf(expected[6]));
+}
+
+testHandler.expected = expected;
+
+module.exports = testHandler;
diff --git a/encoding/yaml/__test__/samples-common/construct-custom.yml b/encoding/yaml/__test__/samples-common/construct-custom.yml
new file mode 100644
index 000000000000..7144683225b5
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-custom.yml
@@ -0,0 +1,22 @@
+---
+- !tag1
+  x: 1
+- !tag1
+  x: 1
+  'y': 2
+  z: 3
+- !tag2
+  10
+- !tag3
+  x: 1
+- !tag3
+  x: 1
+  'y': 2
+  z: 3
+- !tag3
+  =: 1
+  'y': 2
+  z: 3
+- !foo
+  my-parameter: foo
+  my-another-parameter: [1,2,3]
diff --git a/encoding/yaml/__test__/samples-common/construct-float.js b/encoding/yaml/__test__/samples-common/construct-float.js
new file mode 100644
index 000000000000..38c697d1bc1d
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-float.js
@@ -0,0 +1,31 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+
+var expected = {
+  canonical: 685230.15,
+  exponential: 685230.15,
+  fixed: 685230.15,
+  sexagesimal: 685230.15,
+  'negative infinity': Number.NEGATIVE_INFINITY,
+  'not a number': NaN
+};
+
+function testHandler(actual) {
+  assert.strictEqual(Object.prototype.toString.call(actual), '[object Object]');
+  assert.strictEqual(Object.keys(actual).sort().join(','), Object.keys(expected).sort().join(','));
+
+  assert.strictEqual(actual['canonical'],         expected['canonical']);
+  assert.strictEqual(actual['exponential'],       expected['exponential']);
+  assert.strictEqual(actual['fixed'],             expected['fixed']);
+  assert.strictEqual(actual['sexagesimal'],       expected['sexagesimal']);
+  assert.strictEqual(actual['negative infinity'], expected['negative infinity']);
+
+  assert(Number.isNaN(actual['not a number']));
+}
+
+testHandler.expected = expected;
+
+module.exports = testHandler;
diff --git a/encoding/yaml/__test__/samples-common/construct-float.yml b/encoding/yaml/__test__/samples-common/construct-float.yml
new file mode 100644
index 000000000000..b662c6236283
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-float.yml
@@ -0,0 +1,6 @@
+canonical: 6.8523015e+5
+exponential: 685.230_15e+03
+fixed: 685_230.15
+sexagesimal: 190:20:30.15
+negative infinity: -.inf
+not a number: .NaN
diff --git a/encoding/yaml/__test__/samples-common/construct-int.js b/encoding/yaml/__test__/samples-common/construct-int.js
new file mode 100644
index 000000000000..39027cb05886
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-int.js
@@ -0,0 +1,12 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  canonical: 685230,
+  decimal: 685230,
+  octal: 685230,
+  hexadecimal: 685230,
+  binary: 685230,
+  sexagesimal: 685230
+};
diff --git a/encoding/yaml/__test__/samples-common/construct-int.yml b/encoding/yaml/__test__/samples-common/construct-int.yml
new file mode 100644
index 000000000000..852c3148eed8
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-int.yml
@@ -0,0 +1,6 @@
+canonical: 685230
+decimal: +685_230
+octal: 02472256
+hexadecimal: 0x_0A_74_AE
+binary: 0b1010_0111_0100_1010_1110
+sexagesimal: 190:20:30
diff --git a/encoding/yaml/__test__/samples-common/construct-javascript-function.js b/encoding/yaml/__test__/samples-common/construct-javascript-function.js
new file mode 100644
index 000000000000..64e66eb00262
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-javascript-function.js
@@ -0,0 +1,53 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+
+
+function testHandler(actual) {
+  var expected = testHandler.expected;
+
+  assert.strictEqual(actual.length, expected.length);
+
+  assert.strictEqual(actual.length, expected.length);
+
+  assert.strictEqual(
+    actual[0](),
+    expected[0]());
+
+  assert.strictEqual(
+    actual[1](10, 20),
+    expected[1](10, 20));
+
+  assert.deepEqual(
+    actual[2]('book'),
+    expected[2]('book'));
+}
+
+testHandler.expected = [
+  function () {
+    return 42;
+  },
+  function () {
+    return 72;
+  },
+  function () {
+    return 23;
+  },
+  function (x, y) {
+    return x + y;
+  },
+  function (foo) {
+    var result = 'There is my ' + foo + ' at the table.';
+
+    return {
+      first: 42,
+      second: 'sum',
+      third: result
+    };
+  }
+];
+
+
+module.exports = testHandler;
diff --git a/encoding/yaml/__test__/samples-common/construct-javascript-function.yml b/encoding/yaml/__test__/samples-common/construct-javascript-function.yml
new file mode 100644
index 000000000000..ca945e2c2300
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-javascript-function.yml
@@ -0,0 +1,14 @@
+- !!js/function 'function () { return 42 }'
+- !!js/function '() => { return 72 }'
+- !!js/function '() => 23'
+- !!js/function 'function (x, y) { return x + y; } '
+- !!js/function |
+  function (foo) {
+    var result = 'There is my ' + foo + ' at the table.';
+
+    return {
+      first: 42,
+      second: 'sum',
+      third: result
+    };
+  }
\ No newline at end of file
diff --git a/encoding/yaml/__test__/samples-common/construct-javascript-regexp.js b/encoding/yaml/__test__/samples-common/construct-javascript-regexp.js
new file mode 100644
index 000000000000..8d3cfc52c4f2
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-javascript-regexp.js
@@ -0,0 +1,11 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = [
+  /fo{2,}/,
+  /[wv]orlds?/g,
+  /^spec/im,
+  /ba+r/,
+  /ba.z*/gim
+];
diff --git a/encoding/yaml/__test__/samples-common/construct-javascript-regexp.yml b/encoding/yaml/__test__/samples-common/construct-javascript-regexp.yml
new file mode 100644
index 000000000000..f3ad62f97a8f
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-javascript-regexp.yml
@@ -0,0 +1,5 @@
+- !!js/regexp /fo{2,}/
+- !!js/regexp /[wv]orlds?/g
+- !!js/regexp /^spec/im
+- !!js/regexp '/ba+r/'
+- !!js/regexp '/ba.z*/gim'
diff --git a/encoding/yaml/__test__/samples-common/construct-javascript-undefined.js b/encoding/yaml/__test__/samples-common/construct-javascript-undefined.js
new file mode 100644
index 000000000000..53150b0f029e
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-javascript-undefined.js
@@ -0,0 +1,10 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = [
+  undefined,
+  undefined,
+  undefined,
+  undefined
+];
diff --git a/encoding/yaml/__test__/samples-common/construct-javascript-undefined.yml b/encoding/yaml/__test__/samples-common/construct-javascript-undefined.yml
new file mode 100644
index 000000000000..4df49db96723
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-javascript-undefined.yml
@@ -0,0 +1,4 @@
+- !!js/undefined
+- !!js/undefined ''
+- !!js/undefined 'foobar'
+- !!js/undefined hello world
diff --git a/encoding/yaml/__test__/samples-common/construct-map.js b/encoding/yaml/__test__/samples-common/construct-map.js
new file mode 100644
index 000000000000..b5247c47c78f
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-map.js
@@ -0,0 +1,17 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  'Block style': {
+    Clark: 'Evans',
+    Brian: 'Ingerson',
+    Oren: 'Ben-Kiki'
+  },
+  'Flow style': {
+    Clark: 'Evans',
+    Brian: 'Ingerson',
+    Oren: 'Ben-Kiki'
+  },
+  'foo,bar': 'baz'
+};
diff --git a/encoding/yaml/__test__/samples-common/construct-map.yml b/encoding/yaml/__test__/samples-common/construct-map.yml
new file mode 100644
index 000000000000..74e006f28a4f
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-map.yml
@@ -0,0 +1,11 @@
+# Unordered set of key: value pairs.
+Block style: !!map
+  Clark : Evans
+  Brian : Ingerson
+  Oren  : Ben-Kiki
+Flow style: !!map { Clark: Evans, Brian: Ingerson, Oren: Ben-Kiki }
+
+# YAML has no restrictions on key type, so it can be an array
+? - foo
+  - bar
+: baz
diff --git a/encoding/yaml/__test__/samples-common/construct-merge.js b/encoding/yaml/__test__/samples-common/construct-merge.js
new file mode 100644
index 000000000000..33f0754e46b2
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-merge.js
@@ -0,0 +1,14 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = [
+  { x: 1, y: 2 },
+  { x: 0, y: 2 },
+  { r: 10 },
+  { r: 1 },
+  { x: 1, y: 2, r: 10, label: 'center/big' },
+  { x: 1, y: 2, r: 10, label: 'center/big' },
+  { x: 1, y: 2, r: 10, label: 'center/big' },
+  { x: 1, y: 2, r: 10, label: 'center/big' }
+];
diff --git a/encoding/yaml/__test__/samples-common/construct-merge.yml b/encoding/yaml/__test__/samples-common/construct-merge.yml
new file mode 100644
index 000000000000..3fdb2e203c26
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-merge.yml
@@ -0,0 +1,27 @@
+---
+- &CENTER { x: 1, 'y': 2 }
+- &LEFT { x: 0, 'y': 2 }
+- &BIG { r: 10 }
+- &SMALL { r: 1 }
+
+# All the following maps are equal:
+
+- # Explicit keys
+  x: 1
+  'y': 2
+  r: 10
+  label: center/big
+
+- # Merge one map
+  << : *CENTER
+  r: 10
+  label: center/big
+
+- # Merge multiple maps
+  << : [ *CENTER, *BIG ]
+  label: center/big
+
+- # Override
+  << : [ *BIG, *LEFT, *SMALL ]
+  x: 1
+  label: center/big
diff --git a/encoding/yaml/__test__/samples-common/construct-null.js b/encoding/yaml/__test__/samples-common/construct-null.js
new file mode 100644
index 000000000000..32fdbf2cd3cd
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-null.js
@@ -0,0 +1,22 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = [
+  null,
+  {
+    empty: null,
+    canonical: null,
+    english: null,
+    'null': 'null key'
+  },
+  {
+    sparse: [
+      null,
+      '2nd entry',
+      null,
+      '4th entry',
+      null
+    ]
+  }
+];
diff --git a/encoding/yaml/__test__/samples-common/construct-null.yml b/encoding/yaml/__test__/samples-common/construct-null.yml
new file mode 100644
index 000000000000..9ad0344cfea6
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-null.yml
@@ -0,0 +1,18 @@
+# A document may be null.
+---
+---
+# This mapping has four keys,
+# one has a value.
+empty:
+canonical: ~
+english: null
+~: null key
+---
+# This sequence has five
+# entries, two have values.
+sparse:
+  - ~
+  - 2nd entry
+  -
+  - 4th entry
+  - Null
diff --git a/encoding/yaml/__test__/samples-common/construct-omap.js b/encoding/yaml/__test__/samples-common/construct-omap.js
new file mode 100644
index 000000000000..2d00da65f295
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-omap.js
@@ -0,0 +1,16 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  Bestiary: [
+    { aardvark : 'African pig-like ant eater. Ugly.'        },
+    { anteater : 'South-American ant eater. Two species.'   },
+    { anaconda : 'South-American constrictor snake. Scaly.' }
+  ],
+  Numbers: [
+    { one   : 1 },
+    { two   : 2 },
+    { three : 3 }
+  ]
+};
diff --git a/encoding/yaml/__test__/samples-common/construct-omap.yml b/encoding/yaml/__test__/samples-common/construct-omap.yml
new file mode 100644
index 000000000000..4fa0f45f26ff
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-omap.yml
@@ -0,0 +1,8 @@
+# Explicitly typed ordered map (dictionary).
+Bestiary: !!omap
+  - aardvark: African pig-like ant eater. Ugly.
+  - anteater: South-American ant eater. Two species.
+  - anaconda: South-American constrictor snake. Scaly.
+  # Etc.
+# Flow style
+Numbers: !!omap [ one: 1, two: 2, three : 3 ]
diff --git a/encoding/yaml/__test__/samples-common/construct-pairs.js b/encoding/yaml/__test__/samples-common/construct-pairs.js
new file mode 100644
index 000000000000..1ea1ec4410a0
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-pairs.js
@@ -0,0 +1,16 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  'Block tasks': [
+    [ 'meeting', 'with team.' ],
+    [ 'meeting', 'with boss.' ],
+    [ 'break', 'lunch.' ],
+    [ 'meeting', 'with client.' ]
+  ],
+  'Flow tasks': [
+    [ 'meeting', 'with team' ],
+    [ 'meeting', 'with boss' ]
+  ]
+};
diff --git a/encoding/yaml/__test__/samples-common/construct-pairs.yml b/encoding/yaml/__test__/samples-common/construct-pairs.yml
new file mode 100644
index 000000000000..05f55b942606
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-pairs.yml
@@ -0,0 +1,7 @@
+# Explicitly typed pairs.
+Block tasks: !!pairs
+  - meeting: with team.
+  - meeting: with boss.
+  - break: lunch.
+  - meeting: with client.
+Flow tasks: !!pairs [ meeting: with team, meeting: with boss ]
diff --git a/encoding/yaml/__test__/samples-common/construct-seq.js b/encoding/yaml/__test__/samples-common/construct-seq.js
new file mode 100644
index 000000000000..f36f02293fcb
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-seq.js
@@ -0,0 +1,28 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  'Block style': [
+    'Mercury',
+    'Venus',
+    'Earth',
+    'Mars',
+    'Jupiter',
+    'Saturn',
+    'Uranus',
+    'Neptune',
+    'Pluto'
+  ],
+  'Flow style': [
+    'Mercury',
+    'Venus',
+    'Earth',
+    'Mars',
+    'Jupiter',
+    'Saturn',
+    'Uranus',
+    'Neptune',
+    'Pluto'
+  ]
+};
diff --git a/encoding/yaml/__test__/samples-common/construct-seq.yml b/encoding/yaml/__test__/samples-common/construct-seq.yml
new file mode 100644
index 000000000000..bb92fd11f162
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-seq.yml
@@ -0,0 +1,15 @@
+# Ordered sequence of nodes
+Block style: !!seq
+- Mercury   # Rotates - no light/dark sides.
+- Venus     # Deadliest. Aptly named.
+- Earth     # Mostly dirt.
+- Mars      # Seems empty.
+- Jupiter   # The king.
+- Saturn    # Pretty.
+- Uranus    # Where the sun hardly shines.
+- Neptune   # Boring. No rings.
+- Pluto     # You call this a planet?
+Flow style: !!seq [ Mercury, Venus, Earth, Mars,      # Rocks
+                    Jupiter, Saturn, Uranus, Neptune, # Gas
+                    Pluto ]                           # Overrated
+
diff --git a/encoding/yaml/__test__/samples-common/construct-set.js b/encoding/yaml/__test__/samples-common/construct-set.js
new file mode 100644
index 000000000000..803866bf35c5
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-set.js
@@ -0,0 +1,16 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  'baseball players': {
+    'Mark McGwire': null,
+    'Sammy Sosa': null,
+    'Ken Griffey': null
+  },
+  'baseball teams': {
+    'Boston Red Sox': null,
+    'Detroit Tigers': null,
+    'New York Yankees': null
+  }
+};
diff --git a/encoding/yaml/__test__/samples-common/construct-set.yml b/encoding/yaml/__test__/samples-common/construct-set.yml
new file mode 100644
index 000000000000..e05dc885796e
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-set.yml
@@ -0,0 +1,7 @@
+# Explicitly typed set.
+baseball players: !!set
+  ? Mark McGwire
+  ? Sammy Sosa
+  ? Ken Griffey
+# Flow style
+baseball teams: !!set { Boston Red Sox, Detroit Tigers, New York Yankees }
diff --git a/encoding/yaml/__test__/samples-common/construct-str-ascii.js b/encoding/yaml/__test__/samples-common/construct-str-ascii.js
new file mode 100644
index 000000000000..9b5197a2744d
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-str-ascii.js
@@ -0,0 +1,5 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = 'ascii string';
diff --git a/encoding/yaml/__test__/samples-common/construct-str-ascii.yml b/encoding/yaml/__test__/samples-common/construct-str-ascii.yml
new file mode 100644
index 000000000000..0d93013b5d9b
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-str-ascii.yml
@@ -0,0 +1 @@
+--- !!str "ascii string"
diff --git a/encoding/yaml/__test__/samples-common/construct-str-utf8.js b/encoding/yaml/__test__/samples-common/construct-str-utf8.js
new file mode 100644
index 000000000000..1bb7e4aa062d
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-str-utf8.js
@@ -0,0 +1,7 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+/*eslint-disable max-len*/
+
+module.exports = '\u042d\u0442\u043e \u0443\u043d\u0438\u043a\u043e\u0434\u043d\u0430\u044f \u0441\u0442\u0440\u043e\u043a\u0430';
diff --git a/encoding/yaml/__test__/samples-common/construct-str-utf8.yml b/encoding/yaml/__test__/samples-common/construct-str-utf8.yml
new file mode 100644
index 000000000000..e355f184a64c
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-str-utf8.yml
@@ -0,0 +1 @@
+--- !!str "Это уникодная строка"
diff --git a/encoding/yaml/__test__/samples-common/construct-str.js b/encoding/yaml/__test__/samples-common/construct-str.js
new file mode 100644
index 000000000000..6e37bae46f37
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-str.js
@@ -0,0 +1,7 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  string: 'abcd'
+};
diff --git a/encoding/yaml/__test__/samples-common/construct-str.yml b/encoding/yaml/__test__/samples-common/construct-str.yml
new file mode 100644
index 000000000000..606ac6b290dc
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-str.yml
@@ -0,0 +1 @@
+string: abcd
diff --git a/encoding/yaml/__test__/samples-common/construct-string-types.js b/encoding/yaml/__test__/samples-common/construct-string-types.js
new file mode 100644
index 000000000000..be1a4f0451af
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-string-types.js
@@ -0,0 +1,116 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var essay = 'a\n' +
+  'b\n' +
+  '1sdf 2ar 3sdf 4sdf 5sdf 6sdf 7sdf 8sdf 9sdf 10asdf 11asdf ' +
+    '12asdf 13asdf 14asdf 15df 16df long  17df 1890 1900 2000 ' +
+    '2001 2002 baz\n' +
+  '2003 2004 4sdf 4sdf 7sdf 8sdf 9sdf 0sdf 1sdf 2sdf 3sdf ' +
+    '4sdf 5sdf 6sdf long  7sdf 8sdf 9sdf 0sdf 2002 asdfasdf ' +
+    '2003 2006 2020 2021 2022 2023 2024 2025 long  2026 2027 ' +
+    '2028 2029 2030 2031 2032 2033 2034 2035 asdfasdf 02036 ' +
+    '2040 2041 long  2042 2043 2044 2045 2046 2027 2048 ' +
+    '2050 4444 5555 6666 7777 8888 9999 long  asdfasdf ' +
+    'aaaa bbbb cccc dddd eeeee fff ggggggg hhhi iiii jjjj ' +
+    'long  asdfasdfasdfasdfslong                         ' +
+    '                                              xlong  ' +
+    'asdfasdfasdfasdfasdfasdfasdfasd asdf xasdf the  end';
+
+module.exports = {
+  simpleString: 'hello world',
+  simpleStringComma: 'hello, world',
+  stackTrace: 'Error: foo\n' +
+    '    at repl:1:5\n' +
+    '    at REPLServer.defaultEval (repl.js:116:27)\n' +
+    '    at bound (domain.js:254:14)',
+
+  trailingSpace: 'hello space    ',
+  trailingTab: 'hello tab  \t',
+  trailingCR: 'hello newline\n',
+
+  simpleQuotes: 'won\'t you be my neighbor',
+  unprintable: 'number 1 is \u0001 and the biggest byte is \uffff ok',
+
+  multiline: 'hello\nworld\n',
+  multilineChomp: 'hello\nworld',
+  multilineTrailingCR: 'hello\nworld\n\n\n\n\n',
+  multilineTrailingSpace: 'hello\nworld    \nspace\n',
+  multilineTrailingSpaceChomp: 'hello\nworld    \nspace',
+
+  longMultiBigSpace: 'x' + new Array(100).join(' ') + 'y\nworld\n',
+  longMultiBigSpaceChomp: 'x' + new Array(100).join(' ') + 'y\nworld',
+
+  essayNoTrailing: essay,
+  essayManyTrailing: essay + '\n\n\n\n\n\n',
+  essayOneTrailing: essay + '\n',
+
+  neggy: '-1',
+  questy: '?asdf',
+
+  // Example 8.1.
+  blockScalarHeader: [ 'literal\n', ' folded\n', 'keep\n\n', ' strip' ],
+  // Example 8.2.
+  // The ' \t' is a more-indented line as per [177] s-nb-spaced-text.
+  blockIndentationIndicator: [
+    'detected\n', '\n\n# detected\n', ' explicit\n', '\t\ndetected\n'
+  ],
+  // Example 8.6. Empty Scalar Chomping
+  strip: '',
+  clip: '',
+  keep: '\n',
+  // Example 8.10.
+  foldedStyle: '\nfolded line\nnext line\n' +
+    '  * bullet\n\n  * list\n  * lines\n\nlast line\n',
+
+  longMultiChomp: new Array(80).join('lo hel') + '\nworld',
+  longMultiTrailingCR: new Array(80).join('lo hel') + '\nworld\n\n\n\n\n',
+  longMulti: new Array(80).join('lo hel') + '\nworld\n'
+
+};
+
+// now indent the long multi really far
+var obj = module.exports,
+    i;
+
+for (i = 0; i < 5; i++) {
+  obj.indent = {};
+  obj = obj.indent;
+}
+
+obj.ind = module.exports.longMulti;
+
+for (i = 0; i < 5; i++) {
+  obj.indent = {};
+  obj = obj.indent;
+}
+
+obj.ind = module.exports.longMulti;
+
+for (i = 0; i < 5; i++) {
+  obj.indent = {};
+  obj = obj.indent;
+}
+
+obj.ind = module.exports.longMulti;
+
+for (i = 0; i < 5; i++) {
+  obj.indent = {};
+  obj = obj.indent;
+}
+
+obj.ind = module.exports.longMulti;
+
+for (i = 0; i < 5; i++) {
+  obj.indent = {};
+  obj = obj.indent;
+}
+
+obj.ind = module.exports.longMulti;
+
+for (i = 0; i < 5; i++) {
+  obj.indent = {};
+  obj = obj.indent;
+}
+obj.ind = module.exports.longMulti;
diff --git a/encoding/yaml/__test__/samples-common/construct-string-types.yml b/encoding/yaml/__test__/samples-common/construct-string-types.yml
new file mode 100644
index 000000000000..e77f98618d06
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-string-types.yml
@@ -0,0 +1,277 @@
+simpleString: hello world
+simpleStringComma: 'hello, world'
+stackTrace: |-
+  Error: foo
+      at repl:1:5
+      at REPLServer.defaultEval (repl.js:116:27)
+      at bound (domain.js:254:14)
+trailingSpace: 'hello space    '
+trailingTab: "hello tab  \t"
+trailingCR: |
+  hello newline
+simpleQuotes: |-
+  won't you be my neighbor
+unprintable: "number 1 is \x01 and the biggest byte is \uFFFF ok"
+multiline: |
+  hello
+  world
+multilineChomp: |-
+  hello
+  world
+multilineTrailingCR: |+
+  hello
+  world
+
+
+
+
+multilineTrailingSpace: "hello\nworld    \nspace\n"
+multilineTrailingSpaceChomp: "hello\nworld    \nspace"
+longMultiBigSpace: >
+  x                                                                                                   y
+
+  world
+longMultiBigSpaceChomp: >-
+  x                                                                                                   y
+
+  world
+essayNoTrailing: >-
+  a
+
+  b
+
+  1sdf 2ar 3sdf 4sdf 5sdf 6sdf 7sdf 8sdf 9sdf 10asdf 11asdf 12asdf 13asdf 14asdf
+  15df 16df long  17df 1890 1900 2000 2001 2002 baz
+
+  2003 2004 4sdf 4sdf 7sdf 8sdf 9sdf 0sdf 1sdf 2sdf 3sdf 4sdf 5sdf 6sdf
+  long  7sdf 8sdf 9sdf 0sdf 2002 asdfasdf 2003 2006 2020 2021 2022 2023 2024 2025
+  long  2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 asdfasdf 02036 2040
+  2041 long  2042 2043 2044 2045 2046 2027 2048 2050 4444 5555 6666 7777 8888
+  9999 long  asdfasdf aaaa bbbb cccc dddd eeeee fff ggggggg hhhi iiii jjjj
+  long  asdfasdfasdfasdfslong                                                                       xlong  asdfasdfasdfasdfasdfasdfasdfasd
+  asdf xasdf the  end
+essayManyTrailing: >+
+  a
+
+  b
+
+  1sdf 2ar 3sdf 4sdf 5sdf 6sdf 7sdf 8sdf 9sdf 10asdf 11asdf 12asdf 13asdf 14asdf
+  15df 16df long  17df 1890 1900 2000 2001 2002 baz
+
+  2003 2004 4sdf 4sdf 7sdf 8sdf 9sdf 0sdf 1sdf 2sdf 3sdf 4sdf 5sdf 6sdf
+  long  7sdf 8sdf 9sdf 0sdf 2002 asdfasdf 2003 2006 2020 2021 2022 2023 2024 2025
+  long  2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 asdfasdf 02036 2040
+  2041 long  2042 2043 2044 2045 2046 2027 2048 2050 4444 5555 6666 7777 8888
+  9999 long  asdfasdf aaaa bbbb cccc dddd eeeee fff ggggggg hhhi iiii jjjj
+  long  asdfasdfasdfasdfslong                                                                       xlong  asdfasdfasdfasdfasdfasdfasdfasd
+  asdf xasdf the  end
+
+
+
+
+
+essayOneTrailing: >
+  a
+
+  b
+
+  1sdf 2ar 3sdf 4sdf 5sdf 6sdf 7sdf 8sdf 9sdf 10asdf 11asdf 12asdf 13asdf 14asdf
+  15df 16df long  17df 1890 1900 2000 2001 2002 baz
+
+  2003 2004 4sdf 4sdf 7sdf 8sdf 9sdf 0sdf 1sdf 2sdf 3sdf 4sdf 5sdf 6sdf
+  long  7sdf 8sdf 9sdf 0sdf 2002 asdfasdf 2003 2006 2020 2021 2022 2023 2024 2025
+  long  2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 asdfasdf 02036 2040
+  2041 long  2042 2043 2044 2045 2046 2027 2048 2050 4444 5555 6666 7777 8888
+  9999 long  asdfasdf aaaa bbbb cccc dddd eeeee fff ggggggg hhhi iiii jjjj
+  long  asdfasdfasdfasdfslong                                                                       xlong  asdfasdfasdfasdfasdfasdfasdfasd
+  asdf xasdf the  end
+neggy: '-1'
+questy: '?asdf'
+blockScalarHeader:
+- | # Empty header
+ literal
+- >1 # Indentation indicator
+  folded
+- |+ # Chomping indicator
+ keep
+
+- >1- # Both indicators
+  strip
+blockIndentationIndicator:
+- |
+ detected
+- >
+ 
+  
+  # detected
+- |1
+  explicit
+- >
+ 	
+ detected
+strip: >-
+
+clip: >
+
+keep: |+
+
+foldedStyle: >
+
+ folded
+ line
+
+ next
+ line
+   * bullet
+
+   * list
+   * lines
+
+ last
+ line
+
+# Comment
+longMultiChomp: >-
+  lo hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hel
+
+  world
+longMultiTrailingCR: >+
+  lo hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hel
+
+  world
+
+
+
+
+longMulti: >
+  lo hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hello hello hello hello hello hello hello hello hello hello hello hello
+  hello hel
+
+  world
+indent:
+  indent:
+    indent:
+      indent:
+        indent:
+          ind: >
+            lo hello hello hello hello hello hello hello hello hello hello hello
+            hello hello hello hello hello hello hello hello hello hello hello
+            hello hello hello hello hello hello hello hello hello hello hello
+            hello hello hello hello hello hello hello hello hello hello hello
+            hello hello hello hello hello hello hello hello hello hello hello
+            hello hello hello hello hello hello hello hello hello hello hello
+            hello hello hello hello hello hello hello hello hello hello hello
+            hello hel
+
+            world
+          indent:
+            indent:
+              indent:
+                indent:
+                  indent:
+                    ind: >
+                      lo hello hello hello hello hello hello hello hello hello
+                      hello hello hello hello hello hello hello hello hello hello
+                      hello hello hello hello hello hello hello hello hello hello
+                      hello hello hello hello hello hello hello hello hello hello
+                      hello hello hello hello hello hello hello hello hello hello
+                      hello hello hello hello hello hello hello hello hello hello
+                      hello hello hello hello hello hello hello hello hello hello
+                      hello hello hello hello hello hello hello hello hello hel
+
+                      world
+                    indent:
+                      indent:
+                        indent:
+                          indent:
+                            indent:
+                              ind: >
+                                lo hello hello hello hello hello hello hello
+                                hello hello hello hello hello hello hello hello
+                                hello hello hello hello hello hello hello hello
+                                hello hello hello hello hello hello hello hello
+                                hello hello hello hello hello hello hello hello
+                                hello hello hello hello hello hello hello hello
+                                hello hello hello hello hello hello hello hello
+                                hello hello hello hello hello hello hello hello
+                                hello hello hello hello hello hello hello hello
+                                hello hello hello hello hello hello hello hel
+
+                                world
+                              indent:
+                                indent:
+                                  indent:
+                                    indent:
+                                      indent:
+                                        ind: >
+                                          lo hello hello hello hello hello hello
+                                          hello hello hello hello hello hello hello
+                                          hello hello hello hello hello hello hello
+                                          hello hello hello hello hello hello hello
+                                          hello hello hello hello hello hello hello
+                                          hello hello hello hello hello hello hello
+                                          hello hello hello hello hello hello hello
+                                          hello hello hello hello hello hello hello
+                                          hello hello hello hello hello hello hello
+                                          hello hello hello hello hello hello hello
+                                          hello hello hello hello hello hello hello
+                                          hello hello hel
+
+                                          world
+                                        indent:
+                                          indent:
+                                            indent:
+                                              indent:
+                                                indent:
+                                                  ind: >
+                                                    lo hello hello hello hello hello hello
+                                                    hello hello hello hello hello hello hello
+                                                    hello hello hello hello hello hello hello
+                                                    hello hello hello hello hello hello hello
+                                                    hello hello hello hello hello hello hello
+                                                    hello hello hello hello hello hello hello
+                                                    hello hello hello hello hello hello hello
+                                                    hello hello hello hello hello hello hello
+                                                    hello hello hello hello hello hello hello
+                                                    hello hello hello hello hello hello hello
+                                                    hello hello hello hello hello hello hello
+                                                    hello hello hel
+
+                                                    world
+                                                  indent:
+                                                    indent:
+                                                      indent:
+                                                        indent:
+                                                          indent:
+                                                            ind: >
+                                                              lo hello hello hello hello hello hello
+                                                              hello hello hello hello hello hello hello
+                                                              hello hello hello hello hello hello hello
+                                                              hello hello hello hello hello hello hello
+                                                              hello hello hello hello hello hello hello
+                                                              hello hello hello hello hello hello hello
+                                                              hello hello hello hello hello hello hello
+                                                              hello hello hello hello hello hello hello
+                                                              hello hello hello hello hello hello hello
+                                                              hello hello hello hello hello hello hello
+                                                              hello hello hello hello hello hello hello
+                                                              hello hello hel
+
+                                                              world
diff --git a/encoding/yaml/__test__/samples-common/construct-timestamp.js b/encoding/yaml/__test__/samples-common/construct-timestamp.js
new file mode 100644
index 000000000000..4590a309696c
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-timestamp.js
@@ -0,0 +1,12 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  canonical:        new Date(Date.UTC(2001, 11, 15, 2, 59, 43, 100)),
+  'valid iso8601':    new Date(Date.UTC(2001, 11, 15, 2, 59, 43, 100)),
+  'space separated':  new Date(Date.UTC(2001, 11, 15, 2, 59, 43, 100)),
+  'no time zone (Z)': new Date(Date.UTC(2001, 11, 15, 2, 59, 43, 100)),
+  'date (00:00:00Z)': new Date(Date.UTC(2002, 11, 14)),
+  'not a date': '2002-1-1'
+};
diff --git a/encoding/yaml/__test__/samples-common/construct-timestamp.yml b/encoding/yaml/__test__/samples-common/construct-timestamp.yml
new file mode 100644
index 000000000000..7cd9ac6bd1ce
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-timestamp.yml
@@ -0,0 +1,6 @@
+canonical:        2001-12-15T02:59:43.1Z
+valid iso8601:    2001-12-14t21:59:43.10-05:00
+space separated:  2001-12-14 21:59:43.10 -5
+no time zone (Z): 2001-12-15 2:59:43.10
+date (00:00:00Z): 2002-12-14
+not a date:       2002-1-1
diff --git a/encoding/yaml/__test__/samples-common/construct-value.js b/encoding/yaml/__test__/samples-common/construct-value.js
new file mode 100644
index 000000000000..192a0086642d
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-value.js
@@ -0,0 +1,18 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = [
+  {
+    'link with': [
+      'library1.dll',
+      'library2.dll'
+    ]
+  },
+  {
+    'link with': [
+      { '=': 'library1.dll', version: 1.2 },
+      { '=': 'library2.dll', version: 2.3 }
+    ]
+  }
+];
diff --git a/encoding/yaml/__test__/samples-common/construct-value.yml b/encoding/yaml/__test__/samples-common/construct-value.yml
new file mode 100644
index 000000000000..3eb79198889e
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/construct-value.yml
@@ -0,0 +1,10 @@
+---     # Old schema
+link with:
+  - library1.dll
+  - library2.dll
+---     # New schema
+link with:
+  - = : library1.dll
+    version: 1.2
+  - = : library2.dll
+    version: 2.3
diff --git a/encoding/yaml/__test__/samples-common/dump-empty-collections.js b/encoding/yaml/__test__/samples-common/dump-empty-collections.js
new file mode 100644
index 000000000000..5e36090086f7
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/dump-empty-collections.js
@@ -0,0 +1,8 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  emptyArray:  [],
+  emptyObject: {}
+};
diff --git a/encoding/yaml/__test__/samples-common/dump-empty-collections.yml b/encoding/yaml/__test__/samples-common/dump-empty-collections.yml
new file mode 100644
index 000000000000..69575751898c
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/dump-empty-collections.yml
@@ -0,0 +1,2 @@
+emptyArray:  []
+emptyObject: {}
diff --git a/encoding/yaml/__test__/samples-common/duplicate-mapping-key.js b/encoding/yaml/__test__/samples-common/duplicate-mapping-key.js
new file mode 100644
index 000000000000..9902c59acea3
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/duplicate-mapping-key.js
@@ -0,0 +1,10 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  foo: {
+    baz: 'bat',
+    foo: 'duplicate key'
+  }
+};
diff --git a/encoding/yaml/__test__/samples-common/duplicate-mapping-key.yml b/encoding/yaml/__test__/samples-common/duplicate-mapping-key.yml
new file mode 100644
index 000000000000..e2b22b397f62
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/duplicate-mapping-key.yml
@@ -0,0 +1,3 @@
+foo:
+  baz: bat
+  foo: duplicate key
diff --git a/encoding/yaml/__test__/samples-common/duplicate-merge-key.js b/encoding/yaml/__test__/samples-common/duplicate-merge-key.js
new file mode 100644
index 000000000000..0fb70b7e6e03
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/duplicate-merge-key.js
@@ -0,0 +1,11 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = {
+  x: 1,
+  y: 2,
+  foo: 'bar',
+  z: 3,
+  t: 4
+};
diff --git a/encoding/yaml/__test__/samples-common/duplicate-merge-key.yml b/encoding/yaml/__test__/samples-common/duplicate-merge-key.yml
new file mode 100644
index 000000000000..cebc3a18c48f
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/duplicate-merge-key.yml
@@ -0,0 +1,4 @@
+---
+<<: {x: 1, y: 2}
+foo: bar
+<<: {z: 3, t: 4}
diff --git a/encoding/yaml/__test__/samples-common/emitting-unacceptable-unicode-character-bug.js b/encoding/yaml/__test__/samples-common/emitting-unacceptable-unicode-character-bug.js
new file mode 100644
index 000000000000..ce802314d387
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/emitting-unacceptable-unicode-character-bug.js
@@ -0,0 +1,5 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = '\udd00';
diff --git a/encoding/yaml/__test__/samples-common/emitting-unacceptable-unicode-character-bug.yml b/encoding/yaml/__test__/samples-common/emitting-unacceptable-unicode-character-bug.yml
new file mode 100644
index 000000000000..2a5df00dfa5c
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/emitting-unacceptable-unicode-character-bug.yml
@@ -0,0 +1 @@
+"\udd00"
diff --git a/encoding/yaml/__test__/samples-common/invalid-single-quote-bug.js b/encoding/yaml/__test__/samples-common/invalid-single-quote-bug.js
new file mode 100644
index 000000000000..e4fdddd80c45
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/invalid-single-quote-bug.js
@@ -0,0 +1,8 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = [
+  "foo 'bar'",
+  "foo\n'bar'"
+];
diff --git a/encoding/yaml/__test__/samples-common/invalid-single-quote-bug.yml b/encoding/yaml/__test__/samples-common/invalid-single-quote-bug.yml
new file mode 100644
index 000000000000..76ef7ae30b0f
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/invalid-single-quote-bug.yml
@@ -0,0 +1,2 @@
+- "foo 'bar'"
+- "foo\n'bar'"
diff --git a/encoding/yaml/__test__/samples-common/more-floats.js b/encoding/yaml/__test__/samples-common/more-floats.js
new file mode 100644
index 000000000000..6f3c2e570f95
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/more-floats.js
@@ -0,0 +1,31 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+
+var expected = [
+  0.0,
+  1.0,
+  -1.0,
+  Number.POSITIVE_INFINITY,
+  Number.NEGATIVE_INFINITY,
+  NaN,
+  NaN
+];
+
+function testHandler(actual) {
+  assert.strictEqual(Object.prototype.toString.call(actual), '[object Array]');
+  assert.strictEqual(actual.length, 7);
+  assert.strictEqual(actual[0], expected[0]);
+  assert.strictEqual(actual[1], expected[1]);
+  assert.strictEqual(actual[2], expected[2]);
+  assert.strictEqual(actual[3], expected[3]);
+  assert.strictEqual(actual[4], expected[4]);
+  assert(Number.isNaN(actual[5]));
+  assert(Number.isNaN(actual[6]));
+}
+
+testHandler.expected = expected;
+
+module.exports = testHandler;
diff --git a/encoding/yaml/__test__/samples-common/more-floats.yml b/encoding/yaml/__test__/samples-common/more-floats.yml
new file mode 100644
index 000000000000..399eb177b6e6
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/more-floats.yml
@@ -0,0 +1 @@
+[0.0, +1.0, -1.0, +.inf, -.inf, .nan, .nan]
diff --git a/encoding/yaml/__test__/samples-common/negative-float-bug.js b/encoding/yaml/__test__/samples-common/negative-float-bug.js
new file mode 100644
index 000000000000..b65ec48c0faa
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/negative-float-bug.js
@@ -0,0 +1,5 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = -1.0;
diff --git a/encoding/yaml/__test__/samples-common/negative-float-bug.yml b/encoding/yaml/__test__/samples-common/negative-float-bug.yml
new file mode 100644
index 000000000000..18e16e38c5de
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/negative-float-bug.yml
@@ -0,0 +1 @@
+-1.0
diff --git a/encoding/yaml/__test__/samples-common/single-dot-is-not-float-bug.js b/encoding/yaml/__test__/samples-common/single-dot-is-not-float-bug.js
new file mode 100644
index 000000000000..0fd08d34b67e
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/single-dot-is-not-float-bug.js
@@ -0,0 +1,5 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = '.';
diff --git a/encoding/yaml/__test__/samples-common/single-dot-is-not-float-bug.yml b/encoding/yaml/__test__/samples-common/single-dot-is-not-float-bug.yml
new file mode 100644
index 000000000000..9c558e357c41
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/single-dot-is-not-float-bug.yml
@@ -0,0 +1 @@
+.
diff --git a/encoding/yaml/__test__/samples-common/timestamp-bugs.js b/encoding/yaml/__test__/samples-common/timestamp-bugs.js
new file mode 100644
index 000000000000..8d378934c854
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/timestamp-bugs.js
@@ -0,0 +1,12 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = [
+  new Date(Date.UTC(2001, 11, 15, 3, 29, 43, 100)),
+  new Date(Date.UTC(2001, 11, 14, 16, 29, 43, 100)),
+  new Date(Date.UTC(2001, 11, 14, 21, 59, 43, 1)),
+  new Date(Date.UTC(2001, 11, 14, (21 - 1), 59, 43, 0)),
+  new Date(Date.UTC(2001, 11, 14, (21 + 1), (59 + 30), 43, 0)),
+  new Date(Date.UTC(2005, 6, 8, 17, 35, 4, 517))
+];
diff --git a/encoding/yaml/__test__/samples-common/timestamp-bugs.yml b/encoding/yaml/__test__/samples-common/timestamp-bugs.yml
new file mode 100644
index 000000000000..721d290820ce
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/timestamp-bugs.yml
@@ -0,0 +1,6 @@
+- 2001-12-14 21:59:43.10 -5:30
+- 2001-12-14 21:59:43.10 +5:30
+- 2001-12-14 21:59:43.00101
+- 2001-12-14 21:59:43+1
+- 2001-12-14 21:59:43-1:30
+- 2005-07-08 17:35:04.517600
diff --git a/encoding/yaml/__test__/samples-common/utf8-implicit.js b/encoding/yaml/__test__/samples-common/utf8-implicit.js
new file mode 100644
index 000000000000..33f04ea54784
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/utf8-implicit.js
@@ -0,0 +1,5 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = 'implicit UTF-8';
diff --git a/encoding/yaml/__test__/samples-common/utf8-implicit.yml b/encoding/yaml/__test__/samples-common/utf8-implicit.yml
new file mode 100644
index 000000000000..9d8081e9e89c
--- /dev/null
+++ b/encoding/yaml/__test__/samples-common/utf8-implicit.yml
@@ -0,0 +1 @@
+--- implicit UTF-8
diff --git a/encoding/yaml/__test__/samples-load-errors/a-nasty-libyaml-bug.yml b/encoding/yaml/__test__/samples-load-errors/a-nasty-libyaml-bug.yml
new file mode 100644
index 000000000000..f97d49f85edc
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/a-nasty-libyaml-bug.yml
@@ -0,0 +1 @@
+[ [
\ No newline at end of file
diff --git a/encoding/yaml/__test__/samples-load-errors/document-separator-in-quoted-scalar.yml b/encoding/yaml/__test__/samples-load-errors/document-separator-in-quoted-scalar.yml
new file mode 100644
index 000000000000..9eeb0d6fdd7d
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/document-separator-in-quoted-scalar.yml
@@ -0,0 +1,11 @@
+---
+"this --- is correct"
+---
+"this
+...is also
+correct"
+---
+"a quoted scalar
+cannot contain
+---
+document separators"
diff --git a/encoding/yaml/__test__/samples-load-errors/duplicate-key.js b/encoding/yaml/__test__/samples-load-errors/duplicate-key.js
new file mode 100644
index 000000000000..3fa97b044082
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/duplicate-key.js
@@ -0,0 +1,5 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = { foo: 'baz' };
diff --git a/encoding/yaml/__test__/samples-load-errors/duplicate-key.yml b/encoding/yaml/__test__/samples-load-errors/duplicate-key.yml
new file mode 100644
index 000000000000..84deb8f20a82
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/duplicate-key.yml
@@ -0,0 +1,3 @@
+---
+foo: bar
+foo: baz
diff --git a/encoding/yaml/__test__/samples-load-errors/duplicate-tag-directive.yml b/encoding/yaml/__test__/samples-load-errors/duplicate-tag-directive.yml
new file mode 100644
index 000000000000..50c81a06a017
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/duplicate-tag-directive.yml
@@ -0,0 +1,3 @@
+%TAG    !foo!   bar
+%TAG    !foo!   baz
+--- foo
diff --git a/encoding/yaml/__test__/samples-load-errors/duplicate-value-key.js b/encoding/yaml/__test__/samples-load-errors/duplicate-value-key.js
new file mode 100644
index 000000000000..0801e502962a
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/duplicate-value-key.js
@@ -0,0 +1,5 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+module.exports = { foo: 'bar', '=': 2 };
diff --git a/encoding/yaml/__test__/samples-load-errors/duplicate-value-key.yml b/encoding/yaml/__test__/samples-load-errors/duplicate-value-key.yml
new file mode 100644
index 000000000000..b34a1d6988a1
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/duplicate-value-key.yml
@@ -0,0 +1,4 @@
+---
+=: 1
+foo: bar
+=: 2
diff --git a/encoding/yaml/__test__/samples-load-errors/duplicate-yaml-directive.yml b/encoding/yaml/__test__/samples-load-errors/duplicate-yaml-directive.yml
new file mode 100644
index 000000000000..9b723905f3bc
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/duplicate-yaml-directive.yml
@@ -0,0 +1,3 @@
+%YAML   1.1
+%YAML   1.1
+--- foo
diff --git a/encoding/yaml/__test__/samples-load-errors/expected-mapping.yml b/encoding/yaml/__test__/samples-load-errors/expected-mapping.yml
new file mode 100644
index 000000000000..82aed98aa4a2
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/expected-mapping.yml
@@ -0,0 +1 @@
+--- !!map [not, a, map]
diff --git a/encoding/yaml/__test__/samples-load-errors/expected-scalar.yml b/encoding/yaml/__test__/samples-load-errors/expected-scalar.yml
new file mode 100644
index 000000000000..7b3171e88bef
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/expected-scalar.yml
@@ -0,0 +1 @@
+--- !!str [not a scalar]
diff --git a/encoding/yaml/__test__/samples-load-errors/expected-sequence.yml b/encoding/yaml/__test__/samples-load-errors/expected-sequence.yml
new file mode 100644
index 000000000000..08074ea52669
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/expected-sequence.yml
@@ -0,0 +1 @@
+--- !!seq {foo, bar, baz}
diff --git a/encoding/yaml/__test__/samples-load-errors/fetch-complex-value-bug.yml b/encoding/yaml/__test__/samples-load-errors/fetch-complex-value-bug.yml
new file mode 100644
index 000000000000..25fac24e62b9
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/fetch-complex-value-bug.yml
@@ -0,0 +1,2 @@
+? "foo"
+ : "bar"
diff --git a/encoding/yaml/__test__/samples-load-errors/forbidden-entry.yml b/encoding/yaml/__test__/samples-load-errors/forbidden-entry.yml
new file mode 100644
index 000000000000..f2e307962480
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/forbidden-entry.yml
@@ -0,0 +1,2 @@
+test: - foo
+      - bar
diff --git a/encoding/yaml/__test__/samples-load-errors/forbidden-key.yml b/encoding/yaml/__test__/samples-load-errors/forbidden-key.yml
new file mode 100644
index 000000000000..da9b471ddfaa
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/forbidden-key.yml
@@ -0,0 +1,2 @@
+test: ? foo
+      : bar
diff --git a/encoding/yaml/__test__/samples-load-errors/forbidden-value.yml b/encoding/yaml/__test__/samples-load-errors/forbidden-value.yml
new file mode 100644
index 000000000000..efd7ce583ddf
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/forbidden-value.yml
@@ -0,0 +1 @@
+test: key: value
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-anchor-2.yml b/encoding/yaml/__test__/samples-load-errors/invalid-anchor-2.yml
new file mode 100644
index 000000000000..bfc4ff01f386
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-anchor-2.yml
@@ -0,0 +1,8 @@
+---
+- [
+    &correct foo,
+    *correct,
+    *correct]   # still correct
+- *correct: still correct
+- &correct-or-not[foo, bar]
+
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-base64-data-2.yml b/encoding/yaml/__test__/samples-load-errors/invalid-base64-data-2.yml
new file mode 100644
index 000000000000..2553a4f329b6
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-base64-data-2.yml
@@ -0,0 +1,2 @@
+--- !!binary
+    двоичные данные в base64
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-base64-data.yml b/encoding/yaml/__test__/samples-load-errors/invalid-base64-data.yml
new file mode 100644
index 000000000000..798abbae9afd
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-base64-data.yml
@@ -0,0 +1,2 @@
+--- !!binary
+    binary data encoded in base64 should be here.
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-block-scalar-indicator.yml b/encoding/yaml/__test__/samples-load-errors/invalid-block-scalar-indicator.yml
new file mode 100644
index 000000000000..16a6db1833cb
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-block-scalar-indicator.yml
@@ -0,0 +1,2 @@
+--- > what is this?  # a comment
+data
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-character.yml b/encoding/yaml/__test__/samples-load-errors/invalid-character.yml
new file mode 100644
index 000000000000..03687b02d41c
Binary files /dev/null and b/encoding/yaml/__test__/samples-load-errors/invalid-character.yml differ
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-directive-line.yml b/encoding/yaml/__test__/samples-load-errors/invalid-directive-line.yml
new file mode 100644
index 000000000000..0892eb66dde8
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-directive-line.yml
@@ -0,0 +1,2 @@
+%YAML   1.1 ?   # extra symbol
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-directive-name-1.yml b/encoding/yaml/__test__/samples-load-errors/invalid-directive-name-1.yml
new file mode 100644
index 000000000000..153fd889aedf
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-directive-name-1.yml
@@ -0,0 +1,2 @@
+%   # no name at all
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-directive-name-2.yml b/encoding/yaml/__test__/samples-load-errors/invalid-directive-name-2.yml
new file mode 100644
index 000000000000..3732a06a34aa
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-directive-name-2.yml
@@ -0,0 +1,2 @@
+%invalid-characters:in-directive name
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-escape-character.yml b/encoding/yaml/__test__/samples-load-errors/invalid-escape-character.yml
new file mode 100644
index 000000000000..a95ab7678642
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-escape-character.yml
@@ -0,0 +1 @@
+"some escape characters are \ncorrect, but this one \?\nis not\n"
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-escape-numbers.yml b/encoding/yaml/__test__/samples-load-errors/invalid-escape-numbers.yml
new file mode 100644
index 000000000000..614ec9f5ad7e
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-escape-numbers.yml
@@ -0,0 +1 @@
+"hm.... \u123?"
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-indentation-indicator-1.yml b/encoding/yaml/__test__/samples-load-errors/invalid-indentation-indicator-1.yml
new file mode 100644
index 000000000000..a3cd12f5fe5a
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-indentation-indicator-1.yml
@@ -0,0 +1,2 @@
+--- >0  # not valid
+data
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-indentation-indicator-2.yml b/encoding/yaml/__test__/samples-load-errors/invalid-indentation-indicator-2.yml
new file mode 100644
index 000000000000..eefb6ecd2950
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-indentation-indicator-2.yml
@@ -0,0 +1,2 @@
+--- >-0
+data
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-item-without-trailing-break.yml b/encoding/yaml/__test__/samples-load-errors/invalid-item-without-trailing-break.yml
new file mode 100644
index 000000000000..fdcf6c6b77a3
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-item-without-trailing-break.yml
@@ -0,0 +1,2 @@
+-
+-0
\ No newline at end of file
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-merge-1.yml b/encoding/yaml/__test__/samples-load-errors/invalid-merge-1.yml
new file mode 100644
index 000000000000..fc3c2844d9b4
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-merge-1.yml
@@ -0,0 +1,2 @@
+foo: bar
+<<: baz
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-merge-2.yml b/encoding/yaml/__test__/samples-load-errors/invalid-merge-2.yml
new file mode 100644
index 000000000000..8e88615c5945
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-merge-2.yml
@@ -0,0 +1,2 @@
+foo: bar
+<<: [x: 1, y: 2, z, t: 4]
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-omap-1.yml b/encoding/yaml/__test__/samples-load-errors/invalid-omap-1.yml
new file mode 100644
index 000000000000..28633926e16f
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-omap-1.yml
@@ -0,0 +1,3 @@
+--- !!omap
+foo: bar
+baz: bat
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-omap-2.yml b/encoding/yaml/__test__/samples-load-errors/invalid-omap-2.yml
new file mode 100644
index 000000000000..c377dfb81ab9
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-omap-2.yml
@@ -0,0 +1,3 @@
+--- !!omap
+- foo: bar
+- baz
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-omap-3.yml b/encoding/yaml/__test__/samples-load-errors/invalid-omap-3.yml
new file mode 100644
index 000000000000..2a4f50d9846a
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-omap-3.yml
@@ -0,0 +1,4 @@
+--- !!omap
+- foo: bar
+- baz: bar
+  bar: bar
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-pairs-1.yml b/encoding/yaml/__test__/samples-load-errors/invalid-pairs-1.yml
new file mode 100644
index 000000000000..42d19aecfcc9
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-pairs-1.yml
@@ -0,0 +1,3 @@
+--- !!pairs
+foo: bar
+baz: bat
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-pairs-2.yml b/encoding/yaml/__test__/samples-load-errors/invalid-pairs-2.yml
new file mode 100644
index 000000000000..31389eaeb247
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-pairs-2.yml
@@ -0,0 +1,3 @@
+--- !!pairs
+- foo: bar
+- baz
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-pairs-3.yml b/encoding/yaml/__test__/samples-load-errors/invalid-pairs-3.yml
new file mode 100644
index 000000000000..f8d7704edff6
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-pairs-3.yml
@@ -0,0 +1,4 @@
+--- !!pairs
+- foo: bar
+- baz: bar
+  bar: bar
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-simple-key.yml b/encoding/yaml/__test__/samples-load-errors/invalid-simple-key.yml
new file mode 100644
index 000000000000..a58deecf9762
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-simple-key.yml
@@ -0,0 +1,3 @@
+key: value
+invalid simple key
+next key: next value
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-starting-character.yml b/encoding/yaml/__test__/samples-load-errors/invalid-starting-character.yml
new file mode 100644
index 000000000000..bb81c60ce9ea
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-starting-character.yml
@@ -0,0 +1 @@
+@@@@@@@@@@@@@@@@@@@
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-tag-2.yml b/encoding/yaml/__test__/samples-load-errors/invalid-tag-2.yml
new file mode 100644
index 000000000000..3a36700a450d
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-tag-2.yml
@@ -0,0 +1 @@
+- !prefix!foo#bar baz
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-tag-directive-handle.yml b/encoding/yaml/__test__/samples-load-errors/invalid-tag-directive-handle.yml
new file mode 100644
index 000000000000..42b5d7e99ec6
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-tag-directive-handle.yml
@@ -0,0 +1,2 @@
+%TAG !!! !!!
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-tag-handle-1.yml b/encoding/yaml/__test__/samples-load-errors/invalid-tag-handle-1.yml
new file mode 100644
index 000000000000..ef0d1430f46b
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-tag-handle-1.yml
@@ -0,0 +1,2 @@
+%TAG    foo bar
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-tag-handle-2.yml b/encoding/yaml/__test__/samples-load-errors/invalid-tag-handle-2.yml
new file mode 100644
index 000000000000..06c7f0e47b48
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-tag-handle-2.yml
@@ -0,0 +1,2 @@
+%TAG    !foo    bar
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-uri-escapes-1.yml b/encoding/yaml/__test__/samples-load-errors/invalid-uri-escapes-1.yml
new file mode 100644
index 000000000000..a6ecb36a6c0a
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-uri-escapes-1.yml
@@ -0,0 +1 @@
+--- !<tag:%x?y> foo
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-uri.yml b/encoding/yaml/__test__/samples-load-errors/invalid-uri.yml
new file mode 100644
index 000000000000..06307e06a1d3
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-uri.yml
@@ -0,0 +1 @@
+--- !foo!   bar
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-1.yml b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-1.yml
new file mode 100644
index 000000000000..e9b4e3a67f78
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-1.yml
@@ -0,0 +1,3 @@
+# No version at all.
+%YAML
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-2.yml b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-2.yml
new file mode 100644
index 000000000000..6aa7740e97a2
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-2.yml
@@ -0,0 +1,2 @@
+%YAML   1e-5
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-3.yml b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-3.yml
new file mode 100644
index 000000000000..345e7842d4a3
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-3.yml
@@ -0,0 +1,2 @@
+%YAML 1.
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-4.yml b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-4.yml
new file mode 100644
index 000000000000..b35ca820b0d2
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-4.yml
@@ -0,0 +1,2 @@
+%YAML 1.132.435
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-5.yml b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-5.yml
new file mode 100644
index 000000000000..7c2b49f5f09c
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-5.yml
@@ -0,0 +1,2 @@
+%YAML A.0
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-6.yml b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-6.yml
new file mode 100644
index 000000000000..bae714fcea6e
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-directive-version-6.yml
@@ -0,0 +1,2 @@
+%YAML 123.C
+---
diff --git a/encoding/yaml/__test__/samples-load-errors/invalid-yaml-version.yml b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-version.yml
new file mode 100644
index 000000000000..dd019488b8c8
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/invalid-yaml-version.yml
@@ -0,0 +1,2 @@
+%YAML   2.0
+--- foo
diff --git a/encoding/yaml/__test__/samples-load-errors/no-block-collection-end.yml b/encoding/yaml/__test__/samples-load-errors/no-block-collection-end.yml
new file mode 100644
index 000000000000..02d4d377832d
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/no-block-collection-end.yml
@@ -0,0 +1,3 @@
+- foo
+- bar
+baz: bar
diff --git a/encoding/yaml/__test__/samples-load-errors/no-block-mapping-end-2.yml b/encoding/yaml/__test__/samples-load-errors/no-block-mapping-end-2.yml
new file mode 100644
index 000000000000..be63571f5127
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/no-block-mapping-end-2.yml
@@ -0,0 +1,3 @@
+? foo
+: bar
+: baz
diff --git a/encoding/yaml/__test__/samples-load-errors/no-block-mapping-end.yml b/encoding/yaml/__test__/samples-load-errors/no-block-mapping-end.yml
new file mode 100644
index 000000000000..1ea921cf8d07
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/no-block-mapping-end.yml
@@ -0,0 +1 @@
+foo: "bar" "baz"
diff --git a/encoding/yaml/__test__/samples-load-errors/no-document-start.yml b/encoding/yaml/__test__/samples-load-errors/no-document-start.yml
new file mode 100644
index 000000000000..c725ec8b6b53
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/no-document-start.yml
@@ -0,0 +1,3 @@
+%YAML   1.1
+# no ---
+foo: bar
diff --git a/encoding/yaml/__test__/samples-load-errors/no-flow-mapping-end.yml b/encoding/yaml/__test__/samples-load-errors/no-flow-mapping-end.yml
new file mode 100644
index 000000000000..8bd1403fdcd2
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/no-flow-mapping-end.yml
@@ -0,0 +1 @@
+{ foo: bar ]
diff --git a/encoding/yaml/__test__/samples-load-errors/no-flow-sequence-end.yml b/encoding/yaml/__test__/samples-load-errors/no-flow-sequence-end.yml
new file mode 100644
index 000000000000..750d973b42c1
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/no-flow-sequence-end.yml
@@ -0,0 +1 @@
+[foo, bar}
diff --git a/encoding/yaml/__test__/samples-load-errors/no-node-1.yml b/encoding/yaml/__test__/samples-load-errors/no-node-1.yml
new file mode 100644
index 000000000000..07b15009842b
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/no-node-1.yml
@@ -0,0 +1 @@
+- !foo ]
diff --git a/encoding/yaml/__test__/samples-load-errors/no-node-2.yml b/encoding/yaml/__test__/samples-load-errors/no-node-2.yml
new file mode 100644
index 000000000000..563e3b341bae
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/no-node-2.yml
@@ -0,0 +1 @@
+- [ !foo } ]
diff --git a/encoding/yaml/__test__/samples-load-errors/remove-possible-simple-key-bug.yml b/encoding/yaml/__test__/samples-load-errors/remove-possible-simple-key-bug.yml
new file mode 100644
index 000000000000..fe1bc6c502aa
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/remove-possible-simple-key-bug.yml
@@ -0,0 +1,3 @@
+foo: &A bar
+*A ]    # The ']' indicator triggers remove_possible_simple_key,
+        # which should raise an error.
diff --git a/encoding/yaml/__test__/samples-load-errors/unclosed-bracket.yml b/encoding/yaml/__test__/samples-load-errors/unclosed-bracket.yml
new file mode 100644
index 000000000000..8c820777f6b8
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/unclosed-bracket.yml
@@ -0,0 +1,6 @@
+test:
+    - [ foo: bar
+# comment the rest of the stream to let the scanner detect the problem.
+#    - baz
+#"we could have detected the unclosed bracket on the above line, but this would forbid such syntax as": {
+#}
diff --git a/encoding/yaml/__test__/samples-load-errors/unclosed-quoted-scalar.yml b/encoding/yaml/__test__/samples-load-errors/unclosed-quoted-scalar.yml
new file mode 100644
index 000000000000..85374294d11b
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/unclosed-quoted-scalar.yml
@@ -0,0 +1,2 @@
+'foo
+ bar
diff --git a/encoding/yaml/__test__/samples-load-errors/undefined-anchor.yml b/encoding/yaml/__test__/samples-load-errors/undefined-anchor.yml
new file mode 100644
index 000000000000..94691032f949
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/undefined-anchor.yml
@@ -0,0 +1,3 @@
+- foo
+- &bar baz
+- *bat
diff --git a/encoding/yaml/__test__/samples-load-errors/undefined-tag-handle.yml b/encoding/yaml/__test__/samples-load-errors/undefined-tag-handle.yml
new file mode 100644
index 000000000000..82ba335c6d71
--- /dev/null
+++ b/encoding/yaml/__test__/samples-load-errors/undefined-tag-handle.yml
@@ -0,0 +1 @@
+--- !foo!bar    baz
diff --git a/encoding/yaml/__test__/support/schema.js b/encoding/yaml/__test__/support/schema.js
new file mode 100644
index 000000000000..0c63b15feebc
--- /dev/null
+++ b/encoding/yaml/__test__/support/schema.js
@@ -0,0 +1,115 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var util = require('util');
+var yaml = require('../../lib/js-yaml');
+
+
+function Tag1(parameters) {
+  this.x = parameters.x;
+  this.y = parameters.y || 0;
+  this.z = parameters.z || 0;
+}
+
+
+function Tag2() {
+  Tag1.apply(this, arguments);
+}
+util.inherits(Tag2, Tag1);
+
+
+function Tag3() {
+  Tag2.apply(this, arguments);
+}
+util.inherits(Tag3, Tag2);
+
+
+function Foo(parameters) {
+  this.myParameter        = parameters.myParameter;
+  this.myAnotherParameter = parameters.myAnotherParameter;
+}
+
+
+var TEST_SCHEMA = yaml.Schema.create([
+  // NOTE: Type order matters!
+  // Inherited classes must precede their parents because the dumper
+  // doesn't inspect class inheritance and just picks first suitable
+  // class from this array.
+  new yaml.Type('!tag3', {
+    kind: 'mapping',
+    resolve: function (data) {
+      if (data === null) return false;
+      if (!Object.prototype.hasOwnProperty.call(data, '=') &&
+          !Object.prototype.hasOwnProperty.call(data, 'x')) {
+        return false;
+      }
+      if (!Object.keys(data).every(function (k) { return k === '=' || k === 'x' || k === 'y' || k === 'z'; })) {
+        return false;
+      }
+      return true;
+    },
+    construct: function (data) {
+      return new Tag3({ x: (data['='] || data.x), y: data.y, z: data.z });
+    },
+    instanceOf: Tag3,
+    represent: function (object) {
+      return { '=': object.x, y: object.y, z: object.z };
+    }
+  }),
+  new yaml.Type('!tag2', {
+    kind: 'scalar',
+    construct: function (data) {
+      return new Tag2({ x: (typeof data === 'number') ? data : parseInt(data, 10) });
+    },
+    instanceOf: Tag2,
+    represent: function (object) {
+      return String(object.x);
+    }
+  }),
+  new yaml.Type('!tag1', {
+    kind: 'mapping',
+    resolve: function (data) {
+      if (data === null) return false;
+      if (!Object.prototype.hasOwnProperty.call(data, 'x')) return false;
+      if (!Object.keys(data).every(function (k) { return k === 'x' || k === 'y' || k === 'z'; })) {
+        return false;
+      }
+      return true;
+    },
+    construct: function (data) {
+      return new Tag1({ x: data.x, y: data.y, z: data.z });
+    },
+    instanceOf: Tag1
+  }),
+  new yaml.Type('!foo', {
+    kind: 'mapping',
+    resolve: function (data) {
+      if (data === null) return false;
+      if (!Object.keys(data).every(function (k) { return k === 'my-parameter' || k === 'my-another-parameter'; })) {
+        return false;
+      }
+      return true;
+    },
+    construct: function (data) {
+      return new Foo({
+        myParameter:        data['my-parameter'],
+        myAnotherParameter: data['my-another-parameter']
+      });
+    },
+    instanceOf: Foo,
+    represent: function (object) {
+      return {
+        'my-parameter':         object.myParameter,
+        'my-another-parameter': object.myAnotherParameter
+      };
+    }
+  })
+]);
+
+
+module.exports.Tag1 = Tag1;
+module.exports.Tag2 = Tag2;
+module.exports.Tag3 = Tag3;
+module.exports.Foo = Foo;
+module.exports.TEST_SCHEMA = TEST_SCHEMA;
diff --git a/encoding/yaml/__test__/units/alias-nodes.js b/encoding/yaml/__test__/units/alias-nodes.js
new file mode 100644
index 000000000000..ea8069053fb7
--- /dev/null
+++ b/encoding/yaml/__test__/units/alias-nodes.js
@@ -0,0 +1,66 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../lib/js-yaml');
+
+
+function TestClass(data) {
+  var self = this;
+  Object.keys(data).forEach(function (key) { self[key] = data[key]; });
+}
+
+var TestClassYaml = new yaml.Type('!test', {
+  kind: 'mapping',
+  construct: function (data) { return new TestClass(data); }
+});
+
+var TEST_SCHEMA = yaml.Schema.create([ TestClassYaml ]);
+
+
+suite('Alias nodes', function () {
+  suite('Resolving of an alias node should result the resolved and contructed value of the anchored node', function () {
+    test('Simple built-in primitives', function () {
+      assert.strictEqual(yaml.load('[&1 "foobar", *1]')[1], 'foobar');
+      assert.strictEqual(yaml.load('[&1 ~, *1]')[1], null);
+      assert.strictEqual(yaml.load('[&1 true, *1]')[1], true);
+      assert.strictEqual(yaml.load('[&1 42, *1]')[1], 42);
+    });
+
+    test('Simple built-in objects', function () {
+      assert.deepEqual(yaml.load('[&1 [a, b, c, d], *1]')[1], [ 'a', 'b', 'c', 'd' ]);
+      assert.deepEqual(yaml.load('[&1 {a: b, c: d}, *1]')[1], { a: 'b', c: 'd' });
+    });
+
+    test('Recursive built-in objects', function () {
+      var actual = yaml.load('[&1 {self: *1}, *1]')[1];
+
+      assert(actual === actual.self);
+    });
+
+    test("JavaScript-specific objects (JS-YAML's own extension)", function () {
+      var actual = yaml.load('[&1 !!js/function "function sum(a, b) { return a + b }", *1]')[1];
+
+      assert.strictEqual(Object.prototype.toString.call(actual), '[object Function]');
+      assert.strictEqual(actual(10, 5), 15);
+    });
+
+    test('Simple custom objects', function () {
+      var expected = new TestClass({ a: 'b', c: 'd' }),
+          actual = yaml.load('[&1 !test {a: b, c: d}, *1]', { schema: TEST_SCHEMA })[1];
+
+      assert(actual instanceof TestClass);
+      assert.deepEqual(actual, expected);
+    });
+
+    // TODO: Not implemented yet (see issue #141)
+    test.skip('Recursive custom objects', function () {
+      var actual = yaml.load('[&1 !test {self: *1}, *1]', { schema: TEST_SCHEMA })[1];
+
+      assert(actual instanceof TestClass);
+      assert(actual.self instanceof TestClass);
+      assert(actual === actual.self);
+    });
+  });
+});
diff --git a/encoding/yaml/__test__/units/bom-strip.js b/encoding/yaml/__test__/units/bom-strip.js
new file mode 100644
index 000000000000..169abca0c7df
--- /dev/null
+++ b/encoding/yaml/__test__/units/bom-strip.js
@@ -0,0 +1,12 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('BOM strip', function () {
+  assert.deepEqual(yaml.safeLoad('\uFEFFfoo: bar\n'), { foo: 'bar' });
+  assert.deepEqual(yaml.safeLoad('foo: bar\n'), { foo: 'bar' });
+});
diff --git a/encoding/yaml/__test__/units/character-set.js b/encoding/yaml/__test__/units/character-set.js
new file mode 100644
index 000000000000..a94ea3183d60
--- /dev/null
+++ b/encoding/yaml/__test__/units/character-set.js
@@ -0,0 +1,29 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+
+test('Allow astral characters', function () {
+  assert.deepEqual(yaml.load('𝑘𝑒𝑦: 𝑣𝑎𝑙𝑢𝑒'), { '𝑘𝑒𝑦': '𝑣𝑎𝑙𝑢𝑒' });
+});
+
+test('Forbid non-printable characters', function () {
+  assert.throws(function () { yaml.load('\x01'); }, yaml.YAMLException);
+  assert.throws(function () { yaml.load('\x7f'); }, yaml.YAMLException);
+  assert.throws(function () { yaml.load('\x9f'); }, yaml.YAMLException);
+});
+
+test('Forbid lone surrogates', function () {
+  assert.throws(function () { yaml.load('\udc00\ud800'); }, yaml.YAMLException);
+});
+
+test('Allow non-printable characters inside quoted scalars', function () {
+  assert.strictEqual(yaml.load('"\x7f\x9f\udc00\ud800"'), '\x7f\x9f\udc00\ud800');
+});
+
+test('Forbid control sequences inside quoted scalars', function () {
+  assert.throws(function () { yaml.load('"\x03"'); }, yaml.YAMLException);
+});
diff --git a/encoding/yaml/__test__/units/dump-scalar-styles.js b/encoding/yaml/__test__/units/dump-scalar-styles.js
new file mode 100644
index 000000000000..fdd7cd1872ef
--- /dev/null
+++ b/encoding/yaml/__test__/units/dump-scalar-styles.js
@@ -0,0 +1,247 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../..');
+
+// Indents lines by 2 spaces. Empty lines (\n only) are not indented.
+function indent(string) {
+  return string.replace(/^.+/gm, '  ' + '$&');
+}
+
+function getLength(s) {
+  return s.length;
+}
+
+// Repeats a string n times.
+function repeat(string, n) {
+  return (new Array(n + 1)).join(string);
+}
+
+suite('Scalar style dump:', function () {
+
+  suite('Plain style', function () {
+    test('is preferred', function () {
+      [ 'plain',
+        'hello world',
+        'pizza 3.14159',
+        // cannot be misinterpreted as a number
+        '127.0.0.1',
+        // quotes are allowed after the first character
+        'quoted"scalar',
+        'here\'s to "quotes"',
+        // additional allowed characters
+        '100% safe non-first characters? Of course!',
+        'Jack & Jill <well@example.com>'
+      ].forEach(function (string) {
+        assert.strictEqual(yaml.safeDump(string), string + '\n');
+      });
+    });
+
+    test('disallows flow indicators inside flow collections', function () {
+      assert.strictEqual(yaml.safeDump({ quote: 'mispell [sic]' }, { flowLevel: 0 }),
+        "{quote: 'mispell [sic]'}\n");
+      assert.strictEqual(yaml.safeDump({ key: 'no commas, either' }, { flowLevel: 0 }),
+        "{key: 'no commas, either'}\n");
+    });
+  });
+
+  suite('Single- and double-quoted styles', function () {
+    test('quote strings of ambiguous type', function () {
+      assert.strictEqual(yaml.safeDump('Yes'), '\'Yes\'\n');
+      assert.strictEqual(yaml.safeDump('true'), '\'true\'\n');
+      assert.strictEqual(yaml.safeDump('42'), '\'42\'\n');
+      assert.strictEqual(yaml.safeDump('99.9'), '\'99.9\'\n');
+      assert.strictEqual(yaml.safeDump('127.0001'), '\'127.0001\'\n');
+      assert.strictEqual(yaml.safeDump('1.23015e+3'), '\'1.23015e+3\'\n');
+    });
+
+    test('quote leading/trailing whitespace', function () {
+      assert.strictEqual(yaml.safeDump(' leading space'), '\' leading space\'\n');
+      assert.strictEqual(yaml.safeDump('trailing space '), '\'trailing space \'\n');
+    });
+
+    test('quote leading quotes', function () {
+      assert.strictEqual(yaml.safeDump("'singles double'"), "'''singles double'''\n");
+      assert.strictEqual(yaml.safeDump('"single double'), '\'"single double\'\n');
+    });
+
+    test('escape \\ and " in double-quoted', function () {
+      assert.strictEqual(yaml.safeDump('\u0007 escape\\ escaper"'), '"\\a escape\\\\ escaper\\""\n');
+    });
+
+    test('escape non-printables', function () {
+      assert.strictEqual(yaml.safeDump('a\nb\u0001c'), '"a\\nb\\x01c"\n');
+    });
+  });
+
+  suite('Literal style', function () {
+    var content = 'a\nb \n\n c\n  d', indented = indent(content);
+
+    test('preserves trailing newlines using chomping', function () {
+      assert.strictEqual(yaml.safeDump({ a: '\n', b: '\n\n', c: 'c\n', d: 'd\nd' }),
+        'a: |+\n\nb: |+\n\n\nc: |\n  c\nd: |-\n  d\n  d\n');
+      assert.strictEqual(yaml.safeDump('\n'),               '|+\n' + '\n');
+      assert.strictEqual(yaml.safeDump('\n\n'),             '|+\n' + '\n\n');
+
+      assert.strictEqual(yaml.safeDump(content),            '|-\n' + indented + '\n');
+      assert.strictEqual(yaml.safeDump(content + '\n'),     '|\n'  + indented + '\n');
+      assert.strictEqual(yaml.safeDump(content + '\n\n'),   '|+\n' + indented + '\n\n');
+      assert.strictEqual(yaml.safeDump(content + '\n\n\n'), '|+\n' + indented + '\n\n\n');
+    });
+
+    test('accepts leading whitespace', function () {
+      assert.strictEqual(yaml.safeDump('   ' + content), '|2-\n   ' + indented + '\n');
+    });
+
+    test('falls back to quoting when required indent indicator is too large', function () {
+      assert.strictEqual(yaml.safeDump(' these go\nup to\neleven', { indent: 11 }),
+        '" these go\\nup to\\neleven"\n');
+    });
+
+    test('does not use block style for multiline key', function () {
+      assert.strictEqual(yaml.safeDump({
+        'push\nand': {
+          you: 'pull'
+        }
+      }), '"push\\nand":\n  you: pull\n');
+    });
+  });
+
+  suite('Folded style', function () {
+    (function () {
+      var content = (function () {
+        var result = '';
+        var i = 1000;
+        for (var para = 1; para <= 7; para++) {
+          result += '\n';
+          // indent paragraphs 3 and 4
+          if (para === 3 || para === 4) {
+            result += repeat(' ', para);
+          }
+          // vary the number of words on the last line
+          for (var count = 2 * (30 / 5) + para - 1; count > 0; count--) {
+            result += i + ' ';
+            if (i % 17 === 0) result += ' ';
+            i++;
+          }
+        }
+        return result;
+      }());
+      var wrapped = '\n' +
+        '1000 1001 1002 1003  1004 1005\n' +
+        '1006 1007 1008 1009 1010 1011 \n' +
+        '\n' +
+        '1012 1013 1014 1015 1016 1017\n' +
+        '1018 1019 1020  1021 1022 1023\n' +
+        '1024 \n' +
+        '   1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037  1038 \n' +
+        '    1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 \n' +
+        '1054  1055 1056 1057 1058 1059\n' +
+        '1060 1061 1062 1063 1064 1065\n' +
+        '1066 1067 1068 1069 \n' +
+        '\n' +
+        '1070 1071  1072 1073 1074 1075\n' +
+        '1076 1077 1078 1079 1080 1081\n' +
+        '1082 1083 1084 1085 1086 \n' +
+        '\n' +
+        '1087 1088  1089 1090 1091 1092\n' +
+        '1093 1094 1095 1096 1097 1098\n' +
+        '1099 1100 1101 1102 1103 1104 ';
+      var indented = indent(wrapped);
+
+      function dumpNarrow(s) {
+        return yaml.safeDump(s, { lineWidth: 30 + 2 });
+      }
+
+      test('wraps lines and ignores more-indented lines ', function () {
+        assert.strictEqual(dumpNarrow(content),            '>-\n' + indented + '\n');
+      });
+
+      test('preserves trailing newlines using chomping', function () {
+        assert.strictEqual(dumpNarrow(content + '\n'),     '>\n'  + indented + '\n');
+        assert.strictEqual(dumpNarrow(content + '\n\n'),   '>+\n' + indented + '\n\n');
+        assert.strictEqual(dumpNarrow(content + '\n\n\n'), '>+\n' + indented + '\n\n\n');
+      });
+    }());
+
+    // Dump and check that dump-then-load preserves content (is the identity function).
+    function dump(input, opts) {
+      var output = yaml.safeDump(input, opts);
+      assert.strictEqual(yaml.safeLoad(output), input, 'Dump then load should preserve content');
+      return output;
+    }
+
+    test('should not cut off a long word at the start of a line', function () {
+      assert.strictEqual(dump('123\n' + repeat('1234567890', 9) + ' hello\ngoodbye'),
+        '>-\n' + indent(
+          '123\n' +
+          '\n' +
+          repeat('1234567890', 9) + '\n' +
+          'hello\n' +
+          '\n' +
+          'goodbye\n'));
+    });
+
+    test('preserves consecutive spaces', function () {
+      var alphabet = 'a bc  def  ghi' + repeat(' ', 70) + 'jk  lmn o\n'
+        + ' p  qrstu     v' + repeat(' ', 80) + '\nw x\n' + 'yz  ';
+      assert.strictEqual(dump(alphabet),
+        '>-\n' + indent(
+          'a bc  def \n' +
+          'ghi' + repeat(' ', 70) + 'jk \n' +
+          'lmn o\n' +
+          ' p  qrstu     v' + repeat(' ', 80) + '\n' +
+          'w x\n' +
+          '\n' +
+          'yz  \n'));
+
+      var indeed = repeat('word. ', 31) + '\n' +
+        [ 2, 3, 5, 7, 11, 13, 17 ]
+          .map(function (n) { return repeat(' ', n); })
+          .join('\n');
+      assert.strictEqual(dump(indeed),
+        '>-\n' + indent(
+          'word. word. word. word. word. word. word. word. word. word. word. word. word.\n' +
+          'word. word. word. word. word. word. word. word. word. word. word. word. word.\n' +
+          'word. word. word. word. word. \n' +
+          [ 2, 3, 5, 7, 11, 13, 17 ]
+            .map(function (n) { return repeat(' ', n); })
+            .join('\n') + '\n'));
+    });
+
+    var story = 'Call me Ishmael. Some years ago—never mind how long precisely—'
+    + 'having little or no money in my purse, '
+    + 'and nothing particular to interest me on shore, '
+    + 'I thought I would sail about a little and see the watery part of the world...';
+    var prefix = 'var short_story = "",';
+    var line = 'longer_story = "' + story + '";';
+
+    test('should fold a long last line missing an ending newline', function () {
+      var content = [ prefix, line ].join('\n');
+
+      var lengths = dump(content).split('\n').map(getLength);
+      assert.deepEqual(lengths, [ 2, 23, 0, 69, 76, 80, 24, 0 ]);
+    });
+
+    test('should not fold a more-indented last line', function functionName() {
+      var content = [ prefix, line, '    ' + line ].join('\n');
+
+      var lengths = dump(content).split('\n').map(getLength);
+      assert.deepEqual(lengths, [ 2, 23, 0, 69, 76, 80, 24, 250, 0 ]);
+    });
+
+    test('should not fold when lineWidth === -1', function () {
+      var content = [ prefix, line, line + line, line ].join('\n');
+
+      assert.strictEqual(dump(content, { lineWidth: -1 }), '|-\n' + indent(content) + '\n');
+    });
+
+    test('falls back to literal style when no lines are foldable', function () {
+      var content = [ prefix, '    ' + line, '    ' + line ].join('\n');
+
+      assert.strictEqual(dump(content), '|-\n' + indent(content) + '\n');
+    });
+  });
+});
diff --git a/encoding/yaml/__test__/units/empty-node-resolving.js b/encoding/yaml/__test__/units/empty-node-resolving.js
new file mode 100644
index 000000000000..efc8836cd60b
--- /dev/null
+++ b/encoding/yaml/__test__/units/empty-node-resolving.js
@@ -0,0 +1,75 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../lib/js-yaml');
+
+
+suite('Resolving explicit tags on empty nodes', function () {
+  test('!!binary', function () {
+    assert.throws(function () { yaml.load('!!binary'); }, yaml.YAMLException);
+  });
+
+  test('!!bool', function () {
+    assert.throws(function () { yaml.load('!!bool'); }, yaml.YAMLException);
+  });
+
+  test('!!float', function () {
+    assert.throws(function () { yaml.load('!!float'); }, yaml.YAMLException);
+  });
+
+  test('!!int', function () {
+    assert.throws(function () { yaml.load('!!int'); }, yaml.YAMLException);
+  });
+
+  test('!!map', function () {
+    assert.deepEqual(yaml.load('!!map'), {});
+  });
+
+  test('!!merge', function () {
+    assert.doesNotThrow(function () { yaml.load('? !!merge\n: []'); });
+  });
+
+  test('!!null', function () {
+    // Fetch null from an array to reduce chance that null is returned because of another bug
+    assert.strictEqual(yaml.load('- !!null')[0], null);
+  });
+
+  test('!!omap', function () {
+    assert.deepEqual(yaml.load('!!omap'), []);
+  });
+
+  test('!!pairs', function () {
+    assert.deepEqual(yaml.load('!!pairs'), []);
+  });
+
+  test('!!seq', function () {
+    assert.deepEqual(yaml.load('!!seq'), []);
+  });
+
+  test('!!set', function () {
+    assert.deepEqual(yaml.load('!!set'), {});
+  });
+
+  test('!!str', function () {
+    assert.strictEqual(yaml.load('!!str'), '');
+  });
+
+  test('!!timestamp', function () {
+    assert.throws(function () { yaml.load('!!timestamp'); }, yaml.YAMLException);
+  });
+
+  test('!!js/function', function () {
+    assert.throws(function () { yaml.load('!!js/function'); }, yaml.YAMLException);
+  });
+
+  test('!!js/regexp', function () {
+    assert.throws(function () { yaml.load('!!js/regexp'); }, yaml.YAMLException);
+  });
+
+  test('!!js/undefined', function () {
+    // Fetch undefined from an array to reduce chance that undefined is returned because of another bug
+    assert.strictEqual(yaml.load('- !!js/undefined')[0], undefined);
+  });
+});
diff --git a/encoding/yaml/__test__/units/is-negative-zero.js b/encoding/yaml/__test__/units/is-negative-zero.js
new file mode 100644
index 000000000000..da78849237ef
--- /dev/null
+++ b/encoding/yaml/__test__/units/is-negative-zero.js
@@ -0,0 +1,15 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+
+var isNegativeZero = require('../../lib/js-yaml/common').isNegativeZero;
+
+
+test('isNegativeZero', function () {
+  assert(!isNegativeZero(0));
+  assert(!isNegativeZero(0.0));
+  assert(isNegativeZero(-0));
+  assert(isNegativeZero(-0.0));
+});
diff --git a/encoding/yaml/__test__/units/mark.js b/encoding/yaml/__test__/units/mark.js
new file mode 100644
index 000000000000..d1d9d84bd892
--- /dev/null
+++ b/encoding/yaml/__test__/units/mark.js
@@ -0,0 +1,45 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var path   = require('path');
+var fs     = require('fs');
+var Mark   = require('../../lib/js-yaml/mark');
+
+
+test('Mark', function () {
+  var filepath = path.join(__dirname, 'mark.txt'),
+      filedata = fs.readFileSync(filepath, 'utf8');
+
+  filedata.split('---\n').slice(1).forEach(function (input) {
+    var index = 0, line = 0, column = 0,
+        mark, snippet, data, pointer, temp;
+
+    assert(input.indexOf('*') >= 0);
+
+    while (input[index] !== '*') {
+      if (input[index] === '\n') {
+        line += 1;
+        column = 0;
+      } else {
+        column += 1;
+      }
+      index += 1;
+    }
+
+    mark = new Mark(filepath, input, index, line, column);
+    snippet = mark.getSnippet(2, 79);
+
+    assert(typeof snippet, 'string');
+
+    temp = snippet.split('\n');
+    assert.strictEqual(temp.length, 2);
+
+    data = temp[0];
+    pointer = temp[1];
+
+    assert(data.length < 82);
+    assert.strictEqual(data[pointer.length - 1], '*');
+  });
+});
diff --git a/encoding/yaml/__test__/units/mark.txt b/encoding/yaml/__test__/units/mark.txt
new file mode 100644
index 000000000000..7b08ee43e5fd
--- /dev/null
+++ b/encoding/yaml/__test__/units/mark.txt
@@ -0,0 +1,38 @@
+---
+*The first line.
+The last line.
+---
+The first*line.
+The last line.
+---
+The first line.*
+The last line.
+---
+The first line.
+*The last line.
+---
+The first line.
+The last*line.
+---
+The first line.
+The last line.*
+---
+The first line.
+*The selected line.
+The last line.
+---
+The first line.
+The selected*line.
+The last line.
+---
+The first line.
+The selected line.*
+The last line.
+---
+*The only line.
+---
+The only*line.
+---
+The only line.*
+---
+Loooooooooooooooooooooooooooooooooooooooooooooong*Liiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiine
diff --git a/encoding/yaml/__test__/units/parse-function-security.js b/encoding/yaml/__test__/units/parse-function-security.js
new file mode 100644
index 000000000000..8ad194609098
--- /dev/null
+++ b/encoding/yaml/__test__/units/parse-function-security.js
@@ -0,0 +1,25 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var fs     = require('fs');
+var path   = require('path');
+var yaml   = require('../../lib/js-yaml');
+
+
+var badThings = [];
+
+
+global.makeBadThing = function (thing) {
+  badThings.push(thing);
+};
+
+
+test('Function constructor must not allow to execute any code while parsing.', function () {
+  var filename = path.join(__dirname, 'parse-function-security.yml'),
+      contents = fs.readFileSync(filename, 'utf8');
+
+  assert.throws(function () { yaml.load(contents); }, yaml.YAMLException);
+  assert.deepEqual(badThings, []);
+});
diff --git a/encoding/yaml/__test__/units/parse-function-security.yml b/encoding/yaml/__test__/units/parse-function-security.yml
new file mode 100644
index 000000000000..812e9c9c67ae
--- /dev/null
+++ b/encoding/yaml/__test__/units/parse-function-security.yml
@@ -0,0 +1,3 @@
+tests:
+  - !!js/function 'makeBadThing("BAD THING 1")'
+  - !!js/function 'function () { makeBadThing("BAD THING 2") }.call(this)'
diff --git a/encoding/yaml/__test__/units/single-document-error.js b/encoding/yaml/__test__/units/single-document-error.js
new file mode 100644
index 000000000000..b4a60f3dbdcc
--- /dev/null
+++ b/encoding/yaml/__test__/units/single-document-error.js
@@ -0,0 +1,21 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+test('Loading multidocument source using `load` should cause an error', function () {
+  assert.throws(function () {
+    yaml.load('--- # first document\n--- # second document\n');
+  }, yaml.YAMLException);
+
+  assert.throws(function () {
+    yaml.load('---\nfoo: bar\n---\nfoo: bar\n');
+  }, yaml.YAMLException);
+
+  assert.throws(function () {
+    yaml.load('foo: bar\n---\nfoo: bar\n');
+  }, yaml.YAMLException);
+});
diff --git a/encoding/yaml/__test__/units/skip-invalid.js b/encoding/yaml/__test__/units/skip-invalid.js
new file mode 100644
index 000000000000..35e78122cd5f
--- /dev/null
+++ b/encoding/yaml/__test__/units/skip-invalid.js
@@ -0,0 +1,35 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+
+var sample = {
+  number: 42,
+  undef:  undefined,
+  string: 'hello',
+  func:   function (a, b) { return a + b; },
+  regexp: /^hel+o/,
+  array:  [ 1, 2, 3 ]
+};
+
+
+var expected = {
+  number: 42,
+  string: 'hello',
+  array:  [ 1, 2, 3 ]
+};
+
+
+test('Dumper must throw an exception on invalid type when option `skipInvalid` is false.', function () {
+  assert.throws(function () {
+    yaml.safeDump(sample, { skipInvalid: false });
+  }, yaml.YAMLException);
+});
+
+
+test('Dumper must skip pairs and values with invalid types when option `skipInvalid` is true.', function () {
+  assert.deepEqual(yaml.load(yaml.safeDump(sample, { skipInvalid: true })), expected);
+});
diff --git a/encoding/yaml/__test__/units/sort-keys.js b/encoding/yaml/__test__/units/sort-keys.js
new file mode 100644
index 000000000000..eafc0f162731
--- /dev/null
+++ b/encoding/yaml/__test__/units/sort-keys.js
@@ -0,0 +1,27 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+var sample = { b: 1, a: 2, c: 3 };
+var unsortedExpected = 'b: 1\na: 2\nc: 3\n';
+var simpleExpected = 'a: 2\nb: 1\nc: 3\n';
+var reverseExpected = 'c: 3\nb: 1\na: 2\n';
+
+test('Dumper should sort preserve key insertion order', function () {
+  assert.deepEqual(yaml.safeDump(sample, { sortKeys: false }), unsortedExpected);
+});
+
+test('Dumper should sort keys when sortKeys is true', function () {
+  assert.deepEqual(yaml.safeDump(sample, { sortKeys: true }), simpleExpected);
+});
+
+test('Dumper should sort keys by sortKeys function when specified', function () {
+  assert.deepEqual(yaml.safeDump(sample, {
+    sortKeys: function (a, b) {
+      return a < b ? 1 : a > b ? -1 : 0;
+    }
+  }), reverseExpected);
+});
diff --git a/encoding/yaml/__test__/units/tagmultikind.js b/encoding/yaml/__test__/units/tagmultikind.js
new file mode 100644
index 000000000000..af306a854872
--- /dev/null
+++ b/encoding/yaml/__test__/units/tagmultikind.js
@@ -0,0 +1,40 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+var assert = require('assert');
+var yaml = require('../../');
+
+var tags = [ {
+  tag: 'Include',
+  type: 'scalar'
+}, {
+  tag: 'Include',
+  type: 'mapping'
+} ].map(function (fn) {
+  return new yaml.Type('!' + fn.tag, {
+    kind: fn.type,
+    resolve: function () {
+      return true;
+    },
+    construct: function (obj) {
+      return obj;
+    }
+  });
+});
+
+var schema = yaml.Schema.create(tags);
+
+
+test('Process tag with kind: scalar', function () {
+  assert.deepEqual(yaml.safeLoad('!Include foobar', {
+    schema: schema
+  }), 'foobar');
+});
+
+
+test('Process tag with kind: mapping', function () {
+  assert.deepEqual(yaml.safeLoad('!Include\n  location: foobar', {
+    schema: schema
+  }), { location: 'foobar' });
+});
diff --git a/encoding/yaml/dumper/dumper.ts b/encoding/yaml/dumper/dumper.ts
new file mode 100644
index 000000000000..5b15ba452052
--- /dev/null
+++ b/encoding/yaml/dumper/dumper.ts
@@ -0,0 +1,898 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+/* eslint-disable max-len */
+
+import { YAMLError } from "../error.ts";
+import { RepresentFn, StyleVariant, Type } from "../type.ts";
+import * as common from "../utils.ts";
+import { DumperState, DumperStateOptions } from "./dumper_state.ts";
+
+type Any = common.Any;
+type ArrayObject<T = Any> = common.ArrayObject<T>;
+
+const _toString = Object.prototype.toString;
+const _hasOwnProperty = Object.prototype.hasOwnProperty;
+
+const CHAR_TAB = 0x09; /* Tab */
+const CHAR_LINE_FEED = 0x0a; /* LF */
+const CHAR_SPACE = 0x20; /* Space */
+const CHAR_EXCLAMATION = 0x21; /* ! */
+const CHAR_DOUBLE_QUOTE = 0x22; /* " */
+const CHAR_SHARP = 0x23; /* # */
+const CHAR_PERCENT = 0x25; /* % */
+const CHAR_AMPERSAND = 0x26; /* & */
+const CHAR_SINGLE_QUOTE = 0x27; /* ' */
+const CHAR_ASTERISK = 0x2a; /* * */
+const CHAR_COMMA = 0x2c; /* , */
+const CHAR_MINUS = 0x2d; /* - */
+const CHAR_COLON = 0x3a; /* : */
+const CHAR_GREATER_THAN = 0x3e; /* > */
+const CHAR_QUESTION = 0x3f; /* ? */
+const CHAR_COMMERCIAL_AT = 0x40; /* @ */
+const CHAR_LEFT_SQUARE_BRACKET = 0x5b; /* [ */
+const CHAR_RIGHT_SQUARE_BRACKET = 0x5d; /* ] */
+const CHAR_GRAVE_ACCENT = 0x60; /* ` */
+const CHAR_LEFT_CURLY_BRACKET = 0x7b; /* { */
+const CHAR_VERTICAL_LINE = 0x7c; /* | */
+const CHAR_RIGHT_CURLY_BRACKET = 0x7d; /* } */
+
+const ESCAPE_SEQUENCES: { [char: number]: string } = {};
+
+ESCAPE_SEQUENCES[0x00] = "\\0";
+ESCAPE_SEQUENCES[0x07] = "\\a";
+ESCAPE_SEQUENCES[0x08] = "\\b";
+ESCAPE_SEQUENCES[0x09] = "\\t";
+ESCAPE_SEQUENCES[0x0a] = "\\n";
+ESCAPE_SEQUENCES[0x0b] = "\\v";
+ESCAPE_SEQUENCES[0x0c] = "\\f";
+ESCAPE_SEQUENCES[0x0d] = "\\r";
+ESCAPE_SEQUENCES[0x1b] = "\\e";
+ESCAPE_SEQUENCES[0x22] = '\\"';
+ESCAPE_SEQUENCES[0x5c] = "\\\\";
+ESCAPE_SEQUENCES[0x85] = "\\N";
+ESCAPE_SEQUENCES[0xa0] = "\\_";
+ESCAPE_SEQUENCES[0x2028] = "\\L";
+ESCAPE_SEQUENCES[0x2029] = "\\P";
+
+const DEPRECATED_BOOLEANS_SYNTAX = [
+  "y",
+  "Y",
+  "yes",
+  "Yes",
+  "YES",
+  "on",
+  "On",
+  "ON",
+  "n",
+  "N",
+  "no",
+  "No",
+  "NO",
+  "off",
+  "Off",
+  "OFF"
+];
+
+function encodeHex(character: number): string {
+  const string = character.toString(16).toUpperCase();
+
+  let handle: string;
+  let length: number;
+  if (character <= 0xff) {
+    handle = "x";
+    length = 2;
+  } else if (character <= 0xffff) {
+    handle = "u";
+    length = 4;
+  } else if (character <= 0xffffffff) {
+    handle = "U";
+    length = 8;
+  } else {
+    throw new YAMLError(
+      "code point within a string may not be greater than 0xFFFFFFFF"
+    );
+  }
+
+  return `\\${handle}${common.repeat("0", length - string.length)}${string}`;
+}
+
+// Indents every line in a string. Empty lines (\n only) are not indented.
+function indentString(string: string, spaces: number): string {
+  const ind = common.repeat(" ", spaces),
+    length = string.length;
+  let position = 0,
+    next = -1,
+    result = "",
+    line: string;
+
+  while (position < length) {
+    next = string.indexOf("\n", position);
+    if (next === -1) {
+      line = string.slice(position);
+      position = length;
+    } else {
+      line = string.slice(position, next + 1);
+      position = next + 1;
+    }
+
+    if (line.length && line !== "\n") result += ind;
+
+    result += line;
+  }
+
+  return result;
+}
+
+function generateNextLine(state: DumperState, level: number): string {
+  return `\n${common.repeat(" ", state.indent * level)}`;
+}
+
+function testImplicitResolving(state: DumperState, str: string): boolean {
+  let type: Type;
+  for (
+    let index = 0, length = state.implicitTypes.length;
+    index < length;
+    index += 1
+  ) {
+    type = state.implicitTypes[index];
+
+    if (type.resolve(str)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+// [33] s-white ::= s-space | s-tab
+function isWhitespace(c: number): boolean {
+  return c === CHAR_SPACE || c === CHAR_TAB;
+}
+
+// Returns true if the character can be printed without escaping.
+// From YAML 1.2: "any allowed characters known to be non-printable
+// should also be escaped. [However,] This isn’t mandatory"
+// Derived from nb-char - \t - #x85 - #xA0 - #x2028 - #x2029.
+function isPrintable(c: number): boolean {
+  return (
+    (0x00020 <= c && c <= 0x00007e) ||
+    (0x000a1 <= c && c <= 0x00d7ff && c !== 0x2028 && c !== 0x2029) ||
+    (0x0e000 <= c && c <= 0x00fffd && c !== 0xfeff) /* BOM */ ||
+    (0x10000 <= c && c <= 0x10ffff)
+  );
+}
+
+// Simplified test for values allowed after the first character in plain style.
+function isPlainSafe(c: number): boolean {
+  // Uses a subset of nb-char - c-flow-indicator - ":" - "#"
+  // where nb-char ::= c-printable - b-char - c-byte-order-mark.
+  return (
+    isPrintable(c) &&
+    c !== 0xfeff &&
+    // - c-flow-indicator
+    c !== CHAR_COMMA &&
+    c !== CHAR_LEFT_SQUARE_BRACKET &&
+    c !== CHAR_RIGHT_SQUARE_BRACKET &&
+    c !== CHAR_LEFT_CURLY_BRACKET &&
+    c !== CHAR_RIGHT_CURLY_BRACKET &&
+    // - ":" - "#"
+    c !== CHAR_COLON &&
+    c !== CHAR_SHARP
+  );
+}
+
+// Simplified test for values allowed as the first character in plain style.
+function isPlainSafeFirst(c: number): boolean {
+  // Uses a subset of ns-char - c-indicator
+  // where ns-char = nb-char - s-white.
+  return (
+    isPrintable(c) &&
+    c !== 0xfeff &&
+    !isWhitespace(c) && // - s-white
+    // - (c-indicator ::=
+    // “-” | “?” | “:” | “,” | “[” | “]” | “{” | “}”
+    c !== CHAR_MINUS &&
+    c !== CHAR_QUESTION &&
+    c !== CHAR_COLON &&
+    c !== CHAR_COMMA &&
+    c !== CHAR_LEFT_SQUARE_BRACKET &&
+    c !== CHAR_RIGHT_SQUARE_BRACKET &&
+    c !== CHAR_LEFT_CURLY_BRACKET &&
+    c !== CHAR_RIGHT_CURLY_BRACKET &&
+    // | “#” | “&” | “*” | “!” | “|” | “>” | “'” | “"”
+    c !== CHAR_SHARP &&
+    c !== CHAR_AMPERSAND &&
+    c !== CHAR_ASTERISK &&
+    c !== CHAR_EXCLAMATION &&
+    c !== CHAR_VERTICAL_LINE &&
+    c !== CHAR_GREATER_THAN &&
+    c !== CHAR_SINGLE_QUOTE &&
+    c !== CHAR_DOUBLE_QUOTE &&
+    // | “%” | “@” | “`”)
+    c !== CHAR_PERCENT &&
+    c !== CHAR_COMMERCIAL_AT &&
+    c !== CHAR_GRAVE_ACCENT
+  );
+}
+
+// Determines whether block indentation indicator is required.
+function needIndentIndicator(string: string): boolean {
+  const leadingSpaceRe = /^\n* /;
+  return leadingSpaceRe.test(string);
+}
+
+const STYLE_PLAIN = 1,
+  STYLE_SINGLE = 2,
+  STYLE_LITERAL = 3,
+  STYLE_FOLDED = 4,
+  STYLE_DOUBLE = 5;
+
+// Determines which scalar styles are possible and returns the preferred style.
+// lineWidth = -1 => no limit.
+// Pre-conditions: str.length > 0.
+// Post-conditions:
+//  STYLE_PLAIN or STYLE_SINGLE => no \n are in the string.
+//  STYLE_LITERAL => no lines are suitable for folding (or lineWidth is -1).
+//  STYLE_FOLDED => a line > lineWidth and can be folded (and lineWidth != -1).
+function chooseScalarStyle(
+  string: string,
+  singleLineOnly: boolean,
+  indentPerLevel: number,
+  lineWidth: number,
+  testAmbiguousType: (...args: Any[]) => Any
+): number {
+  const shouldTrackWidth = lineWidth !== -1;
+  let hasLineBreak = false,
+    hasFoldableLine = false, // only checked if shouldTrackWidth
+    previousLineBreak = -1, // count the first line correctly
+    plain =
+      isPlainSafeFirst(string.charCodeAt(0)) &&
+      !isWhitespace(string.charCodeAt(string.length - 1));
+
+  let char: number, i: number;
+  if (singleLineOnly) {
+    // Case: no block styles.
+    // Check for disallowed characters to rule out plain and single.
+    for (i = 0; i < string.length; i++) {
+      char = string.charCodeAt(i);
+      if (!isPrintable(char)) {
+        return STYLE_DOUBLE;
+      }
+      plain = plain && isPlainSafe(char);
+    }
+  } else {
+    // Case: block styles permitted.
+    for (i = 0; i < string.length; i++) {
+      char = string.charCodeAt(i);
+      if (char === CHAR_LINE_FEED) {
+        hasLineBreak = true;
+        // Check if any line can be folded.
+        if (shouldTrackWidth) {
+          hasFoldableLine =
+            hasFoldableLine ||
+            // Foldable line = too long, and not more-indented.
+            (i - previousLineBreak - 1 > lineWidth &&
+              string[previousLineBreak + 1] !== " ");
+          previousLineBreak = i;
+        }
+      } else if (!isPrintable(char)) {
+        return STYLE_DOUBLE;
+      }
+      plain = plain && isPlainSafe(char);
+    }
+    // in case the end is missing a \n
+    hasFoldableLine =
+      hasFoldableLine ||
+      (shouldTrackWidth &&
+        (i - previousLineBreak - 1 > lineWidth &&
+          string[previousLineBreak + 1] !== " "));
+  }
+  // Although every style can represent \n without escaping, prefer block styles
+  // for multiline, since they're more readable and they don't add empty lines.
+  // Also prefer folding a super-long line.
+  if (!hasLineBreak && !hasFoldableLine) {
+    // Strings interpretable as another type have to be quoted;
+    // e.g. the string 'true' vs. the boolean true.
+    return plain && !testAmbiguousType(string) ? STYLE_PLAIN : STYLE_SINGLE;
+  }
+  // Edge case: block indentation indicator can only have one digit.
+  if (indentPerLevel > 9 && needIndentIndicator(string)) {
+    return STYLE_DOUBLE;
+  }
+  // At this point we know block styles are valid.
+  // Prefer literal style unless we want to fold.
+  return hasFoldableLine ? STYLE_FOLDED : STYLE_LITERAL;
+}
+
+// Greedy line breaking.
+// Picks the longest line under the limit each time,
+// otherwise settles for the shortest line over the limit.
+// NB. More-indented lines *cannot* be folded, as that would add an extra \n.
+function foldLine(line: string, width: number): string {
+  if (line === "" || line[0] === " ") return line;
+
+  // Since a more-indented line adds a \n, breaks can't be followed by a space.
+  const breakRe = / [^ ]/g; // note: the match index will always be <= length-2.
+  let match;
+  // start is an inclusive index. end, curr, and next are exclusive.
+  let start = 0,
+    end,
+    curr = 0,
+    next = 0;
+  let result = "";
+
+  // Invariants: 0 <= start <= length-1.
+  //   0 <= curr <= next <= max(0, length-2). curr - start <= width.
+  // Inside the loop:
+  //   A match implies length >= 2, so curr and next are <= length-2.
+  // tslint:disable-next-line:no-conditional-assignment
+  while ((match = breakRe.exec(line))) {
+    next = match.index;
+    // maintain invariant: curr - start <= width
+    if (next - start > width) {
+      end = curr > start ? curr : next; // derive end <= length-2
+      result += `\n${line.slice(start, end)}`;
+      // skip the space that was output as \n
+      start = end + 1; // derive start <= length-1
+    }
+    curr = next;
+  }
+
+  // By the invariants, start <= length-1, so there is something left over.
+  // It is either the whole string or a part starting from non-whitespace.
+  result += "\n";
+  // Insert a break if the remainder is too long and there is a break available.
+  if (line.length - start > width && curr > start) {
+    result += `${line.slice(start, curr)}\n${line.slice(curr + 1)}`;
+  } else {
+    result += line.slice(start);
+  }
+
+  return result.slice(1); // drop extra \n joiner
+}
+
+// (See the note for writeScalar.)
+function dropEndingNewline(string: string): string {
+  return string[string.length - 1] === "\n" ? string.slice(0, -1) : string;
+}
+
+// Note: a long line without a suitable break point will exceed the width limit.
+// Pre-conditions: every char in str isPrintable, str.length > 0, width > 0.
+function foldString(string: string, width: number): string {
+  // In folded style, $k$ consecutive newlines output as $k+1$ newlines—
+  // unless they're before or after a more-indented line, or at the very
+  // beginning or end, in which case $k$ maps to $k$.
+  // Therefore, parse each chunk as newline(s) followed by a content line.
+  const lineRe = /(\n+)([^\n]*)/g;
+
+  // first line (possibly an empty line)
+  let result = ((): string => {
+    let nextLF = string.indexOf("\n");
+    nextLF = nextLF !== -1 ? nextLF : string.length;
+    lineRe.lastIndex = nextLF;
+    // eslint-disable-next-line @typescript-eslint/no-use-before-define
+    return foldLine(string.slice(0, nextLF), width);
+  })();
+  // If we haven't reached the first content line yet, don't add an extra \n.
+  let prevMoreIndented = string[0] === "\n" || string[0] === " ";
+  let moreIndented;
+
+  // rest of the lines
+  let match;
+  // tslint:disable-next-line:no-conditional-assignment
+  while ((match = lineRe.exec(string))) {
+    const prefix = match[1],
+      line = match[2];
+    moreIndented = line[0] === " ";
+    result +=
+      prefix +
+      (!prevMoreIndented && !moreIndented && line !== "" ? "\n" : "") +
+      // eslint-disable-next-line @typescript-eslint/no-use-before-define
+      foldLine(line, width);
+    prevMoreIndented = moreIndented;
+  }
+
+  return result;
+}
+
+// Escapes a double-quoted string.
+function escapeString(string: string): string {
+  let result = "";
+  let char, nextChar;
+  let escapeSeq;
+
+  for (let i = 0; i < string.length; i++) {
+    char = string.charCodeAt(i);
+    // Check for surrogate pairs (reference Unicode 3.0 section "3.7 Surrogates").
+    if (char >= 0xd800 && char <= 0xdbff /* high surrogate */) {
+      nextChar = string.charCodeAt(i + 1);
+      if (nextChar >= 0xdc00 && nextChar <= 0xdfff /* low surrogate */) {
+        // Combine the surrogate pair and store it escaped.
+        result += encodeHex(
+          (char - 0xd800) * 0x400 + nextChar - 0xdc00 + 0x10000
+        );
+        // Advance index one extra since we already used that char here.
+        i++;
+        continue;
+      }
+    }
+    escapeSeq = ESCAPE_SEQUENCES[char];
+    result +=
+      !escapeSeq && isPrintable(char)
+        ? string[i]
+        : escapeSeq || encodeHex(char);
+  }
+
+  return result;
+}
+
+// Pre-conditions: string is valid for a block scalar, 1 <= indentPerLevel <= 9.
+function blockHeader(string: string, indentPerLevel: number): string {
+  const indentIndicator = needIndentIndicator(string)
+    ? String(indentPerLevel)
+    : "";
+
+  // note the special case: the string '\n' counts as a "trailing" empty line.
+  const clip = string[string.length - 1] === "\n";
+  const keep = clip && (string[string.length - 2] === "\n" || string === "\n");
+  const chomp = keep ? "+" : clip ? "" : "-";
+
+  return `${indentIndicator}${chomp}\n`;
+}
+
+// Note: line breaking/folding is implemented for only the folded style.
+// NB. We drop the last trailing newline (if any) of a returned block scalar
+//  since the dumper adds its own newline. This always works:
+//    • No ending newline => unaffected; already using strip "-" chomping.
+//    • Ending newline    => removed then restored.
+//  Importantly, this keeps the "+" chomp indicator from gaining an extra line.
+function writeScalar(
+  state: DumperState,
+  string: string,
+  level: number,
+  iskey: boolean
+): void {
+  state.dump = ((): string => {
+    if (string.length === 0) {
+      return "''";
+    }
+    if (
+      !state.noCompatMode &&
+      DEPRECATED_BOOLEANS_SYNTAX.indexOf(string) !== -1
+    ) {
+      return `'${string}'`;
+    }
+
+    const indent = state.indent * Math.max(1, level); // no 0-indent scalars
+    // As indentation gets deeper, let the width decrease monotonically
+    // to the lower bound min(state.lineWidth, 40).
+    // Note that this implies
+    //  state.lineWidth ≤ 40 + state.indent: width is fixed at the lower bound.
+    //  state.lineWidth > 40 + state.indent: width decreases until the lower
+    //  bound.
+    // This behaves better than a constant minimum width which disallows
+    // narrower options, or an indent threshold which causes the width
+    // to suddenly increase.
+    const lineWidth =
+      state.lineWidth === -1
+        ? -1
+        : Math.max(Math.min(state.lineWidth, 40), state.lineWidth - indent);
+
+    // Without knowing if keys are implicit/explicit,
+    // assume implicit for safety.
+    const singleLineOnly =
+      iskey ||
+      // No block styles in flow mode.
+      (state.flowLevel > -1 && level >= state.flowLevel);
+    function testAmbiguity(str: string): boolean {
+      return testImplicitResolving(state, str);
+    }
+
+    switch (
+      chooseScalarStyle(
+        string,
+        singleLineOnly,
+        state.indent,
+        lineWidth,
+        testAmbiguity
+      )
+    ) {
+      case STYLE_PLAIN:
+        return string;
+      case STYLE_SINGLE:
+        return `'${string.replace(/'/g, "''")}'`;
+      case STYLE_LITERAL:
+        return `|${blockHeader(string, state.indent)}${dropEndingNewline(
+          indentString(string, indent)
+        )}`;
+      case STYLE_FOLDED:
+        return `>${blockHeader(string, state.indent)}${dropEndingNewline(
+          indentString(foldString(string, lineWidth), indent)
+        )}`;
+      case STYLE_DOUBLE:
+        return `"${escapeString(string)}"`;
+      default:
+        throw new YAMLError("impossible error: invalid scalar style");
+    }
+  })();
+}
+
+function writeFlowSequence(
+  state: DumperState,
+  level: number,
+  object: Any
+): void {
+  let _result = "";
+  const _tag = state.tag;
+
+  for (let index = 0, length = object.length; index < length; index += 1) {
+    // Write only valid elements.
+    // eslint-disable-next-line @typescript-eslint/no-use-before-define
+    if (writeNode(state, level, object[index], false, false)) {
+      if (index !== 0) _result += `,${!state.condenseFlow ? " " : ""}`;
+      _result += state.dump;
+    }
+  }
+
+  state.tag = _tag;
+  state.dump = `[${_result}]`;
+}
+
+function writeBlockSequence(
+  state: DumperState,
+  level: number,
+  object: Any,
+  compact = false
+): void {
+  let _result = "";
+  const _tag = state.tag;
+
+  for (let index = 0, length = object.length; index < length; index += 1) {
+    // Write only valid elements.
+    // eslint-disable-next-line @typescript-eslint/no-use-before-define
+    if (writeNode(state, level + 1, object[index], true, true)) {
+      if (!compact || index !== 0) {
+        _result += generateNextLine(state, level);
+      }
+
+      if (state.dump && CHAR_LINE_FEED === state.dump.charCodeAt(0)) {
+        _result += "-";
+      } else {
+        _result += "- ";
+      }
+
+      _result += state.dump;
+    }
+  }
+
+  state.tag = _tag;
+  state.dump = _result || "[]"; // Empty sequence if no valid values.
+}
+
+function writeFlowMapping(
+  state: DumperState,
+  level: number,
+  object: Any
+): void {
+  let _result = "";
+  const _tag = state.tag,
+    objectKeyList = Object.keys(object);
+
+  let pairBuffer: string, objectKey: string, objectValue: Any;
+  for (
+    let index = 0, length = objectKeyList.length;
+    index < length;
+    index += 1
+  ) {
+    pairBuffer = state.condenseFlow ? '"' : "";
+
+    if (index !== 0) pairBuffer += ", ";
+
+    objectKey = objectKeyList[index];
+    objectValue = object[objectKey];
+
+    // eslint-disable-next-line @typescript-eslint/no-use-before-define
+    if (!writeNode(state, level, objectKey, false, false)) {
+      continue; // Skip this pair because of invalid key;
+    }
+
+    if (state.dump.length > 1024) pairBuffer += "? ";
+
+    pairBuffer += `${state.dump}${state.condenseFlow ? '"' : ""}:${
+      state.condenseFlow ? "" : " "
+    }`;
+
+    // eslint-disable-next-line @typescript-eslint/no-use-before-define
+    if (!writeNode(state, level, objectValue, false, false)) {
+      continue; // Skip this pair because of invalid value.
+    }
+
+    pairBuffer += state.dump;
+
+    // Both key and value are valid.
+    _result += pairBuffer;
+  }
+
+  state.tag = _tag;
+  state.dump = `{${_result}}`;
+}
+
+function writeBlockMapping(
+  state: DumperState,
+  level: number,
+  object: Any,
+  compact = false
+): void {
+  const _tag = state.tag,
+    objectKeyList = Object.keys(object);
+  let _result = "";
+
+  // Allow sorting keys so that the output file is deterministic
+  if (state.sortKeys === true) {
+    // Default sorting
+    objectKeyList.sort();
+  } else if (typeof state.sortKeys === "function") {
+    // Custom sort function
+    objectKeyList.sort(state.sortKeys);
+  } else if (state.sortKeys) {
+    // Something is wrong
+    throw new YAMLError("sortKeys must be a boolean or a function");
+  }
+
+  let pairBuffer = "",
+    objectKey: string,
+    objectValue: Any,
+    explicitPair: boolean;
+  for (
+    let index = 0, length = objectKeyList.length;
+    index < length;
+    index += 1
+  ) {
+    pairBuffer = "";
+
+    if (!compact || index !== 0) {
+      pairBuffer += generateNextLine(state, level);
+    }
+
+    objectKey = objectKeyList[index];
+    objectValue = object[objectKey];
+
+    // eslint-disable-next-line @typescript-eslint/no-use-before-define
+    if (!writeNode(state, level + 1, objectKey, true, true, true)) {
+      continue; // Skip this pair because of invalid key.
+    }
+
+    explicitPair =
+      (state.tag !== null && state.tag !== "?") ||
+      (state.dump && state.dump.length > 1024);
+
+    if (explicitPair) {
+      if (state.dump && CHAR_LINE_FEED === state.dump.charCodeAt(0)) {
+        pairBuffer += "?";
+      } else {
+        pairBuffer += "? ";
+      }
+    }
+
+    pairBuffer += state.dump;
+
+    if (explicitPair) {
+      pairBuffer += generateNextLine(state, level);
+    }
+
+    // eslint-disable-next-line @typescript-eslint/no-use-before-define
+    if (!writeNode(state, level + 1, objectValue, true, explicitPair)) {
+      continue; // Skip this pair because of invalid value.
+    }
+
+    if (state.dump && CHAR_LINE_FEED === state.dump.charCodeAt(0)) {
+      pairBuffer += ":";
+    } else {
+      pairBuffer += ": ";
+    }
+
+    pairBuffer += state.dump;
+
+    // Both key and value are valid.
+    _result += pairBuffer;
+  }
+
+  state.tag = _tag;
+  state.dump = _result || "{}"; // Empty mapping if no valid pairs.
+}
+
+function detectType(
+  state: DumperState,
+  object: Any,
+  explicit = false
+): boolean {
+  const typeList = explicit ? state.explicitTypes : state.implicitTypes;
+
+  let type: Type;
+  let style: StyleVariant;
+  let _result: string;
+  for (let index = 0, length = typeList.length; index < length; index += 1) {
+    type = typeList[index];
+
+    if (
+      (type.instanceOf || type.predicate) &&
+      (!type.instanceOf ||
+        (typeof object === "object" && object instanceof type.instanceOf)) &&
+      (!type.predicate || type.predicate(object))
+    ) {
+      state.tag = explicit ? type.tag : "?";
+
+      if (type.represent) {
+        style = state.styleMap[type.tag] || type.defaultStyle;
+
+        if (_toString.call(type.represent) === "[object Function]") {
+          _result = (type.represent as RepresentFn)(object, style);
+        } else if (_hasOwnProperty.call(type.represent, style)) {
+          _result = (type.represent as ArrayObject<RepresentFn>)[style](
+            object,
+            style
+          );
+        } else {
+          throw new YAMLError(
+            `!<${type.tag}> tag resolver accepts not "${style}" style`
+          );
+        }
+
+        state.dump = _result;
+      }
+
+      return true;
+    }
+  }
+
+  return false;
+}
+
+// Serializes `object` and writes it to global `result`.
+// Returns true on success, or false on invalid object.
+//
+function writeNode(
+  state: DumperState,
+  level: number,
+  object: Any,
+  block: boolean,
+  compact: boolean,
+  iskey = false
+): boolean {
+  state.tag = null;
+  state.dump = object;
+
+  if (!detectType(state, object, false)) {
+    detectType(state, object, true);
+  }
+
+  const type = _toString.call(state.dump);
+
+  if (block) {
+    block = state.flowLevel < 0 || state.flowLevel > level;
+  }
+
+  const objectOrArray = type === "[object Object]" || type === "[object Array]";
+
+  let duplicateIndex = -1;
+  let duplicate = false;
+  if (objectOrArray) {
+    duplicateIndex = state.duplicates.indexOf(object);
+    duplicate = duplicateIndex !== -1;
+  }
+
+  if (
+    (state.tag !== null && state.tag !== "?") ||
+    duplicate ||
+    (state.indent !== 2 && level > 0)
+  ) {
+    compact = false;
+  }
+
+  if (duplicate && state.usedDuplicates[duplicateIndex]) {
+    state.dump = `*ref_${duplicateIndex}`;
+  } else {
+    if (objectOrArray && duplicate && !state.usedDuplicates[duplicateIndex]) {
+      state.usedDuplicates[duplicateIndex] = true;
+    }
+    if (type === "[object Object]") {
+      if (block && Object.keys(state.dump).length !== 0) {
+        writeBlockMapping(state, level, state.dump, compact);
+        if (duplicate) {
+          state.dump = `&ref_${duplicateIndex}${state.dump}`;
+        }
+      } else {
+        writeFlowMapping(state, level, state.dump);
+        if (duplicate) {
+          state.dump = `&ref_${duplicateIndex} ${state.dump}`;
+        }
+      }
+    } else if (type === "[object Array]") {
+      const arrayLevel = state.noArrayIndent && level > 0 ? level - 1 : level;
+      if (block && state.dump.length !== 0) {
+        writeBlockSequence(state, arrayLevel, state.dump, compact);
+        if (duplicate) {
+          state.dump = `&ref_${duplicateIndex}${state.dump}`;
+        }
+      } else {
+        writeFlowSequence(state, arrayLevel, state.dump);
+        if (duplicate) {
+          state.dump = `&ref_${duplicateIndex} ${state.dump}`;
+        }
+      }
+    } else if (type === "[object String]") {
+      if (state.tag !== "?") {
+        writeScalar(state, state.dump, level, iskey);
+      }
+    } else {
+      if (state.skipInvalid) return false;
+      throw new YAMLError(`unacceptable kind of an object to dump ${type}`);
+    }
+
+    if (state.tag !== null && state.tag !== "?") {
+      state.dump = `!<${state.tag}> ${state.dump}`;
+    }
+  }
+
+  return true;
+}
+
+function inspectNode(
+  object: Any,
+  objects: Any[],
+  duplicatesIndexes: number[]
+): void {
+  if (object !== null && typeof object === "object") {
+    const index = objects.indexOf(object);
+    if (index !== -1) {
+      if (duplicatesIndexes.indexOf(index) === -1) {
+        duplicatesIndexes.push(index);
+      }
+    } else {
+      objects.push(object);
+
+      if (Array.isArray(object)) {
+        for (let idx = 0, length = object.length; idx < length; idx += 1) {
+          inspectNode(object[idx], objects, duplicatesIndexes);
+        }
+      } else {
+        const objectKeyList = Object.keys(object);
+
+        for (
+          let idx = 0, length = objectKeyList.length;
+          idx < length;
+          idx += 1
+        ) {
+          inspectNode(object[objectKeyList[idx]], objects, duplicatesIndexes);
+        }
+      }
+    }
+  }
+}
+
+function getDuplicateReferences(object: object, state: DumperState): void {
+  const objects: Any[] = [],
+    duplicatesIndexes: number[] = [];
+
+  inspectNode(object, objects, duplicatesIndexes);
+
+  const length = duplicatesIndexes.length;
+  for (let index = 0; index < length; index += 1) {
+    state.duplicates.push(objects[duplicatesIndexes[index]]);
+  }
+  state.usedDuplicates = new Array(length);
+}
+
+export function dump(input: Any, options?: DumperStateOptions): string {
+  options = options || {};
+
+  const state = new DumperState(options);
+
+  if (!state.noRefs) getDuplicateReferences(input, state);
+
+  if (writeNode(state, 0, input, true, true)) return `${state.dump}\n`;
+
+  return "";
+}
diff --git a/encoding/yaml/dumper/dumper_state.ts b/encoding/yaml/dumper/dumper_state.ts
new file mode 100644
index 000000000000..c1d7f5fef50f
--- /dev/null
+++ b/encoding/yaml/dumper/dumper_state.ts
@@ -0,0 +1,137 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Schema, SchemaDefinition } from "../schema.ts";
+import { State } from "../state.ts";
+import { StyleVariant, Type } from "../type.ts";
+import { ArrayObject, Any } from "../utils.ts";
+
+const _hasOwnProperty = Object.prototype.hasOwnProperty;
+
+function compileStyleMap(
+  schema: Schema,
+  map?: ArrayObject<StyleVariant> | null
+): ArrayObject<StyleVariant> {
+  if (typeof map === "undefined" || map === null) return {};
+
+  let type: Type;
+  const result: ArrayObject<StyleVariant> = {};
+  const keys = Object.keys(map);
+  let tag: string, style: StyleVariant;
+  for (let index = 0, length = keys.length; index < length; index += 1) {
+    tag = keys[index];
+    style = String(map[tag]) as StyleVariant;
+    if (tag.slice(0, 2) === "!!") {
+      tag = `tag:yaml.org,2002:${tag.slice(2)}`;
+    }
+    type = schema.compiledTypeMap.fallback[tag];
+
+    if (
+      type &&
+      typeof type.styleAliases !== "undefined" &&
+      _hasOwnProperty.call(type.styleAliases, style)
+    ) {
+      style = type.styleAliases[style];
+    }
+
+    result[tag] = style;
+  }
+
+  return result;
+}
+
+export interface DumperStateOptions {
+  /** indentation width to use (in spaces). */
+  indent?: number;
+  /** when true, will not add an indentation level to array elements */
+  noArrayIndent?: boolean;
+  /**
+   * do not throw on invalid types (like function in the safe schema)
+   * and skip pairs and single values with such types.
+   */
+  skipInvalid?: boolean;
+  /**
+   * specifies level of nesting, when to switch from
+   * block to flow style for collections. -1 means block style everwhere
+   */
+  flowLevel?: number;
+  /** Each tag may have own set of styles.	- "tag" => "style" map. */
+  styles?: ArrayObject<StyleVariant> | null;
+  /** specifies a schema to use. */
+  schema?: SchemaDefinition;
+  /**
+   * if true, sort keys when dumping YAML.
+   * If a function, use the function to sort the keys. (default: false)
+   */
+  sortKeys?: boolean | ((a: Any, b: Any) => number);
+  /** set max line width. (default: 80) */
+  lineWidth?: number;
+  /**
+   * if true, don't convert duplicate objects
+   * into references (default: false)
+   */
+  noRefs?: boolean;
+  /**
+   * if true don't try to be compatible with older yaml versions.
+   * Currently: don't quote "yes", "no" and so on,
+   * as required for YAML 1.1 (default: false)
+   */
+  noCompatMode?: boolean;
+  /**
+   * if true flow sequences will be condensed, omitting the
+   * space between `key: value` or `a, b`. Eg. `'[a,b]'` or `{a:{b:c}}`.
+   * Can be useful when using yaml for pretty URL query params
+   * as spaces are %-encoded. (default: false).
+   */
+  condenseFlow?: boolean;
+}
+
+export class DumperState extends State {
+  public indent: number;
+  public noArrayIndent: boolean;
+  public skipInvalid: boolean;
+  public flowLevel: number;
+  public sortKeys: boolean | ((a: Any, b: Any) => number);
+  public lineWidth: number;
+  public noRefs: boolean;
+  public noCompatMode: boolean;
+  public condenseFlow: boolean;
+  public implicitTypes: Type[];
+  public explicitTypes: Type[];
+  public tag: string | null = null;
+  public result: string = "";
+  public duplicates: Any[] = [];
+  public usedDuplicates: Any[] = []; // changed from null to []
+  public styleMap: ArrayObject<StyleVariant>;
+  public dump: Any;
+
+  constructor({
+    schema,
+    indent = 2,
+    noArrayIndent = false,
+    skipInvalid = false,
+    flowLevel = -1,
+    styles = null,
+    sortKeys = false,
+    lineWidth = 80,
+    noRefs = false,
+    noCompatMode = false,
+    condenseFlow = false
+  }: DumperStateOptions) {
+    super(schema);
+    this.indent = Math.max(1, indent);
+    this.noArrayIndent = noArrayIndent;
+    this.skipInvalid = skipInvalid;
+    this.flowLevel = flowLevel;
+    this.styleMap = compileStyleMap(this.schema as Schema, styles);
+    this.sortKeys = sortKeys;
+    this.lineWidth = lineWidth;
+    this.noRefs = noRefs;
+    this.noCompatMode = noCompatMode;
+    this.condenseFlow = condenseFlow;
+
+    this.implicitTypes = (this.schema as Schema).compiledImplicit;
+    this.explicitTypes = (this.schema as Schema).compiledExplicit;
+  }
+}
diff --git a/encoding/yaml/error.ts b/encoding/yaml/error.ts
new file mode 100644
index 000000000000..10420ea29cf7
--- /dev/null
+++ b/encoding/yaml/error.ts
@@ -0,0 +1,21 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Mark } from "./mark.ts";
+
+const { DenoError, ErrorKind } = Deno;
+
+export class YAMLError extends DenoError<typeof ErrorKind.Other> {
+  constructor(
+    message = "(unknown reason)",
+    protected mark: Mark | string = ""
+  ) {
+    super(ErrorKind.Other, `${message} ${mark}`);
+    this.name = this.constructor.name;
+  }
+
+  public toString(_compact: boolean): string {
+    return `${this.name}: ${this.message} ${this.mark}`;
+  }
+}
diff --git a/encoding/yaml/example/dump.ts b/encoding/yaml/example/dump.ts
new file mode 100644
index 000000000000..c4282d657ec3
--- /dev/null
+++ b/encoding/yaml/example/dump.ts
@@ -0,0 +1,22 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { stringify } from "../../yaml.ts";
+
+console.log(
+  stringify({
+    foo: {
+      bar: true,
+      test: [
+        "a",
+        "b",
+        {
+          a: false
+        },
+        {
+          a: false
+        }
+      ]
+    },
+    test: "foobar"
+  })
+);
diff --git a/encoding/yaml/example/inout.ts b/encoding/yaml/example/inout.ts
new file mode 100644
index 000000000000..6a52d808b4b0
--- /dev/null
+++ b/encoding/yaml/example/inout.ts
@@ -0,0 +1,27 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { parse, stringify } from "../../yaml.ts";
+
+const test = {
+  foo: {
+    bar: true,
+    test: [
+      "a",
+      "b",
+      {
+        a: false
+      },
+      {
+        a: false
+      }
+    ]
+  },
+  test: "foobar"
+};
+
+const string = stringify(test);
+if (Deno.inspect(test) === Deno.inspect(parse(string))) {
+  console.log("In-Out as expected.");
+} else {
+  console.log("Someting went wrong.");
+}
diff --git a/encoding/yaml/example/parse.ts b/encoding/yaml/example/parse.ts
new file mode 100644
index 000000000000..31d4c88773be
--- /dev/null
+++ b/encoding/yaml/example/parse.ts
@@ -0,0 +1,19 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { parse } from "../../yaml.ts";
+
+const result = parse(`
+test: toto
+foo:
+  bar: True
+  baz: 1
+  qux: ~
+`);
+console.log(result);
+
+const expected = '{ test: "toto", foo: { bar: true, baz: 1, qux: null } }';
+if (Deno.inspect(result) === expected) {
+  console.log("Output is as expected.");
+} else {
+  console.error("Error during parse. Output is not as expect.", expected);
+}
diff --git a/encoding/yaml/example/sample_document.ts b/encoding/yaml/example/sample_document.ts
new file mode 100644
index 000000000000..7b426c142798
--- /dev/null
+++ b/encoding/yaml/example/sample_document.ts
@@ -0,0 +1,23 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
+
+import { parse } from "../../yaml.ts";
+
+const { readFileSync, cwd } = Deno;
+
+(async () => {
+  const yml = readFileSync(`${cwd()}/example/sample_document.yml`);
+
+  const document = new TextDecoder().decode(yml);
+  const obj = parse(document) as object;
+  console.log(obj);
+
+  let i = 0;
+  for (const o of Object.values(obj)) {
+    console.log(`======${i}`);
+    for (const [key, value] of Object.entries(o)) {
+      console.log(key, value);
+    }
+    i++;
+  }
+})();
diff --git a/encoding/yaml/example/sample_document.yml b/encoding/yaml/example/sample_document.yml
new file mode 100644
index 000000000000..1f3c2eb3e4d6
--- /dev/null
+++ b/encoding/yaml/example/sample_document.yml
@@ -0,0 +1,197 @@
+---
+# Collection Types #############################################################
+################################################################################
+
+# http://yaml.org/type/map.html -----------------------------------------------#
+
+map:
+  # Unordered set of key: value pairs.
+  Block style: !!map
+    Clark : Evans
+    Ingy  : döt Net
+    Oren  : Ben-Kiki
+  Flow style: !!map { Clark: Evans, Ingy: döt Net, Oren: Ben-Kiki }
+
+# http://yaml.org/type/omap.html ----------------------------------------------#
+
+omap:
+  # Explicitly typed ordered map (dictionary).
+  Bestiary: !!omap
+    - aardvark: African pig-like ant eater. Ugly.
+    - anteater: South-American ant eater. Two species.
+    - anaconda: South-American constrictor snake. Scaly.
+    # Etc.
+  # Flow style
+  Numbers: !!omap [ one: 1, two: 2, three : 3 ]
+
+# http://yaml.org/type/pairs.html ---------------------------------------------#
+
+pairs:
+  # Explicitly typed pairs.
+  Block tasks: !!pairs
+    - meeting: with team.
+    - meeting: with boss.
+    - break: lunch.
+    - meeting: with client.
+  Flow tasks: !!pairs [ meeting: with team, meeting: with boss ]
+
+# http://yaml.org/type/set.html -----------------------------------------------#
+
+set:
+  # Explicitly typed set.
+  baseball players: !!set
+    ? Mark McGwire
+    ? Sammy Sosa
+    ? Ken Griffey
+  # Flow style
+  baseball teams: !!set { Boston Red Sox, Detroit Tigers, New York Yankees }
+
+# http://yaml.org/type/seq.html -----------------------------------------------#
+
+seq:
+  # Ordered sequence of nodes
+  Block style: !!seq
+  - Mercury   # Rotates - no light/dark sides.
+  - Venus     # Deadliest. Aptly named.
+  - Earth     # Mostly dirt.
+  - Mars      # Seems empty.
+  - Jupiter   # The king.
+  - Saturn    # Pretty.
+  - Uranus    # Where the sun hardly shines.
+  - Neptune   # Boring. No rings.
+  - Pluto     # You call this a planet?
+  Flow style: !!seq [ Mercury, Venus, Earth, Mars,      # Rocks
+                      Jupiter, Saturn, Uranus, Neptune, # Gas
+                      Pluto ]                           # Overrated
+
+
+# Scalar Types #################################################################
+################################################################################
+
+# http://yaml.org/type/binary.html --------------------------------------------#
+
+binary:
+  canonical: !!binary "\
+    R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5\
+    OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/+\
+    +f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLC\
+    AgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs="
+  generic: !!binary |
+    R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5
+    OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/+
+    +f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLC
+    AgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs=
+  description:
+    The binary value above is a tiny arrow encoded as a gif image.
+
+# http://yaml.org/type/bool.html ----------------------------------------------#
+
+bool:
+  - true
+  - True
+  - TRUE
+  - false
+  - False
+  - FALSE
+
+# http://yaml.org/type/float.html ---------------------------------------------#
+
+float:
+  canonical: 6.8523015e+5
+  exponential: 685.230_15e+03
+  fixed: 685_230.15
+  sexagesimal: 190:20:30.15
+  negative infinity: -.inf
+  not a number: .NaN
+
+# http://yaml.org/type/int.html -----------------------------------------------#
+
+int:
+  canonical: 685230
+  decimal: +685_230
+  octal: 02472256
+  hexadecimal: 0x_0A_74_AE
+  binary: 0b1010_0111_0100_1010_1110
+  sexagesimal: 190:20:30
+
+# http://yaml.org/type/merge.html ---------------------------------------------#
+
+merge:
+  - &CENTER { x: 1, y: 2 }
+  - &LEFT { x: 0, y: 2 }
+  - &BIG { r: 10 }
+  - &SMALL { r: 1 }
+
+  # All the following maps are equal:
+
+  - # Explicit keys
+    x: 1
+    y: 2
+    r: 10
+    label: nothing
+
+  - # Merge one map
+    << : *CENTER
+    r: 10
+    label: center
+
+  - # Merge multiple maps
+    << : [ *CENTER, *BIG ]
+    label: center/big
+
+  - # Override
+    << : [ *BIG, *LEFT, *SMALL ]
+    x: 1
+    label: big/left/small
+
+# http://yaml.org/type/null.html ----------------------------------------------#
+
+null:
+  # This mapping has four keys,
+  # one has a value.
+  empty:
+  canonical: ~
+  english: null
+  ~: null key
+  # This sequence has five
+  # entries, two have values.
+  sparse:
+    - ~
+    - 2nd entry
+    -
+    - 4th entry
+    - Null
+
+# http://yaml.org/type/str.html -----------------------------------------------#
+
+string: abcd
+
+# http://yaml.org/type/timestamp.html -----------------------------------------#
+
+timestamp:
+  canonical:        2001-12-15T02:59:43.1Z
+  valid iso8601:    2001-12-14t21:59:43.10-05:00
+  space separated:  2001-12-14 21:59:43.10 -5
+  no time zone (Z): 2001-12-15 2:59:43.10
+  date (00:00:00Z): 2002-12-14
+
+
+# JavaScript Specific Types ####################################################
+################################################################################
+
+# https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/RegExp
+
+# regexp:
+#   simple: !!js/regexp      foobar
+#   modifiers: !!js/regexp   /foobar/mi
+
+# https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/undefined
+
+# undefined: !!js/undefined ~
+
+# https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function
+
+# function: !!js/function >
+#   function foobar() {
+#     return 'Wow! JS-YAML Rocks!';
+#   }
diff --git a/encoding/yaml/loader/loader.ts b/encoding/yaml/loader/loader.ts
new file mode 100644
index 000000000000..716b928f84f3
--- /dev/null
+++ b/encoding/yaml/loader/loader.ts
@@ -0,0 +1,1814 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+/* eslint-disable no-conditional-assignment */
+/* eslint-disable max-len */
+
+import { YAMLError } from "../error.ts";
+import { Mark } from "../mark.ts";
+import { Type } from "../type.ts";
+import * as common from "../utils.ts";
+import { LoaderState, LoaderStateOptions, ResultType } from "./loader_state.ts";
+
+type Any = common.Any;
+type ArrayObject<T = Any> = common.ArrayObject<T>;
+
+const _hasOwnProperty = Object.prototype.hasOwnProperty;
+
+const CONTEXT_FLOW_IN = 1;
+const CONTEXT_FLOW_OUT = 2;
+const CONTEXT_BLOCK_IN = 3;
+const CONTEXT_BLOCK_OUT = 4;
+
+const CHOMPING_CLIP = 1;
+const CHOMPING_STRIP = 2;
+const CHOMPING_KEEP = 3;
+
+const PATTERN_NON_PRINTABLE = /[\x00-\x08\x0B\x0C\x0E-\x1F\x7F-\x84\x86-\x9F\uFFFE\uFFFF]|[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?:[^\uD800-\uDBFF]|^)[\uDC00-\uDFFF]/;
+const PATTERN_NON_ASCII_LINE_BREAKS = /[\x85\u2028\u2029]/;
+const PATTERN_FLOW_INDICATORS = /[,\[\]\{\}]/;
+const PATTERN_TAG_HANDLE = /^(?:!|!!|![a-z\-]+!)$/i;
+/* eslint-disable-next-line max-len */
+const PATTERN_TAG_URI = /^(?:!|[^,\[\]\{\}])(?:%[0-9a-f]{2}|[0-9a-z\-#;\/\?:@&=\+\$,_\.!~\*'\(\)\[\]])*$/i;
+
+function _class(obj: Any): string {
+  return Object.prototype.toString.call(obj);
+}
+
+function isEOL(c: number): boolean {
+  return c === 0x0a /* LF */ || c === 0x0d /* CR */;
+}
+
+function isWhiteSpace(c: number): boolean {
+  return c === 0x09 /* Tab */ || c === 0x20 /* Space */;
+}
+
+function isWsOrEol(c: number): boolean {
+  return (
+    c === 0x09 /* Tab */ ||
+    c === 0x20 /* Space */ ||
+    c === 0x0a /* LF */ ||
+    c === 0x0d /* CR */
+  );
+}
+
+function isFlowIndicator(c: number): boolean {
+  return (
+    c === 0x2c /* , */ ||
+    c === 0x5b /* [ */ ||
+    c === 0x5d /* ] */ ||
+    c === 0x7b /* { */ ||
+    c === 0x7d /* } */
+  );
+}
+
+function fromHexCode(c: number): number {
+  if (0x30 /* 0 */ <= c && c <= 0x39 /* 9 */) {
+    return c - 0x30;
+  }
+
+  const lc = c | 0x20;
+
+  if (0x61 /* a */ <= lc && lc <= 0x66 /* f */) {
+    return lc - 0x61 + 10;
+  }
+
+  return -1;
+}
+
+function escapedHexLen(c: number): number {
+  if (c === 0x78 /* x */) {
+    return 2;
+  }
+  if (c === 0x75 /* u */) {
+    return 4;
+  }
+  if (c === 0x55 /* U */) {
+    return 8;
+  }
+  return 0;
+}
+
+function fromDecimalCode(c: number): number {
+  if (0x30 /* 0 */ <= c && c <= 0x39 /* 9 */) {
+    return c - 0x30;
+  }
+
+  return -1;
+}
+
+function simpleEscapeSequence(c: number): string {
+  /* eslint:disable:prettier */
+  return c === 0x30 /* 0 */
+    ? "\x00"
+    : c === 0x61 /* a */
+    ? "\x07"
+    : c === 0x62 /* b */
+    ? "\x08"
+    : c === 0x74 /* t */
+    ? "\x09"
+    : c === 0x09 /* Tab */
+    ? "\x09"
+    : c === 0x6e /* n */
+    ? "\x0A"
+    : c === 0x76 /* v */
+    ? "\x0B"
+    : c === 0x66 /* f */
+    ? "\x0C"
+    : c === 0x72 /* r */
+    ? "\x0D"
+    : c === 0x65 /* e */
+    ? "\x1B"
+    : c === 0x20 /* Space */
+    ? " "
+    : c === 0x22 /* " */
+    ? "\x22"
+    : c === 0x2f /* / */
+    ? "/"
+    : c === 0x5c /* \ */
+    ? "\x5C"
+    : c === 0x4e /* N */
+    ? "\x85"
+    : c === 0x5f /* _ */
+    ? "\xA0"
+    : c === 0x4c /* L */
+    ? "\u2028"
+    : c === 0x50 /* P */
+    ? "\u2029"
+    : "";
+  /* eslint:enable:prettier */
+}
+
+function charFromCodepoint(c: number): string {
+  if (c <= 0xffff) {
+    return String.fromCharCode(c);
+  }
+  // Encode UTF-16 surrogate pair
+  // https://en.wikipedia.org/wiki/UTF-16#Code_points_U.2B010000_to_U.2B10FFFF
+  return String.fromCharCode(
+    ((c - 0x010000) >> 10) + 0xd800,
+    ((c - 0x010000) & 0x03ff) + 0xdc00
+  );
+}
+
+const simpleEscapeCheck = new Array(256); // integer, for fast access
+const simpleEscapeMap = new Array(256);
+for (let i = 0; i < 256; i++) {
+  simpleEscapeCheck[i] = simpleEscapeSequence(i) ? 1 : 0;
+  simpleEscapeMap[i] = simpleEscapeSequence(i);
+}
+
+function generateError(state: LoaderState, message: string): YAMLError {
+  return new YAMLError(
+    message,
+    new Mark(
+      state.filename as string,
+      state.input,
+      state.position,
+      state.line,
+      state.position - state.lineStart
+    )
+  );
+}
+
+function throwError(state: LoaderState, message: string): never {
+  throw generateError(state, message);
+}
+
+function throwWarning(state: LoaderState, message: string): void {
+  if (state.onWarning) {
+    state.onWarning.call(null, generateError(state, message));
+  }
+}
+
+interface DirectiveHandlers {
+  [directive: string]: (
+    state: LoaderState,
+    name: string,
+    ...args: Any[]
+  ) => void;
+}
+
+const directiveHandlers: DirectiveHandlers = {
+  YAML(state, name, ...args): void {
+    if (state.version !== null) {
+      return throwError(state, "duplication of %YAML directive");
+    }
+
+    if (args.length !== 1) {
+      return throwError(state, "YAML directive accepts exactly one argument");
+    }
+
+    let match = /^([0-9]+)\.([0-9]+)$/.exec(args[0]);
+
+    if (match === null) {
+      return throwError(state, "ill-formed argument of the YAML directive");
+    }
+
+    let major = parseInt(match[1], 10);
+    let minor = parseInt(match[2], 10);
+
+    if (major !== 1) {
+      return throwError(state, "unacceptable YAML version of the document");
+    }
+
+    state.version = args[0];
+    state.checkLineBreaks = minor < 2;
+
+    if (minor !== 1 && minor !== 2) {
+      return throwWarning(state, "unsupported YAML version of the document");
+    }
+  },
+
+  TAG(state, name, ...args): void {
+    let handle, prefix;
+
+    if (args.length !== 2) {
+      return throwError(state, "TAG directive accepts exactly two arguments");
+    }
+
+    handle = args[0];
+    prefix = args[1];
+
+    if (!PATTERN_TAG_HANDLE.test(handle)) {
+      return throwError(
+        state,
+        "ill-formed tag handle (first argument) of the TAG directive"
+      );
+    }
+
+    if (_hasOwnProperty.call(state.tagMap, handle)) {
+      return throwError(
+        state,
+        `there is a previously declared suffix for "${handle}" tag handle`
+      );
+    }
+
+    if (!PATTERN_TAG_URI.test(prefix)) {
+      return throwError(
+        state,
+        "ill-formed tag prefix (second argument) of the TAG directive"
+      );
+    }
+
+    if (typeof state.tagMap === "undefined") {
+      state.tagMap = {};
+    }
+    state.tagMap[handle] = prefix;
+  }
+};
+
+function captureSegment(
+  state: LoaderState,
+  start: number,
+  end: number,
+  checkJson: boolean
+): void {
+  let result: string;
+  if (start < end) {
+    result = state.input.slice(start, end);
+
+    if (checkJson) {
+      for (
+        let position = 0, length = result.length;
+        position < length;
+        position++
+      ) {
+        const character = result.charCodeAt(position);
+        if (
+          !(character === 0x09 || (0x20 <= character && character <= 0x10ffff))
+        ) {
+          return throwError(state, "expected valid JSON character");
+        }
+      }
+    } else if (PATTERN_NON_PRINTABLE.test(result)) {
+      return throwError(state, "the stream contains non-printable characters");
+    }
+
+    state.result += result;
+  }
+}
+
+function mergeMappings(
+  state: LoaderState,
+  destination: ArrayObject,
+  source: ArrayObject,
+  overridableKeys: ArrayObject<boolean>
+): void {
+  if (!common.isObject(source)) {
+    return throwError(
+      state,
+      "cannot merge mappings; the provided source object is unacceptable"
+    );
+  }
+
+  const keys = Object.keys(source);
+  for (let i = 0, len = keys.length; i < len; i++) {
+    const key = keys[i];
+    if (!_hasOwnProperty.call(destination, key)) {
+      destination[key] = (source as ArrayObject)[key];
+      overridableKeys[key] = true;
+    }
+  }
+}
+
+function storeMappingPair(
+  state: LoaderState,
+  result: ArrayObject | null,
+  overridableKeys: ArrayObject<boolean>,
+  keyTag: string | null,
+  keyNode: Any,
+  valueNode: Any,
+  startLine?: number,
+  startPos?: number
+): ArrayObject {
+  // The output is a plain object here, so keys can only be strings.
+  // We need to convert keyNode to a string, but doing so can hang the process
+  // (deeply nested arrays that explode exponentially using aliases).
+  if (Array.isArray(keyNode)) {
+    keyNode = Array.prototype.slice.call(keyNode);
+
+    for (let index = 0, quantity = keyNode.length; index < quantity; index++) {
+      if (Array.isArray(keyNode[index])) {
+        return throwError(state, "nested arrays are not supported inside keys");
+      }
+
+      if (
+        typeof keyNode === "object" &&
+        _class(keyNode[index]) === "[object Object]"
+      ) {
+        keyNode[index] = "[object Object]";
+      }
+    }
+  }
+
+  // Avoid code execution in load() via toString property
+  // (still use its own toString for arrays, timestamps,
+  // and whatever user schema extensions happen to have @@toStringTag)
+  if (typeof keyNode === "object" && _class(keyNode) === "[object Object]") {
+    keyNode = "[object Object]";
+  }
+
+  keyNode = String(keyNode);
+
+  if (result === null) {
+    result = {};
+  }
+
+  if (keyTag === "tag:yaml.org,2002:merge") {
+    if (Array.isArray(valueNode)) {
+      for (
+        let index = 0, quantity = valueNode.length;
+        index < quantity;
+        index++
+      ) {
+        mergeMappings(state, result, valueNode[index], overridableKeys);
+      }
+    } else {
+      mergeMappings(state, result, valueNode, overridableKeys);
+    }
+  } else {
+    if (
+      !state.json &&
+      !_hasOwnProperty.call(overridableKeys, keyNode) &&
+      _hasOwnProperty.call(result, keyNode)
+    ) {
+      state.line = startLine || state.line;
+      state.position = startPos || state.position;
+      return throwError(state, "duplicated mapping key");
+    }
+    result[keyNode] = valueNode;
+    delete overridableKeys[keyNode];
+  }
+
+  return result;
+}
+
+function readLineBreak(state: LoaderState): void {
+  let ch;
+
+  ch = state.input.charCodeAt(state.position);
+
+  if (ch === 0x0a /* LF */) {
+    state.position++;
+  } else if (ch === 0x0d /* CR */) {
+    state.position++;
+    if (state.input.charCodeAt(state.position) === 0x0a /* LF */) {
+      state.position++;
+    }
+  } else {
+    return throwError(state, "a line break is expected");
+  }
+
+  state.line += 1;
+  state.lineStart = state.position;
+}
+
+function skipSeparationSpace(
+  state: LoaderState,
+  allowComments: boolean,
+  checkIndent: number
+): number {
+  let lineBreaks = 0,
+    ch = state.input.charCodeAt(state.position);
+
+  while (ch !== 0) {
+    while (isWhiteSpace(ch)) {
+      ch = state.input.charCodeAt(++state.position);
+    }
+
+    if (allowComments && ch === 0x23 /* # */) {
+      do {
+        ch = state.input.charCodeAt(++state.position);
+      } while (ch !== 0x0a /* LF */ && ch !== 0x0d /* CR */ && ch !== 0);
+    }
+
+    if (isEOL(ch)) {
+      readLineBreak(state);
+
+      ch = state.input.charCodeAt(state.position);
+      lineBreaks++;
+      state.lineIndent = 0;
+
+      while (ch === 0x20 /* Space */) {
+        state.lineIndent++;
+        ch = state.input.charCodeAt(++state.position);
+      }
+    } else {
+      break;
+    }
+  }
+
+  if (
+    checkIndent !== -1 &&
+    lineBreaks !== 0 &&
+    state.lineIndent < checkIndent
+  ) {
+    throwWarning(state, "deficient indentation");
+  }
+
+  return lineBreaks;
+}
+
+function testDocumentSeparator(state: LoaderState): boolean {
+  let _position = state.position;
+  let ch = state.input.charCodeAt(_position);
+
+  // Condition state.position === state.lineStart is tested
+  // in parent on each call, for efficiency. No needs to test here again.
+  if (
+    (ch === 0x2d /* - */ || ch === 0x2e) /* . */ &&
+    ch === state.input.charCodeAt(_position + 1) &&
+    ch === state.input.charCodeAt(_position + 2)
+  ) {
+    _position += 3;
+
+    ch = state.input.charCodeAt(_position);
+
+    if (ch === 0 || isWsOrEol(ch)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+function writeFoldedLines(state: LoaderState, count: number): void {
+  if (count === 1) {
+    state.result += " ";
+  } else if (count > 1) {
+    state.result += common.repeat("\n", count - 1);
+  }
+}
+
+function readPlainScalar(
+  state: LoaderState,
+  nodeIndent: number,
+  withinFlowCollection: boolean
+): boolean {
+  const kind = state.kind;
+  const result = state.result;
+  let ch = state.input.charCodeAt(state.position);
+
+  if (
+    isWsOrEol(ch) ||
+    isFlowIndicator(ch) ||
+    ch === 0x23 /* # */ ||
+    ch === 0x26 /* & */ ||
+    ch === 0x2a /* * */ ||
+    ch === 0x21 /* ! */ ||
+    ch === 0x7c /* | */ ||
+    ch === 0x3e /* > */ ||
+    ch === 0x27 /* ' */ ||
+    ch === 0x22 /* " */ ||
+    ch === 0x25 /* % */ ||
+    ch === 0x40 /* @ */ ||
+    ch === 0x60 /* ` */
+  ) {
+    return false;
+  }
+
+  let following: number;
+  if (ch === 0x3f /* ? */ || ch === 0x2d /* - */) {
+    following = state.input.charCodeAt(state.position + 1);
+
+    if (
+      isWsOrEol(following) ||
+      (withinFlowCollection && isFlowIndicator(following))
+    ) {
+      return false;
+    }
+  }
+
+  state.kind = "scalar";
+  state.result = "";
+  let captureEnd: number,
+    captureStart = (captureEnd = state.position);
+  let hasPendingContent = false;
+  let line = 0;
+  while (ch !== 0) {
+    if (ch === 0x3a /* : */) {
+      following = state.input.charCodeAt(state.position + 1);
+
+      if (
+        isWsOrEol(following) ||
+        (withinFlowCollection && isFlowIndicator(following))
+      ) {
+        break;
+      }
+    } else if (ch === 0x23 /* # */) {
+      const preceding = state.input.charCodeAt(state.position - 1);
+
+      if (isWsOrEol(preceding)) {
+        break;
+      }
+    } else if (
+      (state.position === state.lineStart && testDocumentSeparator(state)) ||
+      (withinFlowCollection && isFlowIndicator(ch))
+    ) {
+      break;
+    } else if (isEOL(ch)) {
+      line = state.line;
+      const lineStart = state.lineStart;
+      const lineIndent = state.lineIndent;
+      skipSeparationSpace(state, false, -1);
+
+      if (state.lineIndent >= nodeIndent) {
+        hasPendingContent = true;
+        ch = state.input.charCodeAt(state.position);
+        continue;
+      } else {
+        state.position = captureEnd;
+        state.line = line;
+        state.lineStart = lineStart;
+        state.lineIndent = lineIndent;
+        break;
+      }
+    }
+
+    if (hasPendingContent) {
+      captureSegment(state, captureStart, captureEnd, false);
+      writeFoldedLines(state, state.line - line);
+      captureStart = captureEnd = state.position;
+      hasPendingContent = false;
+    }
+
+    if (!isWhiteSpace(ch)) {
+      captureEnd = state.position + 1;
+    }
+
+    ch = state.input.charCodeAt(++state.position);
+  }
+
+  captureSegment(state, captureStart, captureEnd, false);
+
+  if (!common.isNullOrUndefined(state.result)) {
+    return true;
+  }
+
+  state.kind = kind;
+  state.result = result;
+  return false;
+}
+
+function readSingleQuotedScalar(
+  state: LoaderState,
+  nodeIndent: number
+): boolean {
+  let ch, captureStart, captureEnd;
+
+  ch = state.input.charCodeAt(state.position);
+
+  if (ch !== 0x27 /* ' */) {
+    return false;
+  }
+
+  state.kind = "scalar";
+  state.result = "";
+  state.position++;
+  captureStart = captureEnd = state.position;
+
+  while ((ch = state.input.charCodeAt(state.position)) !== 0) {
+    if (ch === 0x27 /* ' */) {
+      captureSegment(state, captureStart, state.position, true);
+      ch = state.input.charCodeAt(++state.position);
+
+      if (ch === 0x27 /* ' */) {
+        captureStart = state.position;
+        state.position++;
+        captureEnd = state.position;
+      } else {
+        return true;
+      }
+    } else if (isEOL(ch)) {
+      captureSegment(state, captureStart, captureEnd, true);
+      writeFoldedLines(state, skipSeparationSpace(state, false, nodeIndent));
+      captureStart = captureEnd = state.position;
+    } else if (
+      state.position === state.lineStart &&
+      testDocumentSeparator(state)
+    ) {
+      return throwError(
+        state,
+        "unexpected end of the document within a single quoted scalar"
+      );
+    } else {
+      state.position++;
+      captureEnd = state.position;
+    }
+  }
+
+  return throwError(
+    state,
+    "unexpected end of the stream within a single quoted scalar"
+  );
+}
+
+function readDoubleQuotedScalar(
+  state: LoaderState,
+  nodeIndent: number
+): boolean {
+  let ch = state.input.charCodeAt(state.position);
+
+  if (ch !== 0x22 /* " */) {
+    return false;
+  }
+
+  state.kind = "scalar";
+  state.result = "";
+  state.position++;
+  let captureEnd: number,
+    captureStart = (captureEnd = state.position);
+  let tmp: number;
+  while ((ch = state.input.charCodeAt(state.position)) !== 0) {
+    if (ch === 0x22 /* " */) {
+      captureSegment(state, captureStart, state.position, true);
+      state.position++;
+      return true;
+    }
+    if (ch === 0x5c /* \ */) {
+      captureSegment(state, captureStart, state.position, true);
+      ch = state.input.charCodeAt(++state.position);
+
+      if (isEOL(ch)) {
+        skipSeparationSpace(state, false, nodeIndent);
+
+        // TODO: rework to inline fn with no type cast?
+      } else if (ch < 256 && simpleEscapeCheck[ch]) {
+        state.result += simpleEscapeMap[ch];
+        state.position++;
+      } else if ((tmp = escapedHexLen(ch)) > 0) {
+        let hexLength = tmp;
+        let hexResult = 0;
+
+        for (; hexLength > 0; hexLength--) {
+          ch = state.input.charCodeAt(++state.position);
+
+          if ((tmp = fromHexCode(ch)) >= 0) {
+            hexResult = (hexResult << 4) + tmp;
+          } else {
+            return throwError(state, "expected hexadecimal character");
+          }
+        }
+
+        state.result += charFromCodepoint(hexResult);
+
+        state.position++;
+      } else {
+        return throwError(state, "unknown escape sequence");
+      }
+
+      captureStart = captureEnd = state.position;
+    } else if (isEOL(ch)) {
+      captureSegment(state, captureStart, captureEnd, true);
+      writeFoldedLines(state, skipSeparationSpace(state, false, nodeIndent));
+      captureStart = captureEnd = state.position;
+    } else if (
+      state.position === state.lineStart &&
+      testDocumentSeparator(state)
+    ) {
+      return throwError(
+        state,
+        "unexpected end of the document within a double quoted scalar"
+      );
+    } else {
+      state.position++;
+      captureEnd = state.position;
+    }
+  }
+
+  return throwError(
+    state,
+    "unexpected end of the stream within a double quoted scalar"
+  );
+}
+
+function readFlowCollection(state: LoaderState, nodeIndent: number): boolean {
+  let ch = state.input.charCodeAt(state.position);
+  let terminator: number;
+  let isMapping = true;
+  let result: ResultType = {};
+  if (ch === 0x5b /* [ */) {
+    terminator = 0x5d; /* ] */
+    isMapping = false;
+    result = [];
+  } else if (ch === 0x7b /* { */) {
+    terminator = 0x7d; /* } */
+  } else {
+    return false;
+  }
+
+  if (
+    state.anchor !== null &&
+    typeof state.anchor != "undefined" &&
+    typeof state.anchorMap != "undefined"
+  ) {
+    state.anchorMap[state.anchor] = result;
+  }
+
+  ch = state.input.charCodeAt(++state.position);
+
+  const tag = state.tag,
+    anchor = state.anchor;
+  let readNext = true;
+  let valueNode,
+    keyNode,
+    keyTag: string | null = (keyNode = valueNode = null),
+    isExplicitPair: boolean,
+    isPair = (isExplicitPair = false);
+  let following = 0,
+    line = 0;
+  const overridableKeys: ArrayObject<boolean> = {};
+  while (ch !== 0) {
+    skipSeparationSpace(state, true, nodeIndent);
+
+    ch = state.input.charCodeAt(state.position);
+
+    if (ch === terminator) {
+      state.position++;
+      state.tag = tag;
+      state.anchor = anchor;
+      state.kind = isMapping ? "mapping" : "sequence";
+      state.result = result;
+      return true;
+    }
+    if (!readNext) {
+      return throwError(state, "missed comma between flow collection entries");
+    }
+
+    keyTag = keyNode = valueNode = null;
+    isPair = isExplicitPair = false;
+
+    if (ch === 0x3f /* ? */) {
+      following = state.input.charCodeAt(state.position + 1);
+
+      if (isWsOrEol(following)) {
+        isPair = isExplicitPair = true;
+        state.position++;
+        skipSeparationSpace(state, true, nodeIndent);
+      }
+    }
+
+    line = state.line;
+    // eslint-disable-next-line @typescript-eslint/no-use-before-define
+    composeNode(state, nodeIndent, CONTEXT_FLOW_IN, false, true);
+    keyTag = state.tag || null;
+    keyNode = state.result;
+    skipSeparationSpace(state, true, nodeIndent);
+
+    ch = state.input.charCodeAt(state.position);
+
+    if ((isExplicitPair || state.line === line) && ch === 0x3a /* : */) {
+      isPair = true;
+      ch = state.input.charCodeAt(++state.position);
+      skipSeparationSpace(state, true, nodeIndent);
+      // eslint-disable-next-line @typescript-eslint/no-use-before-define
+      composeNode(state, nodeIndent, CONTEXT_FLOW_IN, false, true);
+      valueNode = state.result;
+    }
+
+    if (isMapping) {
+      storeMappingPair(
+        state,
+        result,
+        overridableKeys,
+        keyTag,
+        keyNode,
+        valueNode
+      );
+    } else if (isPair) {
+      (result as Array<{}>).push(
+        storeMappingPair(
+          state,
+          null,
+          overridableKeys,
+          keyTag,
+          keyNode,
+          valueNode
+        )
+      );
+    } else {
+      (result as ResultType[]).push(keyNode as ResultType);
+    }
+
+    skipSeparationSpace(state, true, nodeIndent);
+
+    ch = state.input.charCodeAt(state.position);
+
+    if (ch === 0x2c /* , */) {
+      readNext = true;
+      ch = state.input.charCodeAt(++state.position);
+    } else {
+      readNext = false;
+    }
+  }
+
+  return throwError(
+    state,
+    "unexpected end of the stream within a flow collection"
+  );
+}
+
+function readBlockScalar(state: LoaderState, nodeIndent: number): boolean {
+  let chomping = CHOMPING_CLIP,
+    didReadContent = false,
+    detectedIndent = false,
+    textIndent = nodeIndent,
+    emptyLines = 0,
+    atMoreIndented = false;
+
+  let ch = state.input.charCodeAt(state.position);
+
+  let folding = false;
+  if (ch === 0x7c /* | */) {
+    folding = false;
+  } else if (ch === 0x3e /* > */) {
+    folding = true;
+  } else {
+    return false;
+  }
+
+  state.kind = "scalar";
+  state.result = "";
+
+  let tmp = 0;
+  while (ch !== 0) {
+    ch = state.input.charCodeAt(++state.position);
+
+    if (ch === 0x2b /* + */ || ch === 0x2d /* - */) {
+      if (CHOMPING_CLIP === chomping) {
+        chomping = ch === 0x2b /* + */ ? CHOMPING_KEEP : CHOMPING_STRIP;
+      } else {
+        return throwError(state, "repeat of a chomping mode identifier");
+      }
+    } else if ((tmp = fromDecimalCode(ch)) >= 0) {
+      if (tmp === 0) {
+        return throwError(
+          state,
+          "bad explicit indentation width of a block scalar; it cannot be less than one"
+        );
+      } else if (!detectedIndent) {
+        textIndent = nodeIndent + tmp - 1;
+        detectedIndent = true;
+      } else {
+        return throwError(state, "repeat of an indentation width identifier");
+      }
+    } else {
+      break;
+    }
+  }
+
+  if (isWhiteSpace(ch)) {
+    do {
+      ch = state.input.charCodeAt(++state.position);
+    } while (isWhiteSpace(ch));
+
+    if (ch === 0x23 /* # */) {
+      do {
+        ch = state.input.charCodeAt(++state.position);
+      } while (!isEOL(ch) && ch !== 0);
+    }
+  }
+
+  while (ch !== 0) {
+    readLineBreak(state);
+    state.lineIndent = 0;
+
+    ch = state.input.charCodeAt(state.position);
+
+    while (
+      (!detectedIndent || state.lineIndent < textIndent) &&
+      ch === 0x20 /* Space */
+    ) {
+      state.lineIndent++;
+      ch = state.input.charCodeAt(++state.position);
+    }
+
+    if (!detectedIndent && state.lineIndent > textIndent) {
+      textIndent = state.lineIndent;
+    }
+
+    if (isEOL(ch)) {
+      emptyLines++;
+      continue;
+    }
+
+    // End of the scalar.
+    if (state.lineIndent < textIndent) {
+      // Perform the chomping.
+      if (chomping === CHOMPING_KEEP) {
+        state.result += common.repeat(
+          "\n",
+          didReadContent ? 1 + emptyLines : emptyLines
+        );
+      } else if (chomping === CHOMPING_CLIP) {
+        if (didReadContent) {
+          // i.e. only if the scalar is not empty.
+          state.result += "\n";
+        }
+      }
+
+      // Break this `while` cycle and go to the funciton's epilogue.
+      break;
+    }
+
+    // Folded style: use fancy rules to handle line breaks.
+    if (folding) {
+      // Lines starting with white space characters (more-indented lines) are not folded.
+      if (isWhiteSpace(ch)) {
+        atMoreIndented = true;
+        // except for the first content line (cf. Example 8.1)
+        state.result += common.repeat(
+          "\n",
+          didReadContent ? 1 + emptyLines : emptyLines
+        );
+
+        // End of more-indented block.
+      } else if (atMoreIndented) {
+        atMoreIndented = false;
+        state.result += common.repeat("\n", emptyLines + 1);
+
+        // Just one line break - perceive as the same line.
+      } else if (emptyLines === 0) {
+        if (didReadContent) {
+          // i.e. only if we have already read some scalar content.
+          state.result += " ";
+        }
+
+        // Several line breaks - perceive as different lines.
+      } else {
+        state.result += common.repeat("\n", emptyLines);
+      }
+
+      // Literal style: just add exact number of line breaks between content lines.
+    } else {
+      // Keep all line breaks except the header line break.
+      state.result += common.repeat(
+        "\n",
+        didReadContent ? 1 + emptyLines : emptyLines
+      );
+    }
+
+    didReadContent = true;
+    detectedIndent = true;
+    emptyLines = 0;
+    const captureStart = state.position;
+
+    while (!isEOL(ch) && ch !== 0) {
+      ch = state.input.charCodeAt(++state.position);
+    }
+
+    captureSegment(state, captureStart, state.position, false);
+  }
+
+  return true;
+}
+
+function readBlockSequence(state: LoaderState, nodeIndent: number): boolean {
+  let line: number,
+    following: number,
+    detected = false,
+    ch: number;
+  const tag = state.tag,
+    anchor = state.anchor,
+    result: Any[] = [];
+
+  if (
+    state.anchor !== null &&
+    typeof state.anchor !== "undefined" &&
+    typeof state.anchorMap !== "undefined"
+  ) {
+    state.anchorMap[state.anchor] = result;
+  }
+
+  ch = state.input.charCodeAt(state.position);
+
+  while (ch !== 0) {
+    if (ch !== 0x2d /* - */) {
+      break;
+    }
+
+    following = state.input.charCodeAt(state.position + 1);
+
+    if (!isWsOrEol(following)) {
+      break;
+    }
+
+    detected = true;
+    state.position++;
+
+    if (skipSeparationSpace(state, true, -1)) {
+      if (state.lineIndent <= nodeIndent) {
+        result.push(null);
+        ch = state.input.charCodeAt(state.position);
+        continue;
+      }
+    }
+
+    line = state.line;
+    // eslint-disable-next-line @typescript-eslint/no-use-before-define
+    composeNode(state, nodeIndent, CONTEXT_BLOCK_IN, false, true);
+    result.push(state.result);
+    skipSeparationSpace(state, true, -1);
+
+    ch = state.input.charCodeAt(state.position);
+
+    if ((state.line === line || state.lineIndent > nodeIndent) && ch !== 0) {
+      return throwError(state, "bad indentation of a sequence entry");
+    } else if (state.lineIndent < nodeIndent) {
+      break;
+    }
+  }
+
+  if (detected) {
+    state.tag = tag;
+    state.anchor = anchor;
+    state.kind = "sequence";
+    state.result = result;
+    return true;
+  }
+  return false;
+}
+
+function readBlockMapping(
+  state: LoaderState,
+  nodeIndent: number,
+  flowIndent: number
+): boolean {
+  const tag = state.tag,
+    anchor = state.anchor,
+    result = {},
+    overridableKeys = {};
+  let following: number,
+    allowCompact = false,
+    line: number,
+    pos: number,
+    keyTag = null,
+    keyNode = null,
+    valueNode = null,
+    atExplicitKey = false,
+    detected = false,
+    ch: number;
+
+  if (
+    state.anchor !== null &&
+    typeof state.anchor !== "undefined" &&
+    typeof state.anchorMap !== "undefined"
+  ) {
+    state.anchorMap[state.anchor] = result;
+  }
+
+  ch = state.input.charCodeAt(state.position);
+
+  while (ch !== 0) {
+    following = state.input.charCodeAt(state.position + 1);
+    line = state.line; // Save the current line.
+    pos = state.position;
+
+    //
+    // Explicit notation case. There are two separate blocks:
+    // first for the key (denoted by "?") and second for the value (denoted by ":")
+    //
+    if ((ch === 0x3f /* ? */ || ch === 0x3a) /* : */ && isWsOrEol(following)) {
+      if (ch === 0x3f /* ? */) {
+        if (atExplicitKey) {
+          storeMappingPair(
+            state,
+            result,
+            overridableKeys,
+            keyTag as string,
+            keyNode,
+            null
+          );
+          keyTag = keyNode = valueNode = null;
+        }
+
+        detected = true;
+        atExplicitKey = true;
+        allowCompact = true;
+      } else if (atExplicitKey) {
+        // i.e. 0x3A/* : */ === character after the explicit key.
+        atExplicitKey = false;
+        allowCompact = true;
+      } else {
+        return throwError(
+          state,
+          "incomplete explicit mapping pair; a key node is missed; or followed by a non-tabulated empty line"
+        );
+      }
+
+      state.position += 1;
+      ch = following;
+
+      //
+      // Implicit notation case. Flow-style node as the key first, then ":", and the value.
+      //
+      // eslint-disable-next-line @typescript-eslint/no-use-before-define
+    } else if (composeNode(state, flowIndent, CONTEXT_FLOW_OUT, false, true)) {
+      if (state.line === line) {
+        ch = state.input.charCodeAt(state.position);
+
+        while (isWhiteSpace(ch)) {
+          ch = state.input.charCodeAt(++state.position);
+        }
+
+        if (ch === 0x3a /* : */) {
+          ch = state.input.charCodeAt(++state.position);
+
+          if (!isWsOrEol(ch)) {
+            return throwError(
+              state,
+              "a whitespace character is expected after the key-value separator within a block mapping"
+            );
+          }
+
+          if (atExplicitKey) {
+            storeMappingPair(
+              state,
+              result,
+              overridableKeys,
+              keyTag as string,
+              keyNode,
+              null
+            );
+            keyTag = keyNode = valueNode = null;
+          }
+
+          detected = true;
+          atExplicitKey = false;
+          allowCompact = false;
+          keyTag = state.tag;
+          keyNode = state.result;
+        } else if (detected) {
+          return throwError(
+            state,
+            "can not read an implicit mapping pair; a colon is missed"
+          );
+        } else {
+          state.tag = tag;
+          state.anchor = anchor;
+          return true; // Keep the result of `composeNode`.
+        }
+      } else if (detected) {
+        return throwError(
+          state,
+          "can not read a block mapping entry; a multiline key may not be an implicit key"
+        );
+      } else {
+        state.tag = tag;
+        state.anchor = anchor;
+        return true; // Keep the result of `composeNode`.
+      }
+    } else {
+      break; // Reading is done. Go to the epilogue.
+    }
+
+    //
+    // Common reading code for both explicit and implicit notations.
+    //
+    if (state.line === line || state.lineIndent > nodeIndent) {
+      if (
+        // eslint-disable-next-line @typescript-eslint/no-use-before-define
+        composeNode(state, nodeIndent, CONTEXT_BLOCK_OUT, true, allowCompact)
+      ) {
+        if (atExplicitKey) {
+          keyNode = state.result;
+        } else {
+          valueNode = state.result;
+        }
+      }
+
+      if (!atExplicitKey) {
+        storeMappingPair(
+          state,
+          result,
+          overridableKeys,
+          keyTag as string,
+          keyNode,
+          valueNode,
+          line,
+          pos
+        );
+        keyTag = keyNode = valueNode = null;
+      }
+
+      skipSeparationSpace(state, true, -1);
+      ch = state.input.charCodeAt(state.position);
+    }
+
+    if (state.lineIndent > nodeIndent && ch !== 0) {
+      return throwError(state, "bad indentation of a mapping entry");
+    } else if (state.lineIndent < nodeIndent) {
+      break;
+    }
+  }
+
+  //
+  // Epilogue.
+  //
+
+  // Special case: last mapping's node contains only the key in explicit notation.
+  if (atExplicitKey) {
+    storeMappingPair(
+      state,
+      result,
+      overridableKeys,
+      keyTag as string,
+      keyNode,
+      null
+    );
+  }
+
+  // Expose the resulting mapping.
+  if (detected) {
+    state.tag = tag;
+    state.anchor = anchor;
+    state.kind = "mapping";
+    state.result = result;
+  }
+
+  return detected;
+}
+
+function readTagProperty(state: LoaderState): boolean {
+  let position: number,
+    isVerbatim = false,
+    isNamed = false,
+    tagHandle = "",
+    tagName: string,
+    ch: number;
+
+  ch = state.input.charCodeAt(state.position);
+
+  if (ch !== 0x21 /* ! */) return false;
+
+  if (state.tag !== null) {
+    return throwError(state, "duplication of a tag property");
+  }
+
+  ch = state.input.charCodeAt(++state.position);
+
+  if (ch === 0x3c /* < */) {
+    isVerbatim = true;
+    ch = state.input.charCodeAt(++state.position);
+  } else if (ch === 0x21 /* ! */) {
+    isNamed = true;
+    tagHandle = "!!";
+    ch = state.input.charCodeAt(++state.position);
+  } else {
+    tagHandle = "!";
+  }
+
+  position = state.position;
+
+  if (isVerbatim) {
+    do {
+      ch = state.input.charCodeAt(++state.position);
+    } while (ch !== 0 && ch !== 0x3e /* > */);
+
+    if (state.position < state.length) {
+      tagName = state.input.slice(position, state.position);
+      ch = state.input.charCodeAt(++state.position);
+    } else {
+      return throwError(
+        state,
+        "unexpected end of the stream within a verbatim tag"
+      );
+    }
+  } else {
+    while (ch !== 0 && !isWsOrEol(ch)) {
+      if (ch === 0x21 /* ! */) {
+        if (!isNamed) {
+          tagHandle = state.input.slice(position - 1, state.position + 1);
+
+          if (!PATTERN_TAG_HANDLE.test(tagHandle)) {
+            return throwError(
+              state,
+              "named tag handle cannot contain such characters"
+            );
+          }
+
+          isNamed = true;
+          position = state.position + 1;
+        } else {
+          return throwError(
+            state,
+            "tag suffix cannot contain exclamation marks"
+          );
+        }
+      }
+
+      ch = state.input.charCodeAt(++state.position);
+    }
+
+    tagName = state.input.slice(position, state.position);
+
+    if (PATTERN_FLOW_INDICATORS.test(tagName)) {
+      return throwError(
+        state,
+        "tag suffix cannot contain flow indicator characters"
+      );
+    }
+  }
+
+  if (tagName && !PATTERN_TAG_URI.test(tagName)) {
+    return throwError(
+      state,
+      `tag name cannot contain such characters: ${tagName}`
+    );
+  }
+
+  if (isVerbatim) {
+    state.tag = tagName;
+  } else if (
+    typeof state.tagMap !== "undefined" &&
+    _hasOwnProperty.call(state.tagMap, tagHandle)
+  ) {
+    state.tag = state.tagMap[tagHandle] + tagName;
+  } else if (tagHandle === "!") {
+    state.tag = `!${tagName}`;
+  } else if (tagHandle === "!!") {
+    state.tag = `tag:yaml.org,2002:${tagName}`;
+  } else {
+    return throwError(state, `undeclared tag handle "${tagHandle}"`);
+  }
+
+  return true;
+}
+
+function readAnchorProperty(state: LoaderState): boolean {
+  let position: number, ch: number;
+
+  ch = state.input.charCodeAt(state.position);
+
+  if (ch !== 0x26 /* & */) return false;
+
+  if (state.anchor !== null) {
+    return throwError(state, "duplication of an anchor property");
+  }
+
+  ch = state.input.charCodeAt(++state.position);
+  position = state.position;
+
+  while (ch !== 0 && !isWsOrEol(ch) && !isFlowIndicator(ch)) {
+    ch = state.input.charCodeAt(++state.position);
+  }
+
+  if (state.position === position) {
+    return throwError(
+      state,
+      "name of an anchor node must contain at least one character"
+    );
+  }
+
+  state.anchor = state.input.slice(position, state.position);
+  return true;
+}
+
+function readAlias(state: LoaderState): boolean {
+  let _position, alias, ch;
+
+  ch = state.input.charCodeAt(state.position);
+
+  if (ch !== 0x2a /* * */) return false;
+
+  ch = state.input.charCodeAt(++state.position);
+  _position = state.position;
+
+  while (ch !== 0 && !isWsOrEol(ch) && !isFlowIndicator(ch)) {
+    ch = state.input.charCodeAt(++state.position);
+  }
+
+  if (state.position === _position) {
+    return throwError(
+      state,
+      "name of an alias node must contain at least one character"
+    );
+  }
+
+  alias = state.input.slice(_position, state.position);
+
+  if (
+    typeof state.anchorMap !== "undefined" &&
+    !state.anchorMap.hasOwnProperty(alias)
+  ) {
+    return throwError(state, `unidentified alias "${alias}"`);
+  }
+
+  if (typeof state.anchorMap !== "undefined") {
+    state.result = state.anchorMap[alias];
+  }
+  skipSeparationSpace(state, true, -1);
+  return true;
+}
+
+function composeNode(
+  state: LoaderState,
+  parentIndent: number,
+  nodeContext: number,
+  allowToSeek: boolean,
+  allowCompact: boolean
+): boolean {
+  let allowBlockStyles: boolean,
+    allowBlockScalars: boolean,
+    allowBlockCollections: boolean,
+    indentStatus = 1, // 1: this>parent, 0: this=parent, -1: this<parent
+    atNewLine = false,
+    hasContent = false,
+    type: Type,
+    flowIndent: number,
+    blockIndent: number;
+
+  if (state.listener && state.listener !== null) {
+    state.listener("open", state);
+  }
+
+  state.tag = null;
+  state.anchor = null;
+  state.kind = null;
+  state.result = null;
+
+  allowBlockStyles = allowBlockScalars = allowBlockCollections =
+    CONTEXT_BLOCK_OUT === nodeContext || CONTEXT_BLOCK_IN === nodeContext;
+
+  if (allowToSeek) {
+    if (skipSeparationSpace(state, true, -1)) {
+      atNewLine = true;
+
+      if (state.lineIndent > parentIndent) {
+        indentStatus = 1;
+      } else if (state.lineIndent === parentIndent) {
+        indentStatus = 0;
+      } else if (state.lineIndent < parentIndent) {
+        indentStatus = -1;
+      }
+    }
+  }
+
+  if (indentStatus === 1) {
+    while (readTagProperty(state) || readAnchorProperty(state)) {
+      if (skipSeparationSpace(state, true, -1)) {
+        atNewLine = true;
+        allowBlockCollections = allowBlockStyles;
+
+        if (state.lineIndent > parentIndent) {
+          indentStatus = 1;
+        } else if (state.lineIndent === parentIndent) {
+          indentStatus = 0;
+        } else if (state.lineIndent < parentIndent) {
+          indentStatus = -1;
+        }
+      } else {
+        allowBlockCollections = false;
+      }
+    }
+  }
+
+  if (allowBlockCollections) {
+    allowBlockCollections = atNewLine || allowCompact;
+  }
+
+  if (indentStatus === 1 || CONTEXT_BLOCK_OUT === nodeContext) {
+    const cond =
+      CONTEXT_FLOW_IN === nodeContext || CONTEXT_FLOW_OUT === nodeContext;
+    flowIndent = cond ? parentIndent : parentIndent + 1;
+
+    blockIndent = state.position - state.lineStart;
+
+    if (indentStatus === 1) {
+      if (
+        (allowBlockCollections &&
+          (readBlockSequence(state, blockIndent) ||
+            readBlockMapping(state, blockIndent, flowIndent))) ||
+        readFlowCollection(state, flowIndent)
+      ) {
+        hasContent = true;
+      } else {
+        if (
+          (allowBlockScalars && readBlockScalar(state, flowIndent)) ||
+          readSingleQuotedScalar(state, flowIndent) ||
+          readDoubleQuotedScalar(state, flowIndent)
+        ) {
+          hasContent = true;
+        } else if (readAlias(state)) {
+          hasContent = true;
+
+          if (state.tag !== null || state.anchor !== null) {
+            return throwError(
+              state,
+              "alias node should not have Any properties"
+            );
+          }
+        } else if (
+          readPlainScalar(state, flowIndent, CONTEXT_FLOW_IN === nodeContext)
+        ) {
+          hasContent = true;
+
+          if (state.tag === null) {
+            state.tag = "?";
+          }
+        }
+
+        if (state.anchor !== null && typeof state.anchorMap !== "undefined") {
+          state.anchorMap[state.anchor] = state.result;
+        }
+      }
+    } else if (indentStatus === 0) {
+      // Special case: block sequences are allowed to have same indentation level as the parent.
+      // http://www.yaml.org/spec/1.2/spec.html#id2799784
+      hasContent =
+        allowBlockCollections && readBlockSequence(state, blockIndent);
+    }
+  }
+
+  if (state.tag !== null && state.tag !== "!") {
+    if (state.tag === "?") {
+      for (
+        let typeIndex = 0, typeQuantity = state.implicitTypes.length;
+        typeIndex < typeQuantity;
+        typeIndex++
+      ) {
+        type = state.implicitTypes[typeIndex];
+
+        // Implicit resolving is not allowed for non-scalar types, and '?'
+        // non-specific tag is only assigned to plain scalars. So, it isn't
+        // needed to check for 'kind' conformity.
+
+        if (type.resolve(state.result)) {
+          // `state.result` updated in resolver if matched
+          state.result = type.construct(state.result);
+          state.tag = type.tag;
+          if (state.anchor !== null && typeof state.anchorMap !== "undefined") {
+            state.anchorMap[state.anchor] = state.result;
+          }
+          break;
+        }
+      }
+    } else if (
+      _hasOwnProperty.call(state.typeMap[state.kind || "fallback"], state.tag)
+    ) {
+      type = state.typeMap[state.kind || "fallback"][state.tag];
+
+      if (state.result !== null && type.kind !== state.kind) {
+        return throwError(
+          state,
+          `unacceptable node kind for !<${state.tag}> tag; it should be "${
+            type.kind
+          }", not "${state.kind}"`
+        );
+      }
+
+      if (!type.resolve(state.result)) {
+        // `state.result` updated in resolver if matched
+        return throwError(
+          state,
+          `cannot resolve a node with !<${state.tag}> explicit tag`
+        );
+      } else {
+        state.result = type.construct(state.result);
+        if (state.anchor !== null && typeof state.anchorMap !== "undefined") {
+          state.anchorMap[state.anchor] = state.result;
+        }
+      }
+    } else {
+      return throwError(state, `unknown tag !<${state.tag}>`);
+    }
+  }
+
+  if (state.listener && state.listener !== null) {
+    state.listener("close", state);
+  }
+  return state.tag !== null || state.anchor !== null || hasContent;
+}
+
+function readDocument(state: LoaderState): void {
+  const documentStart = state.position;
+  let position: number,
+    directiveName: string,
+    directiveArgs: Any[],
+    hasDirectives = false,
+    ch: number;
+
+  state.version = null;
+  state.checkLineBreaks = state.legacy;
+  state.tagMap = {};
+  state.anchorMap = {};
+
+  while ((ch = state.input.charCodeAt(state.position)) !== 0) {
+    skipSeparationSpace(state, true, -1);
+
+    ch = state.input.charCodeAt(state.position);
+
+    if (state.lineIndent > 0 || ch !== 0x25 /* % */) {
+      break;
+    }
+
+    hasDirectives = true;
+    ch = state.input.charCodeAt(++state.position);
+    position = state.position;
+
+    while (ch !== 0 && !isWsOrEol(ch)) {
+      ch = state.input.charCodeAt(++state.position);
+    }
+
+    directiveName = state.input.slice(position, state.position);
+    directiveArgs = [];
+
+    if (directiveName.length < 1) {
+      return throwError(
+        state,
+        "directive name must not be less than one character in length"
+      );
+    }
+
+    while (ch !== 0) {
+      while (isWhiteSpace(ch)) {
+        ch = state.input.charCodeAt(++state.position);
+      }
+
+      if (ch === 0x23 /* # */) {
+        do {
+          ch = state.input.charCodeAt(++state.position);
+        } while (ch !== 0 && !isEOL(ch));
+        break;
+      }
+
+      if (isEOL(ch)) break;
+
+      position = state.position;
+
+      while (ch !== 0 && !isWsOrEol(ch)) {
+        ch = state.input.charCodeAt(++state.position);
+      }
+
+      directiveArgs.push(state.input.slice(position, state.position));
+    }
+
+    if (ch !== 0) readLineBreak(state);
+
+    if (_hasOwnProperty.call(directiveHandlers, directiveName)) {
+      directiveHandlers[directiveName](state, directiveName, ...directiveArgs);
+    } else {
+      throwWarning(state, `unknown document directive "${directiveName}"`);
+    }
+  }
+
+  skipSeparationSpace(state, true, -1);
+
+  if (
+    state.lineIndent === 0 &&
+    state.input.charCodeAt(state.position) === 0x2d /* - */ &&
+    state.input.charCodeAt(state.position + 1) === 0x2d /* - */ &&
+    state.input.charCodeAt(state.position + 2) === 0x2d /* - */
+  ) {
+    state.position += 3;
+    skipSeparationSpace(state, true, -1);
+  } else if (hasDirectives) {
+    return throwError(state, "directives end mark is expected");
+  }
+
+  composeNode(state, state.lineIndent - 1, CONTEXT_BLOCK_OUT, false, true);
+  skipSeparationSpace(state, true, -1);
+
+  if (
+    state.checkLineBreaks &&
+    PATTERN_NON_ASCII_LINE_BREAKS.test(
+      state.input.slice(documentStart, state.position)
+    )
+  ) {
+    throwWarning(state, "non-ASCII line breaks are interpreted as content");
+  }
+
+  state.documents.push(state.result);
+
+  if (state.position === state.lineStart && testDocumentSeparator(state)) {
+    if (state.input.charCodeAt(state.position) === 0x2e /* . */) {
+      state.position += 3;
+      skipSeparationSpace(state, true, -1);
+    }
+    return;
+  }
+
+  if (state.position < state.length - 1) {
+    return throwError(
+      state,
+      "end of the stream or a document separator is expected"
+    );
+  } else {
+    return;
+  }
+}
+
+function loadDocuments(input: string, options?: LoaderStateOptions): Any[] {
+  input = String(input);
+  options = options || {};
+
+  if (input.length !== 0) {
+    // Add tailing `\n` if not exists
+    if (
+      input.charCodeAt(input.length - 1) !== 0x0a /* LF */ &&
+      input.charCodeAt(input.length - 1) !== 0x0d /* CR */
+    ) {
+      input += "\n";
+    }
+
+    // Strip BOM
+    if (input.charCodeAt(0) === 0xfeff) {
+      input = input.slice(1);
+    }
+  }
+
+  const state = new LoaderState(input, options);
+
+  // Use 0 as string terminator. That significantly simplifies bounds check.
+  state.input += "\0";
+
+  while (state.input.charCodeAt(state.position) === 0x20 /* Space */) {
+    state.lineIndent += 1;
+    state.position += 1;
+  }
+
+  while (state.position < state.length - 1) {
+    readDocument(state);
+  }
+
+  return state.documents;
+}
+
+export type CbFunction = (doc: Any) => void;
+function isCbFunction(fn: Any): fn is CbFunction {
+  return typeof fn === "function";
+}
+
+export function loadAll<T extends CbFunction | LoaderStateOptions>(
+  input: string,
+  iteratorOrOption?: T,
+  options?: LoaderStateOptions
+): T extends CbFunction ? void : Any[] {
+  if (!isCbFunction(iteratorOrOption)) {
+    return loadDocuments(input, iteratorOrOption as LoaderStateOptions) as Any;
+  }
+
+  const documents = loadDocuments(input, options);
+  const iterator = iteratorOrOption;
+  for (let index = 0, length = documents.length; index < length; index++) {
+    iterator(documents[index]);
+  }
+
+  return void 0 as Any;
+}
+
+export function load(input: string, options?: LoaderStateOptions): Any {
+  const documents = loadDocuments(input, options);
+
+  if (documents.length === 0) {
+    return;
+  }
+  if (documents.length === 1) {
+    return documents[0];
+  }
+  throw new YAMLError(
+    "expected a single document in the stream, but found more"
+  );
+}
diff --git a/encoding/yaml/loader/loader_state.ts b/encoding/yaml/loader/loader_state.ts
new file mode 100644
index 000000000000..3fe8458be378
--- /dev/null
+++ b/encoding/yaml/loader/loader_state.ts
@@ -0,0 +1,73 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { YAMLError } from "../error.ts";
+import { Schema, SchemaDefinition, TypeMap } from "../schema.ts";
+import { State } from "../state.ts";
+import { Type } from "../type.ts";
+import { Any, ArrayObject } from "../utils.ts";
+
+export interface LoaderStateOptions {
+  legacy?: boolean;
+  listener?: ((...args: Any[]) => void) | null;
+  /** string to be used as a file path in error/warning messages. */
+  filename?: string;
+  /** specifies a schema to use. */
+  schema?: SchemaDefinition;
+  /** compatibility with JSON.parse behaviour. */
+  json?: boolean;
+  /** function to call on warning messages. */
+  onWarning?(this: null, e?: YAMLError): void;
+}
+
+export type ResultType = [] | {} | string;
+
+export class LoaderState extends State {
+  public documents: Any[] = [];
+  public length: number;
+  public lineIndent = 0;
+  public lineStart = 0;
+  public position = 0;
+  public line = 0;
+  public filename?: string;
+  public onWarning?: (...args: Any[]) => void;
+  public legacy: boolean;
+  public json: boolean;
+  public listener?: ((...args: Any[]) => void) | null;
+  public implicitTypes: Type[];
+  public typeMap: TypeMap;
+
+  public version?: string | null;
+  public checkLineBreaks?: boolean;
+  public tagMap?: ArrayObject;
+  public anchorMap?: ArrayObject;
+  public tag?: string | null;
+  public anchor?: string | null;
+  public kind?: string | null;
+  public result: ResultType | null = "";
+
+  constructor(
+    public input: string,
+    {
+      filename,
+      schema,
+      onWarning,
+      legacy = false,
+      json = false,
+      listener = null
+    }: LoaderStateOptions
+  ) {
+    super(schema);
+    this.filename = filename;
+    this.onWarning = onWarning;
+    this.legacy = legacy;
+    this.json = json;
+    this.listener = listener;
+
+    this.implicitTypes = (this.schema as Schema).compiledImplicit;
+    this.typeMap = (this.schema as Schema).compiledTypeMap;
+
+    this.length = input.length;
+  }
+}
diff --git a/encoding/yaml/parse.ts b/encoding/yaml/parse.ts
new file mode 100644
index 000000000000..d2687094b7a3
--- /dev/null
+++ b/encoding/yaml/parse.ts
@@ -0,0 +1,21 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { CbFunction, load, loadAll } from "./loader/loader.ts";
+import { LoaderStateOptions } from "./loader/loader_state.ts";
+
+export type ParseOptions = LoaderStateOptions;
+
+export function parse(content: string, options?: ParseOptions): unknown {
+  return load(content, options);
+}
+
+export function parseAll(
+  content: string,
+  iterator?: CbFunction,
+  options?: ParseOptions
+): unknown {
+  return loadAll(content, iterator, options);
+}
diff --git a/encoding/yaml/parse_test.ts b/encoding/yaml/parse_test.ts
new file mode 100644
index 000000000000..c52767111cab
--- /dev/null
+++ b/encoding/yaml/parse_test.ts
@@ -0,0 +1,25 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { parse } from "./parse.ts";
+import { test } from "../../testing/mod.ts";
+import { assertEquals } from "../../testing/asserts.ts";
+
+test({
+  name: "parsed correctly",
+  fn(): void {
+    const FIXTURE = `
+        test: toto
+        foo:
+          bar: True
+          baz: 1
+          qux: ~
+        `;
+
+    const ASSERTS = { test: "toto", foo: { bar: true, baz: 1, qux: null } };
+
+    assertEquals(parse(FIXTURE), ASSERTS);
+  }
+});
diff --git a/encoding/yaml/schema/core.ts b/encoding/yaml/schema/core.ts
new file mode 100644
index 000000000000..910e979d8e64
--- /dev/null
+++ b/encoding/yaml/schema/core.ts
@@ -0,0 +1,12 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Schema } from "../schema.ts";
+import { json } from "./json.ts";
+
+// Standard YAML's Core schema.
+// http://www.yaml.org/spec/1.2/spec.html#id2804923
+export const core = new Schema({
+  include: [json]
+});
diff --git a/encoding/yaml/schema/default.ts b/encoding/yaml/schema/default.ts
new file mode 100644
index 000000000000..2618d198bfb0
--- /dev/null
+++ b/encoding/yaml/schema/default.ts
@@ -0,0 +1,15 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Schema } from "../schema.ts";
+import { binary, merge, omap, pairs, set, timestamp } from "../type/mod.ts";
+import { core } from "./core.ts";
+
+// JS-YAML's default schema for `safeLoad` function.
+// It is not described in the YAML specification.
+export const def = new Schema({
+  explicit: [binary, omap, pairs, set],
+  implicit: [timestamp, merge],
+  include: [core]
+});
diff --git a/encoding/yaml/schema/failsafe.ts b/encoding/yaml/schema/failsafe.ts
new file mode 100644
index 000000000000..885d058f37a8
--- /dev/null
+++ b/encoding/yaml/schema/failsafe.ts
@@ -0,0 +1,12 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Schema } from "../schema.ts";
+import { map, seq, str } from "../type/mod.ts";
+
+// Standard YAML's Failsafe schema.
+// http://www.yaml.org/spec/1.2/spec.html#id2802346
+export const failsafe = new Schema({
+  explicit: [str, seq, map]
+});
diff --git a/encoding/yaml/schema/json.ts b/encoding/yaml/schema/json.ts
new file mode 100644
index 000000000000..129b916d3d84
--- /dev/null
+++ b/encoding/yaml/schema/json.ts
@@ -0,0 +1,14 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Schema } from "../schema.ts";
+import { bool, float, int, nil } from "../type/mod.ts";
+import { failsafe } from "./failsafe.ts";
+
+// Standard YAML's JSON schema.
+// http://www.yaml.org/spec/1.2/spec.html#id2803231
+export const json = new Schema({
+  implicit: [nil, bool, int, float],
+  include: [failsafe]
+});
diff --git a/encoding/yaml/schema/mod.ts b/encoding/yaml/schema/mod.ts
new file mode 100644
index 000000000000..27967d29cefc
--- /dev/null
+++ b/encoding/yaml/schema/mod.ts
@@ -0,0 +1,8 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+export { core as CORE_SCHEMA } from "./core.ts";
+export { def as DEFAULT_SCHEMA } from "./default.ts";
+export { failsafe as FAILSAFE_SCHEMA } from "./failsafe.ts";
+export { json as JSON_SCHEMA } from "./json.ts";
diff --git a/encoding/yaml/stringify.ts b/encoding/yaml/stringify.ts
new file mode 100644
index 000000000000..9344c3341e5d
--- /dev/null
+++ b/encoding/yaml/stringify.ts
@@ -0,0 +1,13 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { dump } from "./dumper/dumper.ts";
+import { DumperStateOptions } from "./dumper/dumper_state.ts";
+
+export type DumpOptions = DumperStateOptions;
+
+export function stringify(obj: object, options?: DumpOptions): string {
+  return dump(obj, options);
+}
diff --git a/encoding/yaml/stringify_test.ts b/encoding/yaml/stringify_test.ts
new file mode 100644
index 000000000000..2f03399e744d
--- /dev/null
+++ b/encoding/yaml/stringify_test.ts
@@ -0,0 +1,42 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { test } from "../../testing/mod.ts";
+import { assertEquals } from "../../testing/asserts.ts";
+import { stringify } from "./stringify.ts";
+
+test({
+  name: "stringified correctly",
+  fn(): void {
+    const FIXTURE = {
+      foo: {
+        bar: true,
+        test: [
+          "a",
+          "b",
+          {
+            a: false
+          },
+          {
+            a: false
+          }
+        ]
+      },
+      test: "foobar"
+    };
+
+    const ASSERTS = `foo:
+  bar: true
+  test:
+    - a
+    - b
+    - a: false
+    - a: false
+test: foobar
+`;
+
+    assertEquals(stringify(FIXTURE), ASSERTS);
+  }
+});
diff --git a/encoding/yaml/type/binary.ts b/encoding/yaml/type/binary.ts
new file mode 100644
index 000000000000..863b4f5f0384
--- /dev/null
+++ b/encoding/yaml/type/binary.ts
@@ -0,0 +1,138 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+import { Any } from "../utils.ts";
+
+const { Buffer } = Deno;
+
+// [ 64, 65, 66 ] -> [ padding, CR, LF ]
+const BASE64_MAP =
+  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n\r";
+
+function resolveYamlBinary(data: Any): boolean {
+  if (data === null) return false;
+
+  let code: number;
+  let bitlen = 0;
+  const max = data.length;
+  const map = BASE64_MAP;
+
+  // Convert one by one.
+  for (let idx = 0; idx < max; idx++) {
+    code = map.indexOf(data.charAt(idx));
+
+    // Skip CR/LF
+    if (code > 64) continue;
+
+    // Fail on illegal characters
+    if (code < 0) return false;
+
+    bitlen += 6;
+  }
+
+  // If there are any bits left, source was corrupted
+  return bitlen % 8 === 0;
+}
+
+function constructYamlBinary(data: string): Deno.Buffer {
+  // remove CR/LF & padding to simplify scan
+  const input = data.replace(/[\r\n=]/g, "");
+  const max = input.length;
+  const map = BASE64_MAP;
+
+  // Collect by 6*4 bits (3 bytes)
+
+  const result = [];
+  let bits = 0;
+  for (let idx = 0; idx < max; idx++) {
+    if (idx % 4 === 0 && idx) {
+      result.push((bits >> 16) & 0xff);
+      result.push((bits >> 8) & 0xff);
+      result.push(bits & 0xff);
+    }
+
+    bits = (bits << 6) | map.indexOf(input.charAt(idx));
+  }
+
+  // Dump tail
+
+  const tailbits = (max % 4) * 6;
+
+  if (tailbits === 0) {
+    result.push((bits >> 16) & 0xff);
+    result.push((bits >> 8) & 0xff);
+    result.push(bits & 0xff);
+  } else if (tailbits === 18) {
+    result.push((bits >> 10) & 0xff);
+    result.push((bits >> 2) & 0xff);
+  } else if (tailbits === 12) {
+    result.push((bits >> 4) & 0xff);
+  }
+
+  return new Buffer(new Uint8Array(result));
+}
+
+function representYamlBinary(object: Uint8Array): string {
+  const max = object.length;
+  const map = BASE64_MAP;
+
+  // Convert every three bytes to 4 ASCII characters.
+
+  let result = "";
+  let bits = 0;
+  for (let idx = 0; idx < max; idx++) {
+    if (idx % 3 === 0 && idx) {
+      result += map[(bits >> 18) & 0x3f];
+      result += map[(bits >> 12) & 0x3f];
+      result += map[(bits >> 6) & 0x3f];
+      result += map[bits & 0x3f];
+    }
+
+    bits = (bits << 8) + object[idx];
+  }
+
+  // Dump tail
+
+  const tail = max % 3;
+
+  if (tail === 0) {
+    result += map[(bits >> 18) & 0x3f];
+    result += map[(bits >> 12) & 0x3f];
+    result += map[(bits >> 6) & 0x3f];
+    result += map[bits & 0x3f];
+  } else if (tail === 2) {
+    result += map[(bits >> 10) & 0x3f];
+    result += map[(bits >> 4) & 0x3f];
+    result += map[(bits << 2) & 0x3f];
+    result += map[64];
+  } else if (tail === 1) {
+    result += map[(bits >> 2) & 0x3f];
+    result += map[(bits << 4) & 0x3f];
+    result += map[64];
+    result += map[64];
+  }
+
+  return result;
+}
+
+function isBinary(obj: Any): obj is Deno.Buffer {
+  const buf = new Buffer();
+  try {
+    if (0 > buf.readFromSync(obj as Deno.Buffer)) return true;
+    return false;
+  } catch {
+    return false;
+  } finally {
+    buf.reset();
+  }
+}
+
+export const binary = new Type("tag:yaml.org,2002:binary", {
+  construct: constructYamlBinary,
+  kind: "scalar",
+  predicate: isBinary,
+  represent: representYamlBinary,
+  resolve: resolveYamlBinary
+});
diff --git a/encoding/yaml/type/bool.ts b/encoding/yaml/type/bool.ts
new file mode 100644
index 000000000000..e8f2d47a6a2a
--- /dev/null
+++ b/encoding/yaml/type/bool.ts
@@ -0,0 +1,38 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+import { isBoolean } from "../utils.ts";
+
+function resolveYamlBoolean(data: string): boolean {
+  const max = data.length;
+
+  return (
+    (max === 4 && (data === "true" || data === "True" || data === "TRUE")) ||
+    (max === 5 && (data === "false" || data === "False" || data === "FALSE"))
+  );
+}
+
+function constructYamlBoolean(data: string): boolean {
+  return data === "true" || data === "True" || data === "TRUE";
+}
+
+export const bool = new Type("tag:yaml.org,2002:bool", {
+  construct: constructYamlBoolean,
+  defaultStyle: "lowercase",
+  kind: "scalar",
+  predicate: isBoolean,
+  represent: {
+    lowercase(object: boolean): string {
+      return object ? "true" : "false";
+    },
+    uppercase(object: boolean): string {
+      return object ? "TRUE" : "FALSE";
+    },
+    camelcase(object: boolean): string {
+      return object ? "True" : "False";
+    }
+  },
+  resolve: resolveYamlBoolean
+});
diff --git a/encoding/yaml/type/float.ts b/encoding/yaml/type/float.ts
new file mode 100644
index 000000000000..f5be2e1b9339
--- /dev/null
+++ b/encoding/yaml/type/float.ts
@@ -0,0 +1,130 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { StyleVariant, Type } from "../type.ts";
+import { isNegativeZero, Any } from "../utils.ts";
+
+const YAML_FLOAT_PATTERN = new RegExp(
+  // 2.5e4, 2.5 and integers
+  "^(?:[-+]?(?:0|[1-9][0-9_]*)(?:\\.[0-9_]*)?(?:[eE][-+]?[0-9]+)?" +
+    // .2e4, .2
+    // special case, seems not from spec
+    "|\\.[0-9_]+(?:[eE][-+]?[0-9]+)?" +
+    // 20:59
+    "|[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\\.[0-9_]*" +
+    // .inf
+    "|[-+]?\\.(?:inf|Inf|INF)" +
+    // .nan
+    "|\\.(?:nan|NaN|NAN))$"
+);
+
+function resolveYamlFloat(data: string): boolean {
+  if (
+    !YAML_FLOAT_PATTERN.test(data) ||
+    // Quick hack to not allow integers end with `_`
+    // Probably should update regexp & check speed
+    data[data.length - 1] === "_"
+  ) {
+    return false;
+  }
+
+  return true;
+}
+
+function constructYamlFloat(data: string): number {
+  let value = data.replace(/_/g, "").toLowerCase();
+  const sign = value[0] === "-" ? -1 : 1;
+  const digits: number[] = [];
+
+  if ("+-".indexOf(value[0]) >= 0) {
+    value = value.slice(1);
+  }
+
+  if (value === ".inf") {
+    return sign === 1 ? Number.POSITIVE_INFINITY : Number.NEGATIVE_INFINITY;
+  }
+  if (value === ".nan") {
+    return NaN;
+  }
+  if (value.indexOf(":") >= 0) {
+    value.split(":").forEach(
+      (v): void => {
+        digits.unshift(parseFloat(v));
+      }
+    );
+
+    let valueNb = 0.0;
+    let base = 1;
+
+    digits.forEach(
+      (d): void => {
+        valueNb += d * base;
+        base *= 60;
+      }
+    );
+
+    return sign * valueNb;
+  }
+  return sign * parseFloat(value);
+}
+
+const SCIENTIFIC_WITHOUT_DOT = /^[-+]?[0-9]+e/;
+
+function representYamlFloat(object: Any, style?: StyleVariant): Any {
+  let res;
+
+  if (isNaN(object)) {
+    switch (style) {
+      case "lowercase":
+        return ".nan";
+      case "uppercase":
+        return ".NAN";
+      case "camelcase":
+        return ".NaN";
+    }
+  } else if (Number.POSITIVE_INFINITY === object) {
+    switch (style) {
+      case "lowercase":
+        return ".inf";
+      case "uppercase":
+        return ".INF";
+      case "camelcase":
+        return ".Inf";
+    }
+  } else if (Number.NEGATIVE_INFINITY === object) {
+    switch (style) {
+      case "lowercase":
+        return "-.inf";
+      case "uppercase":
+        return "-.INF";
+      case "camelcase":
+        return "-.Inf";
+    }
+  } else if (isNegativeZero(object)) {
+    return "-0.0";
+  }
+
+  res = object.toString(10);
+
+  // JS stringifier can build scientific format without dots: 5e-100,
+  // while YAML requres dot: 5.e-100. Fix it with simple hack
+
+  return SCIENTIFIC_WITHOUT_DOT.test(res) ? res.replace("e", ".e") : res;
+}
+
+function isFloat(object: Any): boolean {
+  return (
+    Object.prototype.toString.call(object) === "[object Number]" &&
+    (object % 1 !== 0 || isNegativeZero(object))
+  );
+}
+
+export const float = new Type("tag:yaml.org,2002:float", {
+  construct: constructYamlFloat,
+  defaultStyle: "lowercase",
+  kind: "scalar",
+  predicate: isFloat,
+  represent: representYamlFloat,
+  resolve: resolveYamlFloat
+});
diff --git a/encoding/yaml/type/int.ts b/encoding/yaml/type/int.ts
new file mode 100644
index 000000000000..86032d606f76
--- /dev/null
+++ b/encoding/yaml/type/int.ts
@@ -0,0 +1,193 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+import { isNegativeZero, Any } from "../utils.ts";
+
+function isHexCode(c: number): boolean {
+  return (
+    (0x30 /* 0 */ <= c && c <= 0x39) /* 9 */ ||
+    (0x41 /* A */ <= c && c <= 0x46) /* F */ ||
+    (0x61 /* a */ <= c && c <= 0x66) /* f */
+  );
+}
+
+function isOctCode(c: number): boolean {
+  return 0x30 /* 0 */ <= c && c <= 0x37 /* 7 */;
+}
+
+function isDecCode(c: number): boolean {
+  return 0x30 /* 0 */ <= c && c <= 0x39 /* 9 */;
+}
+
+function resolveYamlInteger(data: string): boolean {
+  const max = data.length;
+  let index = 0;
+  let hasDigits = false;
+
+  if (!max) return false;
+
+  let ch = data[index];
+
+  // sign
+  if (ch === "-" || ch === "+") {
+    ch = data[++index];
+  }
+
+  if (ch === "0") {
+    // 0
+    if (index + 1 === max) return true;
+    ch = data[++index];
+
+    // base 2, base 8, base 16
+
+    if (ch === "b") {
+      // base 2
+      index++;
+
+      for (; index < max; index++) {
+        ch = data[index];
+        if (ch === "_") continue;
+        if (ch !== "0" && ch !== "1") return false;
+        hasDigits = true;
+      }
+      return hasDigits && ch !== "_";
+    }
+
+    if (ch === "x") {
+      // base 16
+      index++;
+
+      for (; index < max; index++) {
+        ch = data[index];
+        if (ch === "_") continue;
+        if (!isHexCode(data.charCodeAt(index))) return false;
+        hasDigits = true;
+      }
+      return hasDigits && ch !== "_";
+    }
+
+    // base 8
+    for (; index < max; index++) {
+      ch = data[index];
+      if (ch === "_") continue;
+      if (!isOctCode(data.charCodeAt(index))) return false;
+      hasDigits = true;
+    }
+    return hasDigits && ch !== "_";
+  }
+
+  // base 10 (except 0) or base 60
+
+  // value should not start with `_`;
+  if (ch === "_") return false;
+
+  for (; index < max; index++) {
+    ch = data[index];
+    if (ch === "_") continue;
+    if (ch === ":") break;
+    if (!isDecCode(data.charCodeAt(index))) {
+      return false;
+    }
+    hasDigits = true;
+  }
+
+  // Should have digits and should not end with `_`
+  if (!hasDigits || ch === "_") return false;
+
+  // if !base60 - done;
+  if (ch !== ":") return true;
+
+  // base60 almost not used, no needs to optimize
+  return /^(:[0-5]?[0-9])+$/.test(data.slice(index));
+}
+
+function constructYamlInteger(data: string): number {
+  let value = data;
+  const digits: number[] = [];
+
+  if (value.indexOf("_") !== -1) {
+    value = value.replace(/_/g, "");
+  }
+
+  let sign = 1;
+  let ch = value[0];
+  if (ch === "-" || ch === "+") {
+    if (ch === "-") sign = -1;
+    value = value.slice(1);
+    ch = value[0];
+  }
+
+  if (value === "0") return 0;
+
+  if (ch === "0") {
+    if (value[1] === "b") return sign * parseInt(value.slice(2), 2);
+    if (value[1] === "x") return sign * parseInt(value, 16);
+    return sign * parseInt(value, 8);
+  }
+
+  if (value.indexOf(":") !== -1) {
+    value.split(":").forEach(
+      (v): void => {
+        digits.unshift(parseInt(v, 10));
+      }
+    );
+
+    let valueInt = 0;
+    let base = 1;
+
+    digits.forEach(
+      (d): void => {
+        valueInt += d * base;
+        base *= 60;
+      }
+    );
+
+    return sign * valueInt;
+  }
+
+  return sign * parseInt(value, 10);
+}
+
+function isInteger(object: Any): boolean {
+  return (
+    Object.prototype.toString.call(object) === "[object Number]" &&
+    (object % 1 === 0 && !isNegativeZero(object))
+  );
+}
+
+export const int = new Type("tag:yaml.org,2002:int", {
+  construct: constructYamlInteger,
+  defaultStyle: "decimal",
+  kind: "scalar",
+  predicate: isInteger,
+  represent: {
+    binary(obj: number): string {
+      return obj >= 0
+        ? `0b${obj.toString(2)}`
+        : `-0b${obj.toString(2).slice(1)}`;
+    },
+    octal(obj: number): string {
+      return obj >= 0 ? `0${obj.toString(8)}` : `-0${obj.toString(8).slice(1)}`;
+    },
+    decimal(obj: number): string {
+      return obj.toString(10);
+    },
+    hexadecimal(obj: number): string {
+      return obj >= 0
+        ? `0x${obj.toString(16).toUpperCase()}`
+        : `-0x${obj
+            .toString(16)
+            .toUpperCase()
+            .slice(1)}`;
+    }
+  },
+  resolve: resolveYamlInteger,
+  styleAliases: {
+    binary: [2, "bin"],
+    decimal: [10, "dec"],
+    hexadecimal: [16, "hex"],
+    octal: [8, "oct"]
+  }
+});
diff --git a/encoding/yaml/type/map.ts b/encoding/yaml/type/map.ts
new file mode 100644
index 000000000000..fd4258345044
--- /dev/null
+++ b/encoding/yaml/type/map.ts
@@ -0,0 +1,13 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+import { Any } from "../utils.ts";
+
+export const map = new Type("tag:yaml.org,2002:map", {
+  construct(data): Any {
+    return data !== null ? data : {};
+  },
+  kind: "mapping"
+});
diff --git a/encoding/yaml/type/merge.ts b/encoding/yaml/type/merge.ts
new file mode 100644
index 000000000000..7da8093a29d1
--- /dev/null
+++ b/encoding/yaml/type/merge.ts
@@ -0,0 +1,14 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+
+function resolveYamlMerge(data: string): boolean {
+  return data === "<<" || data === null;
+}
+
+export const merge = new Type("tag:yaml.org,2002:merge", {
+  kind: "scalar",
+  resolve: resolveYamlMerge
+});
diff --git a/encoding/yaml/type/mod.ts b/encoding/yaml/type/mod.ts
new file mode 100644
index 000000000000..1e4a33611898
--- /dev/null
+++ b/encoding/yaml/type/mod.ts
@@ -0,0 +1,17 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+export { binary } from "./binary.ts";
+export { bool } from "./bool.ts";
+export { float } from "./float.ts";
+export { int } from "./int.ts";
+export { map } from "./map.ts";
+export { merge } from "./merge.ts";
+export { nil } from "./nil.ts";
+export { omap } from "./omap.ts";
+export { pairs } from "./pairs.ts";
+export { seq } from "./seq.ts";
+export { set } from "./set.ts";
+export { str } from "./str.ts";
+export { timestamp } from "./timestamp.ts";
diff --git a/encoding/yaml/type/nil.ts b/encoding/yaml/type/nil.ts
new file mode 100644
index 000000000000..60c74c0c49be
--- /dev/null
+++ b/encoding/yaml/type/nil.ts
@@ -0,0 +1,44 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+
+function resolveYamlNull(data: string): boolean {
+  const max = data.length;
+
+  return (
+    (max === 1 && data === "~") ||
+    (max === 4 && (data === "null" || data === "Null" || data === "NULL"))
+  );
+}
+
+function constructYamlNull(): null {
+  return null;
+}
+
+function isNull(object: unknown): object is null {
+  return object === null;
+}
+
+export const nil = new Type("tag:yaml.org,2002:null", {
+  construct: constructYamlNull,
+  defaultStyle: "lowercase",
+  kind: "scalar",
+  predicate: isNull,
+  represent: {
+    canonical(): string {
+      return "~";
+    },
+    lowercase(): string {
+      return "null";
+    },
+    uppercase(): string {
+      return "NULL";
+    },
+    camelcase(): string {
+      return "Null";
+    }
+  },
+  resolve: resolveYamlNull
+});
diff --git a/encoding/yaml/type/omap.ts b/encoding/yaml/type/omap.ts
new file mode 100644
index 000000000000..7f66694b8189
--- /dev/null
+++ b/encoding/yaml/type/omap.ts
@@ -0,0 +1,45 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+import { Any } from "../utils.ts";
+
+const _hasOwnProperty = Object.prototype.hasOwnProperty;
+const _toString = Object.prototype.toString;
+
+function resolveYamlOmap(data: Any): boolean {
+  const objectKeys: string[] = [];
+  let pairKey = "";
+  let pairHasKey = false;
+
+  for (const pair of data) {
+    pairHasKey = false;
+
+    if (_toString.call(pair) !== "[object Object]") return false;
+
+    for (pairKey in pair) {
+      if (_hasOwnProperty.call(pair, pairKey)) {
+        if (!pairHasKey) pairHasKey = true;
+        else return false;
+      }
+    }
+
+    if (!pairHasKey) return false;
+
+    if (objectKeys.indexOf(pairKey) === -1) objectKeys.push(pairKey);
+    else return false;
+  }
+
+  return true;
+}
+
+function constructYamlOmap(data: Any): Any {
+  return data !== null ? data : [];
+}
+
+export const omap = new Type("tag:yaml.org,2002:omap", {
+  construct: constructYamlOmap,
+  kind: "sequence",
+  resolve: resolveYamlOmap
+});
diff --git a/encoding/yaml/type/pairs.ts b/encoding/yaml/type/pairs.ts
new file mode 100644
index 000000000000..66838c897d44
--- /dev/null
+++ b/encoding/yaml/type/pairs.ts
@@ -0,0 +1,48 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+import { Any } from "../utils.ts";
+
+const _toString = Object.prototype.toString;
+
+function resolveYamlPairs(data: Any[][]): boolean {
+  const result = new Array(data.length);
+
+  for (let index = 0; index < data.length; index++) {
+    const pair = data[index];
+
+    if (_toString.call(pair) !== "[object Object]") return false;
+
+    const keys = Object.keys(pair);
+
+    if (keys.length !== 1) return false;
+
+    result[index] = [keys[0], pair[keys[0] as Any]];
+  }
+
+  return true;
+}
+
+function constructYamlPairs(data: string): Any[] {
+  if (data === null) return [];
+
+  const result = new Array(data.length);
+
+  for (let index = 0; index < data.length; index += 1) {
+    const pair = data[index];
+
+    const keys = Object.keys(pair);
+
+    result[index] = [keys[0], pair[keys[0] as Any]];
+  }
+
+  return result;
+}
+
+export const pairs = new Type("tag:yaml.org,2002:pairs", {
+  construct: constructYamlPairs,
+  kind: "sequence",
+  resolve: resolveYamlPairs
+});
diff --git a/encoding/yaml/type/seq.ts b/encoding/yaml/type/seq.ts
new file mode 100644
index 000000000000..89b7124c2b41
--- /dev/null
+++ b/encoding/yaml/type/seq.ts
@@ -0,0 +1,13 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+import { Any } from "../utils.ts";
+
+export const seq = new Type("tag:yaml.org,2002:seq", {
+  construct(data): Any {
+    return data !== null ? data : [];
+  },
+  kind: "sequence"
+});
diff --git a/encoding/yaml/type/set.ts b/encoding/yaml/type/set.ts
new file mode 100644
index 000000000000..3a6cab7e0e09
--- /dev/null
+++ b/encoding/yaml/type/set.ts
@@ -0,0 +1,30 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+import { Any } from "../utils.ts";
+
+const _hasOwnProperty = Object.prototype.hasOwnProperty;
+
+function resolveYamlSet(data: Any): boolean {
+  if (data === null) return true;
+
+  for (const key in data) {
+    if (_hasOwnProperty.call(data, key)) {
+      if (data[key] !== null) return false;
+    }
+  }
+
+  return true;
+}
+
+function constructYamlSet(data: string): Any {
+  return data !== null ? data : {};
+}
+
+export const set = new Type("tag:yaml.org,2002:set", {
+  construct: constructYamlSet,
+  kind: "mapping",
+  resolve: resolveYamlSet
+});
diff --git a/encoding/yaml/type/str.ts b/encoding/yaml/type/str.ts
new file mode 100644
index 000000000000..8c24e9398929
--- /dev/null
+++ b/encoding/yaml/type/str.ts
@@ -0,0 +1,12 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+
+export const str = new Type("tag:yaml.org,2002:str", {
+  construct(data): string {
+    return data !== null ? data : "";
+  },
+  kind: "scalar"
+});
diff --git a/encoding/yaml/type/timestamp.ts b/encoding/yaml/type/timestamp.ts
new file mode 100644
index 000000000000..68b10fbb0b43
--- /dev/null
+++ b/encoding/yaml/type/timestamp.ts
@@ -0,0 +1,95 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { Type } from "../type.ts";
+
+const YAML_DATE_REGEXP = new RegExp(
+  "^([0-9][0-9][0-9][0-9])" + // [1] year
+  "-([0-9][0-9])" + // [2] month
+    "-([0-9][0-9])$" // [3] day
+);
+
+const YAML_TIMESTAMP_REGEXP = new RegExp(
+  "^([0-9][0-9][0-9][0-9])" + // [1] year
+  "-([0-9][0-9]?)" + // [2] month
+  "-([0-9][0-9]?)" + // [3] day
+  "(?:[Tt]|[ \\t]+)" + // ...
+  "([0-9][0-9]?)" + // [4] hour
+  ":([0-9][0-9])" + // [5] minute
+  ":([0-9][0-9])" + // [6] second
+  "(?:\\.([0-9]*))?" + // [7] fraction
+  "(?:[ \\t]*(Z|([-+])([0-9][0-9]?)" + // [8] tz [9] tz_sign [10] tz_hour
+    "(?::([0-9][0-9]))?))?$" // [11] tz_minute
+);
+
+function resolveYamlTimestamp(data: string): boolean {
+  if (data === null) return false;
+  if (YAML_DATE_REGEXP.exec(data) !== null) return true;
+  if (YAML_TIMESTAMP_REGEXP.exec(data) !== null) return true;
+  return false;
+}
+
+function constructYamlTimestamp(data: string): Date {
+  let match = YAML_DATE_REGEXP.exec(data);
+  if (match === null) match = YAML_TIMESTAMP_REGEXP.exec(data);
+
+  if (match === null) throw new Error("Date resolve error");
+
+  // match: [1] year [2] month [3] day
+
+  const year = +match[1];
+  const month = +match[2] - 1; // JS month starts with 0
+  const day = +match[3];
+
+  if (!match[4]) {
+    // no hour
+    return new Date(Date.UTC(year, month, day));
+  }
+
+  // match: [4] hour [5] minute [6] second [7] fraction
+
+  const hour = +match[4];
+  const minute = +match[5];
+  const second = +match[6];
+
+  let fraction = 0;
+  if (match[7]) {
+    let partFraction = match[7].slice(0, 3);
+    while (partFraction.length < 3) {
+      // milli-seconds
+      partFraction += "0";
+    }
+    fraction = +partFraction;
+  }
+
+  // match: [8] tz [9] tz_sign [10] tz_hour [11] tz_minute
+
+  let delta = null;
+  if (match[9]) {
+    const tzHour = +match[10];
+    const tzMinute = +(match[11] || 0);
+    delta = (tzHour * 60 + tzMinute) * 60000; // delta in mili-seconds
+    if (match[9] === "-") delta = -delta;
+  }
+
+  const date = new Date(
+    Date.UTC(year, month, day, hour, minute, second, fraction)
+  );
+
+  if (delta) date.setTime(date.getTime() - delta);
+
+  return date;
+}
+
+function representYamlTimestamp(date: Date): string {
+  return date.toISOString();
+}
+
+export const timestamp = new Type("tag:yaml.org,2002:timestamp", {
+  construct: constructYamlTimestamp,
+  instanceOf: Date,
+  kind: "scalar",
+  represent: representYamlTimestamp,
+  resolve: resolveYamlTimestamp
+});
diff --git a/encoding/yaml/utils.ts b/encoding/yaml/utils.ts
new file mode 100644
index 000000000000..d91338f93c47
--- /dev/null
+++ b/encoding/yaml/utils.ts
@@ -0,0 +1,84 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+/* eslint-disable-next-line @typescript-eslint/no-explicit-any */
+export type Any = any;
+
+export function isNothing(subject: Any): subject is never {
+  return typeof subject === "undefined" || subject === null;
+}
+
+export function isArray(value: unknown): value is Any[] {
+  return Array.isArray(value);
+}
+
+export function isBoolean(value: unknown): value is boolean {
+  return typeof value === "boolean" || value instanceof Boolean;
+}
+
+export function isNull(value: unknown): value is null {
+  return value === null;
+}
+
+export function isNullOrUndefined(value: unknown): value is null | undefined {
+  return value === null || value === undefined;
+}
+
+export function isNumber(value: unknown): value is number {
+  return typeof value === "number" || value instanceof Number;
+}
+
+export function isString(value: unknown): value is string {
+  return typeof value === "string" || value instanceof String;
+}
+
+export function isSymbol(value: unknown): value is symbol {
+  return typeof value === "symbol";
+}
+
+export function isUndefined(value: unknown): value is undefined {
+  return value === undefined;
+}
+
+export function isObject(value: unknown): value is object {
+  return value !== null && typeof value === "object";
+}
+
+export function isError(e: unknown): boolean {
+  return e instanceof Error;
+}
+
+export function isFunction(value: unknown): value is () => void {
+  return typeof value === "function";
+}
+
+export function isRegExp(value: unknown): value is RegExp {
+  return value instanceof RegExp;
+}
+
+export function toArray<T>(sequence: T): T | [] | [T] {
+  if (isArray(sequence)) return sequence;
+  if (isNothing(sequence)) return [];
+
+  return [sequence];
+}
+
+export function repeat(str: string, count: number): string {
+  let result = "";
+
+  for (let cycle = 0; cycle < count; cycle++) {
+    result += str;
+  }
+
+  return result;
+}
+
+export function isNegativeZero(i: number): boolean {
+  return i === 0 && Number.NEGATIVE_INFINITY === 1 / i;
+}
+
+export interface ArrayObject<T = Any> {
+  [P: string]: T;
+}
diff --git a/encoding/yaml_test.ts b/encoding/yaml_test.ts
new file mode 100644
index 000000000000..40de6a94dc35
--- /dev/null
+++ b/encoding/yaml_test.ts
@@ -0,0 +1,4 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import "./yaml/parse_test.ts";
+import "./yaml/stringify_test.ts";