Initial implementation, tests, readme

.eslintrc

@@ -0,0 +1,62 @@
+{
+	"root": true,
+
+	"extends": "@ljharb",
+
+	"globals": {
+		"Iterator": false,
+	},
+
+	"rules": {
+		"array-bracket-newline": 0,
+		"func-name-matching": 0,
+		"id-length": 0,
+		"max-lines-per-function": 0,
+		"multiline-comment-style": 0,
+		"new-cap": [2, {
+			"capIsNewExceptions": [
+				"Call",
+				"CreateIteratorFromClosure",
+				"CreateIterResultObject",
+				"GeneratorResume",
+				"GeneratorResumeAbrupt",
+				"GeneratorStart",
+				"GeneratorValidate",
+				"Get",
+				"GetIntrinsic",
+				"GetIterator",
+				"GetIteratorDirect",
+				"GetIteratorFlattenable",
+				"GetMethod",
+				"IsCallable",
+				"IteratorClose",
+				"IteratorComplete",
+				"IteratorNext",
+				"IteratorStep",
+				"IteratorValue",
+				"NormalCompletion",
+				"OrdinaryHasInstance",
+				"OrdinaryObjectCreate",
+				"PromiseResolve",
+				"ThrowCompletion",
+				"ToBoolean",
+				"ToIntegerOrInfinity",
+				"ToNumber",
+				"ToObject",
+				"Type",
+			],
+		}],
+		"no-negated-condition": 1,
+		"object-curly-newline": 0,
+		"sort-keys": 0,
+	},
+
+	"overrides": [
+		{
+			"files": "test/**",
+			"rules": {
+				"max-params": 0,
+			},
+		},
+	],
+}

.github/FUNDING.yml

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+# These are supported funding model platforms
+
+github: [ljharb]
+patreon: # Replace with a single Patreon username
+open_collective: # Replace with a single Open Collective username
+ko_fi: # Replace with a single Ko-fi username
+tidelift: npm/iterator-helpers
+community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry
+liberapay: # Replace with a single Liberapay username
+issuehunt: # Replace with a single IssueHunt username
+otechie: # Replace with a single Otechie username
+custom: # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']

.github/workflows/node-aught.yml

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+name: 'Tests: node.js < 10'
+
+on: [pull_request, push]
+
+jobs:
+  tests:
+    uses: ljharb/actions/.github/workflows/node.yml@main
+    with:
+      range: '< 10'
+      type: minors
+      command: npm run tests-only
+
+  node:
+    name: 'node < 10'
+    needs: [tests]
+    runs-on: ubuntu-latest
+    steps:
+      - run: 'echo tests completed'

.github/workflows/node-pretest.yml

@@ -0,0 +1,7 @@
+name: 'Tests: pretest/posttest'
+
+on: [pull_request, push]
+
+jobs:
+  tests:
+    uses: ljharb/actions/.github/workflows/pretest.yml@main

.github/workflows/node-tens.yml

@@ -0,0 +1,18 @@
+name: 'Tests: node.js >= 10'
+
+on: [pull_request, push]
+
+jobs:
+  tests:
+    uses: ljharb/actions/.github/workflows/node.yml@main
+    with:
+      range: '>= 10'
+      type: minors
+      command: npm run tests-only
+
+  node:
+    name: 'node >= 10'
+    needs: [tests]
+    runs-on: ubuntu-latest
+    steps:
+      - run: 'echo tests completed'

.github/workflows/rebase.yml

@@ -0,0 +1,9 @@
+name: Automatic Rebase
+
+on: [pull_request_target]
+
+jobs:
+  _:
+    uses: ljharb/actions/.github/workflows/rebase.yml@main
+    secrets:
+      token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/require-allow-edits.yml

@@ -0,0 +1,12 @@
+name: Require “Allow Edits”
+
+on: [pull_request_target]
+
+jobs:
+  _:
+    name: "Require “Allow Edits”"
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: ljharb/require-allow-edits@main

.gitignore

@@ -107,3 +107,5 @@ dist
 npm-shrinkwrap.json
 package-lock.json
 yarn.lock
+
+.npmignore

.npmrc

@@ -1 +1,3 @@
 package-lock=false
+allow-same-version=true
+message=v%s

.nycrc

@@ -0,0 +1,13 @@
+{
+	"all": true,
+	"check-coverage": false,
+	"reporter": ["text-summary", "text", "html", "json"],
+	"lines": 86,
+	"statements": 85.93,
+	"functions": 82.43,
+	"branches": 76.06,
+	"exclude": [
+		"coverage",
+		"test"
+	]
+}

CHANGELOG.md

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+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

Iterator.from/auto.js

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+'use strict';
+
+require('./shim')();

Iterator.from/implementation.js

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+'use strict';
+
+var OrdinaryHasInstance = require('es-abstract/2022/OrdinaryHasInstance');
+var OrdinaryObjectCreate = require('es-abstract/2022/OrdinaryObjectCreate');
+var ToObject = require('es-abstract/2022/ToObject');
+var Type = require('es-abstract/2022/Type');
+
+var GetIteratorFlattenable = require('../aos/GetIteratorFlattenable');
+
+var $Iterator = require('../Iterator/polyfill')();
+var $WrapForValidIteratorPrototype = require('../WrapForValidIteratorPrototype');
+
+var SLOT = require('internal-slot');
+
+module.exports = function from(O) {
+	if (Type(O) === 'String') {
+		// eslint-disable-next-line no-param-reassign
+		O = ToObject(O); // step 1
+	}
+
+	var iteratorRecord = GetIteratorFlattenable(O, 'sync'); // step 2
+
+	var hasInstance = OrdinaryHasInstance($Iterator, iteratorRecord['[[Iterator]]']); // step 3
+
+	if (hasInstance) { // step 4
+		return iteratorRecord['[[Iterator]]']; // step 4.a
+	}
+
+	var wrapper = OrdinaryObjectCreate($WrapForValidIteratorPrototype); // , ['[[Iterated]]']); // step 5
+
+	SLOT.set(wrapper, '[[Iterated]]', iteratorRecord); // step 6
+
+	return wrapper; // step 7
+};

Iterator.from/index.js

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+'use strict';
+
+var callBind = require('call-bind');
+var define = require('define-properties');
+
+var implementation = require('./implementation');
+var getPolyfill = require('./polyfill');
+var shim = require('./shim');
+
+var bound = callBind(getPolyfill(), null);
+
+define(bound, {
+	getPolyfill: getPolyfill,
+	implementation: implementation,
+	shim: shim
+});
+
+module.exports = bound;

Iterator.from/polyfill.js

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+'use strict';
+
+var implementation = require('./implementation');
+
+var $Iterator = require('../Iterator');
+
+module.exports = function getPolyfill() {
+	return typeof $Iterator.from === 'function' ? $Iterator.from : implementation;
+};

Iterator.from/shim.js

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+'use strict';
+
+var getPolyfill = require('./polyfill');
+var define = require('define-properties');
+
+var getIteratorPolyfill = require('../Iterator/polyfill');
+
+module.exports = function shimIteratorFrom() {
+	var $Iterator = getIteratorPolyfill();
+	var polyfill = getPolyfill();
+	define(
+		$Iterator,
+		{ from: polyfill },
+		{ from: function () { return $Iterator.from !== polyfill; } }
+	);
+
+	return polyfill;
+};

Iterator.prototype.constructor/auto.js

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+'use strict';
+
+require('./shim')();

Iterator.prototype.constructor/implementation.js

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+'use strict';
+
+var $Iterator = require('../Iterator/polyfill')();
+
+module.exports = $Iterator;

Iterator.prototype.constructor/index.js

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+'use strict';
+
+var define = require('define-properties');
+var bind = require('function-bind');
+
+var implementation = require('./implementation');
+var getPolyfill = require('./polyfill');
+var shim = require('./shim');
+
+var polyfill = bind.call(getPolyfill());
+
+define(polyfill, {
+	getPolyfill: getPolyfill,
+	implementation: implementation,
+	shim: shim
+});
+
+module.exports = polyfill;

Iterator.prototype.constructor/polyfill.js

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+'use strict';
+
+var implementation = require('./implementation');
+
+module.exports = function getPolyfill() {
+	return implementation;
+};

Iterator.prototype.constructor/shim.js

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+'use strict';
+
+var define = require('define-properties');
+var getPolyfill = require('./polyfill');
+
+var $IteratorPrototype = require('iterator.prototype');
+
+var $Iterator = require('./implementation');
+
+module.exports = function shimIteratorPrototypeCtor() {
+	var polyfill = getPolyfill();
+
+	define(
+		$IteratorPrototype,
+		{ constructor: $Iterator },
+		{ constructor: function () { return $Iterator.constructor !== polyfill; } }
+	);
+
+	return polyfill;
+};

Iterator.prototype.drop/auto.js

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+'use strict';
+
+require('./shim')();

Iterator.prototype.drop/implementation.js

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+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+
+var $RangeError = GetIntrinsic('%RangeError%');
+
+var IteratorClose = require('es-abstract/2022/IteratorClose');
+var IteratorStep = require('es-abstract/2022/IteratorStep');
+var IteratorValue = require('es-abstract/2022/IteratorValue');
+var ToIntegerOrInfinity = require('es-abstract/2022/ToIntegerOrInfinity');
+var ToNumber = require('es-abstract/2022/ToNumber');
+
+var GetIteratorDirect = require('../aos/GetIteratorDirect');
+var CreateIteratorFromClosure = require('../aos/CreateIteratorFromClosure');
+
+var iterHelperProto = require('../IteratorHelperPrototype');
+
+var isNaN = require('es-abstract/helpers/isNaN');
+
+var SLOT = require('internal-slot');
+
+module.exports = function drop(limit) {
+	var iterated = GetIteratorDirect(this); // step 1
+
+	var numLimit = ToNumber(limit); // step 2
+	if (isNaN(numLimit)) {
+		throw new $RangeError('`limit` must be a non-NaN number'); // step 3
+	}
+
+	var integerLimit = ToIntegerOrInfinity(numLimit); // step 4
+	if (integerLimit < 0) {
+		throw new $RangeError('`limit` must be a >= 0'); // step 5
+	}
+
+	var sentinel = {};
+	var remaining = integerLimit; // step 6.a
+	var closure = function () { // step 6
+		var next;
+		while (remaining > 0) { // step 6.b
+			if (remaining !== Infinity) { // step 6.b.i
+				remaining -= 1; // step 6.b.i.1
+			}
+
+			next = IteratorStep(iterated['[[Iterator]]']); // step 6.b.ii
+			if (!next) {
+				// return void undefined; // step 6.b.iii
+				return sentinel;
+			}
+		}
+		// while (true) { // step 6.c
+		next = IteratorStep(iterated['[[Iterator]]']); // step 6.c.i
+		if (!next) {
+			// return void undefined; // step 6.c.ii
+			return sentinel;
+		}
+		try {
+			var value = IteratorValue(next); // step 6.c.iii
+			return value; // step 6.c.iii
+		} catch (e) {
+			// close iterator // step 6.c.icv
+			IteratorClose(
+				iterated['[[Iterator]]'],
+				function () { throw e; }
+			);
+		}
+		// }
+		return void undefined;
+	};
+	SLOT.set(closure, '[[Sentinel]]', sentinel); // for the userland implementation
+
+	return CreateIteratorFromClosure(closure, 'Iterator Helper', iterHelperProto); // step 4
+};