Remove "generator" output mode (#12)

Drops Node v6 support

.github/workflows/test.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        node-version: [6.x, 8.x, 10.x, 12.x]
+        node-version: [8.x, 10.x, 12.x, 14.x]
 
     runs-on: ${{ matrix.os }}
 

src/index.ts

@@ -4,9 +4,6 @@ import { parseScript } from 'esprima';
 import { visit, namedTypes as n, builders as b } from 'ast-types';
 import { Context, RunningScriptOptions, runInNewContext } from 'vm';
 
-import _supportsAsync from './supports-async';
-import generatorToPromiseFn from './generator-to-promise';
-
 /**
  * Compiles sync JavaScript code into JavaScript with async Functions.
  *
@@ -18,8 +15,7 @@ import generatorToPromiseFn from './generator-to-promise';
 
 function degenerator(
 	code: string,
-	_names: degenerator.DegeneratorNames,
-	{ output = 'async' }: degenerator.DegeneratorOptions = {}
+	_names: degenerator.DegeneratorNames
 ): string {
 	if (!Array.isArray(_names)) {
 		throw new TypeError('an array of async function "names" is required');
@@ -76,20 +72,16 @@ function degenerator(
 								shouldDegenerate = true;
 							}
 							return false;
-						}
+						},
 					});
 
 					if (!shouldDegenerate) {
 						return false;
 					}
 
 					// Got a "function" expression/statement,
-					// convert it into an async or generator function
-					if (output === 'async') {
-						path.node.async = true;
-					} else if (output === 'generator') {
-						path.node.generator = true;
-					}
+					// convert it into an async function
+					path.node.async = true;
 
 					// Add function name to `names` array
 					if (!checkName(path.node.id.name, names)) {
@@ -98,7 +90,7 @@ function degenerator(
 				}
 
 				this.traverse(path);
-			}
+			},
 		});
 	} while (lastNamesLength !== names.length);
 
@@ -112,19 +104,10 @@ function degenerator(
 				const delegate = false;
 				const {
 					name,
-					parent: { node: pNode }
+					parent: { node: pNode },
 				} = path;
 
-				let expr;
-				if (output === 'async') {
-					expr = b.awaitExpression(path.node, delegate);
-				} else if (output === 'generator') {
-					expr = b.yieldExpression(path.node, delegate);
-				} else {
-					throw new Error(
-						'Only "async" and "generator" are allowd `output` values'
-					);
-				}
+				const expr = b.awaitExpression(path.node, delegate);
 
 				if (n.CallExpression.check(pNode)) {
 					pNode.arguments[name] = expr;
@@ -134,7 +117,7 @@ function degenerator(
 			}
 
 			this.traverse(path);
-		}
+		},
 	});
 
 	return generate(ast);
@@ -143,24 +126,16 @@ function degenerator(
 namespace degenerator {
 	export type DegeneratorName = string | RegExp;
 	export type DegeneratorNames = DegeneratorName[];
-	export type DegeneratorOutput = 'async' | 'generator';
-	export interface DegeneratorOptions {
-		output?: DegeneratorOutput;
-	}
-	export interface CompileOptions
-		extends DegeneratorOptions,
-			RunningScriptOptions {
+	export interface CompileOptions extends RunningScriptOptions {
 		sandbox?: Context;
 	}
-	export const supportsAsync = _supportsAsync;
-	export function compile<T extends Function>(
+	export function compile<R, A extends any[] = []>(
 		code: string,
 		returnName: string,
 		names: DegeneratorNames,
 		options: CompileOptions = {}
-	): T {
-		const output = _supportsAsync ? 'async' : 'generator';
-		const compiled = degenerator(code, names, { ...options, output });
+	): (...args: A) => Promise<R> {
+		const compiled = degenerator(code, names);
 		const fn = runInNewContext(
 			`${compiled};${returnName}`,
 			options.sandbox,
@@ -171,23 +146,25 @@ namespace degenerator {
 				`Expected a "function" to be returned for \`${returnName}\`, but got "${typeof fn}"`
 			);
 		}
-		if (isAsyncFunction(fn)) {
-			return fn;
-		} else {
-			const rtn = (generatorToPromiseFn(fn) as unknown) as T;
-			Object.defineProperty(rtn, 'toString', {
-				value: fn.toString.bind(fn),
-				enumerable: false
-			});
-			return rtn;
-		}
+		const r = function (this: any, ...args: A): Promise<R> {
+			try {
+				const p = fn.apply(this, args);
+				if (typeof p.then === 'function') {
+					return p;
+				}
+				return Promise.resolve(p);
+			} catch (err) {
+				return Promise.reject(err);
+			}
+		};
+		Object.defineProperty(r, 'toString', {
+			value: fn.toString.bind(fn),
+			enumerable: false,
+		});
+		return r;
 	}
 }
 
-function isAsyncFunction(fn: any): boolean {
-	return typeof fn === 'function' && fn.constructor.name === 'AsyncFunction';
-}
-
 /**
  * Returns `true` if `node` has a matching name to one of the entries in the
  * `names` array.

test/assignment.expected.js

@@ -3,9 +3,9 @@ var biz = foo;
 function foo() {
     return 42;
 }
-function* bar() {
-    return yield baz();
+async function bar() {
+    return await baz();
 }
-function* bir() {
-    return yield biz();
+async function bir() {
+    return await biz();
 }

test/basic.expected.js

@@ -1,3 +1,3 @@
-function* foo() {
-    return (yield a('bar')) || (yield b());
+async function foo() {
+    return await a('bar') || await b();
 }

test/get-example.expected.js

@@ -1,7 +1,7 @@
-function* myFn() {
-    var one = yield get('https://google.com');
-    var two = yield get('http://nodejs.org');
-    var three = JSON.parse(yield get('http://jsonip.org'));
+async function myFn() {
+    var one = await get('https://google.com');
+    var two = await get('http://nodejs.org');
+    var three = JSON.parse(await get('http://jsonip.org'));
     return [
         one,
         two,

test/multiple.expected.js

@@ -1,9 +1,9 @@
-function* foo() {
-    return yield baz();
+async function foo() {
+    return await baz();
 }
-function* bar() {
-    return yield foo(baz);
+async function bar() {
+    return await foo(baz);
 }
-function* baz() {
-    return yield bar();
+async function baz() {
+    return await bar();
 }

test/pac-resolver-gh-3.expected.js

@@ -1,22 +1,22 @@
-function* FindProxyForURL(url, host) {
-    if (yield isHostInAnySubnet(host, [
+async function FindProxyForURL(url, host) {
+    if (await isHostInAnySubnet(host, [
             '10.1.2.0',
             '10.1.3.0'
         ], '255.255.255.0')) {
         return 'HTTPS proxy.example.com';
     }
-    if (yield isHostInAnySubnet(host, [
+    if (await isHostInAnySubnet(host, [
             '10.2.2.0',
             '10.2.3.0'
         ], '255.255.255.0')) {
         return 'HTTPS proxy.example.com';
     }
     return 'DIRECT';
 }
-function* isHostInAnySubnet(host, subnets, mask) {
+async function isHostInAnySubnet(host, subnets, mask) {
     var subnets_length = subnets.length;
     for (i = 0; i < subnets_length; i++) {
-        if (yield isInNet(host, subnets[i], mask)) {
+        if (await isInNet(host, subnets[i], mask)) {
             return true;
         }
     }

test/partial.expected.js

@@ -1,12 +1,12 @@
-function* foo() {
-    return yield baz();
+async function foo() {
+    return await baz();
 }
-function* bar() {
-    return yield foo(baz);
+async function bar() {
+    return await foo(baz);
 }
-function* baz() {
-    return yield bar();
+async function baz() {
+    return await bar();
 }
 function shouldntChange() {
     return 42;
-}
+}