[Breaking] 2018/2019: GetIterator: Add hint parameter

BREAKING CHANGE: This is backwards incompatible, as the `hint` parameter is added between the `obj` and `method` parameters.
ljharb · Nov 4, 2019 · b967be4 · b967be4
1 parent ddbba60
commit b967be4
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Showing 7 changed files with 135 additions and 34 deletions.
diff --git a/.gitattributes b/.gitattributes
@@ -279,7 +279,6 @@
 2018/DeletePropertyOrThrow.js	spackled linguist-generated=true
 2018/FromPropertyDescriptor.js	spackled linguist-generated=true
 2018/Get.js	spackled linguist-generated=true
-2018/GetIterator.js	spackled linguist-generated=true
 2018/GetMethod.js	spackled linguist-generated=true
 2018/GetOwnPropertyKeys.js	spackled linguist-generated=true
 2018/GetPrototypeFromConstructor.js	spackled linguist-generated=true
@@ -302,7 +301,6 @@
 2018/IsPromise.js	spackled linguist-generated=true
 2018/IsPropertyKey.js	spackled linguist-generated=true
 2018/IsRegExp.js	spackled linguist-generated=true
-2018/IterableToList.js	spackled linguist-generated=true
 2018/IteratorClose.js	spackled linguist-generated=true
 2018/IteratorComplete.js	spackled linguist-generated=true
 2018/IteratorNext.js	spackled linguist-generated=true
@@ -519,6 +517,7 @@
 2020/EnumerableOwnPropertyNames.js	spackled linguist-generated=true
 2020/FromPropertyDescriptor.js	spackled linguist-generated=true
 2020/Get.js	spackled linguist-generated=true
+2020/GetIterator.js	spackled linguist-generated=true
 2020/GetMethod.js	spackled linguist-generated=true
 2020/GetOwnPropertyKeys.js	spackled linguist-generated=true
 2020/GetPrototypeFromConstructor.js	spackled linguist-generated=true
@@ -543,6 +542,7 @@
 2020/IsPropertyKey.js	spackled linguist-generated=true
 2020/IsRegExp.js	spackled linguist-generated=true
 2020/IsStringPrefix.js	spackled linguist-generated=true
+2020/IterableToList.js	spackled linguist-generated=true
 2020/IteratorClose.js	spackled linguist-generated=true
 2020/IteratorComplete.js	spackled linguist-generated=true
 2020/IteratorNext.js	spackled linguist-generated=true

diff --git a/2018/GetIterator.js b/2018/GetIterator.js
@@ -3,6 +3,10 @@
 var GetIntrinsic = require('../GetIntrinsic');
 
 var $TypeError = GetIntrinsic('%TypeError%');
+var $asyncIterator = GetIntrinsic('%Symbol.asyncIterator%', true);
+
+var inspect = require('object-inspect');
+var hasSymbols = require('has-symbols')();
 
 var getIteratorMethod = require('../helpers/getIteratorMethod');
 var AdvanceStringIndex = require('./AdvanceStringIndex');
@@ -11,25 +15,48 @@ var GetMethod = require('./GetMethod');
 var IsArray = require('./IsArray');
 var Type = require('./Type');
 
-// https://ecma-international.org/ecma-262/6.0/#sec-getiterator
-
-module.exports = function GetIterator(obj, method) {
-	var actualMethod = method;
+// https://ecma-international.org/ecma-262/9.0/#sec-getiterator
+module.exports = function GetIterator(obj, hint, method) {
+	var actualHint = hint;
 	if (arguments.length < 2) {
-		actualMethod = getIteratorMethod(
-			{
+		actualHint = 'sync';
+	}
+	if (actualHint !== 'sync' && actualHint !== 'async') {
+		throw new $TypeError("Assertion failed: `hint` must be one of 'sync' or 'async', got " + inspect(hint));
+	}
+	var actualMethod = method;
+	if (arguments.length < 3) {
+		if (actualHint === 'async') {
+			if (hasSymbols && $asyncIterator) {
+				actualMethod = GetMethod(obj, $asyncIterator);
+			}
+			if (actualMethod === undefined) {
+				throw new $TypeError("async from sync iterators aren't currently supported");
+			}
+		} else {
+			actualMethod = getIteratorMethod({
 				AdvanceStringIndex: AdvanceStringIndex,
 				GetMethod: GetMethod,
 				IsArray: IsArray,
 				Type: Type
-			},
-			obj
-		);
+			}, obj);
+		}
 	}
+
 	var iterator = Call(actualMethod, obj);
 	if (Type(iterator) !== 'Object') {
 		throw new $TypeError('iterator must return an object');
 	}
 
 	return iterator;
+
+	// TODO: This should return an IteratorRecord
+	/*
+	var nextMethod = GetV(iterator, 'next');
+	return {
+		'[[Iterator]]': iterator,
+		'[[NextMethod]]': nextMethod,
+		'[[Done]]': false
+	};
+	*/
 };
diff --git a/2018/IterableToList.js b/2018/IterableToList.js
@@ -7,10 +7,10 @@ var GetIterator = require('./GetIterator');
 var IteratorStep = require('./IteratorStep');
 var IteratorValue = require('./IteratorValue');
 
-// https://www.ecma-international.org/ecma-262/8.0/#sec-iterabletolist
+// https://www.ecma-international.org/ecma-262/9.0/#sec-iterabletolist
 
 module.exports = function IterableToList(items, method) {
-	var iterator = GetIterator(items, method);
+	var iterator = GetIterator(items, 'sync', method);
 	var values = [];
 	var next = true;
 	while (next) {

diff --git a/2019/GetIterator.js b/2019/GetIterator.js
diff --git a/2019/IterableToList.js b/2019/IterableToList.js
diff --git a/2020/GetIterator.js b/2020/GetIterator.js
diff --git a/test/tests.js b/test/tests.js
@@ -4000,6 +4000,56 @@ var es2018 = function ES2018(ES, ops, expectedMissing, skips) {
 		t.end();
 	});
 
+	test('GetIterator', function (t) {
+		try {
+			ES.GetIterator({}, null);
+		} catch (e) {
+			t.ok(e.message.indexOf("Assertion failed: `hint` must be one of 'sync' or 'async'" >= 0));
+		}
+
+		var arr = [1, 2];
+		testIterator(t, ES.GetIterator(arr), arr);
+
+		testIterator(t, ES.GetIterator('abc'), 'abc'.split(''));
+
+		t.test('Symbol.iterator', { skip: !v.hasSymbols }, function (st) {
+			var m = new Map();
+			m.set(1, 'a');
+			m.set(2, 'b');
+
+			testIterator(st, ES.GetIterator(m), [[1, 'a'], [2, 'b']]);
+
+			st.end();
+		});
+
+		t.test('Symbol.asyncIterator', { skip: !v.hasSymbols || !Symbol.asyncIterator }, function (st) {
+			try {
+				ES.GetIterator(arr, 'async');
+			} catch (e) {
+				st.ok(e.message.indexOf("async from sync iterators aren't currently supported") >= 0);
+			}
+
+			/** @type {AsyncIterator<any>} */
+			var it = {
+				next: function () {
+					return Promise.resolve({
+						done: true
+					});
+				}
+			};
+			var obj = {};
+			obj[Symbol.asyncIterator] = function () {
+				return it;
+			};
+
+			st.equal(ES.GetIterator(obj, 'async'), it);
+
+			st.end();
+		});
+
+		t.end();
+	});
+
 	test('PromiseResolve', function (t) {
 		t.test('Promises unsupported', { skip: typeof Promise === 'function' }, function (st) {
 			st['throws'](