v8/test/mjsunit/es6/map-iterator-4.js
Hai Dang 60d3ce727f Add iterator protectors for JSMapIterator/JSSet/JSSetIterator.
The MapIterator protector protects the original iteration behaviors of
Map.prototype.keys(), Map.prototype.values(), and Set.prototype.entries().
It does not protect the original iteration behavior of
Map.prototype[Symbol.iterator](). The protector is invalidated when:
* The 'next' property is set on an object where the property holder is the
  %MapIteratorPrototype% (e.g. because the object is that very prototype).
* The 'Symbol.iterator' property is set on an object where the property
  holder is the %IteratorPrototype%. Note that this also invalidates the
  SetIterator protector (see below).

The SetIterator protector protects the original iteration behavior of
Set.prototype.keys(), Set.prototype.values(), Set.prototype.entries(),
and Set.prototype[Symbol.iterator](). The protector is invalidated when:
* The 'next' property is set on an object where the property holder is the
  %SetIteratorPrototype% (e.g. because the object is that very prototype).
* The 'Symbol.iterator' property is set on an object where the property
  holder is the %SetPrototype% OR %IteratorPrototype%. This means that
  setting Symbol.iterator on a MapIterator object can also invalidate the
  SetIterator protector, and vice versa, setting Symbol.iterator on a
  SetIterator object can also invalidate the MapIterator. This is an over-
  approximation for the sake of simplicity.

Bug: v8:7980
Change-Id: I54ad6e4c7f19ccc27d7001f6c4b6c8d6ea4ee871
Reviewed-on: https://chromium-review.googlesource.com/c/1273102
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Hai Dang <dhai@google.com>
Cr-Commit-Position: refs/heads/master@{#56530}
2018-10-10 14:10:29 +00:00

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JavaScript

// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Flags: --allow-natives-syntax --no-stress-opt
var map = new Map([[1,2], [2,3], [3,4]]);
assertTrue(%MapIteratorProtector());
assertTrue(%SetIteratorProtector());
// This changes %MapIteratorPrototype%. No more tests should be run after this
// in the same instance.
var iterator = map.keys();
iterator.__proto__.next = () => ({done: true});
assertFalse(%MapIteratorProtector());
assertTrue(%SetIteratorProtector());
assertEquals([], [...map]);
assertEquals([], [...map.entries()]);
assertEquals([], [...map.keys()]);
assertEquals([], [...map.values()]);
assertEquals([], [...iterator]);