accessor-map-sharing.js

// Copyright 2012 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
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//
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// Flags: --allow-natives-syntax

// Handy abbreviations.
var dp = Object.defineProperty;
var gop = Object.getOwnPropertyDescriptor;

function getter() { return 111; }
function setter(x) { print(222); }
function anotherGetter() { return 333; }
function anotherSetter(x) { print(444); }
var obj1, obj2, obj3, obj4;

// Two objects with the same getter.
obj1 = {};
dp(obj1, "alpha", { get: getter });
obj2 = {};
dp(obj2, "alpha", { get: getter });
assertTrue(%HaveSameMap(obj1, obj2));

// Two objects with the same getter, oldskool.
obj1 = {};
obj1.__defineGetter__("bravo", getter);
assertEquals(getter, obj1.__lookupGetter__("bravo"));
obj2 = {};
obj2.__defineGetter__("bravo", getter);
assertEquals(getter, obj2.__lookupGetter__("bravo"));
assertTrue(%HaveSameMap(obj1, obj2));

// Two objects with the same setter.
obj1 = {};
dp(obj1, "charlie", { set: setter });
obj2 = {};
dp(obj2, "charlie", { set: setter });
assertTrue(%HaveSameMap(obj1, obj2));

// Two objects with the same setter, oldskool.
obj1 = {};
obj1.__defineSetter__("delta", setter);
assertEquals(setter, obj1.__lookupSetter__("delta"));
obj2 = {};
obj2.__defineSetter__("delta", setter);
assertEquals(setter, obj2.__lookupSetter__("delta"));
assertTrue(%HaveSameMap(obj1, obj2));

// Two objects with the same getter and setter.
obj1 = {};
dp(obj1, "foxtrot", { get: getter, set: setter });
obj2 = {};
dp(obj2, "foxtrot", { get: getter, set: setter });
assertTrue(%HaveSameMap(obj1, obj2));

// Two objects with the same getter and setter, set separately.
obj1 = {};
dp(obj1, "golf", { get: getter, configurable: true });
dp(obj1, "golf", { set: setter, configurable: true });
obj2 = {};
dp(obj2, "golf", { get: getter, configurable: true });
dp(obj2, "golf", { set: setter, configurable: true });
assertTrue(%HaveSameMap(obj1, obj2));

// Two objects with the same getter and setter, set separately, oldskool.
obj1 = {};
obj1.__defineGetter__("hotel", getter);
obj1.__defineSetter__("hotel", setter);
obj2 = {};
obj2.__defineGetter__("hotel", getter);
obj2.__defineSetter__("hotel", setter);
assertTrue(%HaveSameMap(obj1, obj2));

// Attribute-only change, shouldn't affect previous descriptor properties.
obj1 = {};
dp(obj1, "india", { get: getter, configurable: true, enumerable: true });
assertEquals(getter, gop(obj1, "india").get);
assertTrue(gop(obj1, "india").configurable);
assertTrue(gop(obj1, "india").enumerable);
dp(obj1, "india", { enumerable: false });
assertEquals(getter, gop(obj1, "india").get);
assertTrue(gop(obj1, "india").configurable);
assertFalse(gop(obj1, "india").enumerable);

// Attribute-only change, shouldn't affect objects with previously shared maps.
obj1 = {};
dp(obj1, "juliet", { set: setter, configurable: true, enumerable: false });
assertEquals(setter, gop(obj1, "juliet").set);
assertTrue(gop(obj1, "juliet").configurable);
assertFalse(gop(obj1, "juliet").enumerable);
obj2 = {};
dp(obj2, "juliet", { set: setter, configurable: true, enumerable: false });
assertEquals(setter, gop(obj2, "juliet").set);
assertTrue(gop(obj2, "juliet").configurable);
assertFalse(gop(obj2, "juliet").enumerable);
dp(obj1, "juliet", { set: setter, configurable: false, enumerable: true });
assertEquals(setter, gop(obj1, "juliet").set);
assertFalse(gop(obj1, "juliet").configurable);
assertTrue(gop(obj1, "juliet").enumerable);
assertEquals(setter, gop(obj2, "juliet").set);
assertTrue(gop(obj2, "juliet").configurable);
assertFalse(gop(obj2, "juliet").enumerable);

// Two objects with the different getters.
obj1 = {};
dp(obj1, "kilo", { get: getter });
obj2 = {};
dp(obj2, "kilo", { get: anotherGetter });
assertEquals(getter, gop(obj1, "kilo").get);
assertEquals(anotherGetter, gop(obj2, "kilo").get);
assertFalse(%HaveSameMap(obj1, obj2));

// Two objects with the same getters and different setters.
obj1 = {};
dp(obj1, "lima", { get: getter, set: setter });
obj2 = {};
dp(obj2, "lima", { get: getter, set: anotherSetter });
assertEquals(setter, gop(obj1, "lima").set);
assertEquals(anotherSetter, gop(obj2, "lima").set);
assertFalse(%HaveSameMap(obj1, obj2));

// Even 'undefined' is a kind of getter.
obj1 = {};
dp(obj1, "mike", { get: undefined });
assertTrue("mike" in obj1);
assertEquals(undefined, gop(obj1, "mike").get);
assertEquals(undefined, obj1.__lookupGetter__("mike"));
assertEquals(undefined, gop(obj1, "mike").set);
assertEquals(undefined, obj1.__lookupSetter__("mike"));

// Even 'undefined' is a kind of setter.
obj1 = {};
dp(obj1, "november", { set: undefined });
assertTrue("november" in obj1);
assertEquals(undefined, gop(obj1, "november").get);
assertEquals(undefined, obj1.__lookupGetter__("november"));
assertEquals(undefined, gop(obj1, "november").set);
assertEquals(undefined, obj1.__lookupSetter__("november"));

// Redefining a data property.
obj1 = {};
obj1.oscar = 12345;
dp(obj1, "oscar", { set: setter });
assertEquals(setter, gop(obj1, "oscar").set);

// Re-adding the same getter/attributes pair.
obj1 = {};
dp(obj1, "papa", { get: getter, configurable: true });
dp(obj1, "papa", { get: getter, set: setter, configurable: true });
assertEquals(getter, gop(obj1, "papa").get);
assertEquals(setter, gop(obj1, "papa").set);
assertTrue(gop(obj1, "papa").configurable);
assertFalse(gop(obj1, "papa").enumerable);

// Two objects with the same getter on the prototype chain.
obj1 = {};
dp(obj1, "quebec", { get: getter });
obj2 = Object.create(obj1);
obj3 = Object.create(obj2);
obj4 = Object.create(obj2);
assertTrue(%HaveSameMap(obj3, obj4));

// Two objects with the same setter on the prototype chain.
obj1 = {};
dp(obj1, "romeo", { set: setter });
obj2 = Object.create(obj1);
obj3 = Object.create(obj2);
obj4 = Object.create(obj2);
assertTrue(%HaveSameMap(obj3, obj4));