624 lines
17 KiB
JavaScript
624 lines
17 KiB
JavaScript
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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* @providesModule Map
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* @preventMunge
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* @typechecks
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*/
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/* eslint-disable no-extend-native, no-shadow-restricted-names */
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'use strict';
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var _shouldPolyfillES6Collection = require('_shouldPolyfillES6Collection');
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var guid = require('guid');
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var isNode = require('fbjs/lib/isNode');
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var toIterator = require('toIterator');
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module.exports = (function(global, undefined) {
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// Since our implementation is spec-compliant for the most part we can safely
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// delegate to a built-in version if exists and is implemented correctly.
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// Firefox had gotten a few implementation details wrong across different
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// versions so we guard against that.
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if (!_shouldPolyfillES6Collection('Map')) {
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return global.Map;
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}
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/**
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* == ES6 Map Collection ==
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*
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* This module is meant to implement a Map collection as described in chapter
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* 23.1 of the ES6 specification.
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*
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* Map objects are collections of key/value pairs where both the keys and
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* values may be arbitrary ECMAScript language values. A distinct key value
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* may only occur in one key/value pair within the Map's collection.
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*
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* https://people.mozilla.org/~jorendorff/es6-draft.html#sec-map-objects
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*
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* There only two -- rather small -- diviations from the spec:
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*
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* 1. The use of frozen objects as keys.
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* We decided not to allow and simply throw an error. The reason being is
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* we store a "hash" on the object for fast access to it's place in the
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* internal map entries.
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* If this turns out to be a popular use case it's possible to implement by
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* overiding `Object.freeze` to store a "hash" property on the object
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* for later use with the map.
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*
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* 2. The `size` property on a map object is a regular property and not a
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* computed property on the prototype as described by the spec.
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* The reason being is that we simply want to support ES3 environments
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* which doesn't implement computed properties.
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*
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* == Usage ==
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*
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* var map = new Map(iterable);
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*
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* map.set(key, value);
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* map.get(key); // value
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* map.has(key); // true
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* map.delete(key); // true
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*
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* var iterator = map.keys();
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* iterator.next(); // {value: key, done: false}
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*
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* var iterator = map.values();
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* iterator.next(); // {value: value, done: false}
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*
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* var iterator = map.entries();
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* iterator.next(); // {value: [key, value], done: false}
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*
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* map.forEach(function(value, key){ this === thisArg }, thisArg);
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*
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* map.clear(); // resets map.
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*/
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/**
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* Constants
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*/
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// Kinds of map iterations 23.1.5.3
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var KIND_KEY = 'key';
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var KIND_VALUE = 'value';
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var KIND_KEY_VALUE = 'key+value';
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// In older browsers we can't create a null-prototype object so we have to
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// defend against key collisions with built-in methods.
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var KEY_PREFIX = '$map_';
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// This property will be used as the internal size variable to disallow
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// writing and to issue warnings for writings in development.
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var SECRET_SIZE_PROP;
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if (__DEV__) {
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SECRET_SIZE_PROP = '$size' + guid();
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}
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// In oldIE we use the DOM Node `uniqueID` property to get create the hash.
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var OLD_IE_HASH_PREFIX = 'IE_HASH_';
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class Map {
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/**
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* 23.1.1.1
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* Takes an `iterable` which is basically any object that implements a
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* Symbol.iterator (@@iterator) method. The iterable is expected to be a
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* collection of pairs. Each pair is a key/value pair that will be used
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* to instantiate the map.
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*
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* @param {*} iterable
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*/
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constructor(iterable) {
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if (!isObject(this)) {
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throw new TypeError('Wrong map object type.');
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}
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initMap(this);
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if (iterable != null) {
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var it = toIterator(iterable);
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var next;
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while (!(next = it.next()).done) {
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if (!isObject(next.value)) {
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throw new TypeError('Expected iterable items to be pair objects.');
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}
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this.set(next.value[0], next.value[1]);
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}
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}
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}
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/**
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* 23.1.3.1
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* Clears the map from all keys and values.
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*/
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clear() {
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initMap(this);
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}
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/**
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* 23.1.3.7
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* Check if a key exists in the collection.
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*
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* @param {*} key
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* @return {boolean}
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*/
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has(key) {
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var index = getIndex(this, key);
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return !!(index != null && this._mapData[index]);
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}
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/**
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* 23.1.3.9
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* Adds a key/value pair to the collection.
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*
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* @param {*} key
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* @param {*} value
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* @return {map}
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*/
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set(key, value) {
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var index = getIndex(this, key);
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if (index != null && this._mapData[index]) {
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this._mapData[index][1] = value;
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} else {
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index = this._mapData.push([
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key,
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value
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]) - 1;
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setIndex(this, key, index);
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if (__DEV__) {
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this[SECRET_SIZE_PROP] += 1;
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} else {
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this.size += 1;
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}
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}
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return this;
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}
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/**
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* 23.1.3.6
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* Gets a value associated with a key in the collection.
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*
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* @param {*} key
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* @return {*}
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*/
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get(key) {
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var index = getIndex(this, key);
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if (index == null) {
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return undefined;
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} else {
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return this._mapData[index][1];
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}
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}
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/**
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* 23.1.3.3
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* Delete a key/value from the collection.
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*
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* @param {*} key
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* @return {boolean} Whether the key was found and deleted.
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*/
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delete(key) {
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var index = getIndex(this, key);
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if (index != null && this._mapData[index]) {
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setIndex(this, key, undefined);
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this._mapData[index] = undefined;
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if (__DEV__) {
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this[SECRET_SIZE_PROP] -= 1;
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} else {
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this.size -= 1;
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}
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return true;
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} else {
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return false;
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}
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}
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/**
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* 23.1.3.4
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* Returns an iterator over the key/value pairs (in the form of an Array) in
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* the collection.
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*
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* @return {MapIterator}
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*/
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entries() {
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return new MapIterator(this, KIND_KEY_VALUE);
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}
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/**
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* 23.1.3.8
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* Returns an iterator over the keys in the collection.
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*
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* @return {MapIterator}
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*/
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keys() {
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return new MapIterator(this, KIND_KEY);
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}
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/**
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* 23.1.3.11
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* Returns an iterator over the values pairs in the collection.
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*
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* @return {MapIterator}
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*/
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values() {
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return new MapIterator(this, KIND_VALUE);
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}
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/**
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* 23.1.3.5
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* Iterates over the key/value pairs in the collection calling `callback`
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* with [value, key, map]. An optional `thisArg` can be passed to set the
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* context when `callback` is called.
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*
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* @param {function} callback
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* @param {?object} thisArg
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*/
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forEach(callback, thisArg) {
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if (typeof callback !== 'function') {
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throw new TypeError('Callback must be callable.');
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}
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var boundCallback = callback.bind(thisArg || undefined);
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var mapData = this._mapData;
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// Note that `mapData.length` should be computed on each iteration to
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// support iterating over new items in the map that were added after the
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// start of the iteration.
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for (var i = 0; i < mapData.length; i++) {
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var entry = mapData[i];
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if (entry != null) {
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boundCallback(entry[1], entry[0], this);
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}
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}
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}
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}
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// 23.1.3.12
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Map.prototype[toIterator.ITERATOR_SYMBOL] = Map.prototype.entries;
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class MapIterator {
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/**
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* 23.1.5.1
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* Create a `MapIterator` for a given `map`. While this class is private it
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* will create objects that will be passed around publicily.
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*
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* @param {map} map
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* @param {string} kind
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*/
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constructor(map, kind) {
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if (!(isObject(map) && map._mapData)) {
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throw new TypeError('Object is not a map.');
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}
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if ([KIND_KEY, KIND_KEY_VALUE, KIND_VALUE].indexOf(kind) === -1) {
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throw new Error('Invalid iteration kind.');
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}
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this._map = map;
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this._nextIndex = 0;
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this._kind = kind;
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}
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/**
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* 23.1.5.2.1
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* Get the next iteration.
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*
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* @return {object}
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*/
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next() {
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if (!this instanceof Map) {
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throw new TypeError('Expected to be called on a MapIterator.');
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}
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var map = this._map;
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var index = this._nextIndex;
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var kind = this._kind;
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if (map == null) {
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return createIterResultObject(undefined, true);
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}
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var entries = map._mapData;
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while (index < entries.length) {
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var record = entries[index];
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index += 1;
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this._nextIndex = index;
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if (record) {
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if (kind === KIND_KEY) {
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return createIterResultObject(record[0], false);
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} else if (kind === KIND_VALUE) {
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return createIterResultObject(record[1], false);
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} else if (kind) {
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return createIterResultObject(record, false);
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}
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}
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}
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this._map = undefined;
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return createIterResultObject(undefined, true);
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}
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}
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// We can put this in the class definition once we have computed props
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// transform.
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// 23.1.5.2.2
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MapIterator.prototype[toIterator.ITERATOR_SYMBOL] = function() {
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return this;
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};
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/**
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* Helper Functions.
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*/
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/**
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* Return an index to map.[[MapData]] array for a given Key.
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*
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* @param {map} map
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* @param {*} key
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* @return {?number}
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*/
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function getIndex(map, key) {
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if (isObject(key)) {
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var hash = getHash(key);
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return map._objectIndex[hash];
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} else {
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var prefixedKey = KEY_PREFIX + key;
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if (typeof key === 'string') {
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return map._stringIndex[prefixedKey];
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} else {
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return map._otherIndex[prefixedKey];
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}
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}
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}
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/**
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* Setup an index that refer to the key's location in map.[[MapData]].
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*
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* @param {map} map
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* @param {*} key
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*/
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function setIndex(map, key, index) {
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var shouldDelete = index == null;
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if (isObject(key)) {
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var hash = getHash(key);
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if (shouldDelete) {
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delete map._objectIndex[hash];
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} else {
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map._objectIndex[hash] = index;
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}
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} else {
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var prefixedKey = KEY_PREFIX + key;
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if (typeof key === 'string') {
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if (shouldDelete) {
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delete map._stringIndex[prefixedKey];
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} else {
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map._stringIndex[prefixedKey] = index;
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}
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} else {
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if (shouldDelete) {
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delete map._otherIndex[prefixedKey];
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} else {
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map._otherIndex[prefixedKey] = index;
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}
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}
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}
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}
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/**
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* Instantiate a map with internal slots.
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*
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* @param {map} map
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*/
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function initMap(map) {
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// Data structure design inspired by Traceur's Map implementation.
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// We maintain an internal array for all the entries. The array is needed
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// to remember order. However, to have a reasonable HashMap performance
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// i.e. O(1) for insertion, deletion, and retrieval. We maintain indices
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// in objects for fast look ups. Indices are split up according to data
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// types to avoid collisions.
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map._mapData = [];
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// Object index maps from an object "hash" to index. The hash being a unique
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// property of our choosing that we associate with the object. Association
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// is done by ways of keeping a non-enumerable property on the object.
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// Ideally these would be `Object.create(null)` objects but since we're
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// trying to support ES3 we'll have to gaurd against collisions using
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// prefixes on the keys rather than rely on null prototype objects.
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map._objectIndex = {};
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// String index maps from strings to index.
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map._stringIndex = {};
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// Numbers, booleans, undefined, and null.
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map._otherIndex = {};
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// Unfortunately we have to support ES3 and cannot have `Map.prototype.size`
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// be a getter method but just a regular method. The biggest problem with
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// this is safety. Clients can change the size property easily and possibly
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// without noticing (e.g. `if (map.size = 1) {..}` kind of typo). What we
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// can do to mitigate use getters and setters in development to disallow
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// and issue a warning for changing the `size` property.
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if (__DEV__) {
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if (isES5) {
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// If the `SECRET_SIZE_PROP` property is already defined then we're not
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// in the first call to `initMap` (e.g. coming from `map.clear()`) so
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// all we need to do is reset the size without defining the properties.
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if (map.hasOwnProperty(SECRET_SIZE_PROP)) {
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map[SECRET_SIZE_PROP] = 0;
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} else {
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Object.defineProperty(map, SECRET_SIZE_PROP, {
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value: 0,
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writable: true
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});
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Object.defineProperty(map, 'size', {
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set: (v) => {
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console.error(
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'PLEASE FIX ME: You are changing the map size property which ' +
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'should not be writable and will break in production.'
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);
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throw new Error('The map size property is not writable.');
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},
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get: () => map[SECRET_SIZE_PROP]
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});
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}
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// NOTE: Early return to implement immutable `.size` in DEV.
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return;
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}
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}
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// This is a diviation from the spec. `size` should be a getter on
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// `Map.prototype`. However, we have to support IE8.
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map.size = 0;
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}
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/**
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* Check if something is an object.
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*
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* @param {*} o
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* @return {boolean}
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*/
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function isObject(o) {
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return o != null && (typeof o === 'object' || typeof o === 'function');
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}
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/**
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* Create an iteration object.
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*
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* @param {*} value
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* @param {boolean} done
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* @return {object}
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*/
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function createIterResultObject(value, done) {
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return {value, done};
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}
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// Are we in a legit ES5 environment. Spoiler alert: that doesn't include IE8.
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var isES5 = (function() {
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try {
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Object.defineProperty({}, 'x', {});
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return true;
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} catch (e) {
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return false;
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}
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})();
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/**
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* Check if an object can be extended.
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*
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* @param {object|array|function|regexp} o
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* @return {boolean}
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*/
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function isExtensible(o) {
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if (!isES5) {
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return true;
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} else {
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return Object.isExtensible(o);
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}
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}
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/**
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* IE has a `uniqueID` set on every DOM node. So we construct the hash from
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* this uniqueID to avoid memory leaks and the IE cloneNode bug where it
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* clones properties in addition to the attributes.
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*
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* @param {object} node
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* @return {?string}
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*/
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function getIENodeHash(node) {
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var uniqueID;
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switch (node.nodeType) {
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case 1: // Element
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uniqueID = node.uniqueID;
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break;
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case 9: // Document
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uniqueID = node.documentElement.uniqueID;
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break;
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default:
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return null;
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}
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if (uniqueID) {
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return OLD_IE_HASH_PREFIX + uniqueID;
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} else {
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return null;
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}
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}
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|
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var getHash = (function() {
|
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var propIsEnumerable = Object.prototype.propertyIsEnumerable;
|
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var hashProperty = guid();
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var hashCounter = 0;
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|
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/**
|
|
* Get the "hash" associated with an object.
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*
|
|
* @param {object|array|function|regexp} o
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* @return {number}
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*/
|
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return function getHash(o) { // eslint-disable-line no-shadow
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if (o[hashProperty]) {
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return o[hashProperty];
|
|
} else if (!isES5 &&
|
|
o.propertyIsEnumerable &&
|
|
o.propertyIsEnumerable[hashProperty]) {
|
|
return o.propertyIsEnumerable[hashProperty];
|
|
} else if (!isES5 &&
|
|
isNode(o) &&
|
|
getIENodeHash(o)) {
|
|
return getIENodeHash(o);
|
|
} else if (!isES5 && o[hashProperty]) {
|
|
return o[hashProperty];
|
|
}
|
|
|
|
if (isExtensible(o)) {
|
|
hashCounter += 1;
|
|
if (isES5) {
|
|
Object.defineProperty(o, hashProperty, {
|
|
enumerable: false,
|
|
writable: false,
|
|
configurable: false,
|
|
value: hashCounter
|
|
});
|
|
} else if (o.propertyIsEnumerable) {
|
|
// Since we can't define a non-enumerable property on the object
|
|
// we'll hijack one of the less-used non-enumerable properties to
|
|
// save our hash on it. Addiotionally, since this is a function it
|
|
// will not show up in `JSON.stringify` which is what we want.
|
|
o.propertyIsEnumerable = function() {
|
|
return propIsEnumerable.apply(this, arguments);
|
|
};
|
|
o.propertyIsEnumerable[hashProperty] = hashCounter;
|
|
} else if (isNode(o)) {
|
|
// At this point we couldn't get the IE `uniqueID` to use as a hash
|
|
// and we couldn't use a non-enumerable property to exploit the
|
|
// dontEnum bug so we simply add the `hashProperty` on the node
|
|
// itself.
|
|
o[hashProperty] = hashCounter;
|
|
} else {
|
|
throw new Error('Unable to set a non-enumerable property on object.');
|
|
}
|
|
return hashCounter;
|
|
} else {
|
|
throw new Error('Non-extensible objects are not allowed as keys.');
|
|
}
|
|
};
|
|
})();
|
|
|
|
return Map;
|
|
})(Function('return this')()); // eslint-disable-line no-new-func
|