closure-builder
Version:
Simple Closure, Soy and JavaScript Build system
110 lines (95 loc) • 3.61 kB
JavaScript
// Copyright 2017 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @package
* @supported IE 10+ and other browsers. IE 8 and IE 9 could be supported by
* by making anti-clobbering support optional.
*/
goog.module('goog.html.sanitizer.ElementWeakMap');
goog.module.declareLegacyNamespace();
var noclobber = goog.require('goog.html.sanitizer.noclobber');
// We also need to check if WeakMap has been polyfilled, because we want to use
// ElementWeakMap instead of the polyfill.
/** @const {boolean} */
var NATIVE_WEAKMAP_SUPPORTED = typeof WeakMap != 'undefined' &&
WeakMap.toString().indexOf('[native code]') != -1;
/** @const {string} */
var DATA_ATTRIBUTE_NAME_PREFIX = 'data-elementweakmap-index-';
// Increased every time a new ElementWeakMap is constructed, to guarantee
// that each weakmap uses a different attribute name.
var weakMapCount = 0;
/**
* A weakmap-like implementation for browsers that don't support native WeakMap.
* It uses a data attribute on the key element for O(1) lookups.
* @template T
* @constructor
*/
var ElementWeakMap = function() {
/** @private {!Array<!Element>} */
this.keys_ = [];
/** @private {!Array<!T>} */
this.values_ = [];
/** @private @const {string} */
this.dataAttributeName_ = DATA_ATTRIBUTE_NAME_PREFIX + weakMapCount++;
};
/**
* Stores a `elementKey` -> `value` mapping.
* @param {!Element} elementKey
* @param {!T} value
* @return {!ElementWeakMap}
*/
ElementWeakMap.prototype.set = function(elementKey, value) {
if (noclobber.hasElementAttribute(elementKey, this.dataAttributeName_)) {
var itemIndex = parseInt(
noclobber.getElementAttribute(elementKey, this.dataAttributeName_), 10);
this.values_[itemIndex] = value;
} else {
var itemIndex = this.values_.push(value) - 1;
noclobber.setElementAttribute(
elementKey, this.dataAttributeName_, itemIndex.toString());
this.keys_.push(elementKey);
}
return this;
};
/**
* Gets the value previously stored for `elementKey`, or undefined if no
* value was stored for such key.
* @param {!Element} elementKey
* @return {!Element|undefined}
*/
ElementWeakMap.prototype.get = function(elementKey) {
if (!noclobber.hasElementAttribute(elementKey, this.dataAttributeName_)) {
return undefined;
}
var itemIndex = parseInt(
noclobber.getElementAttribute(elementKey, this.dataAttributeName_), 10);
return this.values_[itemIndex];
};
/** Clears the map. */
ElementWeakMap.prototype.clear = function() {
this.keys_.forEach(function(el) {
noclobber.removeElementAttribute(el, this.dataAttributeName_);
}, this);
this.keys_ = [];
this.values_ = [];
};
/**
* Returns either this weakmap adapter or the native weakmap implmentation, if
* available.
* @return {!ElementWeakMap|!WeakMap}
*/
ElementWeakMap.newWeakMap = function() {
return NATIVE_WEAKMAP_SUPPORTED ? new WeakMap() : new ElementWeakMap();
};
exports = ElementWeakMap;