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56 lines
1.3 KiB
JavaScript
56 lines
1.3 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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var defineProperty = Object.defineProperty;
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function next() {
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return "@@symbol:" + String(Math.random()).slice(2);
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}
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function Symbol(desc) {
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if (!(this instanceof Symbol)) {
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return new Symbol(desc);
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}
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var _symbol = this._symbol = next();
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defineProperty(this, '_desc', {
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value: desc,
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enumerable: false,
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writable: false,
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configurable: false
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});
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defineProperty(Object.prototype, _symbol, {
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set: function(value) {
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defineProperty(this, _symbol, {
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value: value,
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enumerable: false,
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writable: true
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});
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}
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});
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}
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Symbol.prototype.toString = function toString() {
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return this._symbol;
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};
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var globalSymbolRegistry = {};
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Symbol.for = function symbolFor(key) {
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key = String(key);
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return globalSymbolRegistry[key] || (globalSymbolRegistry[key] = Symbol(key));
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};
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Symbol.keyFor = function keyFor(sym) {
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if (!(sym instanceof Symbol)) {
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throw new TypeError("Symbol.keyFor requires a Symbol argument");
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}
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for (var key in globalSymbolRegistry) {
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if (globalSymbolRegistry[key] === sym) {
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return key;
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}
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}
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return undefined;
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};
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module.exports = this.Symbol || Symbol;
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