Source: polyfill/WeakSet.js

  1. // Licensed Materials - Property of IBM
  2. //
  3. // IBM Watson Analytics
  4. //
  5. // (C) Copyright IBM Corp. 2015
  6. //
  7. // US Government Users Restricted Rights - Use, duplication or
  8. // disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
  10. module.exports = ( function( ObjectPolyfill, Symbol )
  11. {
  12. "use strict";
  14. // The property set by the first WeakSet that takes an object as key.
  15. // All WeakSets look at the same property
  16. var KEY_PROP = Symbol( "WeakSet" );
  17. var hOP = Object.prototype.hasOwnProperty;
  18. var nextId = 0;
  20. /**
  21.  * Mimics the implementation of a native {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet WeakSet}.
  22.  * The only way to achieve this is by putting a property on the added value.
  23.  * @class module:barejs/polyfill.WeakSet
  24.  * @param {*} [_iterable]: Optional: an iterable whose values will be added to the WeakSet.
  25.  */
  26. function WeakSet( _iterable )
  27. {
  28.     if ( _iterable )
  29.     {
  30.         for ( var i = 0; i < _iterable.length; ++i )
  31.             this.add( _iterable[i] );
  32.     }
  34.     ObjectPolyfill.defineProperty( this, "_values", { value: [] } );
  35. }
  37. return ( ObjectPolyfill.defineProperties( WeakSet.prototype,
  38. /** @lends module:barejs/polyfill.WeakSet# */
  39. {
  40.     _values: { value: null },
  42.     /**
  43.      * Adds a value to a WeakSet.
  44.      * @function
  45.      * @param _value The value to add.
  46.      * @returns {module:barejs/polyfill.WeakSet} The WeakSet (for chaining)
  47.      */
  48.     add: { value: function add( _value )
  49.     {
  50.         if ( !ObjectPolyfill.isObject( _value ) )
  51.             throw new TypeError( "Invalid value used as WeakSet value" );
  53.         if ( !hOP.call( _value, KEY_PROP ) )
  54.             ObjectPolyfill.defineProperty( _value, KEY_PROP, { value: ++nextId } );
  56.         if ( this._values.indexOf( _value[KEY_PROP] ) < 0 )
  57.             this._values.push( _value[KEY_PROP] );
  59.         return this;
  60.     } },
  62.     /**
  63.      * Check if the WeakSet has an entry for the specified _value.
  64.      * @function
  65.      * @param {object} _value The object to check.
  66.      * @returns {boolean} True if the WeakSet contains _value, false otherwise.
  67.      */
  68.     has: { value: function has( _value )
  69.     {
  70.         // If there is no WeakSet key property on the object, it has never been used as key for a WeakSet
  71.         return ObjectPolyfill.isObject( _value ) && hOP.call( _value, KEY_PROP ) && ( this._values.indexOf( _value[KEY_PROP] ) >= 0 );
  72.     } },
  74.     /**
  75.      * Remove the value from the WeakSet
  76.      * @function
  77.      * @param {object} _value The value to remove.
  78.      * @returns {boolean} True if the value was deleted, false otherwise
  79.      */
  80.     "delete": { value: function _delete( _value )
  81.     {
  82.         var idx = -1;
  84.         if ( ObjectPolyfill.isObject( _value ) && hOP.call( _value, KEY_PROP ) )
  85.             idx = this._values.indexOf( _value[KEY_PROP] );
  87.         if ( idx < 0 )
  88.             return false;
  90.         this._values.splice( idx, 1 );
  92.         return true;
  93.     } }
  94. } ), WeakSet );
  96. }( require( "./Object" ), require( "../Symbol" ) ) );