// Licensed Materials - Property of IBM
//
// IBM Watson Analytics
//
// (C) Copyright IBM Corp. 2015
//
// US Government Users Restricted Rights - Use, duplication or
// disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
module.exports = ( function( ObjectPolyfill, Symbol )
{
"use strict";
// The property set by the first keymap that takes an object as key.
// All WeakMaps look at the same property
var KEY_PROP = Symbol( "WeakMap" );
var hOP = Object.prototype.hasOwnProperty;
var nextId = 0;
/**
* Mimics the implementation of a native {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap WeakMap}.
* The only way to achieve this is by putting a property on the key object.
* @class module:barejs/polyfill.WeakMap
* @param {any} [_iterable=null] Optional: an iterable whose values will be added to the WeakSet.
*/
function WeakMap( _iterable )
{
// Ensure map has no prototype chain (so we can safely use the in operator instead of hasOwnProperty)
ObjectPolyfill.defineProperty( this, "_map", { value: Object.create( null ) } );
if ( _iterable )
{
for ( var i = 0; i < _iterable.length; ++i )
this.set( _iterable[i][0], _iterable[i][1] );
}
}
return ( ObjectPolyfill.defineProperties( WeakMap.prototype,
/** @lends module:barejs/polyfill.WeakMap# */
{
_map: { value: null },
/**
* Adds a new element with a specified key and value to a WeakMap object.
* @function
* @param {object} _key The object to use as key.
* @param _value The value to add.
* @returns {module:barejs/polyfill.WeakMap} The WeakMap (for chaining)
*/
"set": { value: function set( _key, _value )
{
if ( !ObjectPolyfill.isObject( _key ) )
throw new TypeError( "Invalid value used as weak map key" );
if ( !hOP.call( _key, KEY_PROP ) )
ObjectPolyfill.defineProperty( _key, KEY_PROP, { value: ++nextId } );
this._map[ _key[KEY_PROP] ] = _value;
return this;
} },
/**
* Get the value for the specified key
* @function
* @param {object} _key The object to use as key.
* @returns The value, or undefined if the key is not known.
*/
"get": { value: function get( _key )
{
return this.has( _key ) ? this._map[ _key[KEY_PROP] ] : undefined;
} },
/**
* Check if the WeakMap has an entry for the specified key
* @function
* @param {object} _key The object to use as key.
* @returns {boolean} True if there is an entry for the key, false otherwise
*/
has: { value: function has( _key )
{
// If there is no WeakMap key property on the object, it has never been used as key for a WeakMap
return ObjectPolyfill.isObject( _key ) && hOP.call( _key, KEY_PROP ) && ( _key[KEY_PROP] in this._map );
} },
/**
* Remove the value for the specified key
* @function
* @param {object} _key The object to use as key.
* @returns {boolean} True if the entry was deleted, false otherwise
*/
"delete": { value: function _delete( _key )
{
// Remove the entry from our map (will be a NOOP if there is no property for the key value)
// Note: delete is not called if this.has( _key ) returns false. If the delete statement
// (incorrectly) returns false, we force it to return true using "|| true".
return this.has( _key ) && ( ( delete this._map[_key[KEY_PROP]] ) || true );
} }
} ), WeakMap );
}( require( "./Object" ), require( "../Symbol" ) ) );