399 lines
10 KiB
JavaScript
399 lines
10 KiB
JavaScript
/**
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* Contains utilities functions shared by modules
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*
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* Copyright (C) 2010 Mike Gerwitz
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*
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* This file is part of ease.js.
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*
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* ease.js is free software: you can redistribute it and/or modify it under the
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* terms of the GNU Lesser General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
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* for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* @author Mike Gerwitz
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* @package core
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*/
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var propParseKeywords = require( './prop_parser' ).parseKeywords;
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/**
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* Whether getters/setters are supported
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* @var {boolean}
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*/
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var getset = ( Object.prototype.__defineGetter__ === undefined )
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? false
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: true
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;
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/**
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* Whether we can actually define properties, or we need to fall back
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*
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* This check actually attempts to set a property and fails if there's an error.
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* This is needed because IE8 has a broken implementation, yet still defines
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* Object.defineProperty for use with DOM elements. Just another day in the life
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* of a web developer.
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*
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* This test is only performed once, when the module is first loaded. Don't
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* expect a performance hit from it.
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*
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* @type {boolean}
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*/
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var can_define_prop = ( function()
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{
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if ( typeof Object.defineProperty === 'function' )
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{
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try
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{
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// perform test, primarily for IE8
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Object.defineProperty( {}, 'x', {} );
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return true;
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}
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catch ( e ) {}
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}
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return false;
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} )();
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/**
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* Freezes an object if freezing is supported
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*
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* @param {Object} obj object to freeze
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*
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* @return {Object} object passed to function
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*/
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exports.freeze = function( obj )
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{
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// if freezing is not supported (ES5), do nothing
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if ( Object.freeze === undefined )
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{
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return;
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}
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Object.freeze( obj );
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return obj;
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};
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/**
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* Gets/sets whether the system needs to fall back to defining properties in a
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* normal manner when use of Object.defineProperty() is requested
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*
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* This will be set by default if the JS engine does not support the
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* Object.defineProperty method from EcmaScript 5.
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*
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* @param {boolean=} val value, if used as setter
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*
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* @return {boolean|Object} current value if getter, self if setter
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*/
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exports.definePropertyFallback = function( val )
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{
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if ( val === undefined )
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{
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return !can_define_prop;
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}
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can_define_prop = !val;
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exports.defineSecureProp = getDefineSecureProp();
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return exports;
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};
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/**
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* Attempts to define a non-enumerable, non-writable and non-configurable
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* property on the given object
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*
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* If the operation is unsupported, a normal property will be set.
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*
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* @param {Object} obj object to set property on
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* @param {string} prop name of property to set
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* @param {mixed} value value to set
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*
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* @return {undefined}
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*/
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exports.defineSecureProp = getDefineSecureProp();
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/**
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* Clones an object
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*
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* @param {Object} data object to clone
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* @param {boolean} deep perform deep clone (defaults to shallow)
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*
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* @return {Object} cloned object
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*/
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exports.clone = function clone( data, deep )
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{
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deep = !!deep;
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if ( data instanceof Array )
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{
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if ( !deep )
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{
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// return a copy of the array
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return data.slice( 0 );
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}
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// if we're performing a deep clone, we have to loop through each of the
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// elements of the array and clone them
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var ret = [];
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for ( var i = 0, len = data.length; i < len; i++ )
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{
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// clone this element
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ret.push( clone( data[ i ], deep ) );
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}
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return ret;
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}
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else if ( data instanceof Object )
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{
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var newobj = {},
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hasOwn = Object.prototype.hasOwnProperty;
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// copy data to the new object
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for ( prop in data )
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{
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if ( hasOwn.call( data, prop ) )
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{
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newobj[ prop ] = ( deep )
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? clone( data[ prop ] )
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: data[ prop ]
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;
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}
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}
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return newobj;
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}
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// primitive type; cloning unnecessary
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return data;
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};
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/**
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* Parses object properties to determine how they should be interpreted in an
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* Object Oriented manner
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*
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* @param {Object} data properties with names as the key
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* @param {Object} options parser options and callbacks
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*
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* @return undefined
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*/
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exports.propParse = function( data, options )
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{
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// todo: profile; function calls are more expensive than if statements, so
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// it's probably a better idea not to use fvoid
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var fvoid = function() {},
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callbackEach = options.each || undefined,
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callbackProp = options.property || fvoid,
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callbackMethod = options.method || fvoid,
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callbackGetter = options.getter || fvoid,
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callbackSetter = options.setter || fvoid,
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keywordParser = options.keywordParser || propParseKeywords,
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hasOwn = Object.prototype.hasOwnProperty,
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parse_data = {},
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name = '',
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keywords = {},
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value = null,
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getter = false,
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setter = false;
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// for each of the given properties, determine what type of property we're
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// dealing with (in the classic OO sense)
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for ( prop in data )
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{
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// ignore properties of instance prototypes
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if ( !( hasOwn.call( data, prop ) ) )
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{
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continue;
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}
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value = data[ prop ];
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getter = ( ( getset ) ? data.__lookupGetter__( prop ) : null );
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setter = ( ( getset ) ? data.__lookupSetter__( prop ) : null );
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parse_data = keywordParser( prop ) || {};
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name = parse_data.name || prop;
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keywords = parse_data.keywords || {};
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if ( keywords['abstract'] )
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{
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if ( !( value instanceof Array ) )
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{
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throw TypeError(
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"Missing parameter list for abstract method: " + name
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);
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}
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value = exports.createAbstractMethod.apply( this, value );
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}
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// if an 'each' callback was provided, pass the data before parsing it
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if ( callbackEach )
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{
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callbackEach.call( callbackEach, name, value );
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}
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// getter/setter
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if ( getter || setter )
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{
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callbackGetter.call( callbackGetter, name, getter, keywords );
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callbackSetter.call( callbackSetter, name, setter, keywords );
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}
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// method
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else if ( value instanceof Function )
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{
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callbackMethod.call(
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callbackMethod,
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name,
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value,
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exports.isAbstractMethod( value ),
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keywords
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);
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}
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// simple property
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else
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{
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callbackProp.call( callbackProp, name, value, keywords );
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}
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}
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};
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/**
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* Creates an abstract method
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*
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* Abstract methods must be implemented by a subclass and cannot be called
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* directly. If a class contains a single abstract method, the class itself is
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* considered to be abstract and cannot be instantiated. It may only be
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* extended.
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*
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* @param {...string} definition function definition that concrete
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* implementations must follow
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*
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* @return {Function}
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*/
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exports.createAbstractMethod = function()
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{
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var definition = Array.prototype.slice.call( arguments );
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var method = function()
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{
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throw new Error( "Cannot call abstract method" );
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};
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exports.defineSecureProp( method, 'abstractFlag', true );
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exports.defineSecureProp( method, 'definition', definition );
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exports.defineSecureProp( method, '__length', arguments.length );
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return method;
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};
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/**
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* Determines if the given function is an abstract method
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*
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* @param {Function} function function to inspect
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*
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* @return {boolean} true if function is an abstract method, otherwise false
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*/
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exports.isAbstractMethod = function( func )
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{
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return ( ( func instanceof Function ) && ( func.abstractFlag === true ) )
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? true
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: false
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;
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};
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/**
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* Shrinks an array, removing undefined elements
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*
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* Pushes all items onto a new array, removing undefined elements. This ensures
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* that the length of the array represents correctly the number of elements in
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* the array.
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*
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* @param {Array} items array to shrink
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*
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* @return {Array} shrunken array
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*/
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exports.arrayShrink = function( items )
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{
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// copy the methods into a new array by pushing them onto it, to ensure
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// the length property of the array will work properly
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var arr_new = [];
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for ( var i = 0, len = items.length; i < len; i++ )
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{
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var item = items[ i ];
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if ( item === undefined )
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{
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continue;
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}
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arr_new.push( item );
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}
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return arr_new;
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};
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/**
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* Appropriately returns defineSecureProp implementation to avoid check on each
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* invocation
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*
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* @return {function( Object, string, * )}
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*/
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function getDefineSecureProp()
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{
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// falls back to simply defining a normal property
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var fallback = function( obj, prop, value )
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{
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obj[ prop ] = value;
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};
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if ( !can_define_prop )
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{
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return fallback;
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}
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else
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{
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// uses ECMAScript 5's Object.defineProperty() method
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return function( obj, prop, value )
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{
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try
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{
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Object.defineProperty( obj, prop,
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{
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value: value,
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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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}
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catch ( e )
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{
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// let's not have this happen again, as repeatedly throwing
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// exceptions will do nothing but slow down the system
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exports.definePropertyFallback( true );
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// if there's an error (ehem, IE8), fall back
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fallback( obj, prop, value );
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}
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};
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}
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}
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