124 lines
2.9 KiB
JavaScript
124 lines
2.9 KiB
JavaScript
/**
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* Wrapper permitting the definition of abstract classes
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*
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* This doesn't actually introduce any new functionality. Rather, it sets a flag
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* to allow abstract methods within a class, forcing users to clearly state
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* that a class is abstract.
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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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*/
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var Class = require( __dirname + '/class' );
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/**
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* Creates an abstract class
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*
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* @return {Function} abstract class
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*/
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module.exports = exports = function()
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{
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markAbstract( arguments );
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// forward everything to Class
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var result = Class.apply( this, arguments );
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// if we're using the temporary object, then override its methods to permit
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// abstract classes
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if ( !Class.isClass( result ) )
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{
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abstractOverride( result );
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}
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return result;
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};
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/**
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* Creates an abstract class from a class extend operation
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*
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* @return {Function} abstract class
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*/
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exports.extend = function()
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{
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markAbstract( arguments );
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return Class.extend.apply( this, arguments );
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};
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/**
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* Creates an abstract class implementing the given members
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*
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* Simply wraps the class module's implement() method.
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*
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* @return {Object} abstract class
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*/
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exports.implement = function()
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{
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var impl = Class.implement.apply( this, arguments );
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abstractOverride( impl );
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return impl;
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};
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/**
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* Causes a definition to be flagged as abstract
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*
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* This function assumes the last argument to be the definition, which is the
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* common case, and modifies the object referenced by that argument.
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*
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* @param {Arguments} args arguments to parse
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*
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* @return {undefined}
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*/
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function markAbstract( args )
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{
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// the last argument _should_ be the definition
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var dfn = args[ args.length - 1 ];
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if ( typeof dfn === 'object' )
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{
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// mark as abstract
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dfn.___$$abstract$$ = true;
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}
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}
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/**
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* Overrides object members to permit abstract classes
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*
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* @param {Object} obj object to override
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*
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* @return {undefined}
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*/
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function abstractOverride( obj )
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{
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var extend = obj.extend;
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// wrap extend, applying the abstract flag
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obj.extend = function()
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{
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markAbstract( arguments );
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return extend.apply( this, arguments );
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};
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}
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