forked from extern/egroupware
446 lines
10 KiB
JavaScript
446 lines
10 KiB
JavaScript
/**
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* eGroupWare eTemplate2 - JS code for implementing inheritance
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*
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* @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
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* @package etemplate
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* @subpackage api
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* @link http://www.egroupware.org
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* @author Andreas Stöckel
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* @copyright Stylite 2011
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* @version $Id$
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*/
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"use strict";
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/*egw:uses
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et2_core_common;
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*/
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/**
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* Usage of the JS inheritance system
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* ----------------------------------
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*
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* To create a class write
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*
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* MyClass = Class.extend([interfaces, ] functions);
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*
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* where "interfaces" is a single interface or an array of interfaces and
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* functions an object containing the functions the class implements.
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*
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* An interface has to be created in the following way:
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*
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* var IBreathingObject = new Interface({
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* breath: function() {}
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* });
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*
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* var Human = Class.extend(IBreathingObject, {
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* walk: function() {
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* console.log("Walking");
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* },
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* speak: function(_words) {
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* console.log(_words);
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* }
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* });
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*
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* As "Human" does not implement the function "breath", "Human" is treated as
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* abstract. Trying to create an instance of "Human" will throw an exception.
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* However
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*
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* Human.prototype.implements(IBreathingObject);
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*
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* will return true. Lets create a specific class of "Human":
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*
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* var ChuckNorris = Human.extend({
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* breath: function() {
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* console.log("Chuck Norris does not breath, he holds air hostage.");
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* },
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* speak: function(_words) {
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* console.warn("Chuck Norris says:");
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* this._super(_words);
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* }
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* });
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*/
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// The following code is mostly taken from
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// http://ejohn.org/blog/simple-javascript-inheritance/
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// some parts were slightly changed for better understanding. Added possiblity
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// to use interfaces.
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/* Simple JavaScript Inheritance
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* By John Resig http://ejohn.org/
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* MIT Licensed
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*/
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// Inspired by base2 and Prototype
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(function(){
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var initializing = false
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// Check whether "function decompilation" works - fnTest is normally used to
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// check whether a
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var fnTest = /xyz/.test(function(){xyz;}) ? /\b_super\b/ : /.*/;
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// Base "Class" for interfaces - needed to check whether an object is an
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// interface
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this.Interface = function(fncts) {
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for (var key in fncts)
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{
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this[key] = fncts[key];
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}
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};
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/**
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* The addInterfaceFunctions function adds all interface functions the class has
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* to implement to the class prototype.
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*/
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function addInterfaceFunctions(prototype, interfaces)
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{
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// Remember all interface functions in the prototype
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var ifaces = ((typeof prototype["_ifacefuncs"] == "undefined") ? [] :
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prototype["_ifacefuncs"]);
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prototype["_ifacefuncs"] = [];
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for (var i = 0; i < interfaces.length; i++)
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{
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var iface = interfaces[i];
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if (iface instanceof Interface)
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{
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for (var key in iface)
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{
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prototype["_ifacefuncs"].push(key);
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}
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}
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else
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{
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throw("Interfaces must be instance of Interface!");
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}
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}
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for (var i = 0; i < ifaces.length; i++)
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{
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prototype["_ifacefuncs"].push(ifaces[i]);
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}
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};
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function addAttributeFunctions(prototype, _super)
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{
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function _copyMerge(_new, _old)
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{
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var result = {};
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// Copy the new object
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if (typeof _new != "undefined")
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{
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for (var key in _new)
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{
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result[key] = _new[key];
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}
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}
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// Merge the old object
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for (var key in _old)
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{
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if (typeof result[key] == "undefined")
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{
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result[key] = _old[key];
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}
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}
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return result;
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}
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var attributes = {};
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// Copy the old attributes
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for (var key in prototype.attributes)
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{
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attributes[key] = _copyMerge({}, prototype.attributes[key]);
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}
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// Add the old attributes to the new ones. If the attributes already
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// exist, they are merged.
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for (var key in _super.attributes)
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{
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var _old = _super.attributes[key];
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var _new = {};
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attributes[key] = _copyMerge(attributes[key], _old);
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}
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// Validate the attributes
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for (var key in attributes)
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{
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et2_validateAttrib(key, attributes[key]);
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}
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prototype.attributes = attributes;
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};
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function classExtend(interfaces, prop) {
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if (typeof prop == "undefined")
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{
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prop = interfaces;
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interfaces = [];
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}
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// If a single interface is given, encapsulate it in an array
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if (!(interfaces instanceof Array))
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{
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interfaces = [interfaces];
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}
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if (typeof prop.attributes == "undefined")
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{
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prop.attributes = {};
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}
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var _super = this.prototype;
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// Instantiate a base class (but only create the instance,
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// don't run the init constructor)
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initializing = true;
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var prototype = new this();
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initializing = false;
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// Copy the properties over onto the new prototype
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for (var name in prop) {
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// Check if we're overwriting an existing function and check whether
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// the function actually uses "_super" - the RegExp test function
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// silently converts the funciton prop[name] to a string.
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if (typeof prop[name] == "function" &&
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typeof _super[name] == "function" && fnTest.test(prop[name]))
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{
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prototype[name] = (function(name, fn){
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return function() {
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var tmp = this._super;
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// Add a new ._super() method that is the same method
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// but on the super-class
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this._super = _super[name];
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// The method only need to be bound temporarily, so we
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// remove it when we're done executing
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var ret = fn.apply(this, arguments);
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this._super = tmp;
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return ret;
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};
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})(name, prop[name]);
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}
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else
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{
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prototype[name] = prop[name];
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}
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}
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// Add the interface functions and the "implements" function to the
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// prototype
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addInterfaceFunctions(prototype, interfaces);
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// Merge the attributes and create the functions corresponding to the
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// attributes
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addAttributeFunctions(prototype, _super);
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// The dummy class constructor
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function Class() {
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// All construction is actually done in the init method
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if (!initializing)
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{
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// Check whether the object implements all interface functions
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for (var i = 0; i < this._ifacefuncs.length; i++)
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{
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var func = this._ifacefuncs[i];
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if (!(typeof this[func] == "function"))
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{
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throw("Trying to create abstract object, interface " +
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"function '" + func + "' not implemented.");
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}
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}
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if (this.init)
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{
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this.init.apply(this, arguments);
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}
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}
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}
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// Populate our constructed prototype object
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Class.prototype = prototype;
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// Enforce the constructor to be what we expect
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Class.prototype.constructor = Class;
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// And make this class extendable
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Class.extend = classExtend;
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return Class;
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};
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// The base Class implementation (does nothing)
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this.Class = function(){};
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// Create a new Class that inherits from this class. The first parameter
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// is an array which defines a set of interfaces the object has to
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// implement. An interface is simply an object with named functions.
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Class.extend = classExtend;
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// The base class has no attributes
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Class.prototype.attributes = {};
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// Add the basic functions
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/**
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* Returns the value of the given attribute. If the property does not
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* exist, an error message is issued.
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*/
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Class.prototype.getAttribute = function(_name) {
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if (typeof this.attributes[_name] != "undefined" &&
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!this.attributes[_name].ignore)
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{
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if (typeof this["get_" + _name] == "function")
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{
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return this["get_" + _name]();
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}
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else
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{
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return this[_name];
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}
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}
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else
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{
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et2_debug("error", this, "Attribute '" + _name + "' does not exist!");
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}
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}
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/**
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* The setAttribute function sets the attribute with the given name to
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* the given value. _override defines, whether this[_name] will be set,
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* if this key already exists. _override defaults to true. A warning
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* is issued if the attribute does not exist.
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*/
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Class.prototype.setAttribute = function(_name, _value, _override) {
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if (typeof this.attributes[_name] != "undefined")
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{
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if (!this.attributes[_name].ignore)
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{
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if (typeof _override == "undefined")
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{
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_override = true;
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}
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var val = et2_checkType(_value, this.attributes[_name].type,
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_name);
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if (typeof this["set_" + _name] == "function")
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{
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this["set_" + _name](val);
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}
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else if (_override || typeof this[_name] == "undefined")
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{
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this[_name] = val;
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}
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}
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}
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else
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{
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et2_debug("warn", this, "Attribute '" + _name + "' does not exist!");
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}
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}
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/**
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* generateAttributeSet sanitizes the given associative array of attributes
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* (by passing each entry to "et2_checkType" and checking for existance of
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* the attribute) and adds the default values to the associative array.
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*
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* @param _attrs is the associative array containing the attributes.
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*/
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Class.prototype.generateAttributeSet = function(_attrs) {
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// Sanity check and validation
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for (var key in _attrs)
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{
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if (typeof this.attributes[key] != "undefined")
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{
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if (!this.attributes[key].ignore)
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{
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_attrs[key] = et2_checkType(_attrs[key], this.attributes[key].type,
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key);
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}
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}
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else
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{
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// Key does not exist - delete it and issue a warning
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delete(_attrs[key]);
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et2_debug("warn", this, "Attribute '" + key +
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"' does not exist!");
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}
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}
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// Include default values or already set values for this attribute
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for (var key in this.attributes)
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{
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if (typeof _attrs[key] == "undefined")
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{
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var _default = this.attributes[key]["default"];
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if (_default == et2_no_init)
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{
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_default = undefined;
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}
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_attrs[key] = _default;
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}
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}
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return _attrs;
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}
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/**
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* The initAttributes function sets the attributes to their default
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* values. The attributes are not overwritten, which means, that the
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* default is only set, if either a setter exists or this[propName] does
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* not exist yet.
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*/
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Class.prototype.initAttributes = function(_attrs) {
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for (var key in _attrs)
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{
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if (!this.attributes[key].ignore && !(_attrs[key] == undefined))
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{
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this.setAttribute(key, _attrs[key], false);
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}
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}
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}
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/**
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* The implements function can be used to check whether the object
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* implements the given interface.
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*/
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Class.prototype.implements = function(_iface) {
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for (var key in _iface)
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{
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if (this._ifacefuncs.indexOf(key) < 0)
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{
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return false;
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}
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}
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return true;
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}
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/**
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* The instanceOf function can be used to check for both - classes and
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* interfaces. Please don't change the case of this function as this
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* affects IE and Opera support.
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*/
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Class.prototype.instanceOf = function(_obj) {
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if (_obj instanceof Interface)
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{
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return this.implements(_obj);
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}
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else
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{
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return this instanceof _obj;
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}
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}
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}).call(window);
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