egroupware_official/api/js/jsapi/egw_inheritance.js

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/**
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* EGroupWare - JS code for implementing inheritance
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*
* @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
* @package etemplate
* @subpackage api
* @link http://www.egroupware.org
* @author Andreas Stöckel
* @copyright Stylite 2011
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* @version $Id$
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*/
/**
* Usage of the JS inheritance system
* ----------------------------------
*
* To create a class write
*
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* MyClass = Class.extend([interfaces, ] functions);
*
* where "interfaces" is a single interface or an array of interfaces and
* functions an object containing the functions the class implements.
*
* An interface has to be created in the following way:
*
* var IBreathingObject = new Interface({
* breath: function() {}
* });
*
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* var Human = Class.extend(IBreathingObject, {
* walk: function() {
* console.log("Walking");
* },
* speak: function(_words) {
* console.log(_words);
* }
* });
*
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* As "Human" does not implement the function "breath", "Human" is treated as
* abstract. Trying to create an instance of "Human" will throw an exception.
* However
*
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* Human.prototype.implements(IBreathingObject);
*
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* will return true. Lets create a specific class of "Human":
*
* var ChuckNorris = Human.extend({
* breath: function() {
* console.log("Chuck Norris does not breath, he holds air hostage.");
* },
* speak: function(_words) {
* console.warn("Chuck Norris says:");
* this._super(_words);
* }
* });
*/
// The following code is mostly taken from
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// http://ejohn.org/blog/simple-javascript-inheritance/
// some parts were slightly changed for better understanding. Added possiblity
// to use interfaces.
/**
* Simple JavaScript Inheritance
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* By John Resig http://ejohn.org/
* MIT Licensed
*
* Inspired by base2 and Prototype
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*/
(function()
{
"use strict";
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var initializing = false;
/**
* Turn this to "true" to track creation and destruction of elements
*/
var getMem_freeMem_trace = false;
var tracedObjects = {};
// Check whether "function decompilation" works - fnTest is normally used to
// check whether a
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var fnTest = /xyz/.test(function(){xyz;}) ? /\b_super\b/ : /.*/;
/**
* Base "Class" for interfaces - needed to check whether an object is an
* interface
*
* @param {object} fncts
* @class {Interface}
*/
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this.Interface = function(fncts) {
for (var key in fncts)
{
this[key] = fncts[key];
}
};
/**
* The addInterfaceFunctions function adds all interface functions the class has
* to implement to the class prototype.
*
* @param {Class} prototype
* @param {array} interfaces
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*/
function addInterfaceFunctions(prototype, interfaces)
{
// Remember all interface functions in the prototype
var ifaces = ((typeof prototype["_ifacefuncs"] == "undefined") ? [] :
prototype["_ifacefuncs"]);
prototype["_ifacefuncs"] = [];
for (var i = 0; i < interfaces.length; i++)
{
var iface = interfaces[i];
if (iface instanceof Interface)
{
for (var key in iface)
{
prototype["_ifacefuncs"].push(key);
}
}
else
{
throw("Interfaces must be instance of Interface!");
}
}
for (var i = 0; i < ifaces.length; i++)
{
prototype["_ifacefuncs"].push(ifaces[i]);
}
};
function addAttributeFunctions(prototype, _super)
{
function _copyMerge(_new, _old)
{
var result = {};
// Copy the new object
if (typeof _new != "undefined")
{
for (var key in _new)
{
result[key] = _new[key];
}
}
// Merge the old object
for (var key in _old)
{
if (typeof result[key] == "undefined")
{
result[key] = _old[key];
}
}
return result;
}
var attributes = {};
// Copy the old attributes
for (var key in prototype.attributes)
{
attributes[key] = _copyMerge({}, prototype.attributes[key]);
}
// Add the old attributes to the new ones. If the attributes already
// exist, they are merged.
for (var key in _super.attributes)
{
var _old = _super.attributes[key];
attributes[key] = _copyMerge(attributes[key], _old);
}
if(prototype._validate_attributes)
{
prototype._validate_attributes(attributes);
}
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prototype.attributes = attributes;
};
/**
* Create a new Class that inherits from this class. The first parameter
* is an array which defines a set of interfaces the object has to
* implement. An interface is simply an object with named functions.
*
* @param {array} interfaces
* @param {object} prop
* @return {Class}
*/
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function classExtend(interfaces, prop) {
if (typeof prop == "undefined")
{
prop = interfaces;
interfaces = [];
}
// If a single interface is given, encapsulate it in an array
if (!(interfaces instanceof Array))
{
interfaces = [interfaces];
}
if (typeof prop.attributes == "undefined")
{
prop.attributes = {};
}
var _super = this.prototype;
// Instantiate a base class (but only create the instance,
// don't run the init constructor)
initializing = true;
var prototype = new this();
initializing = false;
// Copy the properties over onto the new prototype
for (var name in prop) {
// Check if we're overwriting an existing function and check whether
// the function actually uses "_super" - the RegExp test function
// silently converts the funciton prop[name] to a string.
if (typeof prop[name] == "function" &&
typeof _super[name] == "function" && fnTest.test(prop[name]))
{
prototype[name] = (function(name, fn){
return function() {
var tmp = this._super;
// Add a new ._super() method that is the same method
// but on the super-class
this._super = _super[name];
// The method only need to be bound temporarily, so we
// remove it when we're done executing
var ret = fn.apply(this, arguments);
this._super = tmp;
return ret;
};
})(name, prop[name]);
}
else
{
prototype[name] = prop[name];
}
}
// Add the interface functions and the "implements" function to the
// prototype
addInterfaceFunctions(prototype, interfaces);
// Merge the attributes and create the functions corresponding to the
// attributes
addAttributeFunctions(prototype, _super);
/**
* The dummy class constructor
*
* @constructor {Class}
*/
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function Class() {
// All construction is actually done in the init method
if (!initializing)
{
// Check whether the object implements all interface functions
for (var i = 0; i < this._ifacefuncs.length; i++)
{
var func = this._ifacefuncs[i];
if (!(typeof this[func] == "function"))
{
throw("Trying to create abstract object, interface " +
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"function '" + func + "' not implemented.");
}
}
// Do some tracing of the getMem_freeMem_trace is activated
if (getMem_freeMem_trace)
{
this.__OBJ_UID = "obj_" + egw.uid();
var className = this.className();
tracedObjects[this.__OBJ_UID] = {
"created": new Date().getTime(),
"class": className
};
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egw.debug("log", "*" + this.__OBJ_UID + " (" + className + ")");
}
if (this.init)
{
this.init.apply(this, arguments);
}
}
}
// Populate our constructed prototype object
Class.prototype = prototype;
// Enforce the constructor to be what we expect
Class.prototype.constructor = Class;
/**
* Create a new Class that inherits from this class. The first parameter
* is an array which defines a set of interfaces the object has to
* implement. An interface is simply an object with named functions.
*
* @param {array} interfaces
* @param {object} prop
* @return {Class}
*/
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Class.extend = classExtend;
return Class;
};
// The base Class implementation (does nothing)
this.Class = function(){};
/**
* Create a new Class that inherits from this class. The first parameter
* is an array which defines a set of interfaces the object has to
* implement. An interface is simply an object with named functions.
*
* @param {array} interfaces
* @param {object} prop
* @return {Class}
*/
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Class.extend = classExtend;
// The base class has no attributes
Class.prototype.attributes = {};
Class.prototype._ifacefuncs = [];
// Add the basic functions
/**
* Destructor function - it calls "destroy" if it has been defined and then
* deletes all keys of this element, so that any access to this element will
* eventually throw an exception, making it easier to hunt down memory leaks.
*/
Class.prototype.free = function() {
if (this.destroy)
{
this.destroy();
}
// Trace the freeing of the object
if (getMem_freeMem_trace)
{
delete(tracedObjects[this.__OBJ_UID]);
egw.debug("log", "-" + this.__OBJ_UID);
}
// Delete every object entry
for (var key in this)
{
delete(this[key]);
}
// Don't raise an exception when attempting to free an element multiple
// times.
this.free = function() {};
};
// Some debug functions for memory leak hunting
if (getMem_freeMem_trace)
{
/**
* Prints a list of all objects UIDs which have not been freed yet.
*/
Class.prototype.showTrace = function() {
console.log(tracedObjects);
},
/**
* VERY slow - for debugging only!
*/
Class.prototype.className = function() {
for (var key in window)
{
if (key.substr(0, 3) == "et2" && this.constructor == window[key])
{
return key;
}
}
return "?";
};
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}
/**
* The implements function can be used to check whether the object
* implements the given interface.
*
* @param {Class} _iface interface to check
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*/
Class.prototype.implements = function(_iface) {
for (var key in _iface)
{
if (this._ifacefuncs.indexOf(key) < 0)
{
return false;
}
}
return true;
};
/**
* The instanceOf function can be used to check for both - classes and
* interfaces. Please don't change the case of this function as this
* affects IE and Opera support.
*
* @param {Class} _obj object to check
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*/
Class.prototype.instanceOf = function(_obj) {
if (_obj instanceof Interface)
{
return this.implements(_obj);
}
else
{
return this instanceof _obj;
}
};
}).call(window);