source: Dev/trunk/src/client/dojox/lang/oo/mixin.js

dojo.provide("dojox.lang.oo.mixin");

dojo.experimental("dojox.lang.oo.mixin");

dojo.require("dojox.lang.oo.Filter");
dojo.require("dojox.lang.oo.Decorator");

(function(){
        var oo = dojox.lang.oo, Filter = oo.Filter, Decorator = oo.Decorator, empty = {},
                defaultFilter = function(name){ return name; },
                defaultDecorator = function(name, newValue, oldValue){ return newValue; },
                defaultMixer = function(target, name, newValue, oldValue){ target[name] = newValue; },
                defaults = {},  // for the internal use in the mixin()
                extraNames = dojo._extraNames, extraLen = extraNames.length,

                applyDecorator = oo.applyDecorator = function(decorator, name, newValue, oldValue){
                        // summary:
                        //              applies a decorator unraveling all embedded decorators
                        // decorator: Function
                        //              top-level decorator to apply
                        // name: String
                        //              name of the property
                        // newValue: Object
                        //              new value of the property
                        // oldValue: Object
                        //              old value of the property
                        // returns: Object
                        //              returns the final value of the property
                        if(newValue instanceof Decorator){
                                var d = newValue.decorator;
                                newValue = applyDecorator(decorator, name, newValue.value, oldValue);
                                return d(name, newValue, oldValue);
                        }
                        return decorator(name, newValue, oldValue);
                };

        /*=====
        dojox.lang.oo.__MixinDefaults = {
                // summary:
                //              a dict of default parameters for dojox.lang.oo._mixin
                // decorator: Function
                //              a decorator function to be used in absence of other decorators
                // filter: Function
                //              a filter function to be used in absence of other filters
                // mixer: Function
                //              a mixer function to be used to mix in new properties
        };
        =====*/

        oo.__mixin = function(target, source, decorator, filter, mixer){
                // summary:
                //              mixes in two objects processing decorators and filters
                // target: Object
                //              target to receive new/updated properties
                // source: Object
                //              source of properties
                // defaults: dojox.lang.oo.__MixinDefaults?
                //              default functions for various aspects of mixing
                // returns: Object
                //              target

                var name, targetName, prop, newValue, oldValue, i;

                // start mixing in properties
                for(name in source){
                        prop = source[name];
                        if(!(name in empty) || empty[name] !== prop){
                                targetName = filter(name, target, source, prop);
                                if(targetName && (!(targetName in target) || !(targetName in empty) || empty[targetName] !== prop)){
                                        // name is accepted
                                        oldValue = target[targetName];
                                        newValue = applyDecorator(decorator, targetName, prop, oldValue);
                                        if(oldValue !== newValue){
                                                mixer(target, targetName, newValue, oldValue);
                                        }
                                }
                        }
                }
                if(extraLen){
                        for(i = 0; i < extraLen; ++i){
                                name = extraNames[i];
                                // repeating the body above
                                prop = source[name];
                                if(!(name in empty) || empty[name] !== prop){
                                        targetName = filter(name, target, source, prop);
                                        if(targetName && (!(targetName in target) || !(targetName in empty) || empty[targetName] !== prop)){
                                                // name is accepted
                                                oldValue = target[targetName];
                                                newValue = applyDecorator(decorator, targetName, prop, oldValue);
                                                if(oldValue !== newValue){
                                                        mixer(target, targetName, newValue, oldValue);
                                                }
                                        }
                                }
                        }
                }

                return target;  // Object
        };

        oo.mixin = function(target, source){
                // summary:
                //              mixes in two or more objects processing decorators and filters
                //              using defaults as a fallback
                // target: Object
                //              target to receive new/updated properties
                // source: Object...
                //              source of properties, more than one source is allowed
                // returns: Object
                //              target

                var decorator, filter, i = 1, l = arguments.length;
                for(; i < l; ++i){
                        source = arguments[i];
                        if(source instanceof Filter){
                                filter = source.filter;
                                source = source.bag;
                        }else{
                                filter = defaultFilter;
                        }
                        if(source instanceof Decorator){
                                decorator = source.decorator;
                                source = source.value;
                        }else{
                                decorator = defaultDecorator;
                        }
                        oo.__mixin(target, source, decorator, filter, defaultMixer);
                }
                return target;  // Object
        };
})();