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(function () {

    /**
    * Config is a utility used within an Object to allow the implementer to
    * maintain a list of local configuration properties and listen for changes 
    * to those properties dynamically using CustomEvent. The initial values are 
    * also maintained so that the configuration can be reset at any given point 
    * to its initial state.
    * @namespace YAHOO.util
    * @class Config
    * @constructor
    * @param {Object} owner The owner Object to which this Config Object belongs
    */
    YAHOO.util.Config = function (owner) {

        if (owner) {
            this.init(owner);
        }

        if (!owner) {  YAHOO.log("No owner specified for Config object", "error", "Config"); }

    };


    var Lang = YAHOO.lang,
        CustomEvent = YAHOO.util.CustomEvent,
        Config = YAHOO.util.Config;


    /**
     * Constant representing the CustomEvent type for the config changed event.
     * @property YAHOO.util.Config.CONFIG_CHANGED_EVENT
     * @private
     * @static
     * @final
     */
    Config.CONFIG_CHANGED_EVENT = "configChanged";
    
    /**
     * Constant representing the boolean type string
     * @property YAHOO.util.Config.BOOLEAN_TYPE
     * @private
     * @static
     * @final
     */
    Config.BOOLEAN_TYPE = "boolean";
    
    Config.prototype = {
     
        /**
        * Object reference to the owner of this Config Object
        * @property owner
        * @type Object
        */
        owner: null,
        
        /**
        * Boolean flag that specifies whether a queue is currently 
        * being executed
        * @property queueInProgress
        * @type Boolean
        */
        queueInProgress: false,
        
        /**
        * Maintains the local collection of configuration property objects and 
        * their specified values
        * @property config
        * @private
        * @type Object
        */ 
        config: null,
        
        /**
        * Maintains the local collection of configuration property objects as 
        * they were initially applied.
        * This object is used when resetting a property.
        * @property initialConfig
        * @private
        * @type Object
        */ 
        initialConfig: null,
        
        /**
        * Maintains the local, normalized CustomEvent queue
        * @property eventQueue
        * @private
        * @type Object
        */ 
        eventQueue: null,
        
        /**
        * Custom Event, notifying subscribers when Config properties are set 
        * (setProperty is called without the silent flag
        * @event configChangedEvent
        */
        configChangedEvent: null,
    
        /**
        * Initializes the configuration Object and all of its local members.
        * @method init
        * @param {Object} owner The owner Object to which this Config 
        * Object belongs
        */
        init: function (owner) {
    
            this.owner = owner;
    
            this.configChangedEvent = 
                this.createEvent(Config.CONFIG_CHANGED_EVENT);
    
            this.configChangedEvent.signature = CustomEvent.LIST;
            this.queueInProgress = false;
            this.config = {};
            this.initialConfig = {};
            this.eventQueue = [];
        
        },
        
        /**
        * Validates that the value passed in is a Boolean.
        * @method checkBoolean
        * @param {Object} val The value to validate
        * @return {Boolean} true, if the value is valid
        */ 
        checkBoolean: function (val) {
            return (typeof val == Config.BOOLEAN_TYPE);
        },
        
        /**
        * Validates that the value passed in is a number.
        * @method checkNumber
        * @param {Object} val The value to validate
        * @return {Boolean} true, if the value is valid
        */
        checkNumber: function (val) {
            return (!isNaN(val));
        },
        
        /**
        * Fires a configuration property event using the specified value. 
        * @method fireEvent
        * @private
        * @param {String} key The configuration property's name
        * @param {value} Object The value of the correct type for the property
        */ 
        fireEvent: function ( key, value ) {
            YAHOO.log("Firing Config event: " + key + "=" + value, "info", "Config");
            var property = this.config[key];
        
            if (property && property.event) {
                property.event.fire(value);
            } 
        },
        
        /**
        * Adds a property to the Config Object's private config hash.
        * @method addProperty
        * @param {String} key The configuration property's name
        * @param {Object} propertyObject The Object containing all of this 
        * property's arguments
        */
        addProperty: function ( key, propertyObject ) {
            key = key.toLowerCase();
            YAHOO.log("Added property: " + key, "info", "Config");
        
            this.config[key] = propertyObject;
        
            propertyObject.event = this.createEvent(key, { scope: this.owner });
            propertyObject.event.signature = CustomEvent.LIST;
            
            
            propertyObject.key = key;
        
            if (propertyObject.handler) {
                propertyObject.event.subscribe(propertyObject.handler, 
                    this.owner);
            }
        
            this.setProperty(key, propertyObject.value, true);
            
            if (! propertyObject.suppressEvent) {
                this.queueProperty(key, propertyObject.value);
            }
            
        },
        
        /**
        * Returns a key-value configuration map of the values currently set in  
        * the Config Object.
        * @method getConfig
        * @return {Object} The current config, represented in a key-value map
        */
        getConfig: function () {
        
            var cfg = {},
                currCfg = this.config,
                prop,
                property;
                
            for (prop in currCfg) {
                if (Lang.hasOwnProperty(currCfg, prop)) {
                    property = currCfg[prop];
                    if (property && property.event) {
                        cfg[prop] = property.value;
                    }
                }
            }

            return cfg;
        },
        
        /**
        * Returns the value of specified property.
        * @method getProperty
        * @param {String} key The name of the property
        * @return {Object}  The value of the specified property
        */
        getProperty: function (key) {
            var property = this.config[key.toLowerCase()];
            if (property && property.event) {
                return property.value;
            } else {
                return undefined;
            }
        },
        
        /**
        * Resets the specified property's value to its initial value.
        * @method resetProperty
        * @param {String} key The name of the property
        * @return {Boolean} True is the property was reset, false if not
        */
        resetProperty: function (key) {
    
            key = key.toLowerCase();
        
            var property = this.config[key];
    
            if (property && property.event) {
    
                if (this.initialConfig[key] && 
                    !Lang.isUndefined(this.initialConfig[key])) {
    
                    this.setProperty(key, this.initialConfig[key]);

                    return true;
    
                }
    
            } else {
    
                return false;
            }
    
        },
        
        /**
        * Sets the value of a property. If the silent property is passed as 
        * true, the property's event will not be fired.
        * @method setProperty
        * @param {String} key The name of the property
        * @param {String} value The value to set the property to
        * @param {Boolean} silent Whether the value should be set silently, 
        * without firing the property event.
        * @return {Boolean} True, if the set was successful, false if it failed.
        */
        setProperty: function (key, value, silent) {
        
            var property;
        
            key = key.toLowerCase();
            YAHOO.log("setProperty: " + key + "=" + value, "info", "Config");
        
            if (this.queueInProgress && ! silent) {
                // Currently running through a queue... 
                this.queueProperty(key,value);
                return true;
    
            } else {
                property = this.config[key];
                if (property && property.event) {
                    if (property.validator && !property.validator(value)) {
                        return false;
                    } else {
                        property.value = value;
                        if (! silent) {
                            this.fireEvent(key, value);
                            this.configChangedEvent.fire([key, value]);
                        }
                        return true;
                    }
                } else {
                    return false;
                }
            }
        },
        
        /**
        * Sets the value of a property and queues its event to execute. If the 
        * event is already scheduled to execute, it is
        * moved from its current position to the end of the queue.
        * @method queueProperty
        * @param {String} key The name of the property
        * @param {String} value The value to set the property to
        * @return {Boolean}  true, if the set was successful, false if 
        * it failed.
        */ 
        queueProperty: function (key, value) {
        
            key = key.toLowerCase();
            YAHOO.log("queueProperty: " + key + "=" + value, "info", "Config");
        
            var property = this.config[key],
                foundDuplicate = false,
                iLen,
                queueItem,
                queueItemKey,
                queueItemValue,
                sLen,
                supercedesCheck,
                qLen,
                queueItemCheck,
                queueItemCheckKey,
                queueItemCheckValue,
                i,
                s,
                q;
                                
            if (property && property.event) {
    
                if (!Lang.isUndefined(value) && property.validator && 
                    !property.validator(value)) { // validator
                    return false;
                } else {
        
                    if (!Lang.isUndefined(value)) {
                        property.value = value;
                    } else {
                        value = property.value;
                    }
        
                    foundDuplicate = false;
                    iLen = this.eventQueue.length;
        
                    for (i = 0; i < iLen; i++) {
                        queueItem = this.eventQueue[i];
        
                        if (queueItem) {
                            queueItemKey = queueItem[0];
                            queueItemValue = queueItem[1];

                            if (queueItemKey == key) {
    
                                /*
                                    found a dupe... push to end of queue, null 
                                    current item, and break
                                */
    
                                this.eventQueue[i] = null;
    
                                this.eventQueue.push(
                                    [key, (!Lang.isUndefined(value) ? 
                                    value : queueItemValue)]);
    
                                foundDuplicate = true;
                                break;
                            }
                        }
                    }
                    
                    // this is a refire, or a new property in the queue
    
                    if (! foundDuplicate && !Lang.isUndefined(value)) { 
                        this.eventQueue.push([key, value]);
                    }
                }
        
                if (property.supercedes) {

                    sLen = property.supercedes.length;

                    for (s = 0; s < sLen; s++) {

                        supercedesCheck = property.supercedes[s];
                        qLen = this.eventQueue.length;

                        for (q = 0; q < qLen; q++) {
                            queueItemCheck = this.eventQueue[q];

                            if (queueItemCheck) {
                                queueItemCheckKey = queueItemCheck[0];
                                queueItemCheckValue = queueItemCheck[1];

                                if (queueItemCheckKey == 
                                    supercedesCheck.toLowerCase() ) {

                                    this.eventQueue.push([queueItemCheckKey, 
                                        queueItemCheckValue]);

                                    this.eventQueue[q] = null;
                                    break;

                                }
                            }
                        }
                    }
                }

                YAHOO.log("Config event queue: " + this.outputEventQueue(), "info", "Config");

                return true;
            } else {
                return false;
            }
        },
        
        /**
        * Fires the event for a property using the property's current value.
        * @method refireEvent
        * @param {String} key The name of the property
        */
        refireEvent: function (key) {
    
            key = key.toLowerCase();
        
            var property = this.config[key];
    
            if (property && property.event && 
    
                !Lang.isUndefined(property.value)) {
    
                if (this.queueInProgress) {
    
                    this.queueProperty(key);
    
                } else {
    
                    this.fireEvent(key, property.value);
    
                }
    
            }
        },
        
        /**
        * Applies a key-value Object literal to the configuration, replacing  
        * any existing values, and queueing the property events.
        * Although the values will be set, fireQueue() must be called for their 
        * associated events to execute.
        * @method applyConfig
        * @param {Object} userConfig The configuration Object literal
        * @param {Boolean} init  When set to true, the initialConfig will 
        * be set to the userConfig passed in, so that calling a reset will 
        * reset the properties to the passed values.
        */
        applyConfig: function (userConfig, init) {
        
            var sKey,
                oConfig;

            if (init) {
                oConfig = {};
                for (sKey in userConfig) {
                    if (Lang.hasOwnProperty(userConfig, sKey)) {
                        oConfig[sKey.toLowerCase()] = userConfig[sKey];
                    }
                }
                this.initialConfig = oConfig;
            }

            for (sKey in userConfig) {
                if (Lang.hasOwnProperty(userConfig, sKey)) {
                    this.queueProperty(sKey, userConfig[sKey]);
                }
            }
        },
        
        /**
        * Refires the events for all configuration properties using their 
        * current values.
        * @method refresh
        */
        refresh: function () {

            var prop;

            for (prop in this.config) {
                if (Lang.hasOwnProperty(this.config, prop)) {
                    this.refireEvent(prop);
                }
            }
        },
        
        /**
        * Fires the normalized list of queued property change events
        * @method fireQueue
        */
        fireQueue: function () {
        
            var i, 
                queueItem,
                key,
                value,
                property;
        
            this.queueInProgress = true;
            for (i = 0;i < this.eventQueue.length; i++) {
                queueItem = this.eventQueue[i];
                if (queueItem) {
        
                    key = queueItem[0];
                    value = queueItem[1];
                    property = this.config[key];

                    property.value = value;

                    // Clear out queue entry, to avoid it being 
                    // re-added to the queue by any queueProperty/supercedes
                    // calls which are invoked during fireEvent
                    this.eventQueue[i] = null;

                    this.fireEvent(key,value);
                }
            }
            
            this.queueInProgress = false;
            this.eventQueue = [];
        },
        
        /**
        * Subscribes an external handler to the change event for any 
        * given property. 
        * @method subscribeToConfigEvent
        * @param {String} key The property name
        * @param {Function} handler The handler function to use subscribe to 
        * the property's event
        * @param {Object} obj The Object to use for scoping the event handler 
        * (see CustomEvent documentation)
        * @param {Boolean} overrideContext Optional. If true, will override
        * "this" within the handler to map to the scope Object passed into the
        * method.
        * @return {Boolean} True, if the subscription was successful, 
        * otherwise false.
        */ 
        subscribeToConfigEvent: function (key, handler, obj, overrideContext) {
    
            var property = this.config[key.toLowerCase()];
    
            if (property && property.event) {
                if (!Config.alreadySubscribed(property.event, handler, obj)) {
                    property.event.subscribe(handler, obj, overrideContext);
                }
                return true;
            } else {
                return false;
            }
    
        },
        
        /**
        * Unsubscribes an external handler from the change event for any 
        * given property. 
        * @method unsubscribeFromConfigEvent
        * @param {String} key The property name
        * @param {Function} handler The handler function to use subscribe to 
        * the property's event
        * @param {Object} obj The Object to use for scoping the event 
        * handler (see CustomEvent documentation)
        * @return {Boolean} True, if the unsubscription was successful, 
        * otherwise false.
        */
        unsubscribeFromConfigEvent: function (key, handler, obj) {
            var property = this.config[key.toLowerCase()];
            if (property && property.event) {
                return property.event.unsubscribe(handler, obj);
            } else {
                return false;
            }
        },
        
        /**
        * Returns a string representation of the Config object
        * @method toString
        * @return {String} The Config object in string format.
        */
        toString: function () {
            var output = "Config";
            if (this.owner) {
                output += " [" + this.owner.toString() + "]";
            }
            return output;
        },
        
        /**
        * Returns a string representation of the Config object's current 
        * CustomEvent queue
        * @method outputEventQueue
        * @return {String} The string list of CustomEvents currently queued 
        * for execution
        */
        outputEventQueue: function () {

            var output = "",
                queueItem,
                q,
                nQueue = this.eventQueue.length;
              
            for (q = 0; q < nQueue; q++) {
                queueItem = this.eventQueue[q];
                if (queueItem) {
                    output += queueItem[0] + "=" + queueItem[1] + ", ";
                }
            }
            return output;
        },

        /**
        * Sets all properties to null, unsubscribes all listeners from each 
        * property's change event and all listeners from the configChangedEvent.
        * @method destroy
        */
        destroy: function () {

            var oConfig = this.config,
                sProperty,
                oProperty;


            for (sProperty in oConfig) {
            
                if (Lang.hasOwnProperty(oConfig, sProperty)) {

                    oProperty = oConfig[sProperty];

                    oProperty.event.unsubscribeAll();
                    oProperty.event = null;

                }
            
            }
            
            this.configChangedEvent.unsubscribeAll();
            
            this.configChangedEvent = null;
            this.owner = null;
            this.config = null;
            this.initialConfig = null;
            this.eventQueue = null;
        
        }

    };
    
    
    
    /**
    * Checks to determine if a particular function/Object pair are already 
    * subscribed to the specified CustomEvent
    * @method YAHOO.util.Config.alreadySubscribed
    * @static
    * @param {YAHOO.util.CustomEvent} evt The CustomEvent for which to check 
    * the subscriptions
    * @param {Function} fn The function to look for in the subscribers list
    * @param {Object} obj The execution scope Object for the subscription
    * @return {Boolean} true, if the function/Object pair is already subscribed 
    * to the CustomEvent passed in
    */
    Config.alreadySubscribed = function (evt, fn, obj) {
    
        var nSubscribers = evt.subscribers.length,
            subsc,
            i;

        if (nSubscribers > 0) {
            i = nSubscribers - 1;
            do {
                subsc = evt.subscribers[i];
                if (subsc && subsc.obj == obj && subsc.fn == fn) {
                    return true;
                }
            }
            while (i--);
        }

        return false;

    };

    YAHOO.lang.augmentProto(Config, YAHOO.util.EventProvider);

}());

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