/**
* EventProvider is designed to be used with YAHOO.augment to wrap
* CustomEvents in an interface that allows events to be subscribed to
* and fired by name. This makes it possible for implementing code to
* subscribe to an event that either has not been created yet, or will
* not be created at all.
*
* @Class EventProvider
*/
YAHOO.util.EventProvider = function() { };
YAHOO.util.EventProvider.prototype = {
/**
* Private storage of custom events
* @property __yui_events
* @type Object[]
* @private
*/
__yui_events: null,
/**
* Private storage of custom event subscribers
* @property __yui_subscribers
* @type Object[]
* @private
*/
__yui_subscribers: null,
/**
* Subscribe to a CustomEvent by event type
*
* @method subscribe
* @param p_type {string} the type, or name of the event
* @param p_fn {function} the function to exectute when the event fires
* @param p_obj {Object} An object to be passed along when the event
* fires
* @param p_override {boolean} If true, the obj passed in becomes the
* execution scope of the listener
*/
subscribe: function(p_type, p_fn, p_obj, p_override) {
this.__yui_events = this.__yui_events || {};
var ce = this.__yui_events[p_type];
if (ce) {
ce.subscribe(p_fn, p_obj, p_override);
} else {
this.__yui_subscribers = this.__yui_subscribers || {};
var subs = this.__yui_subscribers;
if (!subs[p_type]) {
subs[p_type] = [];
}
subs[p_type].push(
{ fn: p_fn, obj: p_obj, override: p_override } );
}
},
/**
* Unsubscribes one or more listeners the from the specified event
* @method unsubscribe
* @param p_type {string} The type, or name of the event. If the type
* is not specified, it will attempt to remove
* the listener from all hosted events.
* @param p_fn {Function} The subscribed function to unsubscribe, if not
* supplied, all subscribers will be removed.
* @param p_obj {Object} The custom object passed to subscribe. This is
* optional, but if supplied will be used to
* disambiguate multiple listeners that are the same
* (e.g., you subscribe many object using a function
* that lives on the prototype)
* @return {boolean} true if the subscriber was found and detached.
*/
unsubscribe: function(p_type, p_fn, p_obj) {
this.__yui_events = this.__yui_events || {};
var evts = this.__yui_events;
if (p_type) {
var ce = evts[p_type];
if (ce) {
return ce.unsubscribe(p_fn, p_obj);
}
} else {
var ret = true;
for (var i in evts) {
if (YAHOO.lang.hasOwnProperty(evts, i)) {
ret = ret && evts[i].unsubscribe(p_fn, p_obj);
}
}
return ret;
}
return false;
},
/**
* Removes all listeners from the specified event. If the event type
* is not specified, all listeners from all hosted custom events will
* be removed.
* @method unsubscribeAll
* @param p_type {string} The type, or name of the event
*/
unsubscribeAll: function(p_type) {
return this.unsubscribe(p_type);
},
/**
* Creates a new custom event of the specified type. If a custom event
* by that name already exists, it will not be re-created. In either
* case the custom event is returned.
*
* @method createEvent
*
* @param p_type {string} the type, or name of the event
* @param p_config {object} optional config params. Valid properties are:
*
* <ul>
* <li>
* scope: defines the default execution scope. If not defined
* the default scope will be this instance.
* </li>
* <li>
* silent: if true, the custom event will not generate log messages.
* This is false by default.
* </li>
* <li>
* onSubscribeCallback: specifies a callback to execute when the
* event has a new subscriber. This will fire immediately for
* each queued subscriber if any exist prior to the creation of
* the event.
* </li>
* </ul>
*
* @return {CustomEvent} the custom event
*
*/
createEvent: function(p_type, p_config) {
this.__yui_events = this.__yui_events || {};
var opts = p_config || {};
var events = this.__yui_events;
if (events[p_type]) {
YAHOO.log("EventProvider createEvent skipped: '"+p_type+"' already exists");
} else {
var scope = opts.scope || this;
var silent = (opts.silent);
var ce = new YAHOO.util.CustomEvent(p_type, scope, silent,
YAHOO.util.CustomEvent.FLAT);
events[p_type] = ce;
if (opts.onSubscribeCallback) {
ce.subscribeEvent.subscribe(opts.onSubscribeCallback);
}
this.__yui_subscribers = this.__yui_subscribers || {};
var qs = this.__yui_subscribers[p_type];
if (qs) {
for (var i=0; i<qs.length; ++i) {
ce.subscribe(qs[i].fn, qs[i].obj, qs[i].override);
}
}
}
return events[p_type];
},
/**
* Fire a custom event by name. The callback functions will be executed
* from the scope specified when the event was created, and with the
* following parameters:
* <ul>
* <li>The first argument fire() was executed with</li>
* <li>The custom object (if any) that was passed into the subscribe()
* method</li>
* </ul>
* @method fireEvent
* @param p_type {string} the type, or name of the event
* @param arguments {Object*} an arbitrary set of parameters to pass to
* the handler.
* @return {boolean} the return value from CustomEvent.fire
*
*/
fireEvent: function(p_type, arg1, arg2, etc) {
this.__yui_events = this.__yui_events || {};
var ce = this.__yui_events[p_type];
if (!ce) {
YAHOO.log(p_type + "event fired before it was created.");
return null;
}
var args = [];
for (var i=1; i<arguments.length; ++i) {
args.push(arguments[i]);
}
return ce.fire.apply(ce, args);
},
/**
* Returns true if the custom event of the provided type has been created
* with createEvent.
* @method hasEvent
* @param type {string} the type, or name of the event
*/
hasEvent: function(type) {
if (this.__yui_events) {
if (this.__yui_events[type]) {
return true;
}
}
return false;
}
};