event/js/event-custom.js

	event-custom.js revision ee4d8528357b157539bc45a7324cb16d46a88272

/**
 * Custom event engine, DOM event listener abstraction layer, synthetic DOM
 * events.
 * @module event
 */

/**
 * Return value from all subscribe operations
 * @class Event.Handle
 * @constructor
 * @param evt {Event.Custom} the custom event
 * @param sub {Event.Subscriber} the subscriber
 */

var onsubscribeType = "_event:onsub",
    AFTER = 'after',
    CONFIGS = [
        'broadcast',
        'bubbles',
        'context',
        'configured',
        'currentTarget',
        'defaultFn',
        'details',
        'emitFacade',
        'fireOnce',
        'host',
        'preventable',
        'preventedFn',
        'queuable',
        'silent',
        'stoppedFn',
        'target',
        'type'
    ],

    YUI3_SIGNATURE = 9;

Y.EventHandle = function(evt, sub) {

    /**
     * The custom event
     * @type Event.Custom
     */
    this.evt = evt;

    /**
     * The subscriber object
     * @type Event.Subscriber
     */
    this.sub = sub;
};

Y.EventHandle.prototype = {
    /**
     * Detaches this subscriber
     * @method detach
     */
    detach: function() {

        if (this.evt) {
            // Y.log('EventHandle.detach: ' + this.sub, 'info', 'Event');
            this.evt._delete(this.sub);
        }
    }
};

/**
 * The Event.Custom class lets you define events for your application
 * that can be subscribed to by one or more independent component.
 *
 * @param {String}  type The type of event, which is passed to the callback
 *                  when the event fires
 * @param o configuration object
 * @class Event.Custom
 * @constructor
 */
Y.CustomEvent = function(type, o) {

    // if (arguments.length > 2) {
// this.log('CustomEvent context and silent are now in the config', 'warn', 'Event');
    // }

    o = o || {};

    this.id = Y.stamp(this);

    /**
     * The type of event, returned to subscribers when the event fires
     * @property type
     * @type string
     */
    this.type = type;

    /**
     * The context the the event will fire from by default.  Defaults to the YUI
     * instance.
     * @property context
     * @type object
     */
    this.context = Y;

    this.logSystem = (type == "yui:log");

    /**
     * If 0, this event does not broadcast.  If 1, the YUI instance is notified
     * every time this event fires.  If 2, the YUI instance and the YUI global
     * (if event is enabled on the global) are notified every time this event
     * fires.
     * @property broadcast
     * @type int
     */
    this.broadcast = 0;

    /**
     * By default all custom events are logged in the debug build, set silent
     * to true to disable debug outpu for this event.
     * @property silent
     * @type boolean
     */
    this.silent = this.logSystem;

    // this.queuable = !(this.logSystem);
    this.queuable = false;

    /**
     * The subscribers to this event
     * @property subscribers
     * @type Event.Subscriber{}
     */
    this.subscribers = {};

    /*
     * The publisher has configured this event
     * @property configured
     * @type boolean
     * @default true
     */
    // this.configured = true;

    /**
     * 'After' subscribers
     * @property afters
     * @type Event.Subscriber{}
     */
    this.afters = {};

    /**
     * This event has fired if true
     *
     * @property fired
     * @type boolean
     * @default false;
     */
    this.fired = false;

    /**
     * This event should only fire one time if true, and if
     * it has fired, any new subscribers should be notified
     * immediately.
     *
     * @property fireOnce
     * @type boolean
     * @default false;
     */
    this.fireOnce = false;

    /**
     * Flag for stopPropagation that is modified during fire()
     * 1 means to stop propagation to bubble targets.  2 means
     * to also stop additional subscribers on this target.
     * @property stopped
     * @type int
     */
    this.stopped = 0;

    /**
     * Flag for preventDefault that is modified during fire().
     * if it is not 0, the default behavior for this event
     * @property prevented
     * @type int
     */
    this.prevented = 0;

    /**
     * Specifies the host for this custom event.  This is used
     * to enable event bubbling
     * @property host
     * @type Event.Target
     */
    this.host = null;

    /**
     * The default function to execute after event listeners
     * have fire, but only if the default action was not
     * prevented.
     * @property defaultFn
     * @type Function
     */
    this.defaultFn = null;

    /**
     * The function to execute if a subscriber calls
     * stopPropagation or stopImmediatePropagation
     * @property stoppedFn
     * @type Function
     */
    this.stoppedFn = null;

    /**
     * The function to execute if a subscriber calls
     * preventDefault
     * @property preventedFn
     * @type Function
     */
    this.preventedFn = null;

    /**
     * Specifies whether or not this event's default function
     * can be cancelled by a subscriber by executing preventDefault()
     * on the event facade
     * @property preventable
     * @type boolean
     * @default true
     */
    this.preventable = true;

    /**
     * Specifies whether or not a subscriber can stop the event propagation
     * via stopPropagation(), stopImmediatePropagation(), or halt()
     * @property bubbles
     * @type boolean
     * @default true
     */
    this.bubbles = true;

    /**
     * Supports multiple options for listener signatures in order to
     * port YUI 2 apps.
     * @property signature
     * @type int
     * @default 9
     */
    this.signature = YUI3_SIGNATURE;

    /**
     * If set to true, the custom event will deliver an Event.Facade object
     * that is similar to a DOM event object.
     * @property emitFacade
     * @type boolean
     * @default false
     */
    this.emitFacade = false;

    this.applyConfig(o, true);

    this.log("Creating " + this.type);

    // Only add subscribe events for events that are not generated by
    // Event.Custom
    if (type !== onsubscribeType) {

        /**
         * Custom events provide a custom event that fires whenever there is
         * a new subscriber to the event.  This provides an opportunity to
         * handle the case where there is a non-repeating event that has
         * already fired has a new subscriber.
         *
         * @event subscribeEvent
         * @type Event.Custom
         * @param {Function} fn The function to execute
         * @param {Object}   obj An object to be passed along when the event
         *                       fires
         * @param {boolean|Object}  override If true, the obj passed in becomes
         *                                   the execution context of the listener.
         *                                   if an object, that object becomes the
         *                                   the execution context.
         */
        this.subscribeEvent = new Y.CustomEvent(onsubscribeType, {
                context: this,
                silent: true
            });
    }

};

Y.CustomEvent.prototype = {

    _YUI_EVENT: true,

    /**
     * Apply configuration properties.  Only applies the CONFIG whitelist
     * @method applyConfig
     * @param o hash of properties to apply
     * @param force {boolean} if true, properties that exist on the event
     * will be overwritten.
     */
    applyConfig: function(o, force) {
        if (o) {
            Y.mix(this, o, force, CONFIGS);
        }
    },

    _subscribe: function(fn, context, args, when) {

        if (!fn) {
            Y.error("Invalid callback for CE: " + this.type);
        }

        var se = this.subscribeEvent;
        if (se) {
            se.fire.apply(se, args);
        }

        var s = new Y.Subscriber(fn, context, args, when);


        if (this.fireOnce && this.fired) {

            // this._notify(s);
            // setTimeout(Y.rbind(this._notify, this, s), 0);
            Y.later(0, this, this._notify, s);
        }

        if (when == AFTER) {
            this.afters[s.id] = s;
        } else {
            this.subscribers[s.id] = s;
        }

        return new Y.EventHandle(this, s);

    },

    /**
     * Listen for this event
     * @method subscribe
     * @param {Function} fn        The function to execute
     * @param {Object}   context   Specifies the value of the
     * 'this' keyword in the listener.
     * @param args* 0..n params to provide to the listener
     * @return {Event.Handle} unsubscribe handle
     */
    subscribe: function(fn, context) {
        return this._subscribe(fn, context, arguments, true);
    },

    /**
     * Listen for this event after the normal subscribers have been notified and
     * the default behavior has been applied.  If a normal subscriber prevents the
     * default behavior, it also prevents after listeners from firing.
     * @method after
     * @param {Function} fn        The function to execute
     * @param {Object}   context   Specifies the value of the
     * 'this' keyword in the listener.
     * @param args* 0..n params to provide to the listener
     * @return {Event.Handle} unsubscribe handle
     */
    after: function(fn, context) {
        return this._subscribe(fn, context, arguments, AFTER);
    },

    /**
     * Unsubscribes subscribers.
     * @method unsubscribe
     * @param {Function} fn  The subscribed function to remove, if not supplied
     *                       all will be removed
     * @param {Object}   context The context object passed to subscribe.
     * @return {boolean} True if the subscriber was found and detached.
     */
    unsubscribe: function(fn, context) {

        // if arg[0] typeof unsubscribe handle
        if (fn && fn.detach) {
            return fn.detach();
        }

        if (!fn) {
            return this.unsubscribeAll();
        }

        var found = false, subs = this.subscribers;
        for (var i in subs) {
            if (subs.hasOwnProperty(i)) {
                var s = subs[i];
                if (s && s.contains(fn, context)) {
                    this._delete(s);
                    found = true;
                }
            }
        }

        return found;
    },

    _getFacade: function(args) {

        var ef = this._facade;

        if (!ef) {
            ef = new Y.Event.Facade(this, this.currentTarget);
        }

        // if the first argument is an object literal, apply the
        // properties to the event facade
        var o = args && args[0];
        if (Y.Lang.isObject(o, true) && !o._yuifacade) {
            Y.mix(ef, o, true);
        }

        // update the details field with the arguments
        ef.details = this.details;
        ef.target = this.target;
        ef.currentTarget = this.currentTarget;
        ef.stopped = 0;
        ef.prevented = 0;

        this._facade = ef;

        return this._facade;
    },

    /**
     * Notify a single subscriber
     * @method _notify
     * @param s {Event.Subscriber} the subscriber
     * @param args {Array} the arguments array to apply to the listener
     * @private
     */
    _notify: function(s, args, ef) {

        this.log(this.type + "->" + ": " +  s);

        var ret, c, ct;

        // emit an Event.Facade if this is that sort of event
        // if (this.emitFacade && (!args[0] || !args[0]._yuifacade)) {
        if (this.emitFacade) {

            // @TODO object literal support to fire makes it possible for
            // config info to be passed if we wish.

            if (!ef) {
                ef = this._getFacade(args);
                args[0] = ef;
            }

        }

        // The default context should be the object/element that
        // the listener was bound to.
        ct = (args && Y.Lang.isObject(args[0]) && args[0].currentTarget);
        ret = s.notify(ct || this.context, args, this);

        if (false === ret || this.stopped > 1) {
            this.log(this.type + " cancelled by subscriber");
            return false;
        }

        return true;
    },

    /**
     * Logger abstraction to centralize the application of the silent flag
     * @method log
     * @param msg {string} message to log
     * @param cat {string} log category
     */
    log: function(msg, cat) {
        var es = Y.Env._eventstack, s =  es && es.logging;
        // if (!s && !this.silent) {
        if (!this.silent) {
            Y.log(this.id + ': ' + msg, cat || "info", "event");
        }
    },

    /**
     * Notifies the subscribers.  The callback functions will be executed
     * from the context specified when the event was created, and with the
     * following parameters:
     *   <ul>
     *   <li>The type of event</li>
     *   <li>All of the arguments fire() was executed with as an array</li>
     *   <li>The custom object (if any) that was passed into the subscribe()
     *       method</li>
     *   </ul>
     * @method fire
     * @param {Object*} arguments an arbitrary set of parameters to pass to
     *                            the handler.
     * @return {boolean} false if one of the subscribers returned false,
     *                   true otherwise
     */
    fire: function() {

        var es = Y.Env._eventstack;

        if (es) {

            // var b = this.bubbles, h = this.host;
            // if (b && h) {
            //     b = (h._yuievt.targets.length);
            // }

            // es.silent = (es.silent || this.silent);

            // queue this event if the current item in the queue bubbles
            // if (b && this.queuable && this.type != es.next.type) {
            if (this.queuable && this.type != es.next.type) {

                this.log('queue ' + this.type);

                es.queue.push([this, arguments]);
                return true;
            }

        } else {

            Y.Env._eventstack = {
               // id of the first event in the stack
               id: this.id,
               next: this,
               silent: this.silent,
               logging: (this.type === 'yui:log'),
               stopped: 0,
               prevented: 0,
               queue: []
            };

            es = Y.Env._eventstack;
        }

        var ret = true;

        if (this.fireOnce && this.fired) {

            this.log('fireOnce event: ' + this.type + ' already fired');

        } else {

            // var subs = this.subscribers.slice(), len=subs.length,
            var subs = Y.merge(this.subscribers), s,
                       args=Y.Array(arguments, 0, true), i;

            this.stopped = 0;
            this.prevented = 0;
            this.target = this.target || this.host;

            this.currentTarget = this.host || this.currentTarget;

            this.fired = true;
            this.details = args.slice(); // original arguments in the details

            // this.log("Firing " + this  + ", " + "args: " + args);
            this.log("Firing " + this.type);

            var hasSub = false;
            es.lastLogState = es.logging;


            var ef = null;
            if (this.emitFacade) {

                // this.fire({
                //   foo: 1
                //   bar: 2
                // }
                // this.fire({
                //   bar: 2
                // } // foo is still 1 unless we create a new facade
                this._facade = null;

                ef = this._getFacade(args);
                args[0] = ef;
            }

            for (i in subs) {
                if (subs.hasOwnProperty(i)) {

                    if (!hasSub) {
                        es.logging = (es.logging || (this.type === 'yui:log'));
                        hasSub = true;
                    }

                    // stopImmediatePropagation
                    if (this.stopped == 2) {
                        break;
                    }

                    s = subs[i];
                    if (s && s.fn) {
                        ret = this._notify(s, args, ef);
                        if (false === ret) {
                            this.stopped = 2;
                        }
                    }
                }
            }

            es.logging = (es.lastLogState);

            // bubble if this is hosted in an event target and propagation has not been stopped
            // @TODO check if we need to worry about defaultFn order
            if (this.bubbles && this.host && !this.stopped) {
                es.stopped = 0;
                es.prevented = 0;
                ret = this.host.bubble(this);

                this.stopped = Math.max(this.stopped, es.stopped);
                this.prevented = Math.max(this.prevented, es.prevented);
            }

            // execute the default behavior if not prevented
            // @TODO need context
            if (this.defaultFn && !this.prevented) {
                this.defaultFn.apply(this.host || this, args);
            }

            // process after listeners.  If the default behavior was
            // prevented, the after events don't fire.
            if (!this.prevented && this.stopped < 2) {
                subs = Y.merge(this.afters);
                for (i in subs) {
                    if (subs.hasOwnProperty(i)) {

                        if (!hasSub) {
                            es.logging = (es.logging || (this.type === 'yui:log'));
                            hasSub = true;
                        }

                        // stopImmediatePropagation
                        if (this.stopped == 2) {
                            break;
                        }

                        s = subs[i];
                        if (s && s.fn) {
                            ret = this._notify(s, args, ef);
                            if (false === ret) {
                                this.stopped = 2;
                            }
                        }
                    }
                }
            }
        }

        if (es.id === this.id) {
// console.log('clearing stack: ' + es.id + ', ' + this);

// reset propragation properties while processing the rest of the queue

// process queued events
            var queue = es.queue;

            while (queue.length) {
                // q[0] = the event, q[1] = arguments to fire
                var q = queue.pop(), ce = q[0];

// Y.log('firing queued event ' + ce.type + ', from ' + this);
                es.stopped = 0;
                es.prevented = 0;

// set up stack to allow the next item to be processed
                es.next = ce;

                ret = ce.fire.apply(ce, q[1]);
            }

            Y.Env._eventstack = null;
        }

        return (ret !== false);
    },

    /**
     * Removes all listeners
     * @method unsubscribeAll
     * @return {int} The number of listeners unsubscribed
     */
    unsubscribeAll: function() {
        var subs = this.subscribers, i, l=0;
        for (i in subs) {
            if (subs.hasOwnProperty(i)) {
                this._delete(subs[i]);
                l++;
            }
        }

        this.subscribers={};

        return l;
    },

    /**
     * @method _delete
     * @param subscriber object
     * @private
     */
    _delete: function(s) {

        if (s) {
            delete s.fn;
            delete s.context;
            delete this.subscribers[s.id];
            delete this.afters[s.id];
        }

    },

    /**
     * @method toString
     */
    toString: function() {
         // return "{ CE '" + this.type + "' " + "id: " + this.id +
              // ", host: " + (this.host && Y.stamp(this.host) + " }");
         return this.type;
    },

    /**
     * Stop propagation to bubble targets
     * @method stopPropagation
     */
    stopPropagation: function() {
        this.stopped = 1;
        Y.Env._eventstack.stopped = 1;
        if (this.stoppedFn) {
            this.stoppedFn.call(this.host || this, this);
        }
    },

    /**
     * Stops propagation to bubble targets, and prevents any remaining
     * subscribers on the current target from executing.
     * @method stopImmediatePropagation
     */
    stopImmediatePropagation: function() {
        this.stopped = 2;
        Y.Env._eventstack.stopped = 2;
        if (this.stoppedFn) {
            this.stoppedFn.call(this.host || this, this);
        }
    },

    /**
     * Prevents the execution of this event's defaultFn
     * @method preventDefault
     */
    preventDefault: function() {
        if (this.preventable) {
            this.prevented = 1;
            Y.Env._eventstack.prevented = 1;
        }
        if (this.preventedFn) {
            this.preventedFn.call(this.host || this, this);
        }
    }

};

/////////////////////////////////////////////////////////////////////

/**
 * Stores the subscriber information to be used when the event fires.
 * @param {Function} fn       The wrapped function to execute
 * @param {Object}   context  The value of the keyword 'this' in the listener
 * @param {Array} args*       0..n additional arguments to supply the listener
 *
 * @class Event.Subscriber
 * @constructor
 */
Y.Subscriber = function(fn, context, args) {

    /**
     * The callback that will be execute when the event fires
     * This is wrapped by Y.rbind if obj was supplied.
     * @property fn
     * @type Function
     */
    this.fn = fn;

    /**
     * Optional 'this' keyword for the listener
     * @property context
     * @type Object
     */
    this.context = context;

    /**
     * Unique subscriber id
     * @property id
     * @type String
     */
    this.id = Y.stamp(this);

    /**
     * Optional additional arguments supplied to subscribe().  If present,
     * these will be appended to the arguments supplied to fire()
     * @property args
     * @type Array
     */
    // this.args = args;

    /**
     * }
     * fn bound to obj with additional arguments applied via Y.rbind
     * @property wrappedFn
     * @type Function
     */
    this.wrappedFn = fn;

    if (context) {
        /*
        var a = (args) ? Y.Array(args) : [];
        a.unshift(fn, context);
        // a.unshift(fn);
        m = Y.rbind.apply(Y, a);
        */
        this.wrappedFn = Y.rbind.apply(Y, args);
    }


};

Y.Subscriber.prototype = {

    /**
     * Executes the subscriber.
     * @method notify
     * @param defaultContext The execution context if not overridden
     * by the subscriber
     * @param args {Array} Arguments array for the subscriber
     * @param ce {Event.Custom} The custom event that sent the notification
     */
    notify: function(defaultContext, args, ce) {
        var c = this.context || defaultContext, ret = true,

            f = function() {
                switch (ce.signature) {
                    case 0:
                        ret = this.fn.call(c, ce.type, args, this.context);
                        break;
                    case 1:
                        ret = this.fn.call(c, args[0] || null, this.context);
                        break;
                    default:
                        ret = this.wrappedFn.apply(c, args || []);
                }
            };

        // Ease debugging by only catching errors if we will not re-throw
        // them.
        if (Y.config.throwFail) {
            f.call(this);
        } else {
            try {
                f.call(this);
            } catch(e) {
                Y.error(this + ' failed: ' + e.message, e);
            }
        }

        return ret;
    },

    /**
     * Returns true if the fn and obj match this objects properties.
     * Used by the unsubscribe method to match the right subscriber.
     *
     * @method contains
     * @param {Function} fn the function to execute
     * @param {Object} context optional 'this' keyword for the listener
     * @return {boolean} true if the supplied arguments match this
     *                   subscriber's signature.
     */
    contains: function(fn, context) {
        if (context) {
            return ((this.fn == fn) && this.context == context);
        } else {
            return (this.fn == fn);
        }
    },

    /**
     * @method toString
     */
    toString: function() {
        return "Subscriber " + this.id;
    }
};