[tt-rss.git] / lib / dojo / _base / connect.js

/*
        Copyright (c) 2004-2011, The Dojo Foundation All Rights Reserved.
        Available via Academic Free License >= 2.1 OR the modified BSD license.
        see: http://dojotoolkit.org/license for details
*/


if(!dojo._hasResource["dojo._base.connect"]){ //_hasResource checks added by build. Do not use _hasResource directly in your code.
dojo._hasResource["dojo._base.connect"] = true;
dojo.provide("dojo._base.connect");
dojo.require("dojo._base.lang");


// this file courtesy of the TurboAjax Group, licensed under a Dojo CLA

// low-level delegation machinery
dojo._listener = {
        // create a dispatcher function
        getDispatcher: function(){
                // following comments pulled out-of-line to prevent cloning them
                // in the returned function.
                // - indices (i) that are really in the array of listeners (ls) will
                //   not be in Array.prototype. This is the 'sparse array' trick
                //   that keeps us safe from libs that take liberties with built-in
                //   objects
                // - listener is invoked with current scope (this)
                return function(){
                        var ap = Array.prototype, c = arguments.callee, ls = c._listeners, t = c.target,
                        // return value comes from original target function
                                r = t && t.apply(this, arguments),
                        // make local copy of listener array so it is immutable during processing
                                i, lls = [].concat(ls)
                        ;

                        // invoke listeners after target function
                        for(i in lls){
                                if(!(i in ap)){
                                        lls[i].apply(this, arguments);
                                }
                        }
                        // return value comes from original target function
                        return r;
                };
        },
        // add a listener to an object
        add: function(/*Object*/ source, /*String*/ method, /*Function*/ listener){
                // Whenever 'method' is invoked, 'listener' will have the same scope.
                // Trying to supporting a context object for the listener led to
                // complexity.
                // Non trivial to provide 'once' functionality here
                // because listener could be the result of a dojo.hitch call,
                // in which case two references to the same hitch target would not
                // be equivalent.
                source = source || dojo.global;
                // The source method is either null, a dispatcher, or some other function
                var f = source[method];
                // Ensure a dispatcher
                if(!f || !f._listeners){
                        var d = dojo._listener.getDispatcher();
                        // original target function is special
                        d.target = f;
                        // dispatcher holds a list of listeners
                        d._listeners = [];
                        // redirect source to dispatcher
                        f = source[method] = d;
                }
                // The contract is that a handle is returned that can
                // identify this listener for disconnect.
                //
                // The type of the handle is private. Here is it implemented as Integer.
                // DOM event code has this same contract but handle is Function
                // in non-IE browsers.
                //
                // We could have separate lists of before and after listeners.
                return f._listeners.push(listener); /*Handle*/
        },
        // remove a listener from an object
        remove: function(/*Object*/ source, /*String*/ method, /*Handle*/ handle){
                var f = (source || dojo.global)[method];
                // remember that handle is the index+1 (0 is not a valid handle)
                if(f && f._listeners && handle--){
                        delete f._listeners[handle];
                }
        }
};

// Multiple delegation for arbitrary methods.

// This unit knows nothing about DOM, but we include DOM aware documentation
// and dontFix argument here to help the autodocs. Actual DOM aware code is in
// event.js.

dojo.connect = function(/*Object|null*/ obj,
                                                /*String*/ event,
                                                /*Object|null*/ context,
                                                /*String|Function*/ method,
                                                /*Boolean?*/ dontFix){
        // summary:
        //              `dojo.connect` is the core event handling and delegation method in
        //              Dojo. It allows one function to "listen in" on the execution of
        //              any other, triggering the second whenever the first is called. Many
        //              listeners may be attached to a function, and source functions may
        //              be either regular function calls or DOM events.
        //
        // description:
        //              Connects listeners to actions, so that after event fires, a
        //              listener is called with the same arguments passed to the original
        //              function.
        //
        //              Since `dojo.connect` allows the source of events to be either a
        //              "regular" JavaScript function or a DOM event, it provides a uniform
        //              interface for listening to all the types of events that an
        //              application is likely to deal with though a single, unified
        //              interface. DOM programmers may want to think of it as
        //              "addEventListener for everything and anything".
        //
        //              When setting up a connection, the `event` parameter must be a
        //              string that is the name of the method/event to be listened for. If
        //              `obj` is null, `dojo.global` is assumed, meaning that connections
        //              to global methods are supported but also that you may inadvertently
        //              connect to a global by passing an incorrect object name or invalid
        //              reference.
        //
        //              `dojo.connect` generally is forgiving. If you pass the name of a
        //              function or method that does not yet exist on `obj`, connect will
        //              not fail, but will instead set up a stub method. Similarly, null
        //              arguments may simply be omitted such that fewer than 4 arguments
        //              may be required to set up a connection See the examples for details.
        //
        //              The return value is a handle that is needed to
        //              remove this connection with `dojo.disconnect`.
        //
        // obj:
        //              The source object for the event function.
        //              Defaults to `dojo.global` if null.
        //              If obj is a DOM node, the connection is delegated
        //              to the DOM event manager (unless dontFix is true).
        //
        // event:
        //              String name of the event function in obj.
        //              I.e. identifies a property `obj[event]`.
        //
        // context:
        //              The object that method will receive as "this".
        //
        //              If context is null and method is a function, then method
        //              inherits the context of event.
        //
        //              If method is a string then context must be the source
        //              object object for method (context[method]). If context is null,
        //              dojo.global is used.
        //
        // method:
        //              A function reference, or name of a function in context.
        //              The function identified by method fires after event does.
        //              method receives the same arguments as the event.
        //              See context argument comments for information on method's scope.
        //
        // dontFix:
        //              If obj is a DOM node, set dontFix to true to prevent delegation
        //              of this connection to the DOM event manager.
        //
        // example:
        //              When obj.onchange(), do ui.update():
        //      |       dojo.connect(obj, "onchange", ui, "update");
        //      |       dojo.connect(obj, "onchange", ui, ui.update); // same
        //
        // example:
        //              Using return value for disconnect:
        //      |       var link = dojo.connect(obj, "onchange", ui, "update");
        //      |       ...
        //      |       dojo.disconnect(link);
        //
        // example:
        //              When onglobalevent executes, watcher.handler is invoked:
        //      |       dojo.connect(null, "onglobalevent", watcher, "handler");
        //
        // example:
        //              When ob.onCustomEvent executes, customEventHandler is invoked:
        //      |       dojo.connect(ob, "onCustomEvent", null, "customEventHandler");
        //      |       dojo.connect(ob, "onCustomEvent", "customEventHandler"); // same
        //
        // example:
        //              When ob.onCustomEvent executes, customEventHandler is invoked
        //              with the same scope (this):
        //      |       dojo.connect(ob, "onCustomEvent", null, customEventHandler);
        //      |       dojo.connect(ob, "onCustomEvent", customEventHandler); // same
        //
        // example:
        //              When globalEvent executes, globalHandler is invoked
        //              with the same scope (this):
        //      |       dojo.connect(null, "globalEvent", null, globalHandler);
        //      |       dojo.connect("globalEvent", globalHandler); // same

        // normalize arguments
        var a=arguments, args=[], i=0;
        // if a[0] is a String, obj was omitted
        args.push(dojo.isString(a[0]) ? null : a[i++], a[i++]);
        // if the arg-after-next is a String or Function, context was NOT omitted
        var a1 = a[i+1];
        args.push(dojo.isString(a1)||dojo.isFunction(a1) ? a[i++] : null, a[i++]);
        // absorb any additional arguments
        for(var l=a.length; i<l; i++){  args.push(a[i]); }
        // do the actual work
        return dojo._connect.apply(this, args); /*Handle*/
}

// used by non-browser hostenvs. always overriden by event.js
dojo._connect = function(obj, event, context, method){
        var l=dojo._listener, h=l.add(obj, event, dojo.hitch(context, method));
        return [obj, event, h, l]; // Handle
};

dojo.disconnect = function(/*Handle*/ handle){
        // summary:
        //              Remove a link created by dojo.connect.
        // description:
        //              Removes the connection between event and the method referenced by handle.
        // handle:
        //              the return value of the dojo.connect call that created the connection.
        if(handle && handle[0] !== undefined){
                dojo._disconnect.apply(this, handle);
                // let's not keep this reference
                delete handle[0];
        }
};

dojo._disconnect = function(obj, event, handle, listener){
        listener.remove(obj, event, handle);
};

// topic publish/subscribe

dojo._topics = {};

dojo.subscribe = function(/*String*/ topic, /*Object|null*/ context, /*String|Function*/ method){
        //      summary:
        //              Attach a listener to a named topic. The listener function is invoked whenever the
        //              named topic is published (see: dojo.publish).
        //              Returns a handle which is needed to unsubscribe this listener.
        //      context:
        //              Scope in which method will be invoked, or null for default scope.
        //      method:
        //              The name of a function in context, or a function reference. This is the function that
        //              is invoked when topic is published.
        //      example:
        //      |       dojo.subscribe("alerts", null, function(caption, message){ alert(caption + "\n" + message); });
        //      |       dojo.publish("alerts", [ "read this", "hello world" ]);

        // support for 2 argument invocation (omitting context) depends on hitch
        return [topic, dojo._listener.add(dojo._topics, topic, dojo.hitch(context, method))]; /*Handle*/
};

dojo.unsubscribe = function(/*Handle*/ handle){
        //      summary:
        //              Remove a topic listener.
        //      handle:
        //              The handle returned from a call to subscribe.
        //      example:
        //      |       var alerter = dojo.subscribe("alerts", null, function(caption, message){ alert(caption + "\n" + message); };
        //      |       ...
        //      |       dojo.unsubscribe(alerter);
        if(handle){
                dojo._listener.remove(dojo._topics, handle[0], handle[1]);
        }
};

dojo.publish = function(/*String*/ topic, /*Array*/ args){
        //      summary:
        //              Invoke all listener method subscribed to topic.
        //      topic:
        //              The name of the topic to publish.
        //      args:
        //              An array of arguments. The arguments will be applied
        //              to each topic subscriber (as first class parameters, via apply).
        //      example:
        //      |       dojo.subscribe("alerts", null, function(caption, message){ alert(caption + "\n" + message); };
        //      |       dojo.publish("alerts", [ "read this", "hello world" ]);

        // Note that args is an array, which is more efficient vs variable length
        // argument list.  Ideally, var args would be implemented via Array
        // throughout the APIs.
        var f = dojo._topics[topic];
        if(f){
                f.apply(this, args||[]);
        }
};

dojo.connectPublisher = function(       /*String*/ topic,
                                                                        /*Object|null*/ obj,
                                                                        /*String*/ event){
        //      summary:
        //              Ensure that every time obj.event() is called, a message is published
        //              on the topic. Returns a handle which can be passed to
        //              dojo.disconnect() to disable subsequent automatic publication on
        //              the topic.
        //      topic:
        //              The name of the topic to publish.
        //      obj:
        //              The source object for the event function. Defaults to dojo.global
        //              if null.
        //      event:
        //              The name of the event function in obj.
        //              I.e. identifies a property obj[event].
        //      example:
        //      |       dojo.connectPublisher("/ajax/start", dojo, "xhrGet");
        var pf = function(){ dojo.publish(topic, arguments); }
        return event ? dojo.connect(obj, event, pf) : dojo.connect(obj, pf); //Handle
};

}