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/*
* Module : messenger.js
* Copyright : (c) 2011-2012, Galois, Inc.
*
* Maintainer :
* Stability : Provisional
* Portability: Portable
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
var fiveui = fiveui || {};
(function() {
/**
* @constructor
* @param {{on: function(!string, function(*)), emit: function(!string, *)}}
* channel The object containing on and emit.
*/
fiveui.Messenger = function(channel) {
this.callbacks = {};
this.handlers = {};
this.channel = channel;
this.channel.on(fiveui.Messenger.type, _.bind(this._handler, this));
};
fiveui.Messenger.type = "fiveui_messaging_type";
_.extend(fiveui.Messenger.prototype, {
/**
* @param {!string} type The message type to send.
* @param {?Object} data The payload (which can be null).
* @param {?function(?Object)} callback An optional callback to be
* invoked in response.
*/
send: function(type, data, callback){
var id = null;
if (callback) {
id = this._newId();
this.callbacks[id] = callback;
}
var payload = new fiveui.Messenger.Payload(false, type, data, id);
this.channel.emit(fiveui.Messenger.type, payload);
},
/**
* Register a handler for the specified message type.
*
* @param {!string} type The message type.
* @param {!function(*)} callback The function to call when a message
* of the specified type is received.
*/
register: function(type, callback) {
if(null == this.handlers[type]) {
this.handlers[type] = [];
}
this.handlers[type].push(callback);
},
_handler: function(payload) {
if (payload.isCallback && payload.id != null) {
// this is a callback invocation, lookup the callback and invoke it:
this.callbacks[payload.id](payload.data);
// remove the callback:
this._remove(payload.id);
} else {
// look up a handler and invoke it, passing in the response fn:
var hs = this.handlers[payload.type];
if (hs && hs.length > 0) {
// this is a new incomming message.
// create a response function:
var respond = function(respData) {
this.channel.emit(fiveui.Messenger.type,
new fiveui.Messenger.Payload(true, payload.type, respData, payload.id));
};
// iterate over the handlers, invoking them with the response callback.
_.each(hs, function(h) {
h(payload.data, _.bind(respond, this));
}, this);
}
}
},
/**
* Remove a callback from the map of callbacks.
*
* @param {!number} callbackId The id of the callback to remove.
*/
_remove: function(callbackId) {
delete this.callbacks[callbackId];
},
/**
* @return {!number} The next unique id for a callback.
*/
_newId: function() {
var list = Object.keys(this.callbacks);
return fiveui.utils.getNewId(list);
}
});
/**
* @constructor
* @param {!boolean} isCallback True if this is in response to a
* message, false if this is requesting a callback.
* @param {!string} type
* @param {?Object} data
* @param {!number} id Callback id to invoke, or in which this is a response.
*/
fiveui.Messenger.Payload = function(isCallback, type, data, id) {
this.isCallback = isCallback;
this.type = type;
this.id = id;
this.__defineGetter__('data', function() {
return JSON.parse(this.rawData);
});
this.__defineSetter__('data', function(obj){
this.rawData = JSON.stringify(obj);
});
this.data = data;
};
})();
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