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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
/**
* @fileoverview Implements the global implicit data context for containers.
*/
var opensocial = opensocial || {};
/**
* @type {Object} The namespace declaration for this file.
*/
opensocial.data = opensocial.data || {};
/**
* @type {Object} Global DataContext to contain requested data sets.
*/
opensocial.data.DataContext = function() {
var listeners = [];
var dataSets = {};
/**
* Puts a data set into the global DataContext object. Fires listeners
* if they are satisfied by the associated key being inserted.
*
* @param {string} key The key to associate with this object.
* @param {ResponseItem|Object} obj The data object.
* @param {boolean=} opt_fireListeners Default true.
*/
var putDataSet = function(key, obj, opt_fireListeners) {
if (typeof obj === 'undefined' || obj === null) {
return;
}
dataSets[key] = obj;
if (!(opt_fireListeners === false)) {
fireCallbacks(key);
}
};
/**
* Registers a callback listener for a given set of keys.
* @param {string|Array.} keys Key or set of keys to listen on.
* @param {function(Array.)} callback Function to call when a
* listener is fired.
* @param {booelan} oneTimeListener Remove this listener after first callback?
* @param {boolean} fireIfReady Instantly fire this if all data is available?
*/
var registerListener = function(keys, callback, oneTimeListener, fireIfReady) {
var oneTime = !!oneTimeListener;
var listener = {keys: {}, callback: callback, oneTime: oneTime};
if (typeof keys === 'string') {
listener.keys[keys] = true;
if (keys != '*') {
keys = [keys];
}
} else {
for (var i = 0; i < keys.length; i++) {
listener.keys[keys[i]] = true;
}
}
listeners.push(listener);
// Check to see if this one should fire immediately.
if (fireIfReady && keys !== '*' && isDataReady(listener.keys)) {
window.setTimeout(function() {
maybeFireListener(listener, keys);
}, 1);
}
};
/**
* Checks if the data for a map of keys is available.
* @param {Object.} keys An map of keys to check.
* @return {boolean} Data for all the keys is present.
*/
var isDataReady = function(keys) {
if (keys['*']) {
return true;
}
for (var key in keys) {
if (typeof dataSets[key] === 'undefined') {
return false;
}
}
return true;
};
/**
* Fires a listener for a key, but only if the data is ready for other
* keys this listener is bound to.
* @param {Object} listener The listener object.
* @param {string} key The key that this listener is being fired for.
*/
var maybeFireListener = function(listener, key) {
if (isDataReady(listener.keys)) {
listener.callback(key);
if (listener.oneTime) {
removeListener(listener);
}
}
};
/**
* Removes a listener from the list.
* @param {Object} listener The listener to remove.
*/
var removeListener = function(listener) {
for (var i = 0; i < listeners.length; ++i) {
if (listeners[i] == listener) {
listeners.splice(i, 1);
return;
}
}
};
/**
* Scans all active listeners and fires off any callbacks that inserting this
* key or list of keys satisfies.
* @param {string|Array.} keys The key that was updated.
* @private
*/
var fireCallbacks = function(keys) {
if (typeof(keys) == 'string') {
keys = [keys];
}
for (var i = 0; i < listeners.length; ++i) {
var listener = listeners[i];
for (var j = 0; j < keys.length; j++) {
var key = keys[j];
if (listener.keys[key] || listener.keys['*']) {
maybeFireListener(listener, keys);
break;
}
}
}
};
return {
/**
* Returns a map of existing data.
* @return {Object} A map of current data sets.
* TODO: Add to the spec API?
*/
getData: function() {
var data = {};
for (var key in dataSets) {
if (dataSets.hasOwnProperty(key)) {
data[key] = dataSets[key];
}
}
return data;
},
/**
* Registers a callback listener for a given set of keys.
* @param {string|Array.} keys Key or set of keys to listen on.
* @param {function(Array.)} callback Function to call when a
* listener is fired.
*/
registerListener: function(keys, callback) {
registerListener(keys, callback, false, true);
},
/**
* Private version of registerListener which allows one-time listeners to
* be registered. Not part of the spec. Exposed because needed by
* opensocial-templates.
* @param {string|Array.} keys Key or set of keys to listen on.
* @param {function(Array.)} callback Function to call when a.
*/
registerOneTimeListener_: function(keys, callback) {
registerListener(keys, callback, true, true);
},
/**
* Private version of registerListener which allows listeners to be
* registered that do not fire initially, but only after a data change.
* Exposed because needed by opensocial-templates.
* @param {string|Array.} keys Key or set of keys to listen on.
* @param {function(Array.)} callback Function to call when a.
*/
registerDeferredListener_: function(keys, callback) {
registerListener(keys, callback, false, false);
},
/**
* Retrieve a data set for a given key.
* @param {string} key Key for the requested data set.
* @return {Object} The data set object.
*/
getDataSet: function(key) {
return dataSets[key];
},
/**
* Puts a data set into the global DataContext object. Fires listeners
* if they are satisfied by the associated key being inserted.
*
* @param {string} key The key to associate with this object.
* @param {ResponseItem|Object} obj The data object.
*/
putDataSet: function(key, obj) {
putDataSet(key, obj, true);
},
/**
* Inserts multiple data sets from a JSON object.
* @param {Object.} dataSets a JSON object containing Data
* sets keyed by Data Set Key. All the DataSets are added, before firing
* listeners.
*/
putDataSets: function(dataSets) {
var keys = [];
for (var key in dataSets) {
keys.push(key);
putDataSet(key, dataSets[key], false);
}
fireCallbacks(keys);
}
};
}();
/**
* Accessor to the shared, global DataContext.
*/
opensocial.data.getDataContext = function() {
return opensocial.data.DataContext;
};
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