dashjs
Version:
A reference client implementation for the playback of MPEG DASH via Javascript and compliant browsers.
255 lines (214 loc) • 9.41 kB
JavaScript
/**
* The copyright in this software is being made available under the BSD License,
* included below. This software may be subject to other third party and contributor
* rights, including patent rights, and no such rights are granted under this license.
*
* Copyright (c) 2013, Dash Industry Forum.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation and/or
* other materials provided with the distribution.
* * Neither the name of Dash Industry Forum nor the names of its
* contributors may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @module FactoryMaker
* @ignore
*/
const FactoryMaker = (function () {
let instance;
const singletonContexts = [];
const singletonFactories = {};
const classFactories = {};
function extend(name, childInstance, override, context) {
if (!context[name] && childInstance) {
context[name] = {
instance: childInstance,
override: override
};
}
}
/**
* Use this method from your extended object. this.factory is injected into your object.
* this.factory.getSingletonInstance(this.context, 'VideoModel')
* will return the video model for use in the extended object.
*
* @param {Object} context - injected into extended object as this.context
* @param {string} className - string name found in all dash.js objects
* with name __dashjs_factory_name Will be at the bottom. Will be the same as the object's name.
* @returns {*} Context aware instance of specified singleton name.
* @memberof module:FactoryMaker
* @instance
*/
function getSingletonInstance(context, className) {
for (const i in singletonContexts) {
const obj = singletonContexts[i];
if (obj.context === context && obj.name === className) {
return obj.instance;
}
}
return null;
}
/**
* Use this method to add an singleton instance to the system. Useful for unit testing to mock objects etc.
*
* @param {Object} context
* @param {string} className
* @param {Object} instance
* @memberof module:FactoryMaker
* @instance
*/
function setSingletonInstance(context, className, instance) {
for (const i in singletonContexts) {
const obj = singletonContexts[i];
if (obj.context === context && obj.name === className) {
singletonContexts[i].instance = instance;
return;
}
}
singletonContexts.push({
name: className,
context: context,
instance: instance
});
}
/*------------------------------------------------------------------------------------------*/
// Factories storage Management
/*------------------------------------------------------------------------------------------*/
function getFactoryByName(name, factoriesArray) {
return factoriesArray[name];
}
function updateFactory(name, factory, factoriesArray) {
if (name in factoriesArray) {
factoriesArray[name] = factory;
}
}
/*------------------------------------------------------------------------------------------*/
// Class Factories Management
/*------------------------------------------------------------------------------------------*/
function updateClassFactory(name, factory) {
updateFactory(name, factory, classFactories);
}
function getClassFactoryByName(name) {
return getFactoryByName(name, classFactories);
}
function getClassFactory(classConstructor) {
let factory = getFactoryByName(classConstructor.__dashjs_factory_name, classFactories);
if (!factory) {
factory = function (context) {
if (context === undefined) {
context = {};
}
return {
create: function () {
return merge(classConstructor, context, arguments);
}
};
};
classFactories[classConstructor.__dashjs_factory_name] = factory; // store factory
}
return factory;
}
/*------------------------------------------------------------------------------------------*/
// Singleton Factory MAangement
/*------------------------------------------------------------------------------------------*/
function updateSingletonFactory(name, factory) {
updateFactory(name, factory, singletonFactories);
}
function getSingletonFactoryByName(name) {
return getFactoryByName(name, singletonFactories);
}
function getSingletonFactory(classConstructor) {
let factory = getFactoryByName(classConstructor.__dashjs_factory_name, singletonFactories);
if (!factory) {
factory = function (context) {
let instance;
if (context === undefined) {
context = {};
}
return {
getInstance: function () {
// If we don't have an instance yet check for one on the context
if (!instance) {
instance = getSingletonInstance(context, classConstructor.__dashjs_factory_name);
}
// If there's no instance on the context then create one
if (!instance) {
instance = merge(classConstructor, context, arguments);
singletonContexts.push({
name: classConstructor.__dashjs_factory_name,
context: context,
instance: instance
});
}
return instance;
}
};
};
singletonFactories[classConstructor.__dashjs_factory_name] = factory; // store factory
}
return factory;
}
function merge(classConstructor, context, args) {
let classInstance;
const className = classConstructor.__dashjs_factory_name;
const extensionObject = context[className];
if (extensionObject) {
let extension = extensionObject.instance;
if (extensionObject.override) { //Override public methods in parent but keep parent.
classInstance = classConstructor.apply({context}, args);
extension = extension.apply({
context,
factory: instance,
parent: classInstance
}, args);
for (const prop in extension) {
if (classInstance.hasOwnProperty(prop)) {
classInstance[prop] = extension[prop];
}
}
} else { //replace parent object completely with new object. Same as dijon.
return extension.apply({
context,
factory: instance
}, args);
}
} else {
// Create new instance of the class
classInstance = classConstructor.apply({context}, args);
}
// Add getClassName function to class instance prototype (used by Debug)
classInstance.getClassName = function () {return className;};
return classInstance;
}
instance = {
extend: extend,
getSingletonInstance: getSingletonInstance,
setSingletonInstance: setSingletonInstance,
getSingletonFactory: getSingletonFactory,
getSingletonFactoryByName: getSingletonFactoryByName,
updateSingletonFactory: updateSingletonFactory,
getClassFactory: getClassFactory,
getClassFactoryByName: getClassFactoryByName,
updateClassFactory: updateClassFactory
};
return instance;
}());
export default FactoryMaker;