Files
openmct/platform/framework/src/register/ExtensionRegistrar.js
2016-05-20 13:05:32 -07:00

230 lines
9.6 KiB
JavaScript

/*****************************************************************************
* Open MCT Web, Copyright (c) 2014-2015, United States Government
* as represented by the Administrator of the National Aeronautics and Space
* Administration. All rights reserved.
*
* Open MCT Web is 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.
*
* Open MCT Web includes source code licensed under additional open source
* licenses. See the Open Source Licenses file (LICENSES.md) included with
* this source code distribution or the Licensing information page available
* at runtime from the About dialog for additional information.
*****************************************************************************/
/**
* Module defining ExtensionRegistrar. Created by vwoeltje on 11/3/14.
*/
define(
['../Constants', './PartialConstructor'],
function (Constants, PartialConstructor) {
/**
* Responsible for registering extensions with Angular.
*
* @memberof platform/framework
* @constructor
* @param {angular.Module} the Angular application with which
* extensions should be registered
* @param {Object.<string,function>} customRegistrars an object
* containing custom registration functions, primarily for
* Angular built-ins.
* @param {ExtensionSorter} sorter the sorter which will impose
* priority ordering upon extensions
* @param {*} $log Angular's logging service
*/
function ExtensionRegistrar(app, customRegistrars, sorter, $log) {
// Track which extension categories have already been registered.
// Exceptions will be thrown if the same extension category is
// registered twice.
this.registeredCategories = {};
this.customRegistrars = customRegistrars || {};
this.app = app;
this.sorter = sorter;
this.$log = $log;
}
/**
* Register a group of resolved extensions with the Angular
* module managed by this registrar.
*
* For convenient chaining (particularly from the framework
* initializer's perspective), this returns the Angular
* module with which extensions were registered.
*
* @param {Object.<string, object[]>} extensionGroup an object
* containing key-value pairs, where keys are extension
* categories and values are arrays of resolved
* extensions
* @returns {angular.Module} the application module with
* which extensions were registered
*/
ExtensionRegistrar.prototype.registerExtensions = function (extensionGroup) {
var registeredCategories = this.registeredCategories,
customRegistrars = this.customRegistrars,
app = this.app,
sorter = this.sorter,
$log = this.$log;
// Used to build unique identifiers for individual extensions,
// so that these can be registered separately with Angular
function identify(category, extension, index) {
var name = extension.key ?
("extension-" + extension.key + "#" + index) :
("extension#" + index);
return category + "[" + name + "]";
}
// Echo arguments; used to represent groups of non-built-in
// extensions as a single dependency.
function echo() {
return Array.prototype.slice.call(arguments);
}
// Always return a static value; used to represent plain
// metadata as a single dependency in Angular.
function staticFunction(value) {
return function () {
return value;
};
}
// Utility function; create the second argument for Angular's
// .service service registration method (an array containing
// both dependencies and a factory method for the service.)
function makeServiceArgument(category, extension) {
var dependencies = extension.depends || [],
factory = (typeof extension === 'function') ?
new PartialConstructor(extension) :
staticFunction(extension);
return dependencies.concat([factory]);
}
// Register extension arrays with Angular under an appropriately
// suffixed name, e.g. "types[]"
function registerExtensionArraysForCategory(category, names) {
var name = category + Constants.EXTENSION_SUFFIX;
app.factory(name, names.concat([echo]));
}
function registerExtensionsForCategory(category, extensions) {
var names = [];
function registerExtension(extension, index) {
var name = identify(category, extension, index);
// Track individual extension names as-registered
names.push(name);
app.factory(
name,
makeServiceArgument(category, extension)
);
}
if (registeredCategories[category]) {
$log.warn([
"Tried to register extensions for category ",
category,
" more than once. Ignoring all but first set."
].join(""));
} else {
// Register all extensions. Use custom registration
// code for services, directives, etc; otherwise,
// just register them under generic names.
if (customRegistrars[category]) {
customRegistrars[category](extensions);
} else {
extensions.forEach(registerExtension);
registerExtensionArraysForCategory(category, names);
}
registeredCategories[category] = true;
return true;
}
}
// Check if a declared dependency looks like a dependency on
// an extension category (e.g. is suffixed by [])
function isExtensionDependency(dependency) {
var index = dependency.indexOf(
Constants.EXTENSION_SUFFIX,
dependency.length - Constants.EXTENSION_SUFFIX.length
);
return index !== -1;
}
// Examine a group of resolved dependencies to determine
// which extension categories still need to be satisfied.
function findEmptyExtensionDependencies(extGroup) {
var needed = {},
categories = Object.keys(extGroup),
allExtensions = [];
// Build up an array of all extensions
categories.forEach(function (category) {
allExtensions =
allExtensions.concat(extGroup[category]);
});
// Track all extension dependencies exposed therefrom
allExtensions.forEach(function (extension) {
(extension.depends || []).filter(
isExtensionDependency
).forEach(function (dependency) {
needed[dependency] = true;
});
});
// Remove categories which have been provided
categories.forEach(function (category) {
var dependency = category + Constants.EXTENSION_SUFFIX;
delete needed[dependency];
});
return Object.keys(needed);
}
// Register any extension categories that are depended-upon but
// have not been declared anywhere; such dependencies are then
// satisfied by an empty array, instead of not at all.
function registerEmptyDependencies(extGroup) {
findEmptyExtensionDependencies(extGroup)
.forEach(function (name) {
$log.info("Registering empty extension category " + name);
app.factory(name, [staticFunction([])]);
});
}
// Announce we're entering a new phase
$log.info("Registering extensions...");
// Register all declared extensions by category
Object.keys(extensionGroup).forEach(function (category) {
registerExtensionsForCategory(
category,
sorter.sort(extensionGroup[category])
);
});
// Also handle categories which are needed but not declared
registerEmptyDependencies(extensionGroup);
// Return the application to which these extensions
// have been registered
return app;
};
return ExtensionRegistrar;
}
);