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Injector.js
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| /** | |
| * @constructor | |
| */ | |
| function Injector() { | |
| /** | |
| * @type {!Object.<string, function(Injector=): !Object>} | |
| */ | |
| this.factories = {}; | |
| /** | |
| * @type {!Object.<string, !Object>} | |
| */ | |
| this.services = { | |
| '$injector': this | |
| }; | |
| /** | |
| * @type {Number} | |
| */ | |
| this.idcount = 0; | |
| } | |
| /** | |
| * Adds a service factory. | |
| * @param {string|Function} key A service key. | |
| * @param {function(Injector=): !Object} factory A service factory. | |
| */ | |
| Injector.prototype.addService = function(key, factory) { | |
| var nkey = this.normalize(key); | |
| if (!factory) { | |
| factory = function() { | |
| return this.create(key); | |
| }.bind(this); | |
| } | |
| this.factories[nkey] = factory; | |
| }; | |
| /** | |
| * Returns a service by its key. | |
| * @param {string|Function} key The key of the service to get. | |
| * @return {!Object} The service. | |
| */ | |
| Injector.prototype.getService = function(key) { | |
| var nkey = this.normalize(key); | |
| var service = this.services[nkey]; | |
| if (!service) { | |
| if (!(nkey in this.factories)) | |
| throw "uknown service: " + (key.name || key); | |
| service = this.factories[nkey](); | |
| this.services[nkey] = service; | |
| } | |
| return service; | |
| }; | |
| /** | |
| * Instantiates the given constructor providing it with its dependencies. | |
| * @param {Function} Constructor The constructor function to use. | |
| * @return {!Object} An instance of the constructor. | |
| */ | |
| Injector.prototype.create = function(Constructor) { | |
| var Dependant = function() {}; | |
| Dependant.prototype = Constructor.prototype; | |
| var instance = new Dependant(); | |
| this.inject(Constructor, instance); | |
| return instance; | |
| }; | |
| /** | |
| * Injects dependencies to a constructor in the context of the given instance. | |
| * @param {Function} Constructor The constructor function to use. | |
| * @param {!Object} instance The instance to use. | |
| */ | |
| Injector.prototype.inject = function(Constructor, instance) { | |
| var keys = Constructor.prototype.$deps || []; | |
| var deps = keys.map(this.getService, this); | |
| Constructor.apply(instance, deps); | |
| }; | |
| Injector.prototype.normalize = function(key) { | |
| if (typeof key === 'function') { | |
| if (!key.__injectorId) | |
| key.__injectorId = ++this.idcount; | |
| return key.__injectorId; | |
| } | |
| return key; | |
| }; | |
| // --- define it | |
| function Renderer(backend) { | |
| console.log('@Renderer ctor - ' + backend.draw()); | |
| } | |
| Renderer.prototype.$deps = [Backend]; | |
| function Backend(ponny) { | |
| console.log('@Backend ctor - ' + ponny.speak()); | |
| } | |
| Backend.prototype.$deps = [Ponny]; | |
| Backend.prototype.draw = function() { | |
| return "drawn"; | |
| }; | |
| function Ponny(no) { | |
| console.log('@Ponny ctor - ' + no); | |
| } | |
| Ponny.prototype.speak = function() { | |
| return "moooo..."; | |
| }; | |
| // --- configure it | |
| var injector = new Injector(); | |
| injector.addService(Backend); | |
| injector.addService(Ponny, function() { | |
| return new Ponny(123); | |
| }); | |
| // -- run it | |
| var renderer = injector.create(Renderer); |
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