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ActivationContext.ts
169 lines | 5.1 KiB | video/mp2t | TypeScriptLexer
/ src / main / ts / ActivationContext.ts
import { TraceSource } from "../log/TraceSource";
import { argumentNotEmptyString } from "../safe";
import { Descriptor, ContainerServiceMap, ContainerKeys, TypeOfService, ILifetime, ServiceContainer } from "./interfaces";
import { MapOf } from "../interfaces";
const trace = TraceSource.get("@implab/core/di/ActivationContext");
export interface ActivationContextInfo {
name: string;
service: string;
}
let nextId = 1;
/** This class is created once per `Container.resolve` method call and used to
* cache dependencies and to track created instances. The activation context
* tracks services with `context` activation type.
*/
export class ActivationContext<S extends object> {
_cache: MapOf<any>;
_services: ContainerServiceMap<S>;
_visited: MapOf<any>;
_name: string;
_service: Descriptor<S, any>;
_container: ServiceContainer<S>;
_parent: ActivationContext<S> | undefined;
/** Creates a new activation context with the specified parameters.
* @param container the container which starts the activation process
* @param services the initial service registrations
* @param name the name of the service being activated, this parameter is
* used for the debug purpose.
* @param service the service to activate, this parameter is used for the
* debug purpose.
*/
constructor(container: ServiceContainer<S>, services: ContainerServiceMap<S>, name: string, service: Descriptor<S, any>) {
this._name = name;
this._service = service;
this._visited = {};
this._cache = {};
this._services = services;
this._container = container;
}
/** the name of the current resolving dependency */
getName() {
return this._name;
}
/** Returns the container for which 'resolve' method was called */
getContainer() {
return this._container;
}
/** Resolves the specified dependency in the current context
* @param name The name of the dependency being resolved
*/
resolve<K extends ContainerKeys<S>>(name: K): TypeOfService<S, K>;
/** Resolves the specified dependency with the specified default value if
* the dependency is missing.
*
* @param name The name of the dependency being resolved
* @param def A default value to return in case of the specified dependency
* is missing.
*/
resolve<K extends ContainerKeys<S>, T>(name: K, def: T): TypeOfService<S, K> | T;
/** Resolves the specified dependency and returns undefined in case if the
* dependency is missing.
*
* @param name The name of the dependency being resolved
*/
resolve<K extends ContainerKeys<S>>(name: K, def: undefined): TypeOfService<S, K> | undefined;
resolve<K extends ContainerKeys<S>, T>(name: K, def?: T): TypeOfService<S, K> | T | undefined {
const d = this._services[name];
if (d !== undefined) {
return this.activate(d, name.toString());
} else {
if (arguments.length > 1)
return def;
else
throw new Error(`Service ${name} not found`);
}
}
/**
* registers services local to the the activation context
*
* @name{string} the name of the service
* @service{string} the service descriptor to register
*/
register<K extends keyof S>(name: K, service: Descriptor<S, S[K]>) {
argumentNotEmptyString(name, "name");
this._services[name] = service as any;
}
createLifetime(): ILifetime {
const id = nextId++;
const me = this;
return {
initialize() {
},
has() {
return id in me._cache;
},
get() {
return me._cache[id];
},
store(item: any) {
me._cache[id] = item;
}
};
}
activate<T>(d: Descriptor<S, T>, name: string) {
if (trace.isLogEnabled())
trace.log("enter {0} {1}", name, d);
const ctx = this.enter(d, name);
const v = d.activate(ctx);
if (trace.isLogEnabled())
trace.log(`leave ${name}`);
return v;
}
visit(id: string) {
const count = this._visited[id] || 0;
this._visited[id] = count + 1;
return count;
}
getStack(): ActivationContextInfo[] {
const stack = [{
name: this._name,
service: this._service.toString()
}];
return this._parent ?
stack.concat(this._parent.getStack()) :
stack;
}
private enter(service: Descriptor<S, any>, name: string): this {
const clone = Object.create(this);
clone._name = name;
clone._services = Object.create(this._services);
clone._parent = this;
clone._service = service;
return clone;
}
/** Creates a clone for the current context, used to protect it from modifications */
clone(): this {
const clone = Object.create(this);
clone._services = Object.create(this._services);
return clone;
}
}