Attach injector to instance (#1162)

* initial commit

* cleanup

* more cleanup

* even more cleanup

* EVEN MORE CLEANUP

packages/di/src/lib/context/injector.ts

@@ -1,5 +1,6 @@
-import type { Injector } from "../injector.js";
 import { type Context, createContext } from "./protocol.js";
 
+import type { Injector } from "../injector.js";
+
 export const INJECTOR_CTX: Context<"injector", Injector> =
   createContext("injector");

packages/di/src/lib/inject.ts

@@ -1,4 +1,4 @@
-import { injectables } from "./injector.js";
+import { readInjector } from "./metadata.js";
 import type { InjectionToken } from "./provider.js";
 
 export type Injected<T> = () => T;
@@ -7,9 +7,9 @@ export function inject<This extends object, T>(
   token: InjectionToken<T>,
 ): Injected<T> {
   return function (this: This) {
-    const injector = injectables.get(this);
+    const injector = readInjector(this);
 
-    if (injector === undefined) {
+    if (injector === null) {
       throw new Error(
         `${this.constructor.name} is either not injectable or a service is being called in the constructor. \n Either add the @injectable() to your class or use the @injected callback method.`,
       );

packages/di/src/lib/injectable-el.ts

@@ -2,61 +2,53 @@
 
 import { INJECTOR_CTX } from "./context/injector.js";
 import { ContextRequestEvent } from "./context/protocol.js";
-import { injectables } from "./injector.js";
+import { INJECTOR } from "./injector.js";
+import type { Injector } from "./injector.js";
 import { callLifecycle } from "./lifecycle.js";
 import type { InjectableMetadata } from "./metadata.js";
 import type { ConstructableToken } from "./provider.js";
 
-export function injectableEl<T extends ConstructableToken<HTMLElement>>(
-  Base: T,
-  ctx: ClassDecoratorContext,
-): T {
+export function injectableEl<
+  T extends ConstructableToken<HTMLElement & { [INJECTOR]: Injector }>,
+>(Base: T, ctx: ClassDecoratorContext): T {
   const metadata: InjectableMetadata = ctx.metadata;
 
   const def = {
     [Base.name]: class extends Base {
       constructor(..._: any[]) {
         super();
 
-        const injector = injectables.get(this);
+        const injector = this[INJECTOR];
 
-        if (injector) {
-          this.addEventListener("context-request", (e) => {
-            if (e.target !== this && e.context === INJECTOR_CTX) {
-              e.stopPropagation();
+        this.addEventListener("context-request", (e) => {
+          if (e.target !== this && e.context === INJECTOR_CTX) {
+            e.stopPropagation();
 
-              e.callback(injector);
-            }
-          });
+            e.callback(injector);
+          }
+        });
 
-          callLifecycle(this, injector, metadata?.onCreated);
-        }
+        callLifecycle(this, injector, metadata?.onCreated);
       }
 
       connectedCallback() {
-        const injector = injectables.get(this);
+        const injector = this[INJECTOR];
 
-        if (injector) {
-          this.dispatchEvent(
-            new ContextRequestEvent(INJECTOR_CTX, (ctx) => {
-              injector.parent = ctx;
-            }),
-          );
+        this.dispatchEvent(
+          new ContextRequestEvent(INJECTOR_CTX, (ctx) => {
+            injector.parent = ctx;
+          }),
+        );
 
-          callLifecycle(this, injector, metadata?.onInjected);
-        }
+        callLifecycle(this, injector, metadata?.onInjected);
 
         if (super.connectedCallback) {
           super.connectedCallback();
         }
       }
 
       disconnectedCallback() {
-        const injector = injectables.get(this);
-
-        if (injector) {
-          injector.parent = undefined;
-        }
+        this[INJECTOR].parent = undefined;
 
         if (super.disconnectedCallback) {
           super.disconnectedCallback();

packages/di/src/lib/injectable.test.ts

@@ -2,7 +2,8 @@ import { assert } from "chai";
 
 import { inject } from "./inject.js";
 import { injectable } from "./injectable.js";
-import { Injector, injectables } from "./injector.js";
+import { Injector } from "./injector.js";
+import { readInjector } from "./metadata.js";
 import { StaticToken } from "./provider.js";
 
 it("should locally override a provider", () => {
@@ -30,7 +31,7 @@ it("should define an injector for a service instance", () => {
 
   const instance = new MyService("b");
 
-  assert.ok(injectables.has(instance));
+  assert.ok(readInjector(instance));
   assert.ok(instance.arg === "b");
 });
 
@@ -43,7 +44,7 @@ it("should inject the current service injectable instance", () => {
   const app = new Injector();
   const service = app.inject(MyService);
 
-  assert.equal(service.injector(), injectables.get(service));
+  assert.equal(service.injector(), readInjector(service));
 });
 
 it("should not override the name of the original class", () => {

packages/di/src/lib/injectable.ts

@@ -1,7 +1,7 @@
 (Symbol as any).metadata ??= Symbol("Symbol.metadata");
 
 import { injectableEl } from "./injectable-el.js";
-import { Injector, injectables } from "./injector.js";
+import { INJECTOR, Injector } from "./injector.js";
 import type {
   ConstructableToken,
   InjectionToken,
@@ -21,6 +21,8 @@ export function injectable(opts?: InjectableOpts) {
   ): T {
     const def = {
       [Base.name]: class extends Base {
+        [INJECTOR]: Injector;
+
         constructor(...args: any[]) {
           super(...args);
 
@@ -38,7 +40,7 @@ export function injectable(opts?: InjectableOpts) {
             }
           }
 
-          injectables.set(this, injector);
+          this[INJECTOR] = injector;
         }
       },
     };

packages/di/src/lib/injector.ts

@@ -1,5 +1,5 @@
 import { callLifecycle } from "./lifecycle.js";
-import { readMetadata } from "./metadata.js";
+import { readInjector, readMetadata } from "./metadata.js";
 import {
   type InjectionToken,
   type Provider,
@@ -8,17 +8,14 @@ import {
   StaticToken,
 } from "./provider.js";
 
-/**
- * Keeps track of all Injectable services and their Injector
- */
-export const injectables: WeakMap<object, Injector> = new WeakMap();
-
 export interface InjectorOpts {
   name?: string;
   providers?: Iterable<Provider<any>>;
   parent?: Injector;
 }
 
+export const INJECTOR: unique symbol = Symbol("JOIST_INJECTOR");
+
 /**
  * Injectors create and store instances of services.
  * A service is any constructable class.
@@ -56,13 +53,10 @@ export class Injector {
       const instance = this.#instances.get(token);
 
       const metadata = readMetadata<T>(token);
+      const injector = readInjector(instance) ?? this;
 
       if (metadata) {
-        callLifecycle(
-          instance,
-          injectables.get(instance) ?? this,
-          metadata.onInjected,
-        );
+        callLifecycle(instance, injector, metadata.onInjected);
       }
 
       return instance;
@@ -114,7 +108,7 @@ export class Injector {
      * Only values that are objects are able to have associated injectors
      */
     if (typeof instance === "object" && instance !== null) {
-      const injector = injectables.get(instance);
+      const injector = readInjector(instance) ?? this;
 
       if (injector && injector !== this) {
         /**
@@ -134,8 +128,8 @@ export class Injector {
       const metadata = readMetadata<T>(token);
 
       if (metadata) {
-        callLifecycle(instance, injector ?? this, metadata.onCreated);
-        callLifecycle(instance, injector ?? this, metadata.onInjected);
+        callLifecycle(instance, injector, metadata.onCreated);
+        callLifecycle(instance, injector, metadata.onInjected);
       }
     }
 

packages/di/src/lib/lifecycle.test.ts

@@ -2,8 +2,9 @@ import { assert } from "chai";
 
 import { inject } from "./inject.js";
 import { injectable } from "./injectable.js";
-import { Injector, injectables } from "./injector.js";
+import { Injector } from "./injector.js";
 import { created, injected } from "./lifecycle.js";
+import { readInjector } from "./metadata.js";
 
 it("should call onInit and onInject when a service is first created", () => {
   const i = new Injector();
@@ -55,7 +56,7 @@ it("should pass the injector to all lifecycle callbacks", () => {
   }
 
   const service = i.inject(MyService);
-  const injector = injectables.get(service);
+  const injector = readInjector(service);
 
   assert.equal(service.res[0], injector);
   assert.equal(service.res[0].parent, i);

packages/di/src/lib/metadata.ts

@@ -1,4 +1,4 @@
-import type { Injector } from "./injector.js";
+import { INJECTOR, type Injector } from "./injector.js";
 import type { InjectionToken } from "./provider.js";
 
 export type LifecycleCallback = (i: Injector) => void;
@@ -15,3 +15,11 @@ export function readMetadata<T>(
 
   return metadata;
 }
+
+export function readInjector<T extends object>(target: T): Injector | null {
+  if (INJECTOR in target) {
+    return target[INJECTOR] as Injector;
+  }
+
+  return null;
+}