feat(lib/es2021): Add type parameter to FinalizationRegistry (#42274)

* feat(lib/es2021): Add type parameter to `FinalizationRegistry`

* test(lib/es2021): Add test for generic `FinalizationRegistry`

src/lib/esnext.weakref.d.ts

@@ -15,12 +15,12 @@ interface WeakRefConstructor {
      * Creates a WeakRef instance for the given target object.
      * @param target The target object for the WeakRef instance.
      */
-    new<T extends object>(target?: T): WeakRef<T>;
+    new<T extends object>(target: T): WeakRef<T>;
 }
 
 declare var WeakRef: WeakRefConstructor;
 
-interface FinalizationRegistry {
+interface FinalizationRegistry<T> {
     readonly [Symbol.toStringTag]: "FinalizationRegistry";
 
     /**
@@ -32,7 +32,7 @@ interface FinalizationRegistry {
      * object. If provided (and not undefined), this must be an object. If not provided, the target
      * cannot be unregistered.
      */
-    register(target: object, heldValue: any, unregisterToken?: object): void;
+    register(target: object, heldValue: T, unregisterToken?: object): void;
 
     /**
      * Unregisters an object from the registry.
@@ -43,13 +43,13 @@ interface FinalizationRegistry {
 }
 
 interface FinalizationRegistryConstructor {
-    readonly prototype: FinalizationRegistry;
+    readonly prototype: FinalizationRegistry<any>;
 
     /**
      * Creates a finalization registry with an associated cleanup callback
      * @param cleanupCallback The callback to call after an object in the registry has been reclaimed.
      */
-    new(cleanupCallback: (heldValue: any) => void): FinalizationRegistry;
+    new<T>(cleanupCallback: (heldValue: T) => void): FinalizationRegistry<T>;
 }
 
 declare var FinalizationRegistry: FinalizationRegistryConstructor;

tests/baselines/reference/esNextWeakRefs_IterableWeakMap.js

@@ -0,0 +1,189 @@
+//// [esNextWeakRefs_IterableWeakMap.ts]
+/** `static #cleanup` */
+const IterableWeakMap_cleanup = ({ ref, set }: {
+    readonly ref: WeakRef<object>;
+    readonly set: Set<WeakRef<object>>;
+}) => {
+    set.delete(ref);
+};
+
+// Based on: https://github.com/tc39/proposal-weakrefs/blob/master/README.md#iterable-weakmaps
+export class IterableWeakMap<K extends object, V> implements WeakMap<K, V> {
+    declare readonly [Symbol.toStringTag]: "IterableWeakMap";
+
+    #weakMap = new WeakMap<K, { readonly ref: WeakRef<K>; value: V }>();
+    #refSet = new Set<WeakRef<K>>();
+    #finalizationGroup = new FinalizationRegistry(IterableWeakMap_cleanup);
+
+    constructor(iterable: Iterable<[key: K, value: V]> | null = null) {
+        if (iterable !== null) {
+            for (const { 0: key, 1: value } of iterable) {
+                this.set(key, value);
+            }
+        }
+    }
+
+    set(key: K, value: V): this {
+        const entry = this.#weakMap.get(key);
+        if (entry !== undefined) {
+            entry.value = value;
+        } else {
+            const ref = new WeakRef(key);
+
+            this.#weakMap.set(key, { ref, value });
+            this.#refSet.add(ref);
+            this.#finalizationGroup.register(key, {
+                set: this.#refSet,
+                ref,
+            }, ref);
+        }
+        return this;
+    }
+
+    has(key: K): boolean {
+        return this.#weakMap.has(key);
+    }
+
+    get(key: K): V | undefined {
+        return this.#weakMap.get(key)?.value;
+    }
+
+    delete(key: K): boolean {
+        const entry = this.#weakMap.get(key);
+        if (entry === undefined) {
+            return false;
+        }
+
+        const { ref } = entry;
+        this.#weakMap.delete(key);
+        this.#refSet.delete(ref);
+        this.#finalizationGroup.unregister(ref);
+        return true;
+    }
+
+    declare [Symbol.iterator]: this["entries"];
+    *entries(): Generator<[key: K, value: V], void> {
+        for (const ref of this.#refSet) {
+            const key = ref.deref();
+            if (key === undefined) continue;
+            const { value } = this.#weakMap.get(key)!;
+            yield [key, value];
+        }
+    }
+
+    *keys() {
+        for (const { 0: key } of this) {
+            yield key;
+        }
+    }
+
+    *values() {
+        for (const { 1: value } of this) {
+            yield value;
+        }
+    }
+}
+
+Object.defineProperties(IterableWeakMap.prototype, {
+    [Symbol.iterator]: {
+        configurable: true,
+        enumerable: false,
+        writable: true,
+        value: Object.getOwnPropertyDescriptor(
+            IterableWeakMap.prototype,
+            "entries",
+        )!.value,
+    },
+    [Symbol.toStringTag]: {
+        configurable: true,
+        enumerable: false,
+        writable: false,
+        value: "IterableWeakMap",
+    },
+});
+
+
+//// [esNextWeakRefs_IterableWeakMap.js]
+/** `static #cleanup` */
+const IterableWeakMap_cleanup = ({ ref, set }) => {
+    set.delete(ref);
+};
+// Based on: https://github.com/tc39/proposal-weakrefs/blob/master/README.md#iterable-weakmaps
+export class IterableWeakMap {
+    #weakMap = new WeakMap();
+    #refSet = new Set();
+    #finalizationGroup = new FinalizationRegistry(IterableWeakMap_cleanup);
+    constructor(iterable = null) {
+        if (iterable !== null) {
+            for (const { 0: key, 1: value } of iterable) {
+                this.set(key, value);
+            }
+        }
+    }
+    set(key, value) {
+        const entry = this.#weakMap.get(key);
+        if (entry !== undefined) {
+            entry.value = value;
+        }
+        else {
+            const ref = new WeakRef(key);
+            this.#weakMap.set(key, { ref, value });
+            this.#refSet.add(ref);
+            this.#finalizationGroup.register(key, {
+                set: this.#refSet,
+                ref,
+            }, ref);
+        }
+        return this;
+    }
+    has(key) {
+        return this.#weakMap.has(key);
+    }
+    get(key) {
+        return this.#weakMap.get(key)?.value;
+    }
+    delete(key) {
+        const entry = this.#weakMap.get(key);
+        if (entry === undefined) {
+            return false;
+        }
+        const { ref } = entry;
+        this.#weakMap.delete(key);
+        this.#refSet.delete(ref);
+        this.#finalizationGroup.unregister(ref);
+        return true;
+    }
+    *entries() {
+        for (const ref of this.#refSet) {
+            const key = ref.deref();
+            if (key === undefined)
+                continue;
+            const { value } = this.#weakMap.get(key);
+            yield [key, value];
+        }
+    }
+    *keys() {
+        for (const { 0: key } of this) {
+            yield key;
+        }
+    }
+    *values() {
+        for (const { 1: value } of this) {
+            yield value;
+        }
+    }
+}
+Object.defineProperties(IterableWeakMap.prototype, {
+    [Symbol.iterator]: {
+        configurable: true,
+        enumerable: false,
+        writable: true,
+        value: Object.getOwnPropertyDescriptor(IterableWeakMap.prototype, "entries").value,
+    },
+    [Symbol.toStringTag]: {
+        configurable: true,
+        enumerable: false,
+        writable: false,
+        value: "IterableWeakMap",
+    },
+});