add equality collection element iterators

src/equality-map.ts

@@ -8,6 +8,9 @@ export interface EqualityMap<K, V> extends Iterable<[K, V]> {
   contains(key: K): boolean;
   remove(key: K): V | undefined;
   clear(): void;
+  keys(): IterableIterator<K>;
+  values(): IterableIterator<V>;
+  entries(): IterableIterator<[K, V]>;
 }
 
 class NativeEqualityMap<K, V> implements EqualityMap<K, V> {
@@ -41,6 +44,18 @@ class NativeEqualityMap<K, V> implements EqualityMap<K, V> {
     this.#map.clear();
   }
 
+  keys() {
+    return this.#map.keys();
+  }
+
+  values() {
+    return this.#map.values();
+  }
+
+  entries() {
+    return this.#map.entries();
+  }
+
   [Symbol.iterator]() {
     return this.#map[Symbol.iterator]();
   }
@@ -107,8 +122,26 @@ class CustomEqualityMap<K, V> implements EqualityMap<K, V> {
     this.#list.length = 0;
   }
 
-  [Symbol.iterator]() {
-    return this.#list[Symbol.iterator]();
+  *keys() {
+    for (const entry of this.#list) {
+      yield entry[0];
+    }
+  }
+
+  *values() {
+    for (const entry of this.#list) {
+      yield entry[1];
+    }
+  }
+
+  entries() {
+    return this[Symbol.iterator]();
+  }
+
+  *[Symbol.iterator]() {
+    for (const entry of this.#list) {
+      yield [entry[0], entry[1]] as [K, V]; // no entry mutation allowed!
+    }
   }
 }