Method forEach

data_structures/unstable_multimap.ts:401–420

* Executes a provided function once for each individual value in the map, * in insertion order of keys and values. * * Within a bucket, the set of values to visit is fixed at the time the * bucket is entered, so a callback that mutates the current key's list * (via `add()` or `deleteE

(
    callbackfn: (this: T, value: V, key: K, map: this) => void,
    thisArg?: T,
  )

   * ```
   */
  forEach<T = undefined>(
    callbackfn: (this: T, value: V, key: K, map: this) => void,
    thisArg?: T,
  ): void {
    if (typeof callbackfn !== "function") {
      throw new TypeError(
        `Cannot call MultiMap.prototype.forEach: "callbackfn" is not a function: received ${typeof callbackfn}`,
      );
    }
    // The bucket is snapshotted before the inner loop so mutations to the
    // current key's list (e.g. a callback calling `add()` or splicing via
    // `deleteEntry()`) do not extend, truncate, or shift the visit. This
    // mirrors the per-bucket contract of `Map.prototype.forEach`.
    for (const [key, list] of this.#map) {
      const snapshot = list.slice();
      for (let i = 0; i < snapshot.length; i++) {
        callbackfn.call(thisArg as T, snapshot[i]!, key, this);
      }
    }
  }

  /**
   * Returns an iterator of all `[key, value]` pairs, with each value yielded