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import { Deferred, deferred } from "../deps.ts";
/** @ignore */export class DeferredStack<T> {  private _queue: Deferred<T>[] = [];  private _size = 0;
  constructor(    readonly _maxSize: number,    private _array: T[] = [],    private readonly creator: () => Promise<T>,  ) {    this._size = _array.length;  }
  get size(): number {    return this._size;  }
  get maxSize(): number {    return this._maxSize;  }
  get available(): number {    return this._array.length;  }
  async pop(): Promise<T> {    if (this._array.length) {      return this._array.pop()!;    } else if (this._size < this._maxSize) {      this._size++;      const item = await this.creator();      return item;    }    const defer = deferred<T>();    this._queue.push(defer);    await defer;    return this._array.pop()!;  }
  async push(item: T) {    this._array.push(item);    if (this._queue.length) {      this._queue.shift()!.resolve();    }  }
  reduceSize() {    this._size--;  }}