var { _head: head, _tail, _list, _capacityMask } = this;
    if (head === _tail)
      return @undefined;
    var item = _list[head];
    if (@putByValDirect(_list, head, @undefined), head = this._head = head + 1 & _capacityMask, head < 2 && _tail > 1e4 && _tail <= _list.length >>> 2)
      this._shrinkArray();
    return item;
  }
  peek() {
    if (this._head === this._tail)
      return @undefined;
    return this._list[this._head];
  }
  push(item) {
    var tail = this._tail;
    if (@putByValDirect(this._list, tail, item), this._tail = tail + 1 & this._capacityMask, this._tail === this._head)
      this._growArray();
  }
  toArray(fullCopy) {
    var list = this._list, len = @toLength(list.length);
    if (fullCopy || this._head > this._tail) {
      var _head = @toLength(this._head), _tail = @toLength(this._tail), total = @toLength(len - _head + _tail), array = @newArrayWithSize(total), j = 0;
      for (var i = _head;i < len; i++)
        @putByValDirect(array, j++, list[i]);
      for (var i = 0;i < _tail; i++)
        @putByValDirect(array, j++, list[i]);
      return array;
    } else
      return slice.@call(list, this._head, this._tail);
  }
  clear() {
    this._head = 0, this._tail = 0, this._list.fill(@undefined);
  }
  _growArray() {
    if (this._head)
      this._list = this.toArray(!0), this._head = 0;
    this._tail = @toLength(this._list.length), this._list.length <<= 1, this._capacityMask = this._capacityMask << 1 | 1;
  }
  _shrinkArray() {
    this._list.length >>>= 1, this._capacityMask >>>= 1;
  }
}
$ = Dequeue;
return $})