stage-js/example/common/pool.js

2D HTML5 Rendering and Layout

function Pool() {
  let _create, _exit, _enter, _discard;
  let _list = [],
    _max = 4,
    _name = "";
  let _created = 0,
    _checkedout = 0,
    _checkedin = 0,
    _discarded = 0;

  this.create = function (create) {
    _create = create;
    return this;
  };

  this.exit = function (exit) {
    _exit = exit;
    return this;
  };

  this.enter = function (enter) {
    _enter = enter;
    return this;
  };

  this.discard = function (discard) {
    _discard = discard;
    return this;
  };

  this.max = function (max) {
    if (!arguments.length) {
      return _max;
    }
    _max = max;
    return this;
  };

  this.name = function (name) {
    if (!arguments.length) {
      return _name;
    }
    _name = name;
    return this;
  };

  this.checkOut = function (create) {
    let item;
    if (_list.length) {
      item = _list.shift();
    } else {
      _created++;
      item = (create || _create).apply(this);
    }
    _checkedout++;
    _exit && _exit.call(this, item);
    return item;
  };

  this.checkIn = function (item, discard) {
    if (_list.length < _max) {
      _checkedin++;
      _enter && _enter.call(this, item);
      _list.push(item);
    } else {
      _discarded++;
      (discard = discard || _discard) && discard.call(this, item);
    }
  };

  this.toString = function () {
    return (
      "Pool" +
      (_name ? " (" + _name + ")" : "") +
      ":" +
      " +" +
      _created +
      " >" +
      _checkedout +
      " <" +
      _checkedin +
      " -" +
      _discarded +
      " =" +
      _list.length +
      "/" +
      _max
    );
  };
}

export default Pool;