var shapeCollectionPool = (function () {
  var ob = {
    newShapeCollection: newShapeCollection,
    release: release,
  };

  var _length = 0;
  var _maxLength = 4;
  var pool = createSizedArray(_maxLength);

  function newShapeCollection() {
    var shapeCollection;
    if (_length) {
      _length -= 1;
      shapeCollection = pool[_length];
    } else {
      shapeCollection = new ShapeCollection();
    }
    return shapeCollection;
  }

  function release(shapeCollection) {
    var i;
    var len = shapeCollection._length;
    for (i = 0; i < len; i += 1) {
      shapePool.release(shapeCollection.shapes[i]);
    }
    shapeCollection._length = 0;

    if (_length === _maxLength) {
      pool = pooling.double(pool);
      _maxLength *= 2;
    }
    pool[_length] = shapeCollection;
    _length += 1;
  }

  return ob;
}());