react-virtualized/dist/commonjs/utils/createCallbackMemoizer.js

React components for efficiently rendering large, scrollable lists and tabular data

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _keys = require('babel-runtime/core-js/object/keys');

var _keys2 = _interopRequireDefault(_keys);

exports.default = createCallbackMemoizer;

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/**
 * Helper utility that updates the specified callback whenever any of the specified indices have changed.
 */
function createCallbackMemoizer() {
  var requireAllKeys = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : true;

  var cachedIndices = {};

  return function (_ref) {
    var callback = _ref.callback,
        indices = _ref.indices;

    var keys = (0, _keys2.default)(indices);
    var allInitialized = !requireAllKeys || keys.every(function (key) {
      var value = indices[key];
      return Array.isArray(value) ? value.length > 0 : value >= 0;
    });
    var indexChanged = keys.length !== (0, _keys2.default)(cachedIndices).length || keys.some(function (key) {
      var cachedValue = cachedIndices[key];
      var value = indices[key];

      return Array.isArray(value) ? cachedValue.join(',') !== value.join(',') : cachedValue !== value;
    });

    cachedIndices = indices;

    if (allInitialized && indexChanged) {
      callback(indices);
    }
  };
}