@mui/x-tree-view/esm/internals/utils/selectors.js

The community edition of the MUI X Tree View components.

import { lruMemoize, createSelectorCreator } from 'reselect';
const reselectCreateSelector = createSelectorCreator({
  memoize: lruMemoize,
  memoizeOptions: {
    maxSize: 1,
    equalityCheck: Object.is
  }
});
const cache = new WeakMap();

/**
 * Type of a selector that take the whole tree view state as input and returns a value based on a required plugin.
 * @param {TreeViewState} state The state of the Tree View.
 * @returns {any | undefined} The value of the plugin state.
 */

/**
 * Type of a selector that take the whole tree view state as input and returns a value based on an optional plugin.
 *
 * @param {TreeViewState} state The state of the Tree View.
 * @returns {any | undefined} The value of the plugin state or undefined if the plugin is not registered.
 */

/**
 * Method wrapping reselect's createSelector to provide caching for tree view instances.
 *
 */
export const createSelector = (...createSelectorArgs) => {
  const selector = (state, selectorArgs) => {
    const cacheKey = state.cacheKey;

    // If there is no cache for the current tree view instance, create one.
    let cacheForCurrentTreeViewInstance = cache.get(cacheKey);
    if (!cacheForCurrentTreeViewInstance) {
      cacheForCurrentTreeViewInstance = new Map();
      cache.set(cacheKey, cacheForCurrentTreeViewInstance);
    }

    // If there is a cached selector, execute it.
    const cachedSelector = cacheForCurrentTreeViewInstance.get(createSelectorArgs);
    if (cachedSelector) {
      return cachedSelector(state, selectorArgs);
    }

    // Otherwise, create a new selector and cache it and execute it.
    const fn = reselectCreateSelector(...createSelectorArgs);
    cacheForCurrentTreeViewInstance.set(createSelectorArgs, fn);
    return fn(state, selectorArgs);
  };
  return selector;
};