draft-js/lib/findRangesImmutable.js

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 * 
 * @emails oncall+draft_js
 */
'use strict';

/**
 * Search through an array to find contiguous stretches of elements that
 * match a specified filter function.
 *
 * When ranges are found, execute a specified `found` function to supply
 * the values to the caller.
 */
function findRangesImmutable(haystack, areEqualFn, filterFn, foundFn) {
  if (!haystack.size) {
    return;
  }

  var cursor = 0;
  haystack.reduce(function (value, nextValue, nextIndex) {
    if (!areEqualFn(value, nextValue)) {
      if (filterFn(value)) {
        foundFn(cursor, nextIndex);
      }

      cursor = nextIndex;
    }

    return nextValue;
  });
  filterFn(haystack.last()) && foundFn(cursor, haystack.count());
}

module.exports = findRangesImmutable;