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'use strict';
/** * MongoDB throws an error if there's unused array filters. That is, if `options.arrayFilters` defines * a filter, but none of the `update` keys use it. This should be enough to filter out all unused array * filters. */
module.exports = function removeUnusedArrayFilters(update, arrayFilters) {  const updateKeys = Object.keys(update).    map(key => Object.keys(update[key])).    reduce((cur, arr) => cur.concat(arr), []);  return arrayFilters.filter(obj => {    return _checkSingleFilterKey(obj, updateKeys);  });};
function _checkSingleFilterKey(arrayFilter, updateKeys) {  const firstKey = Object.keys(arrayFilter)[0];
  if (firstKey === '$and' || firstKey === '$or') {    if (!Array.isArray(arrayFilter[firstKey])) {      return false;    }    return arrayFilter[firstKey].find(filter => _checkSingleFilterKey(filter, updateKeys)) != null;  }
  const firstDot = firstKey.indexOf('.');  const arrayFilterKey = firstDot === -1 ? firstKey : firstKey.slice(0, firstDot);
  return updateKeys.find(key => key.includes('$[' + arrayFilterKey + ']')) != null;}