lodash/internal/createCache.js

import SetCache from './SetCache';
import constant from '../utility/constant';
import isNative from '../lang/isNative';
import root from './root';

/** Native method references. */
var Set = isNative(Set = root.Set) && Set;

/* Native method references for those with the same name as other `lodash` methods. */
var nativeCreate = isNative(nativeCreate = Object.create) && nativeCreate;

/**
 * Creates a `Set` cache object to optimize linear searches of large arrays.
 *
 * @private
 * @param {Array} [values] The values to cache.
 * @returns {null|Object} Returns the new cache object if `Set` is supported, else `null`.
 */
var createCache = !(nativeCreate && Set) ? constant(null) : function(values) {
  return new SetCache(values);
};

export default createCache;