Mini Shell

/**
 * lodash 3.1.2 (Custom Build) <https://lodash.com/>
 * Build: `lodash modern modularize exports="npm" -o ./`
 * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var getNative = require('lodash._getnative');

/** Native method references. */
var Set = getNative(global, 'Set');

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

/**
 *
 * Creates a cache object to store unique values.
 *
 * @private
 * @param {Array} [values] The values to cache.
 */
function SetCache(values) {
  var length = values ? values.length : 0;

  this.data = { 'hash': nativeCreate(null), 'set': new Set };
  while (length--) {
    this.push(values[length]);
  }
}

/**
 * Adds `value` to the cache.
 *
 * @private
 * @name push
 * @memberOf SetCache
 * @param {*} value The value to cache.
 */
function cachePush(value) {
  var data = this.data;
  if (typeof value == 'string' || isObject(value)) {
    data.set.add(value);
  } else {
    data.hash[value] = true;
  }
}

/**
 * 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`.
 */
function createCache(values) {
  return (nativeCreate && Set) ? new SetCache(values) : null;
}

/**
 * Checks if `value` is the [language type](https://es5.github.io/#x8) of `Object`.
 * (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an object, else `false`.
 * @example
 *
 * _.isObject({});
 * // => true
 *
 * _.isObject([1, 2, 3]);
 * // => true
 *
 * _.isObject(1);
 * // => false
 */
function isObject(value) {
  // Avoid a V8 JIT bug in Chrome 19-20.
  // See https://code.google.com/p/v8/issues/detail?id=2291 for more details.
  var type = typeof value;
  return !!value && (type == 'object' || type == 'function');
}

// Add functions to the `Set` cache.
SetCache.prototype.push = cachePush;

module.exports = createCache;