lodash/lodash._stack/index.js

/**
 * lodash 4.0.2 (Custom Build) <https://lodash.com/>
 * Build: `lodash modularize exports="npm" -o ./`
 * Copyright 2012-2016 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2016 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var MapCache = require('lodash._mapcache');

/** Used as the size to enable large array optimizations. */
var LARGE_ARRAY_SIZE = 200;

/** Used for built-in method references. */
var arrayProto = Array.prototype;

/** Built-in value references. */
var splice = arrayProto.splice;

/**
 * Creates a stack cache object to store key-value pairs.
 *
 * @private
 * @constructor
 * @param {Array} [values] The values to cache.
 */
function Stack(values) {
  var index = -1,
      length = values ? values.length : 0;

  this.clear();
  while (++index < length) {
    var entry = values[index];
    this.set(entry[0], entry[1]);
  }
}

/**
 * Removes all key-value entries from the stack.
 *
 * @private
 * @name clear
 * @memberOf Stack
 */
function stackClear() {
  this.__data__ = { 'array': [], 'map': null };
}

/**
 * Removes `key` and its value from the stack.
 *
 * @private
 * @name delete
 * @memberOf Stack
 * @param {string} key The key of the value to remove.
 * @returns {boolean} Returns `true` if the entry was removed, else `false`.
 */
function stackDelete(key) {
  var data = this.__data__,
      array = data.array;

  return array ? assocDelete(array, key) : data.map['delete'](key);
}

/**
 * Gets the stack value for `key`.
 *
 * @private
 * @name get
 * @memberOf Stack
 * @param {string} key The key of the value to get.
 * @returns {*} Returns the entry value.
 */
function stackGet(key) {
  var data = this.__data__,
      array = data.array;

  return array ? assocGet(array, key) : data.map.get(key);
}

/**
 * Checks if a stack value for `key` exists.
 *
 * @private
 * @name has
 * @memberOf Stack
 * @param {string} key The key of the entry to check.
 * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
 */
function stackHas(key) {
  var data = this.__data__,
      array = data.array;

  return array ? assocHas(array, key) : data.map.has(key);
}

/**
 * Sets the stack `key` to `value`.
 *
 * @private
 * @name set
 * @memberOf Stack
 * @param {string} key The key of the value to set.
 * @param {*} value The value to set.
 * @returns {Object} Returns the stack cache object.
 */
function stackSet(key, value) {
  var data = this.__data__,
      array = data.array;

  if (array) {
    if (array.length < (LARGE_ARRAY_SIZE - 1)) {
      assocSet(array, key, value);
    } else {
      data.array = null;
      data.map = new MapCache(array);
    }
  }
  var map = data.map;
  if (map) {
    map.set(key, value);
  }
  return this;
}

/**
 * Removes `key` and its value from the associative array.
 *
 * @private
 * @param {Array} array The array to query.
 * @param {string} key The key of the value to remove.
 * @returns {boolean} Returns `true` if the entry was removed, else `false`.
 */
function assocDelete(array, key) {
  var index = assocIndexOf(array, key);
  if (index < 0) {
    return false;
  }
  var lastIndex = array.length - 1;
  if (index == lastIndex) {
    array.pop();
  } else {
    splice.call(array, index, 1);
  }
  return true;
}

/**
 * Gets the associative array value for `key`.
 *
 * @private
 * @param {Array} array The array to query.
 * @param {string} key The key of the value to get.
 * @returns {*} Returns the entry value.
 */
function assocGet(array, key) {
  var index = assocIndexOf(array, key);
  return index < 0 ? undefined : array[index][1];
}

/**
 * Checks if an associative array value for `key` exists.
 *
 * @private
 * @param {Array} array The array to query.
 * @param {string} key The key of the entry to check.
 * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
 */
function assocHas(array, key) {
  return assocIndexOf(array, key) > -1;
}

/**
 * Gets the index at which the first occurrence of `key` is found in `array`
 * of key-value pairs.
 *
 * @private
 * @param {Array} array The array to search.
 * @param {*} key The key to search for.
 * @returns {number} Returns the index of the matched value, else `-1`.
 */
function assocIndexOf(array, key) {
  var length = array.length;
  while (length--) {
    if (eq(array[length][0], key)) {
      return length;
    }
  }
  return -1;
}

/**
 * Sets the associative array `key` to `value`.
 *
 * @private
 * @param {Array} array The array to modify.
 * @param {string} key The key of the value to set.
 * @param {*} value The value to set.
 */
function assocSet(array, key, value) {
  var index = assocIndexOf(array, key);
  if (index < 0) {
    array.push([key, value]);
  } else {
    array[index][1] = value;
  }
}

/**
 * Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/6.0/#sec-samevaluezero)
 * comparison between two values to determine if they are equivalent.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to compare.
 * @param {*} other The other value to compare.
 * @returns {boolean} Returns `true` if the values are equivalent, else `false`.
 * @example
 *
 * var object = { 'user': 'fred' };
 * var other = { 'user': 'fred' };
 *
 * _.eq(object, object);
 * // => true
 *
 * _.eq(object, other);
 * // => false
 *
 * _.eq('a', 'a');
 * // => true
 *
 * _.eq('a', Object('a'));
 * // => false
 *
 * _.eq(NaN, NaN);
 * // => true
 */
function eq(value, other) {
  return value === other || (value !== value && other !== other);
}

// Add functions to the `Stack` cache.
Stack.prototype.clear = stackClear;
Stack.prototype['delete'] = stackDelete;
Stack.prototype.get = stackGet;
Stack.prototype.has = stackHas;
Stack.prototype.set = stackSet;

module.exports = Stack;