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1/**2 * Mnemonist DefaultMap3 * =====================4 *5 * JavaScript implementation of a default map that will return a constructed6 * value any time one tries to access an inexisting key. It's quite similar7 * to python's defaultdict.8 */9 10/**11 * DefaultMap.12 *13 * @constructor14 */15function DefaultMap(factory) {16  if (typeof factory !== 'function')17    throw new Error('mnemonist/DefaultMap.constructor: expecting a function.');18 19  this.items = new Map();20  this.factory = factory;21  this.size = 0;22}23 24/**25 * Method used to clear the structure.26 *27 * @return {undefined}28 */29DefaultMap.prototype.clear = function() {30 31  // Properties32  this.items.clear();33  this.size = 0;34};35 36/**37 * Method used to get the value set for given key. If the key does not exist,38 * the value will be created using the provided factory.39 *40 * @param  {any} key - Target key.41 * @return {any}42 */43DefaultMap.prototype.get = function(key) {44  var value = this.items.get(key);45 46  if (typeof value === 'undefined') {47    value = this.factory(key, this.size);48    this.items.set(key, value);49    this.size++;50  }51 52  return value;53};54 55/**56 * Method used to get the value set for given key. If the key does not exist,57 * a value won't be created.58 *59 * @param  {any} key - Target key.60 * @return {any}61 */62DefaultMap.prototype.peek = function(key) {63  return this.items.get(key);64};65 66/**67 * Method used to set a value for given key.68 *69 * @param  {any} key   - Target key.70 * @param  {any} value - Value.71 * @return {DefaultMap}72 */73DefaultMap.prototype.set = function(key, value) {74  this.items.set(key, value);75  this.size = this.items.size;76 77  return this;78};79 80/**81 * Method used to test the existence of a key in the map.82 *83 * @param  {any} key   - Target key.84 * @return {boolean}85 */86DefaultMap.prototype.has = function(key) {87  return this.items.has(key);88};89 90/**91 * Method used to delete target key.92 *93 * @param  {any} key   - Target key.94 * @return {boolean}95 */96DefaultMap.prototype.delete = function(key) {97  var deleted = this.items.delete(key);98 99  this.size = this.items.size;100 101  return deleted;102};103 104/**105 * Method used to iterate over each of the key/value pairs.106 *107 * @param  {function}  callback - Function to call for each item.108 * @param  {object}    scope    - Optional scope.109 * @return {undefined}110 */111DefaultMap.prototype.forEach = function(callback, scope) {112  scope = arguments.length > 1 ? scope : this;113 114  this.items.forEach(callback, scope);115};116 117/**118 * Iterators.119 */120DefaultMap.prototype.entries = function() {121  return this.items.entries();122};123 124DefaultMap.prototype.keys = function() {125  return this.items.keys();126};127 128DefaultMap.prototype.values = function() {129  return this.items.values();130};131 132/**133 * Attaching the #.entries method to Symbol.iterator if possible.134 */135if (typeof Symbol !== 'undefined')136  DefaultMap.prototype[Symbol.iterator] = DefaultMap.prototype.entries;137 138/**139 * Convenience known methods.140 */141DefaultMap.prototype.inspect = function() {142  return this.items;143};144 145if (typeof Symbol !== 'undefined')146  DefaultMap.prototype[Symbol.for('nodejs.util.inspect.custom')] = DefaultMap.prototype.inspect;147 148/**149 * Typical factories.150 */151DefaultMap.autoIncrement = function() {152  var i = 0;153 154  return function() {155    return i++;156  };157};158 159/**160 * Exporting.161 */162module.exports = DefaultMap;163