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1/**2 * Mnemonist DefaultWeakMap3 * =========================4 *5 * JavaScript implementation of a default weak map that will return a constructed6 * value any time one tries to access an non-existing key. It is similar to7 * DefaultMap but uses ES6 WeakMap that only holds weak reference to keys.8 */9 10/**11 * DefaultWeakMap.12 *13 * @constructor14 */15function DefaultWeakMap(factory) {16  if (typeof factory !== 'function')17    throw new Error('mnemonist/DefaultWeakMap.constructor: expecting a function.');18 19  this.items = new WeakMap();20  this.factory = factory;21}22 23/**24 * Method used to clear the structure.25 *26 * @return {undefined}27 */28DefaultWeakMap.prototype.clear = function() {29 30  // Properties31  this.items = new WeakMap();32};33 34/**35 * Method used to get the value set for given key. If the key does not exist,36 * the value will be created using the provided factory.37 *38 * @param  {any} key - Target key.39 * @return {any}40 */41DefaultWeakMap.prototype.get = function(key) {42  var value = this.items.get(key);43 44  if (typeof value === 'undefined') {45    value = this.factory(key);46    this.items.set(key, value);47  }48 49  return value;50};51 52/**53 * Method used to get the value set for given key. If the key does not exist,54 * a value won't be created.55 *56 * @param  {any} key - Target key.57 * @return {any}58 */59DefaultWeakMap.prototype.peek = function(key) {60  return this.items.get(key);61};62 63/**64 * Method used to set a value for given key.65 *66 * @param  {any} key   - Target key.67 * @param  {any} value - Value.68 * @return {DefaultMap}69 */70DefaultWeakMap.prototype.set = function(key, value) {71  this.items.set(key, value);72  return this;73};74 75/**76 * Method used to test the existence of a key in the map.77 *78 * @param  {any} key   - Target key.79 * @return {boolean}80 */81DefaultWeakMap.prototype.has = function(key) {82  return this.items.has(key);83};84 85/**86 * Method used to delete target key.87 *88 * @param  {any} key   - Target key.89 * @return {boolean}90 */91DefaultWeakMap.prototype.delete = function(key) {92  return this.items.delete(key);93};94 95/**96 * Convenience known methods.97 */98DefaultWeakMap.prototype.inspect = function() {99  return this.items;100};101 102if (typeof Symbol !== 'undefined')103  DefaultWeakMap.prototype[Symbol.for('nodejs.util.inspect.custom')] = DefaultWeakMap.prototype.inspect;104 105/**106 * Exporting.107 */108module.exports = DefaultWeakMap;109