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					163 lines
				
				3.2 KiB
			
		
		
			
		
	
	
					163 lines
				
				3.2 KiB
			| 
								 
											3 years ago
										 
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								/**
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								 * Mnemonist DefaultMap
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								 * =====================
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								 *
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								 * JavaScript implementation of a default map that will return a constructed
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								 * value any time one tries to access an inexisting key. It's quite similar
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								 * to python's defaultdict.
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								 */
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								/**
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								 * DefaultMap.
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								 *
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								 * @constructor
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								 */
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								function DefaultMap(factory) {
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								  if (typeof factory !== 'function')
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								    throw new Error('mnemonist/DefaultMap.constructor: expecting a function.');
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								  this.items = new Map();
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								  this.factory = factory;
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								  this.size = 0;
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								}
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								/**
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								 * Method used to clear the structure.
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								 *
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								 * @return {undefined}
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								 */
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								DefaultMap.prototype.clear = function() {
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								  // Properties
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								  this.items.clear();
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								  this.size = 0;
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								};
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								/**
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								 * Method used to get the value set for given key. If the key does not exist,
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								 * the value will be created using the provided factory.
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								 *
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								 * @param  {any} key - Target key.
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								 * @return {any}
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								 */
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								DefaultMap.prototype.get = function(key) {
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								  var value = this.items.get(key);
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								  if (typeof value === 'undefined') {
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								    value = this.factory(key, this.size);
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								    this.items.set(key, value);
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								    this.size++;
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								  }
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								  return value;
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								};
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								/**
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								 * Method used to get the value set for given key. If the key does not exist,
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								 * a value won't be created.
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								 *
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								 * @param  {any} key - Target key.
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								 * @return {any}
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								 */
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								DefaultMap.prototype.peek = function(key) {
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								  return this.items.get(key);
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								};
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								/**
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								 * Method used to set a value for given key.
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								 *
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								 * @param  {any} key   - Target key.
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								 * @param  {any} value - Value.
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								 * @return {DefaultMap}
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								 */
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								DefaultMap.prototype.set = function(key, value) {
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								  this.items.set(key, value);
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								  this.size = this.items.size;
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								  return this;
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								};
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								/**
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								 * Method used to test the existence of a key in the map.
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								 *
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								 * @param  {any} key   - Target key.
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								 * @return {boolean}
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								 */
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								DefaultMap.prototype.has = function(key) {
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								  return this.items.has(key);
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								};
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								/**
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								 * Method used to delete target key.
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								 *
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								 * @param  {any} key   - Target key.
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								 * @return {boolean}
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								 */
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								DefaultMap.prototype.delete = function(key) {
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								  var deleted = this.items.delete(key);
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								  this.size = this.items.size;
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								  return deleted;
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								};
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								/**
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								 * Method used to iterate over each of the key/value pairs.
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								 *
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								 * @param  {function}  callback - Function to call for each item.
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								 * @param  {object}    scope    - Optional scope.
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								 * @return {undefined}
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								 */
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								DefaultMap.prototype.forEach = function(callback, scope) {
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								  scope = arguments.length > 1 ? scope : this;
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								  this.items.forEach(callback, scope);
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								};
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								/**
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								 * Iterators.
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								 */
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								DefaultMap.prototype.entries = function() {
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								  return this.items.entries();
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								};
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								DefaultMap.prototype.keys = function() {
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								  return this.items.keys();
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								};
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								DefaultMap.prototype.values = function() {
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								  return this.items.values();
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								};
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								/**
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								 * Attaching the #.entries method to Symbol.iterator if possible.
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								 */
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								if (typeof Symbol !== 'undefined')
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								  DefaultMap.prototype[Symbol.iterator] = DefaultMap.prototype.entries;
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								/**
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								 * Convenience known methods.
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								 */
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								DefaultMap.prototype.inspect = function() {
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								  return this.items;
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								};
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								if (typeof Symbol !== 'undefined')
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								  DefaultMap.prototype[Symbol.for('nodejs.util.inspect.custom')] = DefaultMap.prototype.inspect;
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								/**
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								 * Typical factories.
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								 */
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								DefaultMap.autoIncrement = function() {
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								  var i = 0;
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								  return function() {
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								    return i++;
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								  };
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								};
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								/**
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								 * Exporting.
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								 */
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								module.exports = DefaultMap;
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