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163 lines
3.2 KiB
163 lines
3.2 KiB
/**
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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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