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backend/node_modules/mnemonist/default-map.js

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