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backend/node_modules/mnemonist/fuzzy-map.js

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+/**
+ * Mnemonist Fuzzy Map
+ * ====================
+ *
+ * The fuzzy map is a map whose keys are processed by a function before
+ * read/write operations. This can often result in multiple keys accessing
+ * the same resource (example: a map with lowercased keys).
+ */
+var forEach = require('obliterator/foreach');
+
+var identity = function(x) {
+  return x;
+};
+
+/**
+ * FuzzyMap.
+ *
+ * @constructor
+ * @param {array|function} descriptor - Hash functions descriptor.
+ */
+function FuzzyMap(descriptor) {
+  this.items = new Map();
+  this.clear();
+
+  if (Array.isArray(descriptor)) {
+    this.writeHashFunction = descriptor[0];
+    this.readHashFunction = descriptor[1];
+  }
+  else {
+    this.writeHashFunction = descriptor;
+    this.readHashFunction = descriptor;
+  }
+
+  if (!this.writeHashFunction)
+    this.writeHashFunction = identity;
+  if (!this.readHashFunction)
+    this.readHashFunction = identity;
+
+  if (typeof this.writeHashFunction !== 'function')
+    throw new Error('mnemonist/FuzzyMap.constructor: invalid hash function given.');
+
+  if (typeof this.readHashFunction !== 'function')
+    throw new Error('mnemonist/FuzzyMap.constructor: invalid hash function given.');
+}
+
+/**
+ * Method used to clear the structure.
+ *
+ * @return {undefined}
+ */
+FuzzyMap.prototype.clear = function() {
+  this.items.clear();
+
+  // Properties
+  this.size = 0;
+};
+
+/**
+ * Method used to add an item to the FuzzyMap.
+ *
+ * @param  {any} item - Item to add.
+ * @return {FuzzyMap}
+ */
+FuzzyMap.prototype.add = function(item) {
+  var key = this.writeHashFunction(item);
+
+  this.items.set(key, item);
+  this.size = this.items.size;
+
+  return this;
+};
+
+/**
+ * Method used to set an item in the FuzzyMap using the given key.
+ *
+ * @param  {any} key  - Key to use.
+ * @param  {any} item - Item to add.
+ * @return {FuzzyMap}
+ */
+FuzzyMap.prototype.set = function(key, item) {
+  key = this.writeHashFunction(key);
+
+  this.items.set(key, item);
+  this.size = this.items.size;
+
+  return this;
+};
+
+/**
+ * Method used to retrieve an item from the FuzzyMap.
+ *
+ * @param  {any} key - Key to use.
+ * @return {any}
+ */
+FuzzyMap.prototype.get = function(key) {
+  key = this.readHashFunction(key);
+
+  return this.items.get(key);
+};
+
+/**
+ * Method used to test the existence of an item in the map.
+ *
+ * @param  {any} key - Key to check.
+ * @return {boolean}
+ */
+FuzzyMap.prototype.has = function(key) {
+  key = this.readHashFunction(key);
+
+  return this.items.has(key);
+};
+
+/**
+ * Method used to iterate over each of the FuzzyMap's values.
+ *
+ * @param  {function}  callback - Function to call for each item.
+ * @param  {object}    scope    - Optional scope.
+ * @return {undefined}
+ */
+FuzzyMap.prototype.forEach = function(callback, scope) {
+  scope = arguments.length > 1 ? scope : this;
+
+  this.items.forEach(function(value) {
+    callback.call(scope, value, value);
+  });
+};
+
+/**
+ * Method returning an iterator over the FuzzyMap's values.
+ *
+ * @return {FuzzyMapIterator}
+ */
+FuzzyMap.prototype.values = function() {
+  return this.items.values();
+};
+
+/**
+ * Attaching the #.values method to Symbol.iterator if possible.
+ */
+if (typeof Symbol !== 'undefined')
+  FuzzyMap.prototype[Symbol.iterator] = FuzzyMap.prototype.values;
+
+/**
+ * Convenience known method.
+ */
+FuzzyMap.prototype.inspect = function() {
+  var array = Array.from(this.items.values());
+
+  Object.defineProperty(array, 'constructor', {
+    value: FuzzyMap,
+    enumerable: false
+  });
+
+  return array;
+};
+
+if (typeof Symbol !== 'undefined')
+  FuzzyMap.prototype[Symbol.for('nodejs.util.inspect.custom')] = FuzzyMap.prototype.inspect;
+
+/**
+ * Static @.from function taking an arbitrary iterable & converting it into
+ * a structure.
+ *
+ * @param  {Iterable}       iterable   - Target iterable.
+ * @param  {array|function} descriptor - Hash functions descriptor.
+ * @param  {boolean}        useSet     - Whether to use #.set or #.add
+ * @return {FuzzyMap}
+ */
+FuzzyMap.from = function(iterable, descriptor, useSet) {
+  var map = new FuzzyMap(descriptor);
+
+  forEach(iterable, function(value, key) {
+    if (useSet)
+      map.set(key, value);
+    else
+      map.add(value);
+  });
+
+  return map;
+};
+
+/**
+ * Exporting.
+ */
+module.exports = FuzzyMap;