Adding MultiIndex

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## 0.10.0
 
 * Adding `Index`.
+* Adding `MultiIndex`.
 * Adding `MultiMap`.
 * Adding `MultiSet`.
 * Adding `SymSpell`.

README.md

@@ -28,6 +28,7 @@ Full documentation for the library can be found [here](https://yomguithereal.git
 * [Heap](https://yomguithereal.github.io/mnemonist/heap)
 * [Index](https://yomguithereal.github.io/mnemonist/index-structure)
 * [Linked List](https://yomguithereal.github.io/mnemonist/linked-list)
+* [MultiIndex](https://yomguithereal.github.io/mnemonist/multi-index)
 * [MultiMap](https://yomguithereal.github.io/mnemonist/multi-map)
 * [MultiSet](https://yomguithereal.github.io/mnemonist/multi-set)
 * [Queue](https://yomguithereal.github.io/mnemonist/queue)

endpoint.js

@@ -20,6 +20,7 @@ module.exports = {
   MaxHeap: Heap.MaxHeap,
   Index: require('./index.js'),
   LinkedList: require('./linked-list.js'),
+  MultiIndex: require('./multi-index.js'),
   MultiMap: require('./multi-map.js'),
   MultiSet: require('./multi-set.js'),
   Queue: require('./queue.js'),

index.js

@@ -1,6 +1,6 @@
 /**
  * Mnemonist Index
- * ====================
+ * ================
  *
  * The Index is basically an abstract HashMap where given keys or items
  * are hashed by a function to produce a specific key so that one may

multi-index.js

@@ -0,0 +1,193 @@
+/**
+ * Mnemonist MultiIndex
+ * =====================
+ *
+ * Same as the index but relying on a MultiMap rather than a Map.
+ */
+var MultiMap = require('./multi-map.js'),
+    iterateOver = require('./utils/iterate.js');
+
+var identity = function(x) {
+  return x;
+};
+
+/**
+ * MultiIndex.
+ *
+ * @constructor
+ * @param {array|function} descriptor - Hash functions descriptor.
+ * @param {function}       Container  - Container to use.
+ */
+function MultiIndex(descriptor, Container) {
+  this.items = new MultiMap(Container);
+  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/MultiIndex.constructor: invalid hash function given.');
+
+  if (typeof this.readHashFunction !== 'function')
+    throw new Error('mnemonist/MultiIndex.constructor: invalid hash function given.');
+}
+
+/**
+ * Method used to clear the structure.
+ *
+ * @return {undefined}
+ */
+MultiIndex.prototype.clear = function() {
+  this.items.clear();
+
+  // Properties
+  this.size = 0;
+};
+
+/**
+ * Method used to add an item to the index.
+ *
+ * @param  {any} item - Item to add.
+ * @return {MultiIndex}
+ */
+MultiIndex.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 index using the given key.
+ *
+ * @param  {any} key  - Key to use.
+ * @param  {any} item - Item to add.
+ * @return {MultiIndex}
+ */
+MultiIndex.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 index.
+ *
+ * @param  {any} key - Key to use.
+ * @return {MultiIndex}
+ */
+MultiIndex.prototype.get = function(key) {
+  key = this.readHashFunction(key);
+
+  return this.items.get(key);
+};
+
+/**
+ * Method used to iterate over each of the index's values.
+ *
+ * @param  {function}  callback - Function to call for each item.
+ * @param  {object}    scope    - Optional scope.
+ * @return {undefined}
+ */
+MultiIndex.prototype.forEach = function(callback, scope) {
+  scope = arguments.length > 1 ? scope : this;
+
+  this.items.forEach(function(value) {
+    callback.call(scope, value, value);
+  });
+};
+
+
+/**
+ * MultiIndex Iterator class.
+ */
+function MultiIndexIterator(next) {
+  this.next = next;
+}
+
+/**
+ * Method returning an iterator over the index's values.
+ *
+ * @return {MultiIndexIterator}
+ */
+MultiIndex.prototype.values = function() {
+  var iterator = this.items.values();
+
+  Object.defineProperty(iterator, 'constructor', {
+    value: MultiIndexIterator,
+    enumerable: false
+  });
+
+  return iterator;
+};
+
+/**
+ * Attaching the #.values method to Symbol.iterator if possible.
+ */
+if (typeof Symbol !== 'undefined')
+  MultiIndex.prototype[Symbol.iterator] = MultiIndex.prototype.values;
+
+/**
+ * Convenience known method.
+ */
+MultiIndex.prototype.inspect = function() {
+  var array = Array.from(this);
+
+  Object.defineProperty(array, 'constructor', {
+    value: MultiIndex,
+    enumerable: false
+  });
+
+  return array;
+};
+
+/**
+ * Static @.from function taking an abitrary iterable & converting it into
+ * a structure.
+ *
+ * @param  {Iterable}       iterable   - Target iterable.
+ * @param  {array|function} descriptor - Hash functions descriptor.
+ * @param  {function}       Container  - Container to use.
+ * @param  {boolean}        useSet     - Whether to use #.set or #.add
+ * @return {MultiIndex}
+ */
+MultiIndex.from = function(iterable, descriptor, Container, useSet) {
+  if (arguments.length === 3) {
+    if (typeof Container === 'boolean') {
+      useSet = Container;
+      Container = Array;
+    }
+  }
+
+  var index = new MultiIndex(descriptor, Container);
+
+  iterateOver(iterable, function(value, key) {
+    if (useSet)
+      index.set(key, value);
+    else
+      index.add(value);
+  });
+
+  return index;
+};
+
+/**
+ * Exporting.
+ */
+module.exports = MultiIndex;