utils: add map.

lib/utils/map.js

@@ -0,0 +1,124 @@
+/*!
+ * map.js - hash table for bcoin
+ * Copyright (c) 2014-2016, Christopher Jeffrey (MIT License).
+ * https://github.com/bcoin-org/bcoin
+ */
+
+'use strict';
+
+var assert = require('assert');
+
+/**
+ * Map
+ * @constructor
+ */
+
+function Map() {
+  if (!(this instanceof Map))
+    return new Map();
+
+  this.map = {};
+  this.size = 0;
+}
+
+/**
+ * Get map keys.
+ * @returns {String[]}
+ */
+
+Map.prototype.keys = function keys() {
+  return Object.keys(this.map);
+};
+
+/**
+ * Get map values.
+ * @returns {Object[]}
+ */
+
+Map.prototype.values = function values() {
+  var keys = Object.keys(this.map);
+  var values = [];
+  var i, key;
+
+  for (i = 0; i < keys.length; i++) {
+    key = keys[i];
+    values.push(this.map[key]);
+  }
+
+  return values;
+};
+
+/**
+ * Get item from map.
+ * @param {String} key
+ * @returns {Object|null}
+ */
+
+Map.prototype.get = function get(key) {
+  return this.map[key];
+};
+
+/**
+ * Test whether map has an item.
+ * @param {String} key
+ * @returns {Boolean}
+ */
+
+Map.prototype.has = function has(key) {
+  return this.map[key] !== undefined;
+};
+
+/**
+ * Set a key to value in map.
+ * @param {String} key
+ * @param {Object} value
+ * @returns {Boolean}
+ */
+
+Map.prototype.set = function set(key, value) {
+  var item = this.map[key];
+
+  assert(value !== undefined);
+
+  this.map[key] = value;
+
+  if (item === undefined) {
+    this.size++;
+    return true;
+  }
+
+  return false;
+};
+
+/**
+ * Remove an item from map.
+ * @param {String} key
+ * @returns {Object|null}
+ */
+
+Map.prototype.remove = function remove(key) {
+  var item = this.map[key];
+
+  if (item === undefined)
+    return;
+
+  delete this.map[key];
+  this.size--;
+
+  return item;
+};
+
+/**
+ * Reset the map.
+ */
+
+Map.prototype.reset = function reset() {
+  this.map = {};
+  this.size = 0;
+};
+
+/*
+ * Expose
+ */
+
+module.exports = Map;