1 /* -*- Mode: js; js-indent-level: 2; -*- */
3 * Copyright 2011 Mozilla Foundation and contributors
4 * Licensed under the New BSD license. See LICENSE or:
5 * http://opensource.org/licenses/BSD-3-Clause
8 var util = require('./util');
9 var has = Object.prototype.hasOwnProperty;
10 var hasNativeMap = typeof Map !== "undefined";
13 * A data structure which is a combination of an array and a set. Adding a new
14 * member is O(1), testing for membership is O(1), and finding the index of an
15 * element is O(1). Removing elements from the set is not supported. Only
16 * strings are supported for membership.
20 this._set = hasNativeMap ? new Map() : Object.create(null);
24 * Static method for creating ArraySet instances from an existing array.
26 ArraySet.fromArray = function ArraySet_fromArray(aArray, aAllowDuplicates) {
27 var set = new ArraySet();
28 for (var i = 0, len = aArray.length; i < len; i++) {
29 set.add(aArray[i], aAllowDuplicates);
35 * Return how many unique items are in this ArraySet. If duplicates have been
36 * added, than those do not count towards the size.
40 ArraySet.prototype.size = function ArraySet_size() {
41 return hasNativeMap ? this._set.size : Object.getOwnPropertyNames(this._set).length;
45 * Add the given string to this set.
49 ArraySet.prototype.add = function ArraySet_add(aStr, aAllowDuplicates) {
50 var sStr = hasNativeMap ? aStr : util.toSetString(aStr);
51 var isDuplicate = hasNativeMap ? this.has(aStr) : has.call(this._set, sStr);
52 var idx = this._array.length;
53 if (!isDuplicate || aAllowDuplicates) {
54 this._array.push(aStr);
58 this._set.set(aStr, idx);
60 this._set[sStr] = idx;
66 * Is the given string a member of this set?
70 ArraySet.prototype.has = function ArraySet_has(aStr) {
72 return this._set.has(aStr);
74 var sStr = util.toSetString(aStr);
75 return has.call(this._set, sStr);
80 * What is the index of the given string in the array?
84 ArraySet.prototype.indexOf = function ArraySet_indexOf(aStr) {
86 var idx = this._set.get(aStr);
91 var sStr = util.toSetString(aStr);
92 if (has.call(this._set, sStr)) {
93 return this._set[sStr];
97 throw new Error('"' + aStr + '" is not in the set.');
101 * What is the element at the given index?
105 ArraySet.prototype.at = function ArraySet_at(aIdx) {
106 if (aIdx >= 0 && aIdx < this._array.length) {
107 return this._array[aIdx];
109 throw new Error('No element indexed by ' + aIdx);
113 * Returns the array representation of this set (which has the proper indices
114 * indicated by indexOf). Note that this is a copy of the internal array used
115 * for storing the members so that no one can mess with internal state.
117 ArraySet.prototype.toArray = function ArraySet_toArray() {
118 return this._array.slice();
121 exports.ArraySet = ArraySet;