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122 lines
3.1 KiB
122 lines
3.1 KiB
/* -*- Mode: js; js-indent-level: 2; -*- */
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/*
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* Copyright 2011 Mozilla Foundation and contributors
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* Licensed under the New BSD license. See LICENSE or:
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* http://opensource.org/licenses/BSD-3-Clause
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*/
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var util = require('./util');
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var has = Object.prototype.hasOwnProperty;
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var hasNativeMap = typeof Map !== "undefined";
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/**
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* A data structure which is a combination of an array and a set. Adding a new
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* member is O(1), testing for membership is O(1), and finding the index of an
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* element is O(1). Removing elements from the set is not supported. Only
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* strings are supported for membership.
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*/
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function ArraySet() {
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this._array = [];
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this._set = hasNativeMap ? new Map() : Object.create(null);
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}
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/**
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* Static method for creating ArraySet instances from an existing array.
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*/
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ArraySet.fromArray = function ArraySet_fromArray(aArray, aAllowDuplicates) {
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var set = new ArraySet();
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for (var i = 0, len = aArray.length; i < len; i++) {
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set.add(aArray[i], aAllowDuplicates);
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}
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return set;
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};
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/**
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* Return how many unique items are in this ArraySet. If duplicates have been
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* added, than those do not count towards the size.
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*
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* @returns Number
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*/
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ArraySet.prototype.size = function ArraySet_size() {
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return hasNativeMap ? this._set.size : Object.getOwnPropertyNames(this._set).length;
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};
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/**
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* Add the given string to this set.
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*
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* @param String aStr
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*/
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ArraySet.prototype.add = function ArraySet_add(aStr, aAllowDuplicates) {
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var sStr = hasNativeMap ? aStr : util.toSetString(aStr);
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var isDuplicate = hasNativeMap ? this.has(aStr) : has.call(this._set, sStr);
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var idx = this._array.length;
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if (!isDuplicate || aAllowDuplicates) {
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this._array.push(aStr);
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}
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if (!isDuplicate) {
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if (hasNativeMap) {
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this._set.set(aStr, idx);
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} else {
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this._set[sStr] = idx;
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}
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}
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};
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/**
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* Is the given string a member of this set?
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*
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* @param String aStr
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*/
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ArraySet.prototype.has = function ArraySet_has(aStr) {
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if (hasNativeMap) {
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return this._set.has(aStr);
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} else {
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var sStr = util.toSetString(aStr);
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return has.call(this._set, sStr);
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}
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};
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/**
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* What is the index of the given string in the array?
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*
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* @param String aStr
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*/
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ArraySet.prototype.indexOf = function ArraySet_indexOf(aStr) {
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if (hasNativeMap) {
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var idx = this._set.get(aStr);
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if (idx >= 0) {
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return idx;
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}
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} else {
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var sStr = util.toSetString(aStr);
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if (has.call(this._set, sStr)) {
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return this._set[sStr];
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}
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}
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throw new Error('"' + aStr + '" is not in the set.');
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};
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/**
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* What is the element at the given index?
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*
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* @param Number aIdx
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*/
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ArraySet.prototype.at = function ArraySet_at(aIdx) {
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if (aIdx >= 0 && aIdx < this._array.length) {
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return this._array[aIdx];
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}
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throw new Error('No element indexed by ' + aIdx);
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};
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/**
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* Returns the array representation of this set (which has the proper indices
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* indicated by indexOf). Note that this is a copy of the internal array used
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* for storing the members so that no one can mess with internal state.
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*/
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ArraySet.prototype.toArray = function ArraySet_toArray() {
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return this._array.slice();
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};
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exports.ArraySet = ArraySet;
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