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