package.lib.array-set.js Maven / Gradle / Ivy
/* -*- 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
*/
var util = require('./util');
var has = Object.prototype.hasOwnProperty;
var hasNativeMap = typeof Map !== "undefined";
/**
* 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.
*/
function ArraySet() {
this._array = [];
this._set = hasNativeMap ? new Map() : Object.create(null);
}
/**
* Static method for creating ArraySet instances from an existing array.
*/
ArraySet.fromArray = function ArraySet_fromArray(aArray, aAllowDuplicates) {
var set = new ArraySet();
for (var 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
*/
ArraySet.prototype.size = function ArraySet_size() {
return hasNativeMap ? this._set.size : Object.getOwnPropertyNames(this._set).length;
};
/**
* Add the given string to this set.
*
* @param String aStr
*/
ArraySet.prototype.add = function ArraySet_add(aStr, aAllowDuplicates) {
var sStr = hasNativeMap ? aStr : util.toSetString(aStr);
var isDuplicate = hasNativeMap ? this.has(aStr) : has.call(this._set, sStr);
var idx = this._array.length;
if (!isDuplicate || aAllowDuplicates) {
this._array.push(aStr);
}
if (!isDuplicate) {
if (hasNativeMap) {
this._set.set(aStr, idx);
} else {
this._set[sStr] = idx;
}
}
};
/**
* Is the given string a member of this set?
*
* @param String aStr
*/
ArraySet.prototype.has = function ArraySet_has(aStr) {
if (hasNativeMap) {
return this._set.has(aStr);
} else {
var sStr = util.toSetString(aStr);
return has.call(this._set, sStr);
}
};
/**
* What is the index of the given string in the array?
*
* @param String aStr
*/
ArraySet.prototype.indexOf = function ArraySet_indexOf(aStr) {
if (hasNativeMap) {
var idx = this._set.get(aStr);
if (idx >= 0) {
return idx;
}
} else {
var sStr = util.toSetString(aStr);
if (has.call(this._set, sStr)) {
return this._set[sStr];
}
}
throw new Error('"' + aStr + '" is not in the set.');
};
/**
* What is the element at the given index?
*
* @param Number aIdx
*/
ArraySet.prototype.at = function ArraySet_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.
*/
ArraySet.prototype.toArray = function ArraySet_toArray() {
return this._array.slice();
};
exports.ArraySet = ArraySet;