/**

* Copyright (c) Facebook, Inc. and its affiliates.

*

* This source code is licensed under the MIT license found in the

* LICENSE file in the root directory of this source tree.

*/

/*

* 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.

*/

export default class ArraySet {

constructor() {

this.array = [];

this.set = new Map();

}

private array: Array<string>;

private set: Map<string, number>;

/**

* Add the given string to this set.

*/

public add(str: string, allowDuplicates?: boolean): void {

const isDuplicate = this.has(str);

const idx = this.array.length;

if (!isDuplicate || allowDuplicates === true) {

this.array.push(str);

}

if (!isDuplicate) {

this.set.set(str, idx);

}

}

/**

* Is the given string a member of this set?

*/

private has(str: string): boolean {

return this.set.has(str);

}

/**

* What is the index of the given string in the array?

*/

public indexOf(str: string): number {

const idx = this.set.get(str);

if (idx === undefined || idx < 0) {

throw new Error(`${str} is not in the set`);

}

return idx;

}

/**

* 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.

*/

public toArray(): Array<string> {

return this.array.slice();

}

}