sequence-js/src/equality-set.ts

import { Equater, MaybeAsyncEquater } from "./types.js";

export interface EqualitySet<T> extends Iterable<T> {
  readonly size: number;
  add(obj: T): boolean;
  contains(obj: T): boolean;
  remove(obj: T): boolean;
  clear(): void;
  values(): IterableIterator<T>;
}

class NativeEqualitySet<T> implements EqualitySet<T> {
  readonly #set = new Set<T>();

  get size() {
    return this.#set.size;
  }

  add(obj: T) {
    const exists = this.contains(obj);
    this.#set.add(obj);
    return !exists;
  }

  contains(obj: T) {
    return this.#set.has(obj);
  }

  remove(obj: T) {
    return this.#set.delete(obj);
  }

  clear() {
    this.#set.clear();
  }

  values() {
    return this.#set.values();
  }

  [Symbol.iterator]() {
    return this.#set[Symbol.iterator]();
  }
}

class CustomEqualitySet<T> implements EqualitySet<T> {
  readonly #list: T[] = [];
  readonly #equater: Equater<T>;

  constructor(equater: Equater<T>) {
    this.#equater = equater;
  }

  get size() {
    return this.#list.length;
  }

  add(obj: T) {
    if (this.contains(obj)) {
      return false;
    }

    this.#list.push(obj);

    return true;
  }

  contains(obj: T) {
    for (const val of this.#list) {
      if (this.#equater(obj, val)) {
        return true;
      }
    }

    return false;
  }

  remove(obj: T) {
    const length = this.#list.length;

    for (let i = 0; i < length; i++) {
      if (this.#equater(obj, this.#list[i])) {
        this.#list.splice(i, 1);
        return true;
      }
    }

    return false;
  }

  clear() {
    this.#list.length = 0;
  }

  values() {
    return this[Symbol.iterator]();
  }

  [Symbol.iterator]() {
    return this.#list[Symbol.iterator]();
  }
}

export function createEqualitySet<T>(equater?: Equater<T>): EqualitySet<T> {
  return equater ? new CustomEqualitySet(equater) : new NativeEqualitySet<T>();
}

export interface AsyncEqualitySet<T> extends Iterable<T> {
  readonly size: number;
  add(obj: T): Promise<boolean>;
  contains(obj: T): Promise<boolean>;
  remove(obj: T): Promise<boolean>;
  clear(): void;
  values(): IterableIterator<T>;
}

class NativeAsyncEqualitySet<T> implements AsyncEqualitySet<T> {
  readonly #set = new Set<T>();

  get size() {
    return this.#set.size;
  }

  async add(obj: T) {
    const exists = await this.contains(obj);
    this.#set.add(obj);
    return !exists;
  }

  async contains(obj: T) {
    return this.#set.has(obj);
  }

  async remove(obj: T) {
    return this.#set.delete(obj);
  }

  clear() {
    this.#set.clear();
  }

  values() {
    return this.#set.values();
  }

  [Symbol.iterator]() {
    return this.#set[Symbol.iterator]();
  }
}

class CustomAsyncEqualitySet<T> implements AsyncEqualitySet<T> {
  readonly #list: T[] = [];
  readonly #equater: MaybeAsyncEquater<T>;

  constructor(equater: MaybeAsyncEquater<T>) {
    this.#equater = equater;
  }

  get size() {
    return this.#list.length;
  }

  async add(obj: T) {
    if (await this.contains(obj)) {
      return false;
    }

    this.#list.push(obj);

    return true;
  }

  async contains(obj: T) {
    for (const val of this.#list) {
      if (await this.#equater(obj, val)) {
        return true;
      }
    }

    return false;
  }

  async remove(obj: T) {
    const length = this.#list.length;

    for (let i = 0; i < length; i++) {
      if (await this.#equater(obj, this.#list[i])) {
        this.#list.splice(i, 1);
        return true;
      }
    }

    return false;
  }

  clear() {
    this.#list.length = 0;
  }

  values() {
    return this[Symbol.iterator]();
  }

  [Symbol.iterator]() {
    return this.#list[Symbol.iterator]();
  }
}

export function createAsyncEqualitySet<T>(equater?: MaybeAsyncEquater<T>): AsyncEqualitySet<T> {
  return equater ? new CustomAsyncEqualitySet(equater) : new NativeAsyncEqualitySet<T>();
}