@jumpaku/async-result/src/AsyncResult.ts

A typescript library that provides Result, Option, and AsyncResult.

import { Result } from "./Result";

export class AsyncResult<V, E> implements PromiseLike<Result<V, E>> {
  static of<V, E>(result: Result<V, E>): AsyncResult<V, E>;
  static of<V, E>(result: Promise<Result<V, E>>): AsyncResult<V, unknown>;
  static of<V, E, F>(
    result: Promise<Result<V, E>>,
    catchFun: (error: unknown) => F
  ): AsyncResult<V, E | F>;
  static of<V, E, F>(
    result: Result<V, E> | Promise<Result<V, E>>,
    catchFun?: (error: unknown) => F
  ): AsyncResult<V, E | F | unknown> {
    if (Result.isResult(result))
      return new AsyncResult(Promise.resolve(result));
    return catchFun == null
      ? new AsyncResult(result.catch((error: unknown) => Result.failure(error)))
      : new AsyncResult<V, E | F>(
          result.catch((error: unknown) => Result.failure(catchFun(error)))
        );
  }
  static make<V, E>(
    neverThrowExecutor: (
      success: (value: V) => void,
      failure: (error: E) => void
    ) => void
  ): AsyncResult<V, E> {
    return AsyncResult.of(
      new Promise<Result<V, E>>((resolve) =>
        neverThrowExecutor(
          (v: V) => resolve(Result.success(v)),
          (e: E) => resolve(Result.failure(e))
        )
      ),
      (e) => e as E
    );
  }
  static success<V>(v: V): AsyncResult<V, never> {
    return AsyncResult.of(Result.success(v));
  }
  static failure<E>(e: E): AsyncResult<never, E> {
    return AsyncResult.of(Result.failure(e));
  }
  static try<V>(tryFun: () => V | Promise<V>): AsyncResult<V, unknown>;
  static try<V, E>(
    tryFun: () => V | Promise<V>,
    catchFun: (e: unknown) => E
  ): AsyncResult<V, E>;
  static try<V, E>(
    tryFun: () => V | Promise<V>,
    catchFun?: (e: unknown) => E
  ): AsyncResult<V, E | unknown> {
    const promise = new Promise<V>((resolve, reject) => {
      try {
        resolve(tryFun());
      } catch (error) {
        reject(error);
      }
    }).then(Result.success);
    return catchFun == null
      ? AsyncResult.of(promise)
      : AsyncResult.of(promise, catchFun);
  }

  private constructor(readonly promise: Promise<Result<V, E>>) {}

  then<TResult1 = Result<V, E>, TResult2 = never>(
    onfulfilled?:
      | ((value: Result<V, E>) => TResult1 | PromiseLike<TResult1>)
      | undefined
      | null,
    onrejected?:
      | ((reason: unknown) => TResult2 | PromiseLike<TResult2>)
      | undefined
      | null
  ): Promise<TResult1 | TResult2> {
    return this.promise.then(onfulfilled, onrejected);
  }

  match<X, Y>(
    onSuccess: (value: V) => X,
    onFailure: (error: E) => Y
  ): Promise<X | Y> {
    return this.promise.then((result) => result.match(onSuccess, onFailure));
  }
  value(): Promise<V | undefined> {
    return this.promise.then((r) => r.value);
  }
  error(): Promise<E | undefined> {
    return this.promise.then((r) => r.error);
  }
  orNull(): Promise<V | null> {
    return this.promise.then((r) => r.orNull());
  }
  orUndefined(): Promise<V | undefined> {
    return this.promise.then((r) => r.orUndefined());
  }
  orReject<F>(f?: (e: E) => F): Promise<V> {
    return this.promise.then((r) => (f == null ? r.orThrow() : r.orThrow(f)));
  }
  orDefault(value: V): Promise<V> {
    return this.promise.then((r) => r.orDefault(value));
  }
  orRecover(neverThrowFun: (e: E) => V): Promise<V> {
    return this.promise.then((r) => r.orRecover(neverThrowFun));
  }
  onSuccess(neverThrowFun: (value: V) => void): AsyncResult<V, E> {
    this.promise.then((r) => r.onSuccess(neverThrowFun));
    return this;
  }
  onFailure(neverThrowFun: (e: E) => void): AsyncResult<V, E> {
    this.promise.then((r) => r.onFailure(neverThrowFun));
    return this;
  }
  and<U, F>(other: AsyncResult<U, F>): AsyncResult<V | U, E | F> {
    return new AsyncResult<V | U, E | F>(
      this.promise.then((r0) => other.promise.then((r1) => r0.and(r1)))
    );
  }
  or<U, F>(other: AsyncResult<U, F>): AsyncResult<V | U, E | F> {
    return new AsyncResult<V | U, E | F>(
      this.promise.then((r0) => other.promise.then((r1) => r0.or(r1)))
    );
  }
  map<U>(neverThrowFun: (v: V) => U): AsyncResult<U, E> {
    return new AsyncResult(
      this.promise.then((result) => result.map(neverThrowFun))
    );
  }
  tryMap<U>(tryFun: (v: V) => U): AsyncResult<U, unknown>;
  tryMap<U, F>(
    tryFun: (v: V) => U,
    catchFun: (error: unknown) => F
  ): AsyncResult<U, E | F>;
  tryMap<U, F>(
    tryFun: (v: V) => U,
    catchFun?: (error: unknown) => F
  ): AsyncResult<U, E | F | unknown> {
    return (catchFun == null
      ? AsyncResult.try(() => this.promise.then((it) => it.tryMap(tryFun)))
      : AsyncResult.try(
          () => this.promise.then((it) => it.tryMap(tryFun, catchFun)),
          catchFun
        )
    ).flatMap((it) => AsyncResult.of(it));
  }
  flatMap<U, F>(
    neverThrowFun: (v: V) => AsyncResult<U, F>
  ): AsyncResult<U, E | F> {
    const promise = new Promise<Result<U, E | F>>(async (resolve) => {
      (await this.promise)
        .onSuccess((value) => resolve(neverThrowFun(value).promise))
        .onFailure((error) => resolve(Result.failure(error)));
    });
    return new AsyncResult<U, E | F>(promise);
  }
  tryFlatMap<U, F>(
    tryFun: (v: V) => AsyncResult<U, F>
  ): AsyncResult<U, unknown>;
  tryFlatMap<U, F, G>(
    tryFun: (v: V) => AsyncResult<U, F>,
    catchFun: (error: unknown) => G
  ): AsyncResult<U, E | F | G>;
  tryFlatMap<U, F, G>(
    tryFun: (v: V) => AsyncResult<U, F>,
    catchFun?: (error: unknown) => G
  ): AsyncResult<U, E | F | G | unknown> {
    if (catchFun == null) {
      const promise = this.promise
        .then(async (r) =>
          r.isFailure() ? r.castValue<U>() : tryFun(r.value).promise
        )
        .catch((error) => Result.failure<unknown>(error));
      return AsyncResult.of<U, unknown>(promise);
    } else {
      const promise = this.promise
        .then(async (r) =>
          r.isFailure() ? r.castValue<U>() : tryFun(r.value).promise
        )
        .catch((error) => Result.failure<G>(catchFun(error)));
      return AsyncResult.of<U, E | F | G>(promise);
    }
  }
  recover(neverThrowFun: (e: E) => V): AsyncResult<V, never> {
    return new AsyncResult<V, never>(
      this.promise.then((result) => result.recover(neverThrowFun))
    );
  }
  tryRecover(tryFun: (error: E) => V): AsyncResult<V, unknown>;
  tryRecover<F>(
    tryFun: (error: E) => V,
    catchFun: (error: unknown) => F
  ): AsyncResult<V, F>;
  tryRecover<F>(
    tryFun: (error: E) => V,
    catchFun?: (error: unknown) => F
  ): AsyncResult<V, F | unknown> {
    return catchFun == null
      ? AsyncResult.of(
          this.match(Result.success, (e) => Result.try(() => tryFun(e)))
        )
      : AsyncResult.of(
          this.match(Result.success, (e) =>
            Result.try(() => tryFun(e), catchFun)
          )
        );
  }
  flatRecover<F>(
    neverThrowFun: (e: E) => AsyncResult<V, F>
  ): AsyncResult<V, F> {
    const promise = new Promise<Result<V, F>>(async (resolve) => {
      (await this.promise)
        .onSuccess((value) => resolve(Result.success(value)))
        .onFailure((error) => resolve(neverThrowFun(error).promise));
    });
    return new AsyncResult<V, F>(promise);
  }
  tryFlatRecover<F>(
    tryFun: (error: E) => AsyncResult<V, F>
  ): AsyncResult<V, unknown>;
  tryFlatRecover<F, G>(
    tryFun: (error: E) => AsyncResult<V, F>,
    catchFun: (error: unknown) => G
  ): AsyncResult<V, F>;
  tryFlatRecover<F, G>(
    tryFun: (error: E) => AsyncResult<V, F>,
    catchFun?: (error: unknown) => G
  ): AsyncResult<V, F | G | unknown> {
    const promise = new Promise<Result<V, F | G | unknown>>(async (resolve) => {
      (await this.promise)
        .onSuccess((value) => resolve(Result.success(value)))
        .onFailure((error) => {
          try {
            resolve(tryFun(error).promise);
          } catch (e: unknown) {
            if (catchFun == null) resolve(Result.failure<unknown>(e));
            else resolve(Result.failure<G>(catchFun(e)));
          }
        });
    });
    return new AsyncResult<V, F | G | unknown>(promise);
  }
  mapError<F>(neverThrowFun: (error: E) => F): AsyncResult<V, F> {
    return new AsyncResult(
      this.promise.then((result) => result.mapError(neverThrowFun))
    );
  }
  tryMapError<F>(tryFun: (error: E) => F): AsyncResult<V, unknown>;
  tryMapError<F, G>(
    tryFun: (error: E) => F,
    catchFun: (error: unknown) => G
  ): AsyncResult<V, F | G>;
  tryMapError<F, G>(
    tryFun: (error: E) => F,
    catchFun?: (error: unknown) => G
  ): AsyncResult<V, F | G | unknown> {
    return (catchFun == null
      ? AsyncResult.try(() => this.promise.then((it) => it.tryMapError(tryFun)))
      : AsyncResult.try(
          () => this.promise.then((it) => it.tryMapError(tryFun, catchFun)),
          catchFun
        )
    ).flatMap((it) => AsyncResult.of(it));
  }
}