sflow/src/throughs.ts

sflow is a powerful and highly-extensible library designed for processing and manipulating streams of data effortlessly. Inspired by the functional programming paradigm, it provides a rich set of utilities for transforming streams, including chunking, fil

/** pipe upstream through a transform stream */
export const throughs: {
  <T>(stream?: TransformStream<T, T>): TransformStream<T, T>;
  <T, R>(stream: TransformStream<T, R>): TransformStream<T, R>;
  <T, R>(
    fn: (s: ReadableStream<T>) => ReadableStream<R>,
  ): TransformStream<T, R>;
} = (arg: any) => {
  if (!arg) return new TransformStream();
  if (typeof arg !== "function") return throughs((s) => s.pipeThrough(arg));
  const fn = arg;
  const { writable, readable } = new TransformStream();
  return { writable, readable: fn(readable) };
};