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std/io/streams.ts

Deno standard library
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// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
/** Create a `Writer` from a `WritableStreamDefaultReader`. */export function writerFromStreamWriter( streamWriter: WritableStreamDefaultWriter<Uint8Array>,): Deno.Writer { return { async write(p: Uint8Array): Promise<number> { await streamWriter.ready; await streamWriter.write(p); return p.length; }, };}
/** Create a `Reader` from a `ReadableStreamDefaultReader`. */export function readerFromStreamReader( streamReader: ReadableStreamDefaultReader<Uint8Array>,): Deno.Reader { const buffer = new Deno.Buffer();
return { async read(p: Uint8Array): Promise<number | null> { if (buffer.empty()) { const res = await streamReader.read(); if (res.done) { return null; // EOF }
await Deno.writeAll(buffer, res.value); }
return buffer.read(p); }, };}
/** Create a `WritableStream` from a `Writer`. */export function writableStreamFromWriter( writer: Deno.Writer,): WritableStream<Uint8Array> { return new WritableStream({ async write(chunk) { await Deno.writeAll(writer, chunk); }, });}
/** Create a `ReadableStream` from any kind of iterable. * * const r1 = readableStreamFromIterable(["foo, bar, baz"]); * const r2 = readableStreamFromIterable((async function* () { * await new Promise(((r) => setTimeout(r, 1000))); * yield "foo"; * await new Promise(((r) => setTimeout(r, 1000))); * yield "bar"; * await new Promise(((r) => setTimeout(r, 1000))); * yield "baz"; * })());*/export function readableStreamFromIterable<T>( iterable: Iterable<T> | AsyncIterable<T>,): ReadableStream<T> { const iterator: Iterator<T> | AsyncIterator<T> = (iterable as AsyncIterable<T>)[Symbol.asyncIterator]?.() ?? (iterable as Iterable<T>)[Symbol.iterator]?.(); return new ReadableStream({ async pull(controller) { const { value, done } = await iterator.next();
if (done) { controller.close(); } else { controller.enqueue(value); } }, });}