Skip to main content
Using Deno in production at your company? Earn free Deno merch.
Give us feedback
Go to Latest
File
// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
import { DEFAULT_CHUNK_SIZE } from "./_common.ts";import type { Closer, Reader } from "../types.d.ts";
function isCloser(value: unknown): value is Closer { return typeof value === "object" && value != null && "close" in value && // deno-lint-ignore no-explicit-any typeof (value as Record<string, any>)["close"] === "function";}
export interface ReadableStreamFromReaderOptions { /** If the `reader` is also a `Closer`, automatically close the `reader` * when `EOF` is encountered, or a read error occurs. * * @default {true} */ autoClose?: boolean;
/** The size of chunks to allocate to read, the default is ~16KiB, which is * the maximum size that Deno operations can currently support. */ chunkSize?: number;
/** The queuing strategy to create the `ReadableStream` with. */ strategy?: { highWaterMark?: number | undefined; size?: undefined };}
/** * Create a `ReadableStream<Uint8Array>` from a `Reader`. * * When the pull algorithm is called on the stream, a chunk from the reader * will be read. When `null` is returned from the reader, the stream will be * closed along with the reader (if it is also a `Closer`). * * An example converting a `Deno.FsFile` into a readable stream: * * ```ts * import { readableStreamFromReader } from "https://deno.land/std@$STD_VERSION/streams/readable_stream_from_reader.ts"; * * const file = await Deno.open("./file.txt", { read: true }); * const fileStream = readableStreamFromReader(file); * ``` */export function readableStreamFromReader( reader: Reader | (Reader & Closer), options: ReadableStreamFromReaderOptions = {},): ReadableStream<Uint8Array> { const { autoClose = true, chunkSize = DEFAULT_CHUNK_SIZE, strategy, } = options;
return new ReadableStream({ async pull(controller) { const chunk = new Uint8Array(chunkSize); try { const read = await reader.read(chunk); if (read === null) { if (isCloser(reader) && autoClose) { reader.close(); } controller.close(); return; } controller.enqueue(chunk.subarray(0, read)); } catch (e) { controller.error(e); if (isCloser(reader)) { reader.close(); } } }, cancel() { if (isCloser(reader) && autoClose) { reader.close(); } }, }, strategy);}