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std/streams/iterate_reader.ts

Deno standard library
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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
import { DEFAULT_BUFFER_SIZE } from "./_common.ts";import type { Reader, ReaderSync } from "../types.d.ts";
/** Turns a Reader, `r`, into an async iterator. * * ```ts * import { iterateReader } from "https://deno.land/std@$STD_VERSION/streams/iterate_reader.ts"; * * let f = await Deno.open("/etc/passwd"); * for await (const chunk of iterateReader(f)) { * console.log(chunk); * } * f.close(); * ``` * * Second argument can be used to tune size of a buffer. * Default size of the buffer is 32kB. * * ```ts * import { iterateReader } from "https://deno.land/std@$STD_VERSION/streams/iterate_reader.ts"; * * let f = await Deno.open("/etc/passwd"); * const it = iterateReader(f, { * bufSize: 1024 * 1024 * }); * for await (const chunk of it) { * console.log(chunk); * } * f.close(); * ``` */export async function* iterateReader( r: Reader, options?: { bufSize?: number; },): AsyncIterableIterator<Uint8Array> { const bufSize = options?.bufSize ?? DEFAULT_BUFFER_SIZE; const b = new Uint8Array(bufSize); while (true) { const result = await r.read(b); if (result === null) { break; }
yield b.slice(0, result); }}
/** Turns a ReaderSync, `r`, into an iterator. * * ```ts * import { iterateReaderSync } from "https://deno.land/std@$STD_VERSION/streams/iterate_reader.ts"; * * let f = Deno.openSync("/etc/passwd"); * for (const chunk of iterateReaderSync(f)) { * console.log(chunk); * } * f.close(); * ``` * * Second argument can be used to tune size of a buffer. * Default size of the buffer is 32kB. * * ```ts * import { iterateReaderSync } from "https://deno.land/std@$STD_VERSION/streams/iterate_reader.ts";
* let f = await Deno.open("/etc/passwd"); * const iter = iterateReaderSync(f, { * bufSize: 1024 * 1024 * }); * for (const chunk of iter) { * console.log(chunk); * } * f.close(); * ``` * * Iterator uses an internal buffer of fixed size for efficiency; it returns * a view on that buffer on each iteration. It is therefore caller's * responsibility to copy contents of the buffer if needed; otherwise the * next iteration will overwrite contents of previously returned chunk. */export function* iterateReaderSync( r: ReaderSync, options?: { bufSize?: number; },): IterableIterator<Uint8Array> { const bufSize = options?.bufSize ?? DEFAULT_BUFFER_SIZE; const b = new Uint8Array(bufSize); while (true) { const result = r.readSync(b); if (result === null) { break; }
yield b.slice(0, result); }}