deno.land / x / msgpack_javascript@v3.0.0-beta2 / src / utils / stream.ts
12345678910111213141516171819202122232425262728293031323334353637383940414243// utility for whatwg streams
// The living standard of whatwg streams says// ReadableStream is also AsyncIterable, but// as of June 2019, no browser implements it.// See https://streams.spec.whatwg.org/ for detailsexport type ReadableStreamLike<T> = AsyncIterable<T> | ReadableStream<T>;
export function isAsyncIterable<T>(object: ReadableStreamLike<T>): object is AsyncIterable<T> { return (object as any)[Symbol.asyncIterator] != null;}
function assertNonNull<T>(value: T | null | undefined): asserts value is T { if (value == null) { throw new Error("Assertion Failure: value must not be null nor undefined"); }}
export async function* asyncIterableFromStream<T>(stream: ReadableStream<T>): AsyncIterable<T> { const reader = stream.getReader();
try { while (true) { const { done, value } = await reader.read(); if (done) { return; } assertNonNull(value); yield value; } } finally { reader.releaseLock(); }}
export function ensureAsyncIterable<T>(streamLike: ReadableStreamLike<T>): AsyncIterable<T> { if (isAsyncIterable(streamLike)) { return streamLike; } else { return asyncIterableFromStream(streamLike); }}
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