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stream: add async iterator support for v1 streams
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PR-URL: #31316
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Minwoo Jung <[email protected]>
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ronag authored and codebytere committed Feb 17, 2020
1 parent f75fe9a commit 20d0a0e
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Showing 2 changed files with 61 additions and 1 deletion.
18 changes: 18 additions & 0 deletions lib/internal/streams/async_iterator.js
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@ const kLastPromise = Symbol('lastPromise');
const kHandlePromise = Symbol('handlePromise');
const kStream = Symbol('stream');

let Readable;

function createIterResult(value, done) {
return { value, done };
}
Expand Down Expand Up @@ -145,6 +147,22 @@ const ReadableStreamAsyncIteratorPrototype = ObjectSetPrototypeOf({
}, AsyncIteratorPrototype);

const createReadableStreamAsyncIterator = (stream) => {
if (typeof stream.read !== 'function') {
// v1 stream

if (!Readable) {
Readable = require('_stream_readable');
}

const src = stream;
stream = new Readable({ objectMode: true }).wrap(src);
finished(stream, (err) => {
if (typeof src.destroy === 'function') {
src.destroy(err);
}
});
}

const iterator = ObjectCreate(ReadableStreamAsyncIteratorPrototype, {
[kStream]: { value: stream, writable: true },
[kLastResolve]: { value: null, writable: true },
Expand Down
44 changes: 43 additions & 1 deletion test/parallel/test-stream-readable-async-iterators.js
Original file line number Diff line number Diff line change
@@ -1,7 +1,13 @@
'use strict';

const common = require('../common');
const { Readable, Transform, PassThrough, pipeline } = require('stream');
const {
Stream,
Readable,
Transform,
PassThrough,
pipeline
} = require('stream');
const assert = require('assert');

async function tests() {
Expand All @@ -14,6 +20,42 @@ async function tests() {
AsyncIteratorPrototype);
}

{
// v1 stream

const stream = new Stream();
stream.destroy = common.mustCall();
process.nextTick(() => {
stream.emit('data', 'hello');
stream.emit('data', 'world');
stream.emit('end');
});

let res = '';
stream[Symbol.asyncIterator] = Readable.prototype[Symbol.asyncIterator];
for await (const d of stream) {
res += d;
}
assert.strictEqual(res, 'helloworld');
}

{
// v1 stream error

const stream = new Stream();
stream.close = common.mustCall();
process.nextTick(() => {
stream.emit('data', 0);
stream.emit('data', 1);
stream.emit('error', new Error('asd'));
});

const iter = Readable.prototype[Symbol.asyncIterator].call(stream);
iter.next().catch(common.mustCall((err) => {
assert.strictEqual(err.message, 'asd');
}));
}

{
const readable = new Readable({ objectMode: true, read() {} });
readable.push(0);
Expand Down

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