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// Ported from https://github.com/mafintosh/pump with
// permission from the author, Mathias Buus (@mafintosh).
'use strict';
const {
ArrayIsArray,
SymbolAsyncIterator,
SymbolIterator
} = primordials;
let eos;
const { once } = require('internal/util');
const destroyImpl = require('internal/streams/destroy');
const {
ERR_INVALID_ARG_TYPE,
ERR_INVALID_RETURN_VALUE,
ERR_INVALID_CALLBACK,
ERR_MISSING_ARGS,
ERR_STREAM_DESTROYED
} = require('internal/errors').codes;
let EE;
let PassThrough;
let Readable;
function destroyer(stream, reading, writing, callback) {
callback = once(callback);
let finished = false;
stream.on('close', () => {
finished = true;
});
if (eos === undefined) eos = require('internal/streams/end-of-stream');
eos(stream, { readable: reading, writable: writing }, (err) => {
finished = !err;
const rState = stream._readableState;
if (
err &&
err.code === 'ERR_STREAM_PREMATURE_CLOSE' &&
reading &&
(rState && rState.ended && !rState.errored && !rState.errorEmitted)
) {
// Some readable streams will emit 'close' before 'end'. However, since
// this is on the readable side 'end' should still be emitted if the
// stream has been ended and no error emitted. This should be allowed in
// favor of backwards compatibility. Since the stream is piped to a
// destination this should not result in any observable difference.
// We don't need to check if this is a writable premature close since
// eos will only fail with premature close on the reading side for
// duplex streams.
stream
.once('end', callback)
.once('error', callback);
} else {
callback(err);
}
});
return (err) => {
if (finished) return;
finished = true;
destroyImpl.destroyer(stream, err);
callback(err || new ERR_STREAM_DESTROYED('pipe'));
};
}
function popCallback(streams) {
// Streams should never be an empty array. It should always contain at least
// a single stream. Therefore optimize for the average case instead of
// checking for length === 0 as well.
if (typeof streams[streams.length - 1] !== 'function')
throw new ERR_INVALID_CALLBACK(streams[streams.length - 1]);
return streams.pop();
}
function isPromise(obj) {
return !!(obj && typeof obj.then === 'function');
}
function isReadable(obj) {
return !!(obj && typeof obj.pipe === 'function');
}
function isWritable(obj) {
return !!(obj && typeof obj.write === 'function');
}
function isStream(obj) {
return isReadable(obj) || isWritable(obj);
}
function isIterable(obj, isAsync) {
if (!obj) return false;
if (isAsync === true) return typeof obj[SymbolAsyncIterator] === 'function';
if (isAsync === false) return typeof obj[SymbolIterator] === 'function';
return typeof obj[SymbolAsyncIterator] === 'function' ||
typeof obj[SymbolIterator] === 'function';
}
function makeAsyncIterable(val) {
if (isIterable(val)) {
return val;
} else if (isReadable(val)) {
// Legacy streams are not Iterable.
return fromReadable(val);
}
throw new ERR_INVALID_ARG_TYPE(
'val', ['Readable', 'Iterable', 'AsyncIterable'], val);
}
async function* fromReadable(val) {
if (!Readable) {
Readable = require('internal/streams/readable');
}
yield* Readable.prototype[SymbolAsyncIterator].call(val);
}
async function pump(iterable, writable, finish) {
if (!EE) {
EE = require('events');
}
let error;
try {
for await (const chunk of iterable) {
if (!writable.write(chunk)) {
if (writable.destroyed) return;
await EE.once(writable, 'drain');
}
}
writable.end();
} catch (err) {
error = err;
} finally {
finish(error);
}
}
function pipeline(...streams) {
const callback = once(popCallback(streams));
if (ArrayIsArray(streams[0])) streams = streams[0];
if (streams.length < 2) {
throw new ERR_MISSING_ARGS('streams');
}
let error;
let value;
const destroys = [];
let finishCount = 0;
function finish(err) {
const final = --finishCount === 0;
if (err && (!error || error.code === 'ERR_STREAM_PREMATURE_CLOSE')) {
error = err;
}
if (!error && !final) {
return;
}
while (destroys.length) {
destroys.shift()(error);
}
if (final) {
callback(error, value);
}
}
let ret;
for (let i = 0; i < streams.length; i++) {
const stream = streams[i];
const reading = i < streams.length - 1;
const writing = i > 0;
if (isStream(stream)) {
finishCount++;
destroys.push(destroyer(stream, reading, writing, finish));
}
if (i === 0) {
if (typeof stream === 'function') {
ret = stream();
if (!isIterable(ret)) {
throw new ERR_INVALID_RETURN_VALUE(
'Iterable, AsyncIterable or Stream', 'source', ret);
}
} else if (isIterable(stream) || isReadable(stream)) {
ret = stream;
} else {
throw new ERR_INVALID_ARG_TYPE(
'source', ['Stream', 'Iterable', 'AsyncIterable', 'Function'],
stream);
}
} else if (typeof stream === 'function') {
ret = makeAsyncIterable(ret);
ret = stream(ret);
if (reading) {
if (!isIterable(ret, true)) {
throw new ERR_INVALID_RETURN_VALUE(
'AsyncIterable', `transform[${i - 1}]`, ret);
}
} else {
if (!PassThrough) {
PassThrough = require('_stream_passthrough');
}
// If the last argument to pipeline is not a stream
// we must create a proxy stream so that pipeline(...)
// always returns a stream which can be further
// composed through `.pipe(stream)`.
const pt = new PassThrough({
objectMode: true
});
if (isPromise(ret)) {
ret
.then((val) => {
value = val;
pt.end(val);
}, (err) => {
pt.destroy(err);
});
} else if (isIterable(ret, true)) {
finishCount++;
pump(ret, pt, finish);
} else {
throw new ERR_INVALID_RETURN_VALUE(
'AsyncIterable or Promise', 'destination', ret);
}
ret = pt;
finishCount++;
destroys.push(destroyer(ret, false, true, finish));
}
} else if (isStream(stream)) {
if (isReadable(ret)) {
ret.pipe(stream);
// Compat. Before node v10.12.0 stdio used to throw an error so
// pipe() did/does not end() stdio destinations.
// Now they allow it but "secretly" don't close the underlying fd.
if (stream === process.stdout || stream === process.stderr) {
ret.on('end', () => stream.end());
}
} else {
ret = makeAsyncIterable(ret);
finishCount++;
pump(ret, stream, finish);
}
ret = stream;
} else {
const name = reading ? `transform[${i - 1}]` : 'destination';
throw new ERR_INVALID_ARG_TYPE(
name, ['Stream', 'Function'], ret);
}
}
// TODO(ronag): Consider returning a Duplex proxy if the first argument
// is a writable. Would improve composability.
// See, https://github.com/nodejs/node/issues/32020
return ret;
}
module.exports = pipeline;
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