1 // Copyright Joyent, Inc. and other Node contributors.
3 // Permission is hereby granted, free of charge, to any person obtaining a
4 // copy of this software and associated documentation files (the
5 // "Software"), to deal in the Software without restriction, including
6 // without limitation the rights to use, copy, modify, merge, publish,
7 // distribute, sublicense, and/or sell copies of the Software, and to permit
8 // persons to whom the Software is furnished to do so, subject to the
9 // following conditions:
11 // The above copyright notice and this permission notice shall be included
12 // in all copies or substantial portions of the Software.
14 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
15 // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
16 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
17 // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
18 // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
19 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
20 // USE OR OTHER DEALINGS IN THE SOFTWARE.
23 module.exports = Readable;
29 Readable.ReadableState = ReadableState;
32 var EE = require('events').EventEmitter;
34 var EElistenerCount = function EElistenerCount(emitter, type) {
35 return emitter.listeners(type).length;
42 var Stream = require('./internal/streams/stream');
46 var Buffer = require('buffer').Buffer;
48 var OurUint8Array = global.Uint8Array || function () {};
50 function _uint8ArrayToBuffer(chunk) {
51 return Buffer.from(chunk);
54 function _isUint8Array(obj) {
55 return Buffer.isBuffer(obj) || obj instanceof OurUint8Array;
60 var debugUtil = require('util');
64 if (debugUtil && debugUtil.debuglog) {
65 debug = debugUtil.debuglog('stream');
67 debug = function debug() {};
72 var BufferList = require('./internal/streams/buffer_list');
74 var destroyImpl = require('./internal/streams/destroy');
76 var _require = require('./internal/streams/state'),
77 getHighWaterMark = _require.getHighWaterMark;
79 var _require$codes = require('../errors').codes,
80 ERR_INVALID_ARG_TYPE = _require$codes.ERR_INVALID_ARG_TYPE,
81 ERR_STREAM_PUSH_AFTER_EOF = _require$codes.ERR_STREAM_PUSH_AFTER_EOF,
82 ERR_METHOD_NOT_IMPLEMENTED = _require$codes.ERR_METHOD_NOT_IMPLEMENTED,
83 ERR_STREAM_UNSHIFT_AFTER_END_EVENT = _require$codes.ERR_STREAM_UNSHIFT_AFTER_END_EVENT; // Lazy loaded to improve the startup performance.
87 var createReadableStreamAsyncIterator;
90 require('inherits')(Readable, Stream);
92 var errorOrDestroy = destroyImpl.errorOrDestroy;
93 var kProxyEvents = ['error', 'close', 'destroy', 'pause', 'resume'];
95 function prependListener(emitter, event, fn) {
96 // Sadly this is not cacheable as some libraries bundle their own
97 // event emitter implementation with them.
98 if (typeof emitter.prependListener === 'function') return emitter.prependListener(event, fn); // This is a hack to make sure that our error handler is attached before any
99 // userland ones. NEVER DO THIS. This is here only because this code needs
100 // to continue to work with older versions of Node.js that do not include
101 // the prependListener() method. The goal is to eventually remove this hack.
103 if (!emitter._events || !emitter._events[event]) emitter.on(event, fn);else if (Array.isArray(emitter._events[event])) emitter._events[event].unshift(fn);else emitter._events[event] = [fn, emitter._events[event]];
106 function ReadableState(options, stream, isDuplex) {
107 Duplex = Duplex || require('./_stream_duplex');
108 options = options || {}; // Duplex streams are both readable and writable, but share
109 // the same options object.
110 // However, some cases require setting options to different
111 // values for the readable and the writable sides of the duplex stream.
112 // These options can be provided separately as readableXXX and writableXXX.
114 if (typeof isDuplex !== 'boolean') isDuplex = stream instanceof Duplex; // object stream flag. Used to make read(n) ignore n and to
115 // make all the buffer merging and length checks go away
117 this.objectMode = !!options.objectMode;
118 if (isDuplex) this.objectMode = this.objectMode || !!options.readableObjectMode; // the point at which it stops calling _read() to fill the buffer
119 // Note: 0 is a valid value, means "don't call _read preemptively ever"
121 this.highWaterMark = getHighWaterMark(this, options, 'readableHighWaterMark', isDuplex); // A linked list is used to store data chunks instead of an array because the
122 // linked list can remove elements from the beginning faster than
125 this.buffer = new BufferList();
131 this.endEmitted = false;
132 this.reading = false; // a flag to be able to tell if the event 'readable'/'data' is emitted
133 // immediately, or on a later tick. We set this to true at first, because
134 // any actions that shouldn't happen until "later" should generally also
135 // not happen before the first read call.
137 this.sync = true; // whenever we return null, then we set a flag to say
138 // that we're awaiting a 'readable' event emission.
140 this.needReadable = false;
141 this.emittedReadable = false;
142 this.readableListening = false;
143 this.resumeScheduled = false;
144 this.paused = true; // Should close be emitted on destroy. Defaults to true.
146 this.emitClose = options.emitClose !== false; // Should .destroy() be called after 'end' (and potentially 'finish')
148 this.autoDestroy = !!options.autoDestroy; // has it been destroyed
150 this.destroyed = false; // Crypto is kind of old and crusty. Historically, its default string
151 // encoding is 'binary' so we have to make this configurable.
152 // Everything else in the universe uses 'utf8', though.
154 this.defaultEncoding = options.defaultEncoding || 'utf8'; // the number of writers that are awaiting a drain event in .pipe()s
156 this.awaitDrain = 0; // if true, a maybeReadMore has been scheduled
158 this.readingMore = false;
160 this.encoding = null;
162 if (options.encoding) {
163 if (!StringDecoder) StringDecoder = require('string_decoder/').StringDecoder;
164 this.decoder = new StringDecoder(options.encoding);
165 this.encoding = options.encoding;
169 function Readable(options) {
170 Duplex = Duplex || require('./_stream_duplex');
171 if (!(this instanceof Readable)) return new Readable(options); // Checking for a Stream.Duplex instance is faster here instead of inside
172 // the ReadableState constructor, at least with V8 6.5
174 var isDuplex = this instanceof Duplex;
175 this._readableState = new ReadableState(options, this, isDuplex); // legacy
177 this.readable = true;
180 if (typeof options.read === 'function') this._read = options.read;
181 if (typeof options.destroy === 'function') this._destroy = options.destroy;
187 Object.defineProperty(Readable.prototype, 'destroyed', {
188 // making it explicit this property is not enumerable
189 // because otherwise some prototype manipulation in
190 // userland will fail
192 get: function get() {
193 if (this._readableState === undefined) {
197 return this._readableState.destroyed;
199 set: function set(value) {
200 // we ignore the value if the stream
201 // has not been initialized yet
202 if (!this._readableState) {
204 } // backward compatibility, the user is explicitly
205 // managing destroyed
208 this._readableState.destroyed = value;
211 Readable.prototype.destroy = destroyImpl.destroy;
212 Readable.prototype._undestroy = destroyImpl.undestroy;
214 Readable.prototype._destroy = function (err, cb) {
216 }; // Manually shove something into the read() buffer.
217 // This returns true if the highWaterMark has not been hit yet,
218 // similar to how Writable.write() returns true if you should
219 // write() some more.
222 Readable.prototype.push = function (chunk, encoding) {
223 var state = this._readableState;
226 if (!state.objectMode) {
227 if (typeof chunk === 'string') {
228 encoding = encoding || state.defaultEncoding;
230 if (encoding !== state.encoding) {
231 chunk = Buffer.from(chunk, encoding);
235 skipChunkCheck = true;
238 skipChunkCheck = true;
241 return readableAddChunk(this, chunk, encoding, false, skipChunkCheck);
242 }; // Unshift should *always* be something directly out of read()
245 Readable.prototype.unshift = function (chunk) {
246 return readableAddChunk(this, chunk, null, true, false);
249 function readableAddChunk(stream, chunk, encoding, addToFront, skipChunkCheck) {
250 debug('readableAddChunk', chunk);
251 var state = stream._readableState;
253 if (chunk === null) {
254 state.reading = false;
255 onEofChunk(stream, state);
258 if (!skipChunkCheck) er = chunkInvalid(state, chunk);
261 errorOrDestroy(stream, er);
262 } else if (state.objectMode || chunk && chunk.length > 0) {
263 if (typeof chunk !== 'string' && !state.objectMode && Object.getPrototypeOf(chunk) !== Buffer.prototype) {
264 chunk = _uint8ArrayToBuffer(chunk);
268 if (state.endEmitted) errorOrDestroy(stream, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());else addChunk(stream, state, chunk, true);
269 } else if (state.ended) {
270 errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
271 } else if (state.destroyed) {
274 state.reading = false;
276 if (state.decoder && !encoding) {
277 chunk = state.decoder.write(chunk);
278 if (state.objectMode || chunk.length !== 0) addChunk(stream, state, chunk, false);else maybeReadMore(stream, state);
280 addChunk(stream, state, chunk, false);
283 } else if (!addToFront) {
284 state.reading = false;
285 maybeReadMore(stream, state);
287 } // We can push more data if we are below the highWaterMark.
288 // Also, if we have no data yet, we can stand some more bytes.
289 // This is to work around cases where hwm=0, such as the repl.
292 return !state.ended && (state.length < state.highWaterMark || state.length === 0);
295 function addChunk(stream, state, chunk, addToFront) {
296 if (state.flowing && state.length === 0 && !state.sync) {
297 state.awaitDrain = 0;
298 stream.emit('data', chunk);
300 // update the buffer info.
301 state.length += state.objectMode ? 1 : chunk.length;
302 if (addToFront) state.buffer.unshift(chunk);else state.buffer.push(chunk);
303 if (state.needReadable) emitReadable(stream);
306 maybeReadMore(stream, state);
309 function chunkInvalid(state, chunk) {
312 if (!_isUint8Array(chunk) && typeof chunk !== 'string' && chunk !== undefined && !state.objectMode) {
313 er = new ERR_INVALID_ARG_TYPE('chunk', ['string', 'Buffer', 'Uint8Array'], chunk);
319 Readable.prototype.isPaused = function () {
320 return this._readableState.flowing === false;
321 }; // backwards compatibility.
324 Readable.prototype.setEncoding = function (enc) {
325 if (!StringDecoder) StringDecoder = require('string_decoder/').StringDecoder;
326 var decoder = new StringDecoder(enc);
327 this._readableState.decoder = decoder; // If setEncoding(null), decoder.encoding equals utf8
329 this._readableState.encoding = this._readableState.decoder.encoding; // Iterate over current buffer to convert already stored Buffers:
331 var p = this._readableState.buffer.head;
335 content += decoder.write(p.data);
339 this._readableState.buffer.clear();
341 if (content !== '') this._readableState.buffer.push(content);
342 this._readableState.length = content.length;
344 }; // Don't raise the hwm > 1GB
347 var MAX_HWM = 0x40000000;
349 function computeNewHighWaterMark(n) {
351 // TODO(ronag): Throw ERR_VALUE_OUT_OF_RANGE.
354 // Get the next highest power of 2 to prevent increasing hwm excessively in
366 } // This function is designed to be inlinable, so please take care when making
367 // changes to the function body.
370 function howMuchToRead(n, state) {
371 if (n <= 0 || state.length === 0 && state.ended) return 0;
372 if (state.objectMode) return 1;
375 // Only flow one buffer at a time
376 if (state.flowing && state.length) return state.buffer.head.data.length;else return state.length;
377 } // If we're asking for more than the current hwm, then raise the hwm.
380 if (n > state.highWaterMark) state.highWaterMark = computeNewHighWaterMark(n);
381 if (n <= state.length) return n; // Don't have enough
384 state.needReadable = true;
389 } // you can override either this method, or the async _read(n) below.
392 Readable.prototype.read = function (n) {
395 var state = this._readableState;
397 if (n !== 0) state.emittedReadable = false; // if we're doing read(0) to trigger a readable event, but we
398 // already have a bunch of data in the buffer, then just trigger
399 // the 'readable' event and move on.
401 if (n === 0 && state.needReadable && ((state.highWaterMark !== 0 ? state.length >= state.highWaterMark : state.length > 0) || state.ended)) {
402 debug('read: emitReadable', state.length, state.ended);
403 if (state.length === 0 && state.ended) endReadable(this);else emitReadable(this);
407 n = howMuchToRead(n, state); // if we've ended, and we're now clear, then finish it up.
409 if (n === 0 && state.ended) {
410 if (state.length === 0) endReadable(this);
412 } // All the actual chunk generation logic needs to be
413 // *below* the call to _read. The reason is that in certain
414 // synthetic stream cases, such as passthrough streams, _read
415 // may be a completely synchronous operation which may change
416 // the state of the read buffer, providing enough data when
417 // before there was *not* enough.
419 // So, the steps are:
420 // 1. Figure out what the state of things will be after we do
421 // a read from the buffer.
423 // 2. If that resulting state will trigger a _read, then call _read.
424 // Note that this may be asynchronous, or synchronous. Yes, it is
425 // deeply ugly to write APIs this way, but that still doesn't mean
426 // that the Readable class should behave improperly, as streams are
427 // designed to be sync/async agnostic.
428 // Take note if the _read call is sync or async (ie, if the read call
429 // has returned yet), so that we know whether or not it's safe to emit
432 // 3. Actually pull the requested chunks out of the buffer and return.
433 // if we need a readable event, then we need to do some reading.
436 var doRead = state.needReadable;
437 debug('need readable', doRead); // if we currently have less than the highWaterMark, then also read some
439 if (state.length === 0 || state.length - n < state.highWaterMark) {
441 debug('length less than watermark', doRead);
442 } // however, if we've ended, then there's no point, and if we're already
443 // reading, then it's unnecessary.
446 if (state.ended || state.reading) {
448 debug('reading or ended', doRead);
451 state.reading = true;
452 state.sync = true; // if the length is currently zero, then we *need* a readable event.
454 if (state.length === 0) state.needReadable = true; // call internal read method
456 this._read(state.highWaterMark);
458 state.sync = false; // If _read pushed data synchronously, then `reading` will be false,
459 // and we need to re-evaluate how much data we can return to the user.
461 if (!state.reading) n = howMuchToRead(nOrig, state);
465 if (n > 0) ret = fromList(n, state);else ret = null;
468 state.needReadable = state.length <= state.highWaterMark;
472 state.awaitDrain = 0;
475 if (state.length === 0) {
476 // If we have nothing in the buffer, then we want to know
477 // as soon as we *do* get something into the buffer.
478 if (!state.ended) state.needReadable = true; // If we tried to read() past the EOF, then emit end on the next tick.
480 if (nOrig !== n && state.ended) endReadable(this);
483 if (ret !== null) this.emit('data', ret);
487 function onEofChunk(stream, state) {
489 if (state.ended) return;
492 var chunk = state.decoder.end();
494 if (chunk && chunk.length) {
495 state.buffer.push(chunk);
496 state.length += state.objectMode ? 1 : chunk.length;
503 // if we are sync, wait until next tick to emit the data.
504 // Otherwise we risk emitting data in the flow()
505 // the readable code triggers during a read() call
506 emitReadable(stream);
508 // emit 'readable' now to make sure it gets picked up.
509 state.needReadable = false;
511 if (!state.emittedReadable) {
512 state.emittedReadable = true;
513 emitReadable_(stream);
516 } // Don't emit readable right away in sync mode, because this can trigger
517 // another read() call => stack overflow. This way, it might trigger
518 // a nextTick recursion warning, but that's not so bad.
521 function emitReadable(stream) {
522 var state = stream._readableState;
523 debug('emitReadable', state.needReadable, state.emittedReadable);
524 state.needReadable = false;
526 if (!state.emittedReadable) {
527 debug('emitReadable', state.flowing);
528 state.emittedReadable = true;
529 process.nextTick(emitReadable_, stream);
533 function emitReadable_(stream) {
534 var state = stream._readableState;
535 debug('emitReadable_', state.destroyed, state.length, state.ended);
537 if (!state.destroyed && (state.length || state.ended)) {
538 stream.emit('readable');
539 state.emittedReadable = false;
540 } // The stream needs another readable event if
541 // 1. It is not flowing, as the flow mechanism will take
543 // 2. It is not ended.
544 // 3. It is below the highWaterMark, so we can schedule
545 // another readable later.
548 state.needReadable = !state.flowing && !state.ended && state.length <= state.highWaterMark;
550 } // at this point, the user has presumably seen the 'readable' event,
551 // and called read() to consume some data. that may have triggered
552 // in turn another _read(n) call, in which case reading = true if
554 // However, if we're not ended, or reading, and the length < hwm,
555 // then go ahead and try to read some more preemptively.
558 function maybeReadMore(stream, state) {
559 if (!state.readingMore) {
560 state.readingMore = true;
561 process.nextTick(maybeReadMore_, stream, state);
565 function maybeReadMore_(stream, state) {
566 // Attempt to read more data if we should.
568 // The conditions for reading more data are (one of):
569 // - Not enough data buffered (state.length < state.highWaterMark). The loop
570 // is responsible for filling the buffer with enough data if such data
571 // is available. If highWaterMark is 0 and we are not in the flowing mode
572 // we should _not_ attempt to buffer any extra data. We'll get more data
573 // when the stream consumer calls read() instead.
574 // - No data in the buffer, and the stream is in flowing mode. In this mode
575 // the loop below is responsible for ensuring read() is called. Failing to
576 // call read here would abort the flow and there's no other mechanism for
577 // continuing the flow if the stream consumer has just subscribed to the
580 // In addition to the above conditions to keep reading data, the following
581 // conditions prevent the data from being read:
582 // - The stream has ended (state.ended).
583 // - There is already a pending 'read' operation (state.reading). This is a
584 // case where the the stream has called the implementation defined _read()
585 // method, but they are processing the call asynchronously and have _not_
586 // called push() with new data. In this case we skip performing more
587 // read()s. The execution ends in this method again after the _read() ends
588 // up calling push() with more data.
589 while (!state.reading && !state.ended && (state.length < state.highWaterMark || state.flowing && state.length === 0)) {
590 var len = state.length;
591 debug('maybeReadMore read 0');
593 if (len === state.length) // didn't get any data, stop spinning.
597 state.readingMore = false;
598 } // abstract method. to be overridden in specific implementation classes.
599 // call cb(er, data) where data is <= n in length.
600 // for virtual (non-string, non-buffer) streams, "length" is somewhat
601 // arbitrary, and perhaps not very meaningful.
604 Readable.prototype._read = function (n) {
605 errorOrDestroy(this, new ERR_METHOD_NOT_IMPLEMENTED('_read()'));
608 Readable.prototype.pipe = function (dest, pipeOpts) {
610 var state = this._readableState;
612 switch (state.pipesCount) {
618 state.pipes = [state.pipes, dest];
622 state.pipes.push(dest);
626 state.pipesCount += 1;
627 debug('pipe count=%d opts=%j', state.pipesCount, pipeOpts);
628 var doEnd = (!pipeOpts || pipeOpts.end !== false) && dest !== process.stdout && dest !== process.stderr;
629 var endFn = doEnd ? onend : unpipe;
630 if (state.endEmitted) process.nextTick(endFn);else src.once('end', endFn);
631 dest.on('unpipe', onunpipe);
633 function onunpipe(readable, unpipeInfo) {
636 if (readable === src) {
637 if (unpipeInfo && unpipeInfo.hasUnpiped === false) {
638 unpipeInfo.hasUnpiped = true;
647 } // when the dest drains, it reduces the awaitDrain counter
648 // on the source. This would be more elegant with a .once()
649 // handler in flow(), but adding and removing repeatedly is
653 var ondrain = pipeOnDrain(src);
654 dest.on('drain', ondrain);
655 var cleanedUp = false;
658 debug('cleanup'); // cleanup event handlers once the pipe is broken
660 dest.removeListener('close', onclose);
661 dest.removeListener('finish', onfinish);
662 dest.removeListener('drain', ondrain);
663 dest.removeListener('error', onerror);
664 dest.removeListener('unpipe', onunpipe);
665 src.removeListener('end', onend);
666 src.removeListener('end', unpipe);
667 src.removeListener('data', ondata);
668 cleanedUp = true; // if the reader is waiting for a drain event from this
669 // specific writer, then it would cause it to never start
671 // So, if this is awaiting a drain, then we just call it now.
672 // If we don't know, then assume that we are waiting for one.
674 if (state.awaitDrain && (!dest._writableState || dest._writableState.needDrain)) ondrain();
677 src.on('data', ondata);
679 function ondata(chunk) {
681 var ret = dest.write(chunk);
682 debug('dest.write', ret);
685 // If the user unpiped during `dest.write()`, it is possible
686 // to get stuck in a permanently paused state if that write
687 // also returned false.
688 // => Check whether `dest` is still a piping destination.
689 if ((state.pipesCount === 1 && state.pipes === dest || state.pipesCount > 1 && indexOf(state.pipes, dest) !== -1) && !cleanedUp) {
690 debug('false write response, pause', state.awaitDrain);
696 } // if the dest has an error, then stop piping into it.
697 // however, don't suppress the throwing behavior for this.
700 function onerror(er) {
701 debug('onerror', er);
703 dest.removeListener('error', onerror);
704 if (EElistenerCount(dest, 'error') === 0) errorOrDestroy(dest, er);
705 } // Make sure our error handler is attached before userland ones.
708 prependListener(dest, 'error', onerror); // Both close and finish should trigger unpipe, but only once.
711 dest.removeListener('finish', onfinish);
715 dest.once('close', onclose);
717 function onfinish() {
719 dest.removeListener('close', onclose);
723 dest.once('finish', onfinish);
728 } // tell the dest that it's being piped to
731 dest.emit('pipe', src); // start the flow if it hasn't been started already.
733 if (!state.flowing) {
734 debug('pipe resume');
741 function pipeOnDrain(src) {
742 return function pipeOnDrainFunctionResult() {
743 var state = src._readableState;
744 debug('pipeOnDrain', state.awaitDrain);
745 if (state.awaitDrain) state.awaitDrain--;
747 if (state.awaitDrain === 0 && EElistenerCount(src, 'data')) {
748 state.flowing = true;
754 Readable.prototype.unpipe = function (dest) {
755 var state = this._readableState;
758 }; // if we're not piping anywhere, then do nothing.
760 if (state.pipesCount === 0) return this; // just one destination. most common case.
762 if (state.pipesCount === 1) {
763 // passed in one, but it's not the right one.
764 if (dest && dest !== state.pipes) return this;
765 if (!dest) dest = state.pipes; // got a match.
768 state.pipesCount = 0;
769 state.flowing = false;
770 if (dest) dest.emit('unpipe', this, unpipeInfo);
772 } // slow case. multiple pipe destinations.
777 var dests = state.pipes;
778 var len = state.pipesCount;
780 state.pipesCount = 0;
781 state.flowing = false;
783 for (var i = 0; i < len; i++) {
784 dests[i].emit('unpipe', this, {
790 } // try to find the right one.
793 var index = indexOf(state.pipes, dest);
794 if (index === -1) return this;
795 state.pipes.splice(index, 1);
796 state.pipesCount -= 1;
797 if (state.pipesCount === 1) state.pipes = state.pipes[0];
798 dest.emit('unpipe', this, unpipeInfo);
800 }; // set up data events if they are asked for
801 // Ensure readable listeners eventually get something
804 Readable.prototype.on = function (ev, fn) {
805 var res = Stream.prototype.on.call(this, ev, fn);
806 var state = this._readableState;
809 // update readableListening so that resume() may be a no-op
810 // a few lines down. This is needed to support once('readable').
811 state.readableListening = this.listenerCount('readable') > 0; // Try start flowing on next tick if stream isn't explicitly paused
813 if (state.flowing !== false) this.resume();
814 } else if (ev === 'readable') {
815 if (!state.endEmitted && !state.readableListening) {
816 state.readableListening = state.needReadable = true;
817 state.flowing = false;
818 state.emittedReadable = false;
819 debug('on readable', state.length, state.reading);
823 } else if (!state.reading) {
824 process.nextTick(nReadingNextTick, this);
832 Readable.prototype.addListener = Readable.prototype.on;
834 Readable.prototype.removeListener = function (ev, fn) {
835 var res = Stream.prototype.removeListener.call(this, ev, fn);
837 if (ev === 'readable') {
838 // We need to check if there is someone still listening to
839 // readable and reset the state. However this needs to happen
840 // after readable has been emitted but before I/O (nextTick) to
841 // support once('readable', fn) cycles. This means that calling
842 // resume within the same tick will have no
844 process.nextTick(updateReadableListening, this);
850 Readable.prototype.removeAllListeners = function (ev) {
851 var res = Stream.prototype.removeAllListeners.apply(this, arguments);
853 if (ev === 'readable' || ev === undefined) {
854 // We need to check if there is someone still listening to
855 // readable and reset the state. However this needs to happen
856 // after readable has been emitted but before I/O (nextTick) to
857 // support once('readable', fn) cycles. This means that calling
858 // resume within the same tick will have no
860 process.nextTick(updateReadableListening, this);
866 function updateReadableListening(self) {
867 var state = self._readableState;
868 state.readableListening = self.listenerCount('readable') > 0;
870 if (state.resumeScheduled && !state.paused) {
871 // flowing needs to be set to true now, otherwise
872 // the upcoming resume will not flow.
873 state.flowing = true; // crude way to check if we should resume
874 } else if (self.listenerCount('data') > 0) {
879 function nReadingNextTick(self) {
880 debug('readable nexttick read 0');
882 } // pause() and resume() are remnants of the legacy readable stream API
883 // If the user uses them, then switch into old mode.
886 Readable.prototype.resume = function () {
887 var state = this._readableState;
889 if (!state.flowing) {
890 debug('resume'); // we flow only if there is no one listening
891 // for readable, but we still have to call
894 state.flowing = !state.readableListening;
898 state.paused = false;
902 function resume(stream, state) {
903 if (!state.resumeScheduled) {
904 state.resumeScheduled = true;
905 process.nextTick(resume_, stream, state);
909 function resume_(stream, state) {
910 debug('resume', state.reading);
912 if (!state.reading) {
916 state.resumeScheduled = false;
917 stream.emit('resume');
919 if (state.flowing && !state.reading) stream.read(0);
922 Readable.prototype.pause = function () {
923 debug('call pause flowing=%j', this._readableState.flowing);
925 if (this._readableState.flowing !== false) {
927 this._readableState.flowing = false;
931 this._readableState.paused = true;
935 function flow(stream) {
936 var state = stream._readableState;
937 debug('flow', state.flowing);
939 while (state.flowing && stream.read() !== null) {
942 } // wrap an old-style stream as the async data source.
943 // This is *not* part of the readable stream interface.
944 // It is an ugly unfortunate mess of history.
947 Readable.prototype.wrap = function (stream) {
950 var state = this._readableState;
952 stream.on('end', function () {
953 debug('wrapped end');
955 if (state.decoder && !state.ended) {
956 var chunk = state.decoder.end();
957 if (chunk && chunk.length) _this.push(chunk);
962 stream.on('data', function (chunk) {
963 debug('wrapped data');
964 if (state.decoder) chunk = state.decoder.write(chunk); // don't skip over falsy values in objectMode
966 if (state.objectMode && (chunk === null || chunk === undefined)) return;else if (!state.objectMode && (!chunk || !chunk.length)) return;
968 var ret = _this.push(chunk);
974 }); // proxy all the other methods.
975 // important when wrapping filters and duplexes.
977 for (var i in stream) {
978 if (this[i] === undefined && typeof stream[i] === 'function') {
979 this[i] = function methodWrap(method) {
980 return function methodWrapReturnFunction() {
981 return stream[method].apply(stream, arguments);
985 } // proxy certain important events.
988 for (var n = 0; n < kProxyEvents.length; n++) {
989 stream.on(kProxyEvents[n], this.emit.bind(this, kProxyEvents[n]));
990 } // when we try to consume some more bytes, simply unpause the
991 // underlying stream.
994 this._read = function (n) {
995 debug('wrapped _read', n);
1006 if (typeof Symbol === 'function') {
1007 Readable.prototype[Symbol.asyncIterator] = function () {
1008 if (createReadableStreamAsyncIterator === undefined) {
1009 createReadableStreamAsyncIterator = require('./internal/streams/async_iterator');
1012 return createReadableStreamAsyncIterator(this);
1016 Object.defineProperty(Readable.prototype, 'readableHighWaterMark', {
1017 // making it explicit this property is not enumerable
1018 // because otherwise some prototype manipulation in
1019 // userland will fail
1021 get: function get() {
1022 return this._readableState.highWaterMark;
1025 Object.defineProperty(Readable.prototype, 'readableBuffer', {
1026 // making it explicit this property is not enumerable
1027 // because otherwise some prototype manipulation in
1028 // userland will fail
1030 get: function get() {
1031 return this._readableState && this._readableState.buffer;
1034 Object.defineProperty(Readable.prototype, 'readableFlowing', {
1035 // making it explicit this property is not enumerable
1036 // because otherwise some prototype manipulation in
1037 // userland will fail
1039 get: function get() {
1040 return this._readableState.flowing;
1042 set: function set(state) {
1043 if (this._readableState) {
1044 this._readableState.flowing = state;
1047 }); // exposed for testing purposes only.
1049 Readable._fromList = fromList;
1050 Object.defineProperty(Readable.prototype, 'readableLength', {
1051 // making it explicit this property is not enumerable
1052 // because otherwise some prototype manipulation in
1053 // userland will fail
1055 get: function get() {
1056 return this._readableState.length;
1058 }); // Pluck off n bytes from an array of buffers.
1059 // Length is the combined lengths of all the buffers in the list.
1060 // This function is designed to be inlinable, so please take care when making
1061 // changes to the function body.
1063 function fromList(n, state) {
1065 if (state.length === 0) return null;
1067 if (state.objectMode) ret = state.buffer.shift();else if (!n || n >= state.length) {
1068 // read it all, truncate the list
1069 if (state.decoder) ret = state.buffer.join('');else if (state.buffer.length === 1) ret = state.buffer.first();else ret = state.buffer.concat(state.length);
1070 state.buffer.clear();
1072 // read part of list
1073 ret = state.buffer.consume(n, state.decoder);
1078 function endReadable(stream) {
1079 var state = stream._readableState;
1080 debug('endReadable', state.endEmitted);
1082 if (!state.endEmitted) {
1084 process.nextTick(endReadableNT, state, stream);
1088 function endReadableNT(state, stream) {
1089 debug('endReadableNT', state.endEmitted, state.length); // Check that we didn't get one last unshift.
1091 if (!state.endEmitted && state.length === 0) {
1092 state.endEmitted = true;
1093 stream.readable = false;
1096 if (state.autoDestroy) {
1097 // In case of duplex streams we need a way to detect
1098 // if the writable side is ready for autoDestroy as well
1099 var wState = stream._writableState;
1101 if (!wState || wState.autoDestroy && wState.finished) {
1108 if (typeof Symbol === 'function') {
1109 Readable.from = function (iterable, opts) {
1110 if (from === undefined) {
1111 from = require('./internal/streams/from');
1114 return from(Readable, iterable, opts);
1118 function indexOf(xs, x) {
1119 for (var i = 0, l = xs.length; i < l; i++) {
1120 if (xs[i] === x) return i;