name : _stream_readable.js // Copyright Joyent, Inc. and other Node contributors. // // Permission is hereby granted, free of charge, to any person obtaining a // copy of this software and associated documentation files (the // "Software"), to deal in the Software without restriction, including // without limitation the rights to use, copy, modify, merge, publish, // distribute, sublicense, and/or sell copies of the Software, and to permit // persons to whom the Software is furnished to do so, subject to the // following conditions: // // The above copyright notice and this permission notice shall be included // in all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE // USE OR OTHER DEALINGS IN THE SOFTWARE. 'use strict'; module.exports = Readable; /*<replacement>*/ var Duplex; /*</replacement>*/ Readable.ReadableState = ReadableState; /*<replacement>*/ var EE = require('events').EventEmitter; var EElistenerCount = function EElistenerCount(emitter, type) { return emitter.listeners(type).length; }; /*</replacement>*/ /*<replacement>*/ var Stream = require('./internal/streams/stream'); /*</replacement>*/ var Buffer = require('buffer').Buffer; var OurUint8Array = (typeof global !== 'undefined' ? global : typeof window !== 'undefined' ? window : typeof self !== 'undefined' ? self : {}).Uint8Array || function () {}; function _uint8ArrayToBuffer(chunk) { return Buffer.from(chunk); } function _isUint8Array(obj) { return Buffer.isBuffer(obj) || obj instanceof OurUint8Array; } /*<replacement>*/ var debugUtil = require('util'); var debug; if (debugUtil && debugUtil.debuglog) { debug = debugUtil.debuglog('stream'); } else { debug = function debug() {}; } /*</replacement>*/ var BufferList = require('./internal/streams/buffer_list'); var destroyImpl = require('./internal/streams/destroy'); var _require = require('./internal/streams/state'), getHighWaterMark = _require.getHighWaterMark; var _require$codes = require('../errors').codes, ERR_INVALID_ARG_TYPE = _require$codes.ERR_INVALID_ARG_TYPE, ERR_STREAM_PUSH_AFTER_EOF = _require$codes.ERR_STREAM_PUSH_AFTER_EOF, ERR_METHOD_NOT_IMPLEMENTED = _require$codes.ERR_METHOD_NOT_IMPLEMENTED, ERR_STREAM_UNSHIFT_AFTER_END_EVENT = _require$codes.ERR_STREAM_UNSHIFT_AFTER_END_EVENT; // Lazy loaded to improve the startup performance. var StringDecoder; var createReadableStreamAsyncIterator; var from; require('inherits')(Readable, Stream); var errorOrDestroy = destroyImpl.errorOrDestroy; var kProxyEvents = ['error', 'close', 'destroy', 'pause', 'resume']; function prependListener(emitter, event, fn) { // Sadly this is not cacheable as some libraries bundle their own // event emitter implementation with them. 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 // userland ones. NEVER DO THIS. This is here only because this code needs // to continue to work with older versions of Node.js that do not include // the prependListener() method. The goal is to eventually remove this hack. 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]]; } function ReadableState(options, stream, isDuplex) { Duplex = Duplex || require('./_stream_duplex'); options = options || {}; // Duplex streams are both readable and writable, but share // the same options object. // However, some cases require setting options to different // values for the readable and the writable sides of the duplex stream. // These options can be provided separately as readableXXX and writableXXX. if (typeof isDuplex !== 'boolean') isDuplex = stream instanceof Duplex; // object stream flag. Used to make read(n) ignore n and to // make all the buffer merging and length checks go away this.objectMode = !!options.objectMode; if (isDuplex) this.objectMode = this.objectMode || !!options.readableObjectMode; // the point at which it stops calling _read() to fill the buffer // Note: 0 is a valid value, means "don't call _read preemptively ever" this.highWaterMark = getHighWaterMark(this, options, 'readableHighWaterMark', isDuplex); // A linked list is used to store data chunks instead of an array because the // linked list can remove elements from the beginning faster than // array.shift() this.buffer = new BufferList(); this.length = 0; this.pipes = null; this.pipesCount = 0; this.flowing = null; this.ended = false; this.endEmitted = false; this.reading = false; // a flag to be able to tell if the event 'readable'/'data' is emitted // immediately, or on a later tick. We set this to true at first, because // any actions that shouldn't happen until "later" should generally also // not happen before the first read call. this.sync = true; // whenever we return null, then we set a flag to say // that we're awaiting a 'readable' event emission. this.needReadable = false; this.emittedReadable = false; this.readableListening = false; this.resumeScheduled = false; this.paused = true; // Should close be emitted on destroy. Defaults to true. this.emitClose = options.emitClose !== false; // Should .destroy() be called after 'end' (and potentially 'finish') this.autoDestroy = !!options.autoDestroy; // has it been destroyed this.destroyed = false; // Crypto is kind of old and crusty. Historically, its default string // encoding is 'binary' so we have to make this configurable. // Everything else in the universe uses 'utf8', though. this.defaultEncoding = options.defaultEncoding || 'utf8'; // the number of writers that are awaiting a drain event in .pipe()s this.awaitDrain = 0; // if true, a maybeReadMore has been scheduled this.readingMore = false; this.decoder = null; this.encoding = null; if (options.encoding) { if (!StringDecoder) StringDecoder = require('string_decoder/').StringDecoder; this.decoder = new StringDecoder(options.encoding); this.encoding = options.encoding; } } function Readable(options) { Duplex = Duplex || require('./_stream_duplex'); if (!(this instanceof Readable)) return new Readable(options); // Checking for a Stream.Duplex instance is faster here instead of inside // the ReadableState constructor, at least with V8 6.5 var isDuplex = this instanceof Duplex; this._readableState = new ReadableState(options, this, isDuplex); // legacy this.readable = true; if (options) { if (typeof options.read === 'function') this._read = options.read; if (typeof options.destroy === 'function') this._destroy = options.destroy; } Stream.call(this); } Object.defineProperty(Readable.prototype, 'destroyed', { // making it explicit this property is not enumerable // because otherwise some prototype manipulation in // userland will fail enumerable: false, get: function get() { if (this._readableState === undefined) { return false; } return this._readableState.destroyed; }, set: function set(value) { // we ignore the value if the stream // has not been initialized yet if (!this._readableState) { return; } // backward compatibility, the user is explicitly // managing destroyed this._readableState.destroyed = value; } }); Readable.prototype.destroy = destroyImpl.destroy; Readable.prototype._undestroy = destroyImpl.undestroy; Readable.prototype._destroy = function (err, cb) { cb(err); }; // Manually shove something into the read() buffer. // This returns true if the highWaterMark has not been hit yet, // similar to how Writable.write() returns true if you should // write() some more. Readable.prototype.push = function (chunk, encoding) { var state = this._readableState; var skipChunkCheck; if (!state.objectMode) { if (typeof chunk === 'string') { encoding = encoding || state.defaultEncoding; if (encoding !== state.encoding) { chunk = Buffer.from(chunk, encoding); encoding = ''; } skipChunkCheck = true; } } else { skipChunkCheck = true; } return readableAddChunk(this, chunk, encoding, false, skipChunkCheck); }; // Unshift should *always* be something directly out of read() Readable.prototype.unshift = function (chunk) { return readableAddChunk(this, chunk, null, true, false); }; function readableAddChunk(stream, chunk, encoding, addToFront, skipChunkCheck) { debug('readableAddChunk', chunk); var state = stream._readableState; if (chunk === null) { state.reading = false; onEofChunk(stream, state); } else { var er; if (!skipChunkCheck) er = chunkInvalid(state, chunk); if (er) { errorOrDestroy(stream, er); } else if (state.objectMode || chunk && chunk.length > 0) { if (typeof chunk !== 'string' && !state.objectMode && Object.getPrototypeOf(chunk) !== Buffer.prototype) { chunk = _uint8ArrayToBuffer(chunk); } if (addToFront) { if (state.endEmitted) errorOrDestroy(stream, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());else addChunk(stream, state, chunk, true); } else if (state.ended) { errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF()); } else if (state.destroyed) { return false; } else { state.reading = false; if (state.decoder && !encoding) { chunk = state.decoder.write(chunk); if (state.objectMode || chunk.length !== 0) addChunk(stream, state, chunk, false);else maybeReadMore(stream, state); } else { addChunk(stream, state, chunk, false); } } } else if (!addToFront) { state.reading = false; maybeReadMore(stream, state); } } // We can push more data if we are below the highWaterMark. // Also, if we have no data yet, we can stand some more bytes. // This is to work around cases where hwm=0, such as the repl. return !state.ended && (state.length < state.highWaterMark || state.length === 0); } function addChunk(stream, state, chunk, addToFront) { if (state.flowing && state.length === 0 && !state.sync) { state.awaitDrain = 0; stream.emit('data', chunk); } else { // update the buffer info. state.length += state.objectMode ? 1 : chunk.length; if (addToFront) state.buffer.unshift(chunk);else state.buffer.push(chunk); if (state.needReadable) emitReadable(stream); } maybeReadMore(stream, state); } function chunkInvalid(state, chunk) { var er; if (!_isUint8Array(chunk) && typeof chunk !== 'string' && chunk !== undefined && !state.objectMode) { er = new ERR_INVALID_ARG_TYPE('chunk', ['string', 'Buffer', 'Uint8Array'], chunk); } return er; } Readable.prototype.isPaused = function () { return this._readableState.flowing === false; }; // backwards compatibility. Readable.prototype.setEncoding = function (enc) { if (!StringDecoder) StringDecoder = require('string_decoder/').StringDecoder; var decoder = new StringDecoder(enc); this._readableState.decoder = decoder; // If setEncoding(null), decoder.encoding equals utf8 this._readableState.encoding = this._readableState.decoder.encoding; // Iterate over current buffer to convert already stored Buffers: var p = this._readableState.buffer.head; var content = ''; while (p !== null) { content += decoder.write(p.data); p = p.next; } this._readableState.buffer.clear(); if (content !== '') this._readableState.buffer.push(content); this._readableState.length = content.length; return this; }; // Don't raise the hwm > 1GB var MAX_HWM = 0x40000000; function computeNewHighWaterMark(n) { if (n >= MAX_HWM) { // TODO(ronag): Throw ERR_VALUE_OUT_OF_RANGE. n = MAX_HWM; } else { // Get the next highest power of 2 to prevent increasing hwm excessively in // tiny amounts n--; n |= n >>> 1; n |= n >>> 2; n |= n >>> 4; n |= n >>> 8; n |= n >>> 16; n++; } return n; } // This function is designed to be inlinable, so please take care when making // changes to the function body. function howMuchToRead(n, state) { if (n <= 0 || state.length === 0 && state.ended) return 0; if (state.objectMode) return 1; if (n !== n) { // Only flow one buffer at a time if (state.flowing && state.length) return state.buffer.head.data.length;else return state.length; } // If we're asking for more than the current hwm, then raise the hwm. if (n > state.highWaterMark) state.highWaterMark = computeNewHighWaterMark(n); if (n <= state.length) return n; // Don't have enough if (!state.ended) { state.needReadable = true; return 0; } return state.length; } // you can override either this method, or the async _read(n) below. Readable.prototype.read = function (n) { debug('read', n); n = parseInt(n, 10); var state = this._readableState; var nOrig = n; if (n !== 0) state.emittedReadable = false; // if we're doing read(0) to trigger a readable event, but we // already have a bunch of data in the buffer, then just trigger // the 'readable' event and move on. if (n === 0 && state.needReadable && ((state.highWaterMark !== 0 ? state.length >= state.highWaterMark : state.length > 0) || state.ended)) { debug('read: emitReadable', state.length, state.ended); if (state.length === 0 && state.ended) endReadable(this);else emitReadable(this); return null; } n = howMuchToRead(n, state); // if we've ended, and we're now clear, then finish it up. if (n === 0 && state.ended) { if (state.length === 0) endReadable(this); return null; } // All the actual chunk generation logic needs to be // *below* the call to _read. The reason is that in certain // synthetic stream cases, such as passthrough streams, _read // may be a completely synchronous operation which may change // the state of the read buffer, providing enough data when // before there was *not* enough. // // So, the steps are: // 1. Figure out what the state of things will be after we do // a read from the buffer. // // 2. If that resulting state will trigger a _read, then call _read. // Note that this may be asynchronous, or synchronous. Yes, it is // deeply ugly to write APIs this way, but that still doesn't mean // that the Readable class should behave improperly, as streams are // designed to be sync/async agnostic. // Take note if the _read call is sync or async (ie, if the read call // has returned yet), so that we know whether or not it's safe to emit // 'readable' etc. // // 3. Actually pull the requested chunks out of the buffer and return. // if we need a readable event, then we need to do some reading. var doRead = state.needReadable; debug('need readable', doRead); // if we currently have less than the highWaterMark, then also read some if (state.length === 0 || state.length - n < state.highWaterMark) { doRead = true; debug('length less than watermark', doRead); } // however, if we've ended, then there's no point, and if we're already // reading, then it's unnecessary. if (state.ended || state.reading) { doRead = false; debug('reading or ended', doRead); } else if (doRead) { debug('do read'); state.reading = true; state.sync = true; // if the length is currently zero, then we *need* a readable event. if (state.length === 0) state.needReadable = true; // call internal read method this._read(state.highWaterMark); state.sync = false; // If _read pushed data synchronously, then `reading` will be false, // and we need to re-evaluate how much data we can return to the user. if (!state.reading) n = howMuchToRead(nOrig, state); } var ret; if (n > 0) ret = fromList(n, state);else ret = null; if (ret === null) { state.needReadable = state.length <= state.highWaterMark; n = 0; } else { state.length -= n; state.awaitDrain = 0; } if (state.length === 0) { // If we have nothing in the buffer, then we want to know // as soon as we *do* get something into the buffer. if (!state.ended) state.needReadable = true; // If we tried to read() past the EOF, then emit end on the next tick. if (nOrig !== n && state.ended) endReadable(this); } if (ret !== null) this.emit('data', ret); return ret; }; function onEofChunk(stream, state) { debug('onEofChunk'); if (state.ended) return; if (state.decoder) { var chunk = state.decoder.end(); if (chunk && chunk.length) { state.buffer.push(chunk); state.length += state.objectMode ? 1 : chunk.length; } } state.ended = true; if (state.sync) { // if we are sync, wait until next tick to emit the data. // Otherwise we risk emitting data in the flow() // the readable code triggers during a read() call emitReadable(stream); } else { // emit 'readable' now to make sure it gets picked up. state.needReadable = false; if (!state.emittedReadable) { state.emittedReadable = true; emitReadable_(stream); } } } // Don't emit readable right away in sync mode, because this can trigger // another read() call => stack overflow. This way, it might trigger // a nextTick recursion warning, but that's not so bad. function emitReadable(stream) { var state = stream._readableState; debug('emitReadable', state.needReadable, state.emittedReadable); state.needReadable = false; if (!state.emittedReadable) { debug('emitReadable', state.flowing); state.emittedReadable = true; process.nextTick(emitReadable_, stream); } } function emitReadable_(stream) { var state = stream._readableState; debug('emitReadable_', state.destroyed, state.length, state.ended); if (!state.destroyed && (state.length || state.ended)) { stream.emit('readable'); state.emittedReadable = false; } // The stream needs another readable event if // 1. It is not flowing, as the flow mechanism will take // care of it. // 2. It is not ended. // 3. It is below the highWaterMark, so we can schedule // another readable later. state.needReadable = !state.flowing && !state.ended && state.length <= state.highWaterMark; flow(stream); } // at this point, the user has presumably seen the 'readable' event, // and called read() to consume some data. that may have triggered // in turn another _read(n) call, in which case reading = true if // it's in progress. // However, if we're not ended, or reading, and the length < hwm, // then go ahead and try to read some more preemptively. function maybeReadMore(stream, state) { if (!state.readingMore) { state.readingMore = true; process.nextTick(maybeReadMore_, stream, state); } } function maybeReadMore_(stream, state) { // Attempt to read more data if we should. // // The conditions for reading more data are (one of): // - Not enough data buffered (state.length < state.highWaterMark). The loop // is responsible for filling the buffer with enough data if such data // is available. If highWaterMark is 0 and we are not in the flowing mode // we should _not_ attempt to buffer any extra data. We'll get more data // when the stream consumer calls read() instead. // - No data in the buffer, and the stream is in flowing mode. In this mode // the loop below is responsible for ensuring read() is called. Failing to // call read here would abort the flow and there's no other mechanism for // continuing the flow if the stream consumer has just subscribed to the // 'data' event. // // In addition to the above conditions to keep reading data, the following // conditions prevent the data from being read: // - The stream has ended (state.ended). // - There is already a pending 'read' operation (state.reading). This is a // case where the the stream has called the implementation defined _read() // method, but they are processing the call asynchronously and have _not_ // called push() with new data. In this case we skip performing more // read()s. The execution ends in this method again after the _read() ends // up calling push() with more data. while (!state.reading && !state.ended && (state.length < state.highWaterMark || state.flowing && state.length === 0)) { var len = state.length; debug('maybeReadMore read 0'); stream.read(0); if (len === state.length) // didn't get any data, stop spinning. break; } state.readingMore = false; } // abstract method. to be overridden in specific implementation classes. // call cb(er, data) where data is <= n in length. // for virtual (non-string, non-buffer) streams, "length" is somewhat // arbitrary, and perhaps not very meaningful. Readable.prototype._read = function (n) { errorOrDestroy(this, new ERR_METHOD_NOT_IMPLEMENTED('_read()')); }; Readable.prototype.pipe = function (dest, pipeOpts) { var src = this; var state = this._readableState; switch (state.pipesCount) { case 0: state.pipes = dest; break; case 1: state.pipes = [state.pipes, dest]; break; default: state.pipes.push(dest); break; } state.pipesCount += 1; debug('pipe count=%d opts=%j', state.pipesCount, pipeOpts); var doEnd = (!pipeOpts || pipeOpts.end !== false) && dest !== process.stdout && dest !== process.stderr; var endFn = doEnd ? onend : unpipe; if (state.endEmitted) process.nextTick(endFn);else src.once('end', endFn); dest.on('unpipe', onunpipe); function onunpipe(readable, unpipeInfo) { debug('onunpipe'); if (readable === src) { if (unpipeInfo && unpipeInfo.hasUnpiped === false) { unpipeInfo.hasUnpiped = true; cleanup(); } } } function onend() { debug('onend'); dest.end(); } // when the dest drains, it reduces the awaitDrain counter // on the source. This would be more elegant with a .once() // handler in flow(), but adding and removing repeatedly is // too slow. var ondrain = pipeOnDrain(src); dest.on('drain', ondrain); var cleanedUp = false; function cleanup() { debug('cleanup'); // cleanup event handlers once the pipe is broken dest.removeListener('close', onclose); dest.removeListener('finish', onfinish); dest.removeListener('drain', ondrain); dest.removeListener('error', onerror); dest.removeListener('unpipe', onunpipe); src.removeListener('end', onend); src.removeListener('end', unpipe); src.removeListener('data', ondata); cleanedUp = true; // if the reader is waiting for a drain event from this // specific writer, then it would cause it to never start // flowing again. // So, if this is awaiting a drain, then we just call it now. // If we don't know, then assume that we are waiting for one. if (state.awaitDrain && (!dest._writableState || dest._writableState.needDrain)) ondrain(); } src.on('data', ondata); function ondata(chunk) { debug('ondata'); var ret = dest.write(chunk); debug('dest.write', ret); if (ret === false) { // If the user unpiped during `dest.write()`, it is possible // to get stuck in a permanently paused state if that write // also returned false. // => Check whether `dest` is still a piping destination. if ((state.pipesCount === 1 && state.pipes === dest || state.pipesCount > 1 && indexOf(state.pipes, dest) !== -1) && !cleanedUp) { debug('false write response, pause', state.awaitDrain); state.awaitDrain++; } src.pause(); } } // if the dest has an error, then stop piping into it. // however, don't suppress the throwing behavior for this. function onerror(er) { debug('onerror', er); unpipe(); dest.removeListener('error', onerror); if (EElistenerCount(dest, 'error') === 0) errorOrDestroy(dest, er); } // Make sure our error handler is attached before userland ones. prependListener(dest, 'error', onerror); // Both close and finish should trigger unpipe, but only once. function onclose() { dest.removeListener('finish', onfinish); unpipe(); } dest.once('close', onclose); function onfinish() { debug('onfinish'); dest.removeListener('close', onclose); unpipe(); } dest.once('finish', onfinish); function unpipe() { debug('unpipe'); src.unpipe(dest); } // tell the dest that it's being piped to dest.emit('pipe', src); // start the flow if it hasn't been started already. if (!state.flowing) { debug('pipe resume'); src.resume(); } return dest; }; function pipeOnDrain(src) { return function pipeOnDrainFunctionResult() { var state = src._readableState; debug('pipeOnDrain', state.awaitDrain); if (state.awaitDrain) state.awaitDrain--; if (state.awaitDrain === 0 && EElistenerCount(src, 'data')) { state.flowing = true; flow(src); } }; } Readable.prototype.unpipe = function (dest) { var state = this._readableState; var unpipeInfo = { hasUnpiped: false }; // if we're not piping anywhere, then do nothing. if (state.pipesCount === 0) return this; // just one destination. most common case. if (state.pipesCount === 1) { // passed in one, but it's not the right one. if (dest && dest !== state.pipes) return this; if (!dest) dest = state.pipes; // got a match. state.pipes = null; state.pipesCount = 0; state.flowing = false; if (dest) dest.emit('unpipe', this, unpipeInfo); return this; } // slow case. multiple pipe destinations. if (!dest) { // remove all. var dests = state.pipes; var len = state.pipesCount; state.pipes = null; state.pipesCount = 0; state.flowing = false; for (var i = 0; i < len; i++) dests[i].emit('unpipe', this, { hasUnpiped: false }); return this; } // try to find the right one. var index = indexOf(state.pipes, dest); if (index === -1) return this; state.pipes.splice(index, 1); state.pipesCount -= 1; if (state.pipesCount === 1) state.pipes = state.pipes[0]; dest.emit('unpipe', this, unpipeInfo); return this; }; // set up data events if they are asked for // Ensure readable listeners eventually get something Readable.prototype.on = function (ev, fn) { var res = Stream.prototype.on.call(this, ev, fn); var state = this._readableState; if (ev === 'data') { // update readableListening so that resume() may be a no-op // a few lines down. This is needed to support once('readable'). state.readableListening = this.listenerCount('readable') > 0; // Try start flowing on next tick if stream isn't explicitly paused if (state.flowing !== false) this.resume(); } else if (ev === 'readable') { if (!state.endEmitted && !state.readableListening) { state.readableListening = state.needReadable = true; state.flowing = false; state.emittedReadable = false; debug('on readable', state.length, state.reading); if (state.length) { emitReadable(this); } else if (!state.reading) { process.nextTick(nReadingNextTick, this); } } } return res; }; Readable.prototype.addListener = Readable.prototype.on; Readable.prototype.removeListener = function (ev, fn) { var res = Stream.prototype.removeListener.call(this, ev, fn); if (ev === 'readable') { // We need to check if there is someone still listening to // readable and reset the state. However this needs to happen // after readable has been emitted but before I/O (nextTick) to // support once('readable', fn) cycles. This means that calling // resume within the same tick will have no // effect. process.nextTick(updateReadableListening, this); } return res; }; Readable.prototype.removeAllListeners = function (ev) { var res = Stream.prototype.removeAllListeners.apply(this, arguments); if (ev === 'readable' || ev === undefined) { // We need to check if there is someone still listening to // readable and reset the state. However this needs to happen // after readable has been emitted but before I/O (nextTick) to // support once('readable', fn) cycles. This means that calling // resume within the same tick will have no // effect. process.nextTick(updateReadableListening, this); } return res; }; function updateReadableListening(self) { var state = self._readableState; state.readableListening = self.listenerCount('readable') > 0; if (state.resumeScheduled && !state.paused) { // flowing needs to be set to true now, otherwise // the upcoming resume will not flow. state.flowing = true; // crude way to check if we should resume } else if (self.listenerCount('data') > 0) { self.resume(); } } function nReadingNextTick(self) { debug('readable nexttick read 0'); self.read(0); } // pause() and resume() are remnants of the legacy readable stream API // If the user uses them, then switch into old mode. Readable.prototype.resume = function () { var state = this._readableState; if (!state.flowing) { debug('resume'); // we flow only if there is no one listening // for readable, but we still have to call // resume() state.flowing = !state.readableListening; resume(this, state); } state.paused = false; return this; }; function resume(stream, state) { if (!state.resumeScheduled) { state.resumeScheduled = true; process.nextTick(resume_, stream, state); } } function resume_(stream, state) { debug('resume', state.reading); if (!state.reading) { stream.read(0); } state.resumeScheduled = false; stream.emit('resume'); flow(stream); if (state.flowing && !state.reading) stream.read(0); } Readable.prototype.pause = function () { debug('call pause flowing=%j', this._readableState.flowing); if (this._readableState.flowing !== false) { debug('pause'); this._readableState.flowing = false; this.emit('pause'); } this._readableState.paused = true; return this; }; function flow(stream) { var state = stream._readableState; debug('flow', state.flowing); while (state.flowing && stream.read() !== null); } // wrap an old-style stream as the async data source. // This is *not* part of the readable stream interface. // It is an ugly unfortunate mess of history. Readable.prototype.wrap = function (stream) { var _this = this; var state = this._readableState; var paused = false; stream.on('end', function () { debug('wrapped end'); if (state.decoder && !state.ended) { var chunk = state.decoder.end(); if (chunk && chunk.length) _this.push(chunk); } _this.push(null); }); stream.on('data', function (chunk) { debug('wrapped data'); if (state.decoder) chunk = state.decoder.write(chunk); // don't skip over falsy values in objectMode if (state.objectMode && (chunk === null || chunk === undefined)) return;else if (!state.objectMode && (!chunk || !chunk.length)) return; var ret = _this.push(chunk); if (!ret) { paused = true; stream.pause(); } }); // proxy all the other methods. // important when wrapping filters and duplexes. for (var i in stream) { if (this[i] === undefined && typeof stream[i] === 'function') { this[i] = function methodWrap(method) { return function methodWrapReturnFunction() { return stream[method].apply(stream, arguments); }; }(i); } } // proxy certain important events. for (var n = 0; n < kProxyEvents.length; n++) { stream.on(kProxyEvents[n], this.emit.bind(this, kProxyEvents[n])); } // when we try to consume some more bytes, simply unpause the // underlying stream. this._read = function (n) { debug('wrapped _read', n); if (paused) { paused = false; stream.resume(); } }; return this; }; if (typeof Symbol === 'function') { Readable.prototype[Symbol.asyncIterator] = function () { if (createReadableStreamAsyncIterator === undefined) { createReadableStreamAsyncIterator = require('./internal/streams/async_iterator'); } return createReadableStreamAsyncIterator(this); }; } Object.defineProperty(Readable.prototype, 'readableHighWaterMark', { // making it explicit this property is not enumerable // because otherwise some prototype manipulation in // userland will fail enumerable: false, get: function get() { return this._readableState.highWaterMark; } }); Object.defineProperty(Readable.prototype, 'readableBuffer', { // making it explicit this property is not enumerable // because otherwise some prototype manipulation in // userland will fail enumerable: false, get: function get() { return this._readableState && this._readableState.buffer; } }); Object.defineProperty(Readable.prototype, 'readableFlowing', { // making it explicit this property is not enumerable // because otherwise some prototype manipulation in // userland will fail enumerable: false, get: function get() { return this._readableState.flowing; }, set: function set(state) { if (this._readableState) { this._readableState.flowing = state; } } }); // exposed for testing purposes only. Readable._fromList = fromList; Object.defineProperty(Readable.prototype, 'readableLength', { // making it explicit this property is not enumerable // because otherwise some prototype manipulation in // userland will fail enumerable: false, get: function get() { return this._readableState.length; } }); // Pluck off n bytes from an array of buffers. // Length is the combined lengths of all the buffers in the list. // This function is designed to be inlinable, so please take care when making // changes to the function body. function fromList(n, state) { // nothing buffered if (state.length === 0) return null; var ret; if (state.objectMode) ret = state.buffer.shift();else if (!n || n >= state.length) { // read it all, truncate the list if (state.decoder) ret = state.buffer.join('');else if (state.buffer.length === 1) ret = state.buffer.first();else ret = state.buffer.concat(state.length); state.buffer.clear(); } else { // read part of list ret = state.buffer.consume(n, state.decoder); } return ret; } function endReadable(stream) { var state = stream._readableState; debug('endReadable', state.endEmitted); if (!state.endEmitted) { state.ended = true; process.nextTick(endReadableNT, state, stream); } } function endReadableNT(state, stream) { debug('endReadableNT', state.endEmitted, state.length); // Check that we didn't get one last unshift. if (!state.endEmitted && state.length === 0) { state.endEmitted = true; stream.readable = false; stream.emit('end'); if (state.autoDestroy) { // In case of duplex streams we need a way to detect // if the writable side is ready for autoDestroy as well var wState = stream._writableState; if (!wState || wState.autoDestroy && wState.finished) { stream.destroy(); } } } } if (typeof Symbol === 'function') { Readable.from = function (iterable, opts) { if (from === undefined) { from = require('./internal/streams/from'); } return from(Readable, iterable, opts); }; } function indexOf(xs, x) { for (var i = 0, l = xs.length; i < l; i++) { if (xs[i] === x) return i; } return -1; }