'use strict';

var _commonjsHelpers = require('../../../_virtual/_commonjsHelpers.js');
var EventEmitter = require('events');
var stream = require('./internal/streams/stream.js');
var require$$0 = require('buffer');
var require$$0$1 = require('util');
var buffer_list = require('./internal/streams/buffer_list.js');
var destroy = require('./internal/streams/destroy.js');
var state = require('./internal/streams/state.js');
var errors = require('../errors.js');
var inherits = require('../../inherits/inherits.js');
var _stream_duplex = require('./_stream_duplex.js');
var string_decoder = require('../node_modules/string_decoder/lib/string_decoder.js');
var async_iterator = require('./internal/streams/async_iterator.js');
var from = require('./internal/streams/from.js');

var _stream_readable;
var hasRequired_stream_readable;

function require_stream_readable () {
	if (hasRequired_stream_readable) return _stream_readable;
	hasRequired_stream_readable = 1;

	_stream_readable = Readable;

	/*<replacement>*/
	var Duplex;
	/*</replacement>*/

	Readable.ReadableState = ReadableState;

	/*<replacement>*/
	EventEmitter.EventEmitter;
	var EElistenerCount = function EElistenerCount(emitter, type) {
	  return emitter.listeners(type).length;
	};
	/*</replacement>*/

	/*<replacement>*/
	var Stream = stream.__require();
	/*</replacement>*/

	var Buffer = require$$0.Buffer;
	var OurUint8Array = (typeof _commonjsHelpers.commonjsGlobal !== 'undefined' ? _commonjsHelpers.commonjsGlobal : 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$$0$1;
	var debug;
	if (debugUtil && debugUtil.debuglog) {
	  debug = debugUtil.debuglog('stream');
	} else {
	  debug = function debug() {};
	}
	/*</replacement>*/

	var BufferList = buffer_list.__require();
	var destroyImpl = destroy.__require();
	var _require = state.__require(),
	  getHighWaterMark = _require.getHighWaterMark;
	var _require$codes = errors.__require().codes,
	  ERR_INVALID_ARG_TYPE = _require$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$1;
	inherits.__require()(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 || _stream_duplex.__require();
	  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 = string_decoder.__require().StringDecoder;
	    this.decoder = new StringDecoder(options.encoding);
	    this.encoding = options.encoding;
	  }
	}
	function Readable(options) {
	  Duplex = Duplex || _stream_duplex.__require();
	  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 = string_decoder.__require().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 = async_iterator.__require();
	    }
	    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$1 === undefined) {
	      from$1 = from.__require();
	    }
	    return from$1(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;
	}
	return _stream_readable;
}

exports.__require = require_stream_readable;
