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854 lines
23 KiB
854 lines
23 KiB
// Copyright Joyent, Inc. and other Node contributors.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and associated documentation files (the
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// "Software"), to deal in the Software without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Software, and to permit
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// persons to whom the Software is furnished to do so, subject to the
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// following conditions:
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//
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// The above copyright notice and this permission notice shall be included
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// in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
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// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
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// USE OR OTHER DEALINGS IN THE SOFTWARE.
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module.exports = Readable;
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Readable.ReadableState = ReadableState;
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var EE = require('events').EventEmitter;
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var Stream = require('stream');
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var util = require('util');
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var StringDecoder;
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util.inherits(Readable, Stream);
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function ReadableState(options, stream) {
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options = options || {};
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// the point at which it stops calling _read() to fill the buffer
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// Note: 0 is a valid value, means "don't call _read preemptively ever"
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var hwm = options.highWaterMark;
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this.highWaterMark = (hwm || hwm === 0) ? hwm : 16 * 1024;
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// cast to ints.
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this.highWaterMark = ~~this.highWaterMark;
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this.buffer = [];
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this.length = 0;
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this.pipes = null;
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this.pipesCount = 0;
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this.flowing = false;
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this.ended = false;
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this.endEmitted = false;
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this.reading = false;
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// a flag to be able to tell if the onwrite cb is called immediately,
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// or on a later tick. We set this to true at first, becuase any
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// actions that shouldn't happen until "later" should generally also
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// not happen before the first write call.
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this.sync = true;
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// whenever we return null, then we set a flag to say
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// that we're awaiting a 'readable' event emission.
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this.needReadable = false;
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this.emittedReadable = false;
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// object stream flag. Used to make read(n) ignore n and to
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// make all the buffer merging and length checks go away
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this.objectMode = !!options.objectMode;
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// when piping, we only care about 'readable' events that happen
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// after read()ing all the bytes and not getting any pushback.
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this.ranOut = false;
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// the number of writers that are awaiting a drain event in .pipe()s
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this.awaitDrain = 0;
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this.decoder = null;
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if (options.encoding) {
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if (!StringDecoder)
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StringDecoder = require('string_decoder').StringDecoder;
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this.decoder = new StringDecoder(options.encoding);
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}
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}
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function Readable(options) {
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if (!(this instanceof Readable))
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return new Readable(options);
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this._readableState = new ReadableState(options, this);
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// legacy
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this.readable = true;
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Stream.call(this);
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}
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// Manually shove something into the read() buffer.
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// This returns true if the highWaterMark has not been hit yet,
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// similar to how Writable.write() returns true if you should
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// write() some more.
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Readable.prototype.push = function(chunk) {
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var state = this._readableState;
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if (typeof chunk === 'string' && !state.objectMode)
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chunk = new Buffer(chunk, arguments[1]);
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return readableAddChunk(this, state, chunk, false);
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};
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Readable.prototype.unshift = function(chunk) {
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var state = this._readableState;
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if (typeof chunk === 'string' && !state.objectMode)
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chunk = new Buffer(chunk, arguments[1]);
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return readableAddChunk(this, state, chunk, true);
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};
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function readableAddChunk(stream, state, chunk, addToFront) {
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state.reading = false;
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var er = chunkInvalid(state, chunk);
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if (er) {
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stream.emit('error', er);
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} else if (chunk === null || chunk === undefined) {
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onEofChunk(stream, state);
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} else if (state.objectMode || chunk && chunk.length > 0) {
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if (state.decoder)
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chunk = state.decoder.write(chunk);
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// update the buffer info.
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state.length += state.objectMode ? 1 : chunk.length;
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if (addToFront)
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state.buffer.unshift(chunk);
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else
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state.buffer.push(chunk);
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if (state.needReadable)
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emitReadable(stream);
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maybeReadMore(stream, state);
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}
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return needMoreData(state);
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}
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// if it's past the high water mark, we can push in some more.
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// Also, if we have no data yet, we can stand some
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// more bytes. This is to work around cases where hwm=0,
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// such as the repl. Also, if the push() triggered a
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// readable event, and the user called read(largeNumber) such that
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// needReadable was set, then we ought to push more, so that another
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// 'readable' event will be triggered.
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function needMoreData(state) {
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return !state.ended &&
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(state.needReadable ||
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state.length < state.highWaterMark ||
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state.length === 0);
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}
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// backwards compatibility.
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Readable.prototype.setEncoding = function(enc) {
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if (!StringDecoder)
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StringDecoder = require('string_decoder').StringDecoder;
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this._readableState.decoder = new StringDecoder(enc);
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};
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// Don't raise the hwm > 128MB
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var MAX_HWM = 0x800000;
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function roundUpToNextPowerOf2(n) {
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if (n >= MAX_HWM) {
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n = MAX_HWM;
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} else {
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// Get the next highest power of 2
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n--;
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for (var p = 1; p < 32; p <<= 1) n |= n >> p;
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n++;
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}
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return n;
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}
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function howMuchToRead(n, state) {
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if (state.length === 0 && state.ended)
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return 0;
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if (state.objectMode)
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return n === 0 ? 0 : 1;
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if (isNaN(n) || n === null) {
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// only flow one buffer at a time
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if (state.flowing && state.buffer.length)
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return state.buffer[0].length;
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else
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return state.length;
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}
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if (n <= 0)
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return 0;
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// If we're asking for more than the target buffer level,
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// then raise the water mark. Bump up to the next highest
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// power of 2, to prevent increasing it excessively in tiny
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// amounts.
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if (n > state.highWaterMark)
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state.highWaterMark = roundUpToNextPowerOf2(n);
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// don't have that much. return null, unless we've ended.
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if (n > state.length) {
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if (!state.ended) {
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state.needReadable = true;
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return 0;
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} else
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return state.length;
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}
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return n;
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}
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// you can override either this method, or the async _read(n) below.
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Readable.prototype.read = function(n) {
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var state = this._readableState;
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var nOrig = n;
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if (typeof n !== 'number' || n > 0)
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state.emittedReadable = false;
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// if we're doing read(0) to trigger a readable event, but we
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// already have a bunch of data in the buffer, then just trigger
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// the 'readable' event and move on.
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if (n === 0 &&
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state.needReadable &&
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state.length >= state.highWaterMark) {
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emitReadable(this);
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return null;
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}
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n = howMuchToRead(n, state);
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// if we've ended, and we're now clear, then finish it up.
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if (n === 0 && state.ended) {
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if (state.length === 0)
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endReadable(this);
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return null;
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}
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// All the actual chunk generation logic needs to be
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// *below* the call to _read. The reason is that in certain
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// synthetic stream cases, such as passthrough streams, _read
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// may be a completely synchronous operation which may change
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// the state of the read buffer, providing enough data when
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// before there was *not* enough.
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//
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// So, the steps are:
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// 1. Figure out what the state of things will be after we do
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// a read from the buffer.
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//
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// 2. If that resulting state will trigger a _read, then call _read.
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// Note that this may be asynchronous, or synchronous. Yes, it is
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// deeply ugly to write APIs this way, but that still doesn't mean
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// that the Readable class should behave improperly, as streams are
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// designed to be sync/async agnostic.
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// Take note if the _read call is sync or async (ie, if the read call
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// has returned yet), so that we know whether or not it's safe to emit
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// 'readable' etc.
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//
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// 3. Actually pull the requested chunks out of the buffer and return.
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// if we need a readable event, then we need to do some reading.
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var doRead = state.needReadable;
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// if we currently have less than the highWaterMark, then also read some
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if (state.length - n <= state.highWaterMark)
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doRead = true;
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// however, if we've ended, then there's no point, and if we're already
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// reading, then it's unnecessary.
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if (state.ended || state.reading)
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doRead = false;
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if (doRead) {
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state.reading = true;
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state.sync = true;
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// if the length is currently zero, then we *need* a readable event.
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if (state.length === 0)
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state.needReadable = true;
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// call internal read method
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this._read(state.highWaterMark);
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state.sync = false;
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}
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// If _read called its callback synchronously, then `reading`
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// will be false, and we need to re-evaluate how much data we
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// can return to the user.
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if (doRead && !state.reading)
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n = howMuchToRead(nOrig, state);
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var ret;
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if (n > 0)
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ret = fromList(n, state);
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else
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ret = null;
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if (ret === null) {
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state.needReadable = true;
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n = 0;
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}
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state.length -= n;
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// If we have nothing in the buffer, then we want to know
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// as soon as we *do* get something into the buffer.
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if (state.length === 0 && !state.ended)
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state.needReadable = true;
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// If we happened to read() exactly the remaining amount in the
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// buffer, and the EOF has been seen at this point, then make sure
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// that we emit 'end' on the very next tick.
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if (state.ended && !state.endEmitted && state.length === 0)
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endReadable(this);
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return ret;
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};
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function chunkInvalid(state, chunk) {
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var er = null;
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if (!Buffer.isBuffer(chunk) &&
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'string' !== typeof chunk &&
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chunk !== null &&
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chunk !== undefined &&
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!state.objectMode &&
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!er) {
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er = new TypeError('Invalid non-string/buffer chunk');
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}
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return er;
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}
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function onEofChunk(stream, state) {
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state.ended = true;
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if (state.decoder) {
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var chunk = state.decoder.end();
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if (chunk && chunk.length) {
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state.buffer.push(chunk);
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state.length += state.objectMode ? 1 : chunk.length;
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}
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}
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// if we've ended and we have some data left, then emit
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// 'readable' now to make sure it gets picked up.
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if (state.length > 0)
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emitReadable(stream);
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else
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endReadable(stream);
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}
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// Don't emit readable right away in sync mode, because this can trigger
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// another read() call => stack overflow. This way, it might trigger
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// a nextTick recursion warning, but that's not so bad.
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function emitReadable(stream) {
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var state = stream._readableState;
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state.needReadable = false;
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if (state.emittedReadable)
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return;
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state.emittedReadable = true;
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if (state.sync)
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process.nextTick(function() {
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emitReadable_(stream);
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});
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else
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emitReadable_(stream);
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}
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function emitReadable_(stream) {
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var state = stream._readableState;
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stream.emit('readable');
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}
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// at this point, the user has presumably seen the 'readable' event,
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// and called read() to consume some data. that may have triggered
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// in turn another _read(n) call, in which case reading = true if
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// it's in progress.
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// However, if we're not ended, or reading, and the length < hwm,
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// then go ahead and try to read some more right now preemptively.
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function maybeReadMore(stream, state) {
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if (state.sync)
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process.nextTick(function() {
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maybeReadMore_(stream, state);
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});
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else
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maybeReadMore_(stream, state);
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}
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function maybeReadMore_(stream, state) {
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if (!state.reading && !state.ended &&
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state.length < state.highWaterMark) {
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stream.read(0);
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}
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}
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// abstract method. to be overridden in specific implementation classes.
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// call cb(er, data) where data is <= n in length.
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// for virtual (non-string, non-buffer) streams, "length" is somewhat
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// arbitrary, and perhaps not very meaningful.
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Readable.prototype._read = function(n) {
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this.emit('error', new Error('not implemented'));
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};
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Readable.prototype.pipe = function(dest, pipeOpts) {
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var src = this;
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var state = this._readableState;
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switch (state.pipesCount) {
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case 0:
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state.pipes = dest;
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break;
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case 1:
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state.pipes = [state.pipes, dest];
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break;
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default:
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state.pipes.push(dest);
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break;
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}
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state.pipesCount += 1;
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if ((!pipeOpts || pipeOpts.end !== false) &&
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dest !== process.stdout &&
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dest !== process.stderr) {
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src.once('end', onend);
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} else {
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src.once('end', cleanup);
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}
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dest.on('unpipe', onunpipe);
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function onunpipe(readable) {
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if (readable !== src) return;
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cleanup();
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}
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function onend() {
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dest.end();
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}
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// when the dest drains, it reduces the awaitDrain counter
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// on the source. This would be more elegant with a .once()
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// handler in flow(), but adding and removing repeatedly is
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// too slow.
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var ondrain = pipeOnDrain(src);
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dest.on('drain', ondrain);
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function cleanup() {
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// cleanup event handlers once the pipe is broken
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dest.removeListener('close', onclose);
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dest.removeListener('finish', onfinish);
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dest.removeListener('drain', ondrain);
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dest.removeListener('error', onerror);
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dest.removeListener('unpipe', onunpipe);
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src.removeListener('end', onend);
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src.removeListener('end', cleanup);
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// if the reader is waiting for a drain event from this
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// specific writer, then it would cause it to never start
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// flowing again.
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// So, if this is awaiting a drain, then we just call it now.
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// If we don't know, then assume that we are waiting for one.
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if (!dest._writableState || dest._writableState.needDrain)
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ondrain();
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}
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// if the dest has an error, then stop piping into it.
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// however, don't suppress the throwing behavior for this.
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function onerror(er) {
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unpipe();
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if (EE.listenerCount(dest, 'error') === 0)
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dest.emit('error', er);
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}
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dest.once('error', onerror);
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// Both close and finish should trigger unpipe, but only once.
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function onclose() {
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dest.removeListener('finish', onfinish);
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unpipe();
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}
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dest.once('close', onclose);
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function onfinish() {
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dest.removeListener('close', onclose);
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unpipe();
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}
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dest.once('finish', onfinish);
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function unpipe() {
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src.unpipe(dest);
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}
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// tell the dest that it's being piped to
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dest.emit('pipe', src);
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// start the flow if it hasn't been started already.
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if (!state.flowing) {
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// the handler that waits for readable events after all
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// the data gets sucked out in flow.
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// This would be easier to follow with a .once() handler
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// in flow(), but that is too slow.
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this.on('readable', pipeOnReadable);
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state.flowing = true;
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process.nextTick(function() {
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flow(src);
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});
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}
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return dest;
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};
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function pipeOnDrain(src) {
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return function() {
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var dest = this;
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var state = src._readableState;
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state.awaitDrain--;
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if (state.awaitDrain === 0)
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flow(src);
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};
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}
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function flow(src) {
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var state = src._readableState;
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var chunk;
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state.awaitDrain = 0;
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function write(dest, i, list) {
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var written = dest.write(chunk);
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if (false === written) {
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state.awaitDrain++;
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}
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}
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while (state.pipesCount && null !== (chunk = src.read())) {
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if (state.pipesCount === 1)
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write(state.pipes, 0, null);
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else
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state.pipes.forEach(write);
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src.emit('data', chunk);
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// if anyone needs a drain, then we have to wait for that.
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if (state.awaitDrain > 0)
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return;
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}
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// if every destination was unpiped, either before entering this
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|
// function, or in the while loop, then stop flowing.
|
|
//
|
|
// NB: This is a pretty rare edge case.
|
|
if (state.pipesCount === 0) {
|
|
state.flowing = false;
|
|
|
|
// if there were data event listeners added, then switch to old mode.
|
|
if (EE.listenerCount(src, 'data') > 0)
|
|
emitDataEvents(src);
|
|
return;
|
|
}
|
|
|
|
// at this point, no one needed a drain, so we just ran out of data
|
|
// on the next readable event, start it over again.
|
|
state.ranOut = true;
|
|
}
|
|
|
|
function pipeOnReadable() {
|
|
if (this._readableState.ranOut) {
|
|
this._readableState.ranOut = false;
|
|
flow(this);
|
|
}
|
|
}
|
|
|
|
|
|
Readable.prototype.unpipe = function(dest) {
|
|
var state = this._readableState;
|
|
|
|
// 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;
|
|
this.removeListener('readable', pipeOnReadable);
|
|
state.flowing = false;
|
|
if (dest)
|
|
dest.emit('unpipe', this);
|
|
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;
|
|
this.removeListener('readable', pipeOnReadable);
|
|
state.flowing = false;
|
|
|
|
for (var i = 0; i < len; i++)
|
|
dests[i].emit('unpipe', this);
|
|
return this;
|
|
}
|
|
|
|
// try to find the right one.
|
|
var i = state.pipes.indexOf(dest);
|
|
if (i === -1)
|
|
return this;
|
|
|
|
state.pipes.splice(i, 1);
|
|
state.pipesCount -= 1;
|
|
if (state.pipesCount === 1)
|
|
state.pipes = state.pipes[0];
|
|
|
|
dest.emit('unpipe', this);
|
|
|
|
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);
|
|
|
|
if (ev === 'data' && !this._readableState.flowing)
|
|
emitDataEvents(this);
|
|
|
|
if (ev === 'readable')
|
|
this.read(0);
|
|
|
|
return res;
|
|
};
|
|
Readable.prototype.addListener = Readable.prototype.on;
|
|
|
|
// 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() {
|
|
emitDataEvents(this);
|
|
this.read(0);
|
|
this.emit('resume');
|
|
};
|
|
|
|
Readable.prototype.pause = function() {
|
|
emitDataEvents(this, true);
|
|
this.emit('pause');
|
|
};
|
|
|
|
function emitDataEvents(stream, startPaused) {
|
|
var state = stream._readableState;
|
|
|
|
if (state.flowing) {
|
|
// https://github.com/isaacs/readable-stream/issues/16
|
|
throw new Error('Cannot switch to old mode now.');
|
|
}
|
|
|
|
var paused = startPaused || false;
|
|
var readable = false;
|
|
|
|
// convert to an old-style stream.
|
|
stream.readable = true;
|
|
stream.pipe = Stream.prototype.pipe;
|
|
stream.on = stream.addListener = Stream.prototype.on;
|
|
|
|
stream.on('readable', function() {
|
|
readable = true;
|
|
|
|
var c;
|
|
while (!paused && (null !== (c = stream.read())))
|
|
stream.emit('data', c);
|
|
|
|
if (c === null) {
|
|
readable = false;
|
|
stream._readableState.needReadable = true;
|
|
}
|
|
});
|
|
|
|
stream.pause = function() {
|
|
paused = true;
|
|
this.emit('pause');
|
|
};
|
|
|
|
stream.resume = function() {
|
|
paused = false;
|
|
if (readable)
|
|
process.nextTick(function() {
|
|
stream.emit('readable');
|
|
});
|
|
else
|
|
this.read(0);
|
|
this.emit('resume');
|
|
};
|
|
|
|
// now make it start, just in case it hadn't already.
|
|
stream.emit('readable');
|
|
}
|
|
|
|
// 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 state = this._readableState;
|
|
var paused = false;
|
|
|
|
var self = this;
|
|
stream.on('end', function() {
|
|
state.ended = true;
|
|
if (state.decoder) {
|
|
var chunk = state.decoder.end();
|
|
if (chunk && chunk.length)
|
|
self.push(chunk);
|
|
}
|
|
|
|
self.push(null);
|
|
});
|
|
|
|
stream.on('data', function(chunk) {
|
|
if (state.decoder)
|
|
chunk = state.decoder.write(chunk);
|
|
if (!chunk || !chunk.length)
|
|
return;
|
|
|
|
var ret = self.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 (typeof stream[i] === 'function' &&
|
|
typeof this[i] === 'undefined') {
|
|
this[i] = function(method) { return function() {
|
|
return stream[method].apply(stream, arguments);
|
|
}}(i);
|
|
}
|
|
}
|
|
|
|
// proxy certain important events.
|
|
var events = ['error', 'close', 'destroy', 'pause', 'resume'];
|
|
events.forEach(function(ev) {
|
|
stream.on(ev, self.emit.bind(self, ev));
|
|
});
|
|
|
|
// when we try to consume some more bytes, simply unpause the
|
|
// underlying stream.
|
|
self._read = function(n) {
|
|
if (paused) {
|
|
stream.resume();
|
|
paused = false;
|
|
}
|
|
};
|
|
};
|
|
|
|
|
|
|
|
// exposed for testing purposes only.
|
|
Readable._fromList = fromList;
|
|
|
|
// Pluck off n bytes from an array of buffers.
|
|
// Length is the combined lengths of all the buffers in the list.
|
|
function fromList(n, state) {
|
|
var list = state.buffer;
|
|
var length = state.length;
|
|
var stringMode = !!state.decoder;
|
|
var objectMode = !!state.objectMode;
|
|
var ret;
|
|
|
|
// nothing in the list, definitely empty.
|
|
if (list.length === 0)
|
|
return null;
|
|
|
|
if (length === 0)
|
|
ret = null;
|
|
else if (objectMode)
|
|
ret = list.shift();
|
|
else if (!n || n >= length) {
|
|
// read it all, truncate the array.
|
|
if (stringMode)
|
|
ret = list.join('');
|
|
else
|
|
ret = Buffer.concat(list, length);
|
|
list.length = 0;
|
|
} else {
|
|
// read just some of it.
|
|
if (n < list[0].length) {
|
|
// just take a part of the first list item.
|
|
// slice is the same for buffers and strings.
|
|
var buf = list[0];
|
|
ret = buf.slice(0, n);
|
|
list[0] = buf.slice(n);
|
|
} else if (n === list[0].length) {
|
|
// first list is a perfect match
|
|
ret = list.shift();
|
|
} else {
|
|
// complex case.
|
|
// we have enough to cover it, but it spans past the first buffer.
|
|
if (stringMode)
|
|
ret = '';
|
|
else
|
|
ret = new Buffer(n);
|
|
|
|
var c = 0;
|
|
for (var i = 0, l = list.length; i < l && c < n; i++) {
|
|
var buf = list[0];
|
|
var cpy = Math.min(n - c, buf.length);
|
|
|
|
if (stringMode)
|
|
ret += buf.slice(0, cpy);
|
|
else
|
|
buf.copy(ret, c, 0, cpy);
|
|
|
|
if (cpy < buf.length)
|
|
list[0] = buf.slice(cpy);
|
|
else
|
|
list.shift();
|
|
|
|
c += cpy;
|
|
}
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
function endReadable(stream) {
|
|
var state = stream._readableState;
|
|
|
|
// If we get here before consuming all the bytes, then that is a
|
|
// bug in node. Should never happen.
|
|
if (state.length > 0)
|
|
throw new Error('endReadable called on non-empty stream');
|
|
|
|
if (state.endEmitted)
|
|
return;
|
|
state.ended = true;
|
|
state.endEmitted = true;
|
|
process.nextTick(function() {
|
|
stream.readable = false;
|
|
stream.emit('end');
|
|
});
|
|
}
|
|
|