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951 lines
25 KiB
951 lines
25 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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/*<replacement>*/ |
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var isArray = require('isarray'); |
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/*</replacement>*/ |
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/*<replacement>*/ |
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var Buffer = require('buffer').Buffer; |
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/*</replacement>*/ |
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Readable.ReadableState = ReadableState; |
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var EE = require('events').EventEmitter; |
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/*<replacement>*/ |
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if (!EE.listenerCount) EE.listenerCount = function(emitter, type) { |
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return emitter.listeners(type).length; |
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}; |
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/*</replacement>*/ |
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var Stream = require('stream'); |
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/*<replacement>*/ |
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var util = require('core-util-is'); |
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util.inherits = require('inherits'); |
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/*</replacement>*/ |
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var StringDecoder; |
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/*<replacement>*/ |
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var debug = require('util'); |
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if (debug && debug.debuglog) { |
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debug = debug.debuglog('stream'); |
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} else { |
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debug = function () {}; |
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} |
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/*</replacement>*/ |
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util.inherits(Readable, Stream); |
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function ReadableState(options, stream) { |
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var Duplex = require('./_stream_duplex'); |
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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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var defaultHwm = options.objectMode ? 16 : 16 * 1024; |
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this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm; |
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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 = null; |
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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, because 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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this.readableListening = 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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if (stream instanceof Duplex) |
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this.objectMode = this.objectMode || !!options.readableObjectMode; |
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// Crypto is kind of old and crusty. Historically, its default string |
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// encoding is 'binary' so we have to make this configurable. |
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// Everything else in the universe uses 'utf8', though. |
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this.defaultEncoding = options.defaultEncoding || 'utf8'; |
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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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// if true, a maybeReadMore has been scheduled |
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this.readingMore = false; |
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this.decoder = null; |
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this.encoding = 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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this.encoding = options.encoding; |
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} |
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} |
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function Readable(options) { |
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var Duplex = require('./_stream_duplex'); |
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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, encoding) { |
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var state = this._readableState; |
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if (util.isString(chunk) && !state.objectMode) { |
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encoding = encoding || state.defaultEncoding; |
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if (encoding !== state.encoding) { |
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chunk = new Buffer(chunk, encoding); |
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encoding = ''; |
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} |
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} |
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return readableAddChunk(this, state, chunk, encoding, false); |
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}; |
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// Unshift should *always* be something directly out of read() |
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Readable.prototype.unshift = function(chunk) { |
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var state = this._readableState; |
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return readableAddChunk(this, state, chunk, '', true); |
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}; |
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function readableAddChunk(stream, state, chunk, encoding, addToFront) { |
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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 (util.isNullOrUndefined(chunk)) { |
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state.reading = false; |
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if (!state.ended) |
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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.ended && !addToFront) { |
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var e = new Error('stream.push() after EOF'); |
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stream.emit('error', e); |
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} else if (state.endEmitted && addToFront) { |
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var e = new Error('stream.unshift() after end event'); |
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stream.emit('error', e); |
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} else { |
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if (state.decoder && !addToFront && !encoding) |
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chunk = state.decoder.write(chunk); |
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if (!addToFront) |
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state.reading = false; |
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// if we want the data now, just emit it. |
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if (state.flowing && state.length === 0 && !state.sync) { |
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stream.emit('data', chunk); |
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stream.read(0); |
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} else { |
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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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} |
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maybeReadMore(stream, state); |
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} |
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} else if (!addToFront) { |
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state.reading = false; |
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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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this._readableState.encoding = enc; |
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return this; |
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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) || util.isNull(n)) { |
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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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debug('read', n); |
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var state = this._readableState; |
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var nOrig = n; |
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if (!util.isNumber(n) || 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 || state.ended)) { |
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debug('read: emitReadable', state.length, state.ended); |
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if (state.length === 0 && state.ended) |
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endReadable(this); |
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else |
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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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debug('need readable', doRead); |
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// if we currently have less than the highWaterMark, then also read some |
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if (state.length === 0 || state.length - n < state.highWaterMark) { |
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doRead = true; |
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debug('length less than watermark', doRead); |
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} |
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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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debug('reading or ended', doRead); |
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} |
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if (doRead) { |
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debug('do read'); |
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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 pushed data synchronously, then `reading` will be false, |
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// and we need to re-evaluate how much data we 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 (util.isNull(ret)) { |
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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 tried to read() past the EOF, then emit end on the next tick. |
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if (nOrig !== n && state.ended && state.length === 0) |
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endReadable(this); |
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if (!util.isNull(ret)) |
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this.emit('data', ret); |
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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 (!util.isBuffer(chunk) && |
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!util.isString(chunk) && |
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!util.isNullOrUndefined(chunk) && |
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!state.objectMode) { |
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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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if (state.decoder && !state.ended) { |
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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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state.ended = true; |
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// emit 'readable' now to make sure it gets picked up. |
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emitReadable(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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debug('emitReadable', state.flowing); |
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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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} |
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function emitReadable_(stream) { |
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debug('emit readable'); |
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stream.emit('readable'); |
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flow(stream); |
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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 preemptively. |
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function maybeReadMore(stream, state) { |
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if (!state.readingMore) { |
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state.readingMore = true; |
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process.nextTick(function() { |
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maybeReadMore_(stream, state); |
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}); |
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} |
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} |
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function maybeReadMore_(stream, state) { |
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var len = state.length; |
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while (!state.reading && !state.flowing && !state.ended && |
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state.length < state.highWaterMark) { |
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debug('maybeReadMore read 0'); |
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stream.read(0); |
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if (len === state.length) |
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// didn't get any data, stop spinning. |
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break; |
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else |
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len = state.length; |
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} |
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state.readingMore = false; |
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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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debug('pipe count=%d opts=%j', state.pipesCount, pipeOpts); |
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var doEnd = (!pipeOpts || pipeOpts.end !== false) && |
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dest !== process.stdout && |
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dest !== process.stderr; |
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var endFn = doEnd ? onend : cleanup; |
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if (state.endEmitted) |
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process.nextTick(endFn); |
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else |
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src.once('end', endFn); |
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dest.on('unpipe', onunpipe); |
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function onunpipe(readable) { |
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debug('onunpipe'); |
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if (readable === src) { |
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cleanup(); |
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} |
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} |
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function onend() { |
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debug('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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|
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function cleanup() { |
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debug('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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src.removeListener('data', ondata); |
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|
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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 (state.awaitDrain && |
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(!dest._writableState || dest._writableState.needDrain)) |
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ondrain(); |
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} |
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src.on('data', ondata); |
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function ondata(chunk) { |
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debug('ondata'); |
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var ret = dest.write(chunk); |
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if (false === ret) { |
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debug('false write response, pause', |
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src._readableState.awaitDrain); |
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src._readableState.awaitDrain++; |
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src.pause(); |
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} |
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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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debug('onerror', er); |
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unpipe(); |
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dest.removeListener('error', onerror); |
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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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// This is a brutally ugly hack to make sure that our error handler |
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// is attached before any userland ones. NEVER DO THIS. |
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if (!dest._events || !dest._events.error) |
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dest.on('error', onerror); |
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else if (isArray(dest._events.error)) |
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dest._events.error.unshift(onerror); |
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else |
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dest._events.error = [onerror, dest._events.error]; |
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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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debug('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); |
|
|
|
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() { |
|
var state = src._readableState; |
|
debug('pipeOnDrain', state.awaitDrain); |
|
if (state.awaitDrain) |
|
state.awaitDrain--; |
|
if (state.awaitDrain === 0 && EE.listenerCount(src, 'data')) { |
|
state.flowing = true; |
|
flow(src); |
|
} |
|
}; |
|
} |
|
|
|
|
|
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; |
|
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; |
|
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 = indexOf(state.pipes, 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 listening to data, and it has not explicitly been paused, |
|
// then call resume to start the flow of data on the next tick. |
|
if (ev === 'data' && false !== this._readableState.flowing) { |
|
this.resume(); |
|
} |
|
|
|
if (ev === 'readable' && this.readable) { |
|
var state = this._readableState; |
|
if (!state.readableListening) { |
|
state.readableListening = true; |
|
state.emittedReadable = false; |
|
state.needReadable = true; |
|
if (!state.reading) { |
|
var self = this; |
|
process.nextTick(function() { |
|
debug('readable nexttick read 0'); |
|
self.read(0); |
|
}); |
|
} else if (state.length) { |
|
emitReadable(this, state); |
|
} |
|
} |
|
} |
|
|
|
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() { |
|
var state = this._readableState; |
|
if (!state.flowing) { |
|
debug('resume'); |
|
state.flowing = true; |
|
if (!state.reading) { |
|
debug('resume read 0'); |
|
this.read(0); |
|
} |
|
resume(this, state); |
|
} |
|
return this; |
|
}; |
|
|
|
function resume(stream, state) { |
|
if (!state.resumeScheduled) { |
|
state.resumeScheduled = true; |
|
process.nextTick(function() { |
|
resume_(stream, state); |
|
}); |
|
} |
|
} |
|
|
|
function resume_(stream, state) { |
|
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 (false !== this._readableState.flowing) { |
|
debug('pause'); |
|
this._readableState.flowing = false; |
|
this.emit('pause'); |
|
} |
|
return this; |
|
}; |
|
|
|
function flow(stream) { |
|
var state = stream._readableState; |
|
debug('flow', state.flowing); |
|
if (state.flowing) { |
|
do { |
|
var chunk = stream.read(); |
|
} while (null !== chunk && state.flowing); |
|
} |
|
} |
|
|
|
// 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() { |
|
debug('wrapped end'); |
|
if (state.decoder && !state.ended) { |
|
var chunk = state.decoder.end(); |
|
if (chunk && chunk.length) |
|
self.push(chunk); |
|
} |
|
|
|
self.push(null); |
|
}); |
|
|
|
stream.on('data', function(chunk) { |
|
debug('wrapped data'); |
|
if (state.decoder) |
|
chunk = state.decoder.write(chunk); |
|
if (!chunk || !state.objectMode && !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 (util.isFunction(stream[i]) && util.isUndefined(this[i])) { |
|
this[i] = function(method) { return function() { |
|
return stream[method].apply(stream, arguments); |
|
}}(i); |
|
} |
|
} |
|
|
|
// proxy certain important events. |
|
var events = ['error', 'close', 'destroy', 'pause', 'resume']; |
|
forEach(events, 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) { |
|
debug('wrapped _read', n); |
|
if (paused) { |
|
paused = false; |
|
stream.resume(); |
|
} |
|
}; |
|
|
|
return self; |
|
}; |
|
|
|
|
|
|
|
// 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) { |
|
state.ended = true; |
|
process.nextTick(function() { |
|
// Check that we didn't get one last unshift. |
|
if (!state.endEmitted && state.length === 0) { |
|
state.endEmitted = true; |
|
stream.readable = false; |
|
stream.emit('end'); |
|
} |
|
}); |
|
} |
|
} |
|
|
|
function forEach (xs, f) { |
|
for (var i = 0, l = xs.length; i < l; i++) { |
|
f(xs[i], i); |
|
} |
|
} |
|
|
|
function indexOf (xs, x) { |
|
for (var i = 0, l = xs.length; i < l; i++) { |
|
if (xs[i] === x) return i; |
|
} |
|
return -1; |
|
}
|
|
|