Augcl
/
employ-front


								// Copyright Joyent, Inc. and other Node contributors.

								//

								// Permission is hereby granted, free of charge, to any person obtaining a

								// copy of this software and associated documentation files (the

								// "Software"), to deal in the Software without restriction, including

								// without limitation the rights to use, copy, modify, merge, publish,

								// distribute, sublicense, and/or sell copies of the Software, and to permit

								// persons to whom the Software is furnished to do so, subject to the

								// following conditions:

								//

								// The above copyright notice and this permission notice shall be included

								// in all copies or substantial portions of the Software.

								//

								// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

								// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

								// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN

								// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,

								// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR

								// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE

								// USE OR OTHER DEALINGS IN THE SOFTWARE.


								// a transform stream is a readable/writable stream where you do

								// something with the data.  Sometimes it's called a "filter",

								// but that's not a great name for it, since that implies a thing where

								// some bits pass through, and others are simply ignored.  (That would

								// be a valid example of a transform, of course.)

								//

								// While the output is causally related to the input, it's not a

								// necessarily symmetric or synchronous transformation.  For example,

								// a zlib stream might take multiple plain-text writes(), and then

								// emit a single compressed chunk some time in the future.

								//

								// Here's how this works:

								//

								// The Transform stream has all the aspects of the readable and writable

								// stream classes.  When you write(chunk), that calls _write(chunk,cb)

								// internally, and returns false if there's a lot of pending writes

								// buffered up.  When you call read(), that calls _read(n) until

								// there's enough pending readable data buffered up.

								//

								// In a transform stream, the written data is placed in a buffer.  When

								// _read(n) is called, it transforms the queued up data, calling the

								// buffered _write cb's as it consumes chunks.  If consuming a single

								// written chunk would result in multiple output chunks, then the first

								// outputted bit calls the readcb, and subsequent chunks just go into

								// the read buffer, and will cause it to emit 'readable' if necessary.

								//

								// This way, back-pressure is actually determined by the reading side,

								// since _read has to be called to start processing a new chunk.  However,

								// a pathological inflate type of transform can cause excessive buffering

								// here.  For example, imagine a stream where every byte of input is

								// interpreted as an integer from 0-255, and then results in that many

								// bytes of output.  Writing the 4 bytes {ff,ff,ff,ff} would result in

								// 1kb of data being output.  In this case, you could write a very small

								// amount of input, and end up with a very large amount of output.  In

								// such a pathological inflating mechanism, there'd be no way to tell

								// the system to stop doing the transform.  A single 4MB write could

								// cause the system to run out of memory.

								//

								// However, even in such a pathological case, only a single written chunk

								// would be consumed, and then the rest would wait (un-transformed) until

								// the results of the previous transformed chunk were consumed.


								'use strict';


								module.exports = Transform;


								var Duplex = require('./_stream_duplex');


								/*<replacement>*/

								var util = Object.create(require('core-util-is'));

								util.inherits = require('inherits');

								/*</replacement>*/


								util.inherits(Transform, Duplex);


								function afterTransform(er, data) {

								  var ts = this._transformState;

								  ts.transforming = false;


								  var cb = ts.writecb;


								  if (!cb) {

								    return this.emit('error', new Error('write callback called multiple times'));

								  }


								  ts.writechunk = null;

								  ts.writecb = null;


								  if (data != null) // single equals check for both `null` and `undefined`

								    this.push(data);


								  cb(er);


								  var rs = this._readableState;

								  rs.reading = false;

								  if (rs.needReadable || rs.length < rs.highWaterMark) {

								    this._read(rs.highWaterMark);

								  }

								}


								function Transform(options) {

								  if (!(this instanceof Transform)) return new Transform(options);


								  Duplex.call(this, options);


								  this._transformState = {

								    afterTransform: afterTransform.bind(this),

								    needTransform: false,

								    transforming: false,

								    writecb: null,

								    writechunk: null,

								    writeencoding: null

								  };


								  // start out asking for a readable event once data is transformed.

								  this._readableState.needReadable = true;


								  // we have implemented the _read method, and done the other things

								  // that Readable wants before the first _read call, so unset the

								  // sync guard flag.

								  this._readableState.sync = false;


								  if (options) {

								    if (typeof options.transform === 'function') this._transform = options.transform;


								    if (typeof options.flush === 'function') this._flush = options.flush;

								  }


								  // When the writable side finishes, then flush out anything remaining.

								  this.on('prefinish', prefinish);

								}


								function prefinish() {

								  var _this = this;


								  if (typeof this._flush === 'function') {

								    this._flush(function (er, data) {

								      done(_this, er, data);

								    });

								  } else {

								    done(this, null, null);

								  }

								}


								Transform.prototype.push = function (chunk, encoding) {

								  this._transformState.needTransform = false;

								  return Duplex.prototype.push.call(this, chunk, encoding);

								};


								// This is the part where you do stuff!

								// override this function in implementation classes.

								// 'chunk' is an input chunk.

								//

								// Call `push(newChunk)` to pass along transformed output

								// to the readable side.  You may call 'push' zero or more times.

								//

								// Call `cb(err)` when you are done with this chunk.  If you pass

								// an error, then that'll put the hurt on the whole operation.  If you

								// never call cb(), then you'll never get another chunk.

								Transform.prototype._transform = function (chunk, encoding, cb) {

								  throw new Error('_transform() is not implemented');

								};


								Transform.prototype._write = function (chunk, encoding, cb) {

								  var ts = this._transformState;

								  ts.writecb = cb;

								  ts.writechunk = chunk;

								  ts.writeencoding = encoding;

								  if (!ts.transforming) {

								    var rs = this._readableState;

								    if (ts.needTransform || rs.needReadable || rs.length < rs.highWaterMark) this._read(rs.highWaterMark);

								  }

								};


								// Doesn't matter what the args are here.

								// _transform does all the work.

								// That we got here means that the readable side wants more data.

								Transform.prototype._read = function (n) {

								  var ts = this._transformState;


								  if (ts.writechunk !== null && ts.writecb && !ts.transforming) {

								    ts.transforming = true;

								    this._transform(ts.writechunk, ts.writeencoding, ts.afterTransform);

								  } else {

								    // mark that we need a transform, so that any data that comes in

								    // will get processed, now that we've asked for it.

								    ts.needTransform = true;

								  }

								};


								Transform.prototype._destroy = function (err, cb) {

								  var _this2 = this;


								  Duplex.prototype._destroy.call(this, err, function (err2) {

								    cb(err2);

								    _this2.emit('close');

								  });

								};


								function done(stream, er, data) {

								  if (er) return stream.emit('error', er);


								  if (data != null) // single equals check for both `null` and `undefined`

								    stream.push(data);


								  // if there's nothing in the write buffer, then that means

								  // that nothing more will ever be provided

								  if (stream._writableState.length) throw new Error('Calling transform done when ws.length != 0');


								  if (stream._transformState.transforming) throw new Error('Calling transform done when still transforming');


								  return stream.push(null);

								}