byline = function (readStream, options) {
return module.exports.createStream(readStream, options);
}n/a
function LineStream(options) {
stream.Transform.call(this, options);
options = options || {};
// use objectMode to stop the output from being buffered
// which re-concatanates the lines, just without newlines.
this._readableState.objectMode = true;
this._lineBuffer = [];
this._keepEmptyLines = options.keepEmptyLines || false;
this._lastChunkEndedWithCR = false;
// take the source's encoding if we don't have one
var self = this;
this.on('pipe', function(src) {
if (!self.encoding) {
// but we can't do this for old-style streams
if (src instanceof stream.Readable) {
self.encoding = src._readableState.encoding;
}
}
});
}n/a
createLineStream = function (readStream) {
console.log('WARNING: byline#createLineStream is deprecated and will be removed soon');
return createLineStream(readStream);
}n/a
createStream = function (readStream, options) {
if (readStream) {
return createLineStream(readStream, options);
} else {
return new LineStream(options);
}
}...
You just need to add one line to wrap your readable `Stream` with a `LineStream`.
```javascript
var fs = require('fs'),
byline = require('byline');
var stream = fs.createReadStream('sample.txt');
stream = byline.createStream(stream);
stream.on('data', function(line) {
console.log(line);
});
```
# Piping
...function LineStream(options) {
stream.Transform.call(this, options);
options = options || {};
// use objectMode to stop the output from being buffered
// which re-concatanates the lines, just without newlines.
this._readableState.objectMode = true;
this._lineBuffer = [];
this._keepEmptyLines = options.keepEmptyLines || false;
this._lastChunkEndedWithCR = false;
// take the source's encoding if we don't have one
var self = this;
this.on('pipe', function(src) {
if (!self.encoding) {
// but we can't do this for old-style streams
if (src instanceof stream.Readable) {
self.encoding = src._readableState.encoding;
}
}
});
}n/a
function Transform(options) {
if (!(this instanceof Transform))
return new Transform(options);
Duplex.call(this, options);
this._transformState = new TransformState(this);
var stream = this;
// 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.once('prefinish', function() {
if (typeof this._flush === 'function')
this._flush(function(er) {
done(stream, er);
});
else
done(stream);
});
}n/a
_flush = function (done) {
this._pushBuffer(this._chunkEncoding, 0, done);
}n/a
_pushBuffer = function (encoding, keep, done) {
// always buffer the last (possibly partial) line
while (this._lineBuffer.length > keep) {
var line = this._lineBuffer.shift();
// skip empty lines
if (this._keepEmptyLines || line.length > 0 ) {
if (!this.push(this._reencode(line, encoding))) {
// when the high-water mark is reached, defer pushes until the next tick
var self = this;
timers.setImmediate(function() {
self._pushBuffer(encoding, keep, done);
});
return;
}
}
}
done();
}...
if (this._lineBuffer.length > 0) {
this._lineBuffer[this._lineBuffer.length - 1] += lines[0];
lines.shift();
}
this._lastChunkEndedWithCR = chunk[chunk.length - 1] == '\r';
this._lineBuffer = this._lineBuffer.concat(lines);
this._pushBuffer(encoding, 1, done);
};
LineStream.prototype._pushBuffer = function(encoding, keep, done) {
// always buffer the last (possibly partial) line
while (this._lineBuffer.length > keep) {
var line = this._lineBuffer.shift();
// skip empty lines
..._reencode = function (line, chunkEncoding) {
if (this.encoding && this.encoding != chunkEncoding) {
return new Buffer(line, chunkEncoding).toString(this.encoding);
}
else if (this.encoding) {
// this should be the most common case, i.e. we're using an encoded source stream
return line;
}
else {
return new Buffer(line, chunkEncoding);
}
}...
LineStream.prototype._pushBuffer = function(encoding, keep, done) {
// always buffer the last (possibly partial) line
while (this._lineBuffer.length > keep) {
var line = this._lineBuffer.shift();
// skip empty lines
if (this._keepEmptyLines || line.length > 0 ) {
if (!this.push(this._reencode(line, encoding))) {
// when the high-water mark is reached, defer pushes until the next tick
var self = this;
timers.setImmediate(function() {
self._pushBuffer(encoding, keep, done);
});
return;
}
..._transform = function (chunk, encoding, done) {
// decode binary chunks as UTF-8
encoding = encoding || 'utf8';
if (Buffer.isBuffer(chunk)) {
if (encoding == 'buffer') {
chunk = chunk.toString(); // utf8
encoding = 'utf8';
}
else {
chunk = chunk.toString(encoding);
}
}
this._chunkEncoding = encoding;
// see: http://www.unicode.org/reports/tr18/#Line_Boundaries
var lines = chunk.split(/\r\n|[\n\v\f\r\x85\u2028\u2029]/g);
// don't split CRLF which spans chunks
if (this._lastChunkEndedWithCR && chunk[0] == '\n') {
lines.shift();
}
if (this._lineBuffer.length > 0) {
this._lineBuffer[this._lineBuffer.length - 1] += lines[0];
lines.shift();
}
this._lastChunkEndedWithCR = chunk[chunk.length - 1] == '\r';
this._lineBuffer = this._lineBuffer.concat(lines);
this._pushBuffer(encoding, 1, done);
}n/a