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Break up a stream and reassemble it so that each line is a chunk.
split2
is inspired by @dominictarr split
module,
and it is totally API compatible with it.
However, it is based on Node.js core Transform
via readable-stream
matcher
may be a String
, or a RegExp
. Example, read every line in a file ...
fs.createReadStream(file)
.pipe(split2())
.on('data', function (line) {
//each chunk now is a separate line!
})
split
takes the same arguments as string.split
except it defaults to '/\r?\n/', and the optional limit
paremeter is ignored.
String#split
split
takes an optional options object on it's third argument, which
is directly passed as a
Transform
option.
Additionally, the .maxLength
and .skipOverflow
options are implemented, which set limits on the internal
buffer size and the stream's behavior when the limit is exceeded. There is no limit unless maxLength
is set. When
the internal buffer size exceeds maxLength
, the stream emits an error by default. You may also set skipOverflow
to
true to suppress the error and instead skip past any lines that cause the internal buffer to exceed maxLength
.
Calling .destroy
will make the stream emit close
. Use this to perform cleanup logic
var splitFile = function(filename) {
var file = fs.createReadStream(filename)
return file
.pipe(split2())
.on('close', function() {
// destroy the file stream in case the split stream was destroyed
file.destroy()
})
}
var stream = splitFile('my-file.txt')
stream.destroy() // will destroy the input file stream
split2
accepts a function which transforms each line.
fs.createReadStream(file)
.pipe(split2(JSON.parse))
.on('data', function (obj) {
//each chunk now is a js object
})
.on("error", function(error) => {
//handling parsing errors
})
However, in @dominictarr split
the mapper
is wrapped in a try-catch, while here it is not: if your parsing logic can throw, wrap it yourself. Otherwise, you can also use the stream error handling when mapper function throw.
$ node bench.js
benchSplit*10000: 1484.983ms
benchBinarySplit*10000: 1484.080ms
benchSplit*10000: 1407.334ms
benchBinarySplit*10000: 1500.281ms
Benchmark taken on Node 8.11.3, on a Macbook i5 2018.
Copyright (c) 2014-2018, Matteo Collina hello@matteocollina.com
Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.