stdlib-js / streams-node-split

Transform stream which splits streamed data.

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Split Stream

Transform stream which splits streamed data.

Installation

npm install @stdlib/streams-node-split

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var splitStream = require( '@stdlib/streams-node-split' );

splitStream( [options] )

Creates a transform stream which splits streamed data.

var stdout = require( '@stdlib/streams-node-stdout' );

var stream = splitStream();

stream.pipe( stdout );
stream.write( '1\n2\n3' );

stream.end();

// prints: 1 => 2 => 3

The function accepts the following options:

• sep: separator used to split streamed data. Similar to String#split, a separator may be either a regular expression or a string. Default: /\r?\n/.
• objectMode: specifies whether a stream should operate in objectMode. Default: false.
• encoding: specifies how Buffer objects should be decoded to strings. Default: null.
• highWaterMark: specifies the Buffer level at which write() calls start returning false.
• allowHalfOpen: specifies whether a stream should remain open even if one side ends. Default: false.
• writableObjectMode: specifies whether the writable side should be in objectMode. Default: false.

To set stream options,

var opts = {
    'sep': ',',
    'objectMode': true,
    'encoding': 'utf8',
    'highWaterMark': 64,
    'allowHalfOpen': true,
    'writableObjectMode': false // overridden by `objectMode` option when `objectMode=true`
};

var stream = splitStream( opts );

splitStream.factory( [options] )

Returns a function for creating streams which are identically configured according to provided options.

var opts = {
    'sep': '\t',
    'objectMode': true,
    'encoding': 'utf8',
    'highWaterMark': 64
};

var factory = splitStream.factory( opts );

// Create 10 identically configured streams...
var streams = [];
var i;
for ( i = 0; i < 10; i++ ) {
    streams.push( factory() );
}

This method accepts the same options as splitStream().

splitStream.objectMode( [options] )

This method is a convenience function to create streams which always operate in objectMode.

var stdout = require( '@stdlib/streams-node-stdout' );

var stream = splitStream.objectMode({
    'sep': ','
});

stream.pipe( stdout );
stream.write( 'a,b,c' );

stream.end();

// prints: a => b => c

This method accepts the same options as splitStream(); however, the method will always override the objectMode option in options.

Notes

• Similar to String#split, a separator which is a regular expression containing a matching group will result in the separator being retained in the output stream.

  var stdout = require( '@stdlib/streams-node-stdout' );
  
  var stream = splitStream({
      'sep': /(,)/
  });
  
  stream.pipe( stdout );
  stream.write( '1,2,3' );
  
  stream.end();
  
  // prints: 1 => , => 2 => , => 3

Examples

var transformStream = require( '@stdlib/streams-node-transform' );
var stdout = require( '@stdlib/streams-node-stdout' );
var splitStream = require( '@stdlib/streams-node-split' );

function append( chunk, enc, clbk ) {
    clbk( null, chunk.toString()+'\n' );
}

var newline;
var stream;
var i;

// Create a split stream to split tab delimited data:
stream = splitStream({
    'sep': /\t/
});

// Create a transform stream to make newline delimited data...
newline = transformStream({
    'transform': append,
    'objectMode': true
});

// Create a stream pipeline:
stream
    .pipe( newline )
    .pipe( stdout );

// Write data to the pipeline...
for ( i = 0; i < 10; i++ ) {
    stream.write( i+'\t', 'utf8' );
}
stream.end();

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See Also

• @stdlib/streams-node/join: transform stream which joins streamed data.

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Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.