npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

@stdlib/streams-node-from-iterator

v0.2.1

Published

Create a readable stream from an iterator.

Downloads

70

Readme

Iterator Stream

NPM version Build Status Coverage Status

Create a readable stream from an iterator.

Installation

npm install @stdlib/streams-node-from-iterator

Usage

var iteratorStream = require( '@stdlib/streams-node-from-iterator' );

iteratorStream( iterator[, options] )

Returns a readable stream from an iterator.

var inspectStream = require( '@stdlib/streams-node-inspect-sink' );
var randu = require( '@stdlib/random-iter-randu' );

var iStream;
var stream;

function log( chunk, idx ) {
    console.log( chunk.toString() );
    if ( idx === 10 ) {
        stream.destroy();
    }
}

stream = iteratorStream( randu() );
iStream = inspectStream( log );

stream.pipe( iStream );

The function accepts the following options:

  • 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 maximum number of bytes to store in an internal buffer before pausing iteration.
  • sep: separator used to join streamed data. This option is only applicable when a stream is not in objectMode. Default: '\n'.
  • serialize: custom serialization function. This option is only applicable when a stream is not in objectMode.

To set stream options,

var randu = require( '@stdlib/random-iter-randu' );

var opts = {
    'objectMode': true,
    'encoding': 'utf8',
    'highWaterMark': 64
};

var stream = iteratorStream( randu(), opts );

By default, when not operating in objectMode, a returned stream delineates iterated values using a newline character. To specify an alternative separator, set the sep option.

var inspectStream = require( '@stdlib/streams-node-inspect-sink' );
var randu = require( '@stdlib/random-iter-randu' );

function log( chunk ) {
    console.log( chunk.toString() );
}

var it = randu({
    'iter': 10
});

var stream = iteratorStream( it, {
    'sep': ','
});

var iStream = inspectStream( log );

stream.pipe( iStream );

By default, when not operating in objectMode, a returned stream serializes iterated values as JSON strings. To specify custom serialization behavior (either to a string or Buffer), set the serialize option.

var inspectStream = require( '@stdlib/streams-node-inspect-sink' );
var randu = require( '@stdlib/random-iter-randu' );

function serialize( v ) {
    return 'r::' + v.toString();
}

function log( chunk ) {
    console.log( chunk.toString() );
}

var it = randu({
    'iter': 10
});

var stream = iteratorStream( it, {
    'serialize': serialize
});

var iStream = inspectStream( log );

stream.pipe( iStream );

iteratorStream.factory( [options] )

Returns a function for creating readable streams from iterators.

var randu = require( '@stdlib/random-iter-randu' );

var opts = {
    'objectMode': true,
    'encoding': 'utf8',
    'highWaterMark': 64
};

var createStream = iteratorStream.factory( opts );

var stream1 = createStream( randu() );
var stream2 = createStream( randu() );
// ...

The method accepts the same options as iteratorStream().


iteratorStream.objectMode( iterator[, options] )

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

var inspectStream = require( '@stdlib/streams-node-inspect-sink' );
var randu = require( '@stdlib/random-iter-randu' );

function log( v ) {
    console.log( v );
}

var opts = {
    'iter': 10
};
var stream = iteratorStream.objectMode( randu( opts ) );

opts = {
    'objectMode': true
};
var iStream = inspectStream( opts, log );

stream.pipe( iStream );

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


Notes

  • In objectMode, null is a reserved value. If an iterator generates null values (e.g., as a means to encode missing values), the stream will prematurely end. Consider an alternative encoding or explicitly map null values to a different value by wrapping the provided iterator with another iterator.
  • In binary mode, if an iterator generates undefined values, the stream will emit an error. Consider providing a custom serialization function or explicitly map undefined values to a different value by wrapping the provided iterator with another iterator.

Examples

var inspectStream = require( '@stdlib/streams-node-inspect-sink' );
var randu = require( '@stdlib/random-iter-randu' );
var iteratorStream = require( '@stdlib/streams-node-from-iterator' );

function log( v ) {
    console.log( v.toString() );
}

// Create an iterator which generates uniformly distributed pseudorandom numbers:
var opts = {
    'iter': 10
};
var it = randu( opts );

// Convert the iterator to a stream:
opts = {
    'objectMode': true
};
var stream = iteratorStream( it, opts );

// Create a writable stream for inspecting stream data:
opts = {
    'objectMode': true
};
var iStream = inspectStream( opts, log );

// Begin data flow:
stream.pipe( iStream );

See Also


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

Chat


License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.