labeled-stream-splicer

stream splicer with labels

example

Here's an example that exposes a label for deps and pack:

var splicer = require('labeled-stream-splicer');
var through = require('through2');
var deps = require('module-deps');
var pack = require('browser-pack');
var lstream = require('lstream');

var pipeline = splicer.obj([
    'deps', [ deps() ],
    'pack', [ pack({ raw: true }) ]
]);

pipeline.get('deps').unshift(lstream());

pipeline.get('deps').push(through.obj(function (row, enc, next) {
    row.source = row.source.toUpperCase();
    this.push(row);
    next();
}));

process.stdin.pipe(pipeline).pipe(process.stdout);

Here the deps sub-pipeline is augmented with a post-transformation that uppercases its source input.

methods

var splicer = require('labeled-stream-splicer')

The API is the same as stream-splicer, except that pipeline.get(), pipeline.splice(), and pipeline.indexOf() can accept string labels in addition to numeric indexes.

var pipeline = splicer(streams, opts)

Create a pipeline duplex stream given an array of streams. Each stream will be piped to the next. Writes to pipeline get written to the first stream and data for reads from pipeline come from the last stream.

To signify a label, a stream may have a .label property or a string may be placed in the streams array.

For example, for streams [ a, 'foo', b, c, 'bar', d ], this pipeline is constructed internally:

a.pipe(b).pipe(c).pipe(d)

with a label 'foo' that points to b and a label 'bar' that points to d. If a or c has a .label property, that label would be used for addressing.

Input will get written into a. Output will be read from d.

If any of the elements in streams are arrays, they will be converted into nested labeled pipelines. This is useful if you want to expose a hookable pipeline with grouped insertion points.

var pipeline = splicer.obj(streams, opts)

Create a pipeline with opts.objectMode set to true for convenience.

var removed = pipeline.splice(index, howMany, stream, ...)

Splice the pipeline starting at index, removing howMany streams and replacing them with each additional stream argument provided.

The streams that were removed from the splice and returned.

index can be an integer index or a label.

pipeline.push(stream, ...)

Push one or more streams to the end of the pipeline.

The stream arguments may have a label property that will be used for string lookups.

var stream = pipeline.pop()

Pop a stream from the end of the pipeline.

pipeline.unshift(stream, ...)

Unshift one or more streams to the begining of the pipeline.

The stream arguments may have a label property that will be used for string lookups.

var stream = pipeline.shift()

Shift a stream from the begining of the pipeline.

var stream = pipeline.get(index)

Return the stream at index index.

index can be an integer or a string label.

install

With npm do:

npm install labeled-stream-splicer

license

MIT