Filtering streams.
npm install streamfilter[//]: # ( )
[//]: # (This file is automatically generated by a metapak)
[//]: # (module. Do not change it except between the)
[//]: # (content:start/end flags, your changes would)
[//]: # (be overridden.)
[//]: # ( )
[//]: # (::contents:start)
streamfilter is a function based filter for streams inspired per gulp-filter
but no limited to Gulp nor to objectMode streams.
First, install streamfilter in your project:
``sh`
npm install --save streamfilter
There are 3 common usages:
`js
import { StreamFilter } from 'streamfilter';
const filter = new StreamFilter((chunk, encoding, cb) => {
const mustBeFiltered = chunk.length() > 128;
if (mustBeFiltered) {
cb(true);
return;
}
cb(false);
});
// Print to stdout a filtered stdin
process.stdin.pipe(filter).pipe(process.stdout);
`
`js
import { filterStream } from 'streamfilter';
// Here we use the functionnal help
const filter = new filterStream(
// Here we use an async callback instead
async (chunk, encoding) => {
const mustBeFiltered = chunk.length() > 128;
if (mustBeFiltered) {
return true;
}
return false;
},
{
restore: true,
},
);
// Print accepted chunks in stdout
filter.pipe(process.stdout);
// Print filtered one to stderr
filter.restore.pipe(process.stderr);
`
Let's reach total hype!
`js
import { StreamFilter } from 'streamfilter';
import { Transform } from 'stream';
// Filter values
const filter = new StreamFilter(
(chunk, encoding, cb) => {
const mustBeFiltered = chunk.length() > 128;
if (mustBeFiltered) {
cb(true);
return;
}
cb(false);
},
{
restore: true,
passthrough: true,
},
);
// Uppercase strings
const mySuperTransformStream = new Transform({
transform: (chunk, encoding, cb) =>
cb(null, Buffer.from(chunk.toString(encoding).toUpperCase(), encoding)),
});
// Pipe stdin
process.stdin
.pipe(filter)
// Edit kept chunks
.pipe(mySuperTransformStream)
// Restore filtered chunks
.pipe(filter.restore)
// and output!
.pipe(process.stdout);
`
Note that in this case, this is _your_ responsibility to end the restore stream
by piping in another stream or ending it manually.
[//]: # (::contents:end)
Filter piped in streams according to the given filterCallback.
Utility function if you prefer a functional way of using this lib
.$3
Options are passed in as is in the various stream instances spawned by this
module. So, to use the objectMode, simply pass in the options.objectMode
value set to .Returns: StreamFilter - The filtering stream
| Param | Type | Description |
| --- | --- | --- |
| filterCallback | function | Callback applying the filters |
| options | Object | Filtering options |
| options.passthrough | boolean | Set to
true, this option changes the restore stream nature from a readable stream to a passthrough one, allowing you to reuse the filtered chunks in an existing pipeline. |
| options.restore | boolean | Set to true, this option create a readable stream allowing you to use the filtered chunks elsewhere. The restore stream is exposed in the FilterStream instance as a restore` named property. |Kind: global function
Returns: Stream
| Param |
| --- |
| filterCallback |
| options |