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# minipass-pipeline
Create a pipeline of streams using Minipass.
Calls `.pipe()` on all the streams in the list. Returns a stream where
writes got to the first pipe in the chain, and reads are from the last.
Errors are proxied along the chain and emitted on the Pipeline stream.
## USAGE
```js
const Pipeline = require('minipass-pipeline')
// the list of streams to pipeline together,
// a bit like `input | transform | output` in bash
const p = new Pipeline(input, transform, output)
p.write('foo') // writes to input
p.on('data', chunk => doSomething()) // reads from output stream
// less contrived example (but still pretty contrived)...
const decode = new bunzipDecoder()
const unpack = tar.extract({ cwd: 'target-dir' })
const tbz = new Pipeline(decode, unpack)
fs.createReadStream('archive.tbz').pipe(tbz)
// specify any minipass options if you like, as the first argument
// it'll only try to pipeline event emitters with a .pipe() method
const p = new Pipeline({ objectMode: true }, input, transform, output)
// If you don't know the things to pipe in right away, that's fine.
// use p.push(stream) to add to the end, or p.unshift(stream) to the front
const databaseDecoderStreamDoohickey = (connectionInfo) => {
const p = new Pipeline()
logIntoDatabase(connectionInfo).then(connection => {
initializeDecoderRing(connectionInfo).then(decoderRing => {
p.push(connection, decoderRing)
getUpstreamSource(upstream => {
p.unshift(upstream)
})
})
})
// return to caller right away
// emitted data will be upstream -> connection -> decoderRing pipeline
return p
}
```
Pipeline is a [minipass](http://npm.im/minipass) stream, so it's as
synchronous as the streams it wraps. It will buffer data until there is a
reader, but no longer, so make sure to attach your listeners before you
pipe it somewhere else.
## `new Pipeline(opts = {}, ...streams)`
Create a new Pipeline with the specified Minipass options and any streams
provided.
## `pipeline.push(stream, ...)`
Attach one or more streams to the pipeline at the end (read) side of the
pipe chain.
## `pipeline.unshift(stream, ...)`
Attach one or more streams to the pipeline at the start (write) side of the
pipe chain.
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