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node_modules/minipass-pipeline/index.js

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+const Minipass = require('minipass')
+const EE = require('events')
+const isStream = s => s && s instanceof EE && (
+  typeof s.pipe === 'function' || // readable
+  (typeof s.write === 'function' && typeof s.end === 'function') // writable
+)
+
+const _head = Symbol('_head')
+const _tail = Symbol('_tail')
+const _linkStreams = Symbol('_linkStreams')
+const _setHead = Symbol('_setHead')
+const _setTail = Symbol('_setTail')
+const _onError = Symbol('_onError')
+const _onData = Symbol('_onData')
+const _onEnd = Symbol('_onEnd')
+const _onDrain = Symbol('_onDrain')
+const _streams = Symbol('_streams')
+class Pipeline extends Minipass {
+  constructor (opts, ...streams) {
+    if (isStream(opts)) {
+      streams.unshift(opts)
+      opts = {}
+    }
+
+    super(opts)
+    this[_streams] = []
+    if (streams.length)
+      this.push(...streams)
+  }
+
+  [_linkStreams] (streams) {
+    // reduce takes (left,right), and we return right to make it the
+    // new left value.
+    return streams.reduce((src, dest) => {
+      src.on('error', er => dest.emit('error', er))
+      src.pipe(dest)
+      return dest
+    })
+  }
+
+  push (...streams) {
+    this[_streams].push(...streams)
+    if (this[_tail])
+      streams.unshift(this[_tail])
+
+    const linkRet = this[_linkStreams](streams)
+
+    this[_setTail](linkRet)
+    if (!this[_head])
+      this[_setHead](streams[0])
+  }
+
+  unshift (...streams) {
+    this[_streams].unshift(...streams)
+    if (this[_head])
+      streams.push(this[_head])
+
+    const linkRet = this[_linkStreams](streams)
+    this[_setHead](streams[0])
+    if (!this[_tail])
+      this[_setTail](linkRet)
+  }
+
+  destroy (er) {
+    // set fire to the whole thing.
+    this[_streams].forEach(s =>
+      typeof s.destroy === 'function' && s.destroy())
+    return super.destroy(er)
+  }
+
+  // readable interface -> tail
+  [_setTail] (stream) {
+    this[_tail] = stream
+    stream.on('error', er => this[_onError](stream, er))
+    stream.on('data', chunk => this[_onData](stream, chunk))
+    stream.on('end', () => this[_onEnd](stream))
+    stream.on('finish', () => this[_onEnd](stream))
+  }
+
+  // errors proxied down the pipeline
+  // they're considered part of the "read" interface
+  [_onError] (stream, er) {
+    if (stream === this[_tail])
+      this.emit('error', er)
+  }
+  [_onData] (stream, chunk) {
+    if (stream === this[_tail])
+      super.write(chunk)
+  }
+  [_onEnd] (stream) {
+    if (stream === this[_tail])
+      super.end()
+  }
+  pause () {
+    super.pause()
+    return this[_tail] && this[_tail].pause && this[_tail].pause()
+  }
+
+  // NB: Minipass calls its internal private [RESUME] method during
+  // pipe drains, to avoid hazards where stream.resume() is overridden.
+  // Thus, we need to listen to the resume *event*, not override the
+  // resume() method, and proxy *that* to the tail.
+  emit (ev, ...args) {
+    if (ev === 'resume' && this[_tail] && this[_tail].resume)
+      this[_tail].resume()
+    return super.emit(ev, ...args)
+  }
+
+  // writable interface -> head
+  [_setHead] (stream) {
+    this[_head] = stream
+    stream.on('drain', () => this[_onDrain](stream))
+  }
+  [_onDrain] (stream) {
+    if (stream === this[_head])
+      this.emit('drain')
+  }
+  write (chunk, enc, cb) {
+    return this[_head].write(chunk, enc, cb) &&
+      (this.flowing || this.buffer.length === 0)
+  }
+  end (chunk, enc, cb) {
+    this[_head].end(chunk, enc, cb)
+    return this
+  }
+}
+
+module.exports = Pipeline