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var stream = require('readable-stream')
var eos = require('end-of-stream')
var inherits = require('inherits')
var shift = require('stream-shift')
var SIGNAL_FLUSH = (Buffer.from && Buffer.from !== Uint8Array.from)
? Buffer.from([0])
: new Buffer([0])
var onuncork = function(self, fn) {
if (self._corked) self.once('uncork', fn)
else fn()
}
var autoDestroy = function (self, err) {
if (self._autoDestroy) self.destroy(err)
}
var destroyer = function(self, end) {
return function(err) {
if (err) autoDestroy(self, err.message === 'premature close' ? null : err)
else if (end && !self._ended) self.end()
}
}
var end = function(ws, fn) {
if (!ws) return fn()
if (ws._writableState && ws._writableState.finished) return fn()
if (ws._writableState) return ws.end(fn)
ws.end()
fn()
}
var toStreams2 = function(rs) {
return new (stream.Readable)({objectMode:true, highWaterMark:16}).wrap(rs)
}
var Duplexify = function(writable, readable, opts) {
if (!(this instanceof Duplexify)) return new Duplexify(writable, readable, opts)
stream.Duplex.call(this, opts)
this._writable = null
this._readable = null
this._readable2 = null
this._autoDestroy = !opts || opts.autoDestroy !== false
this._forwardDestroy = !opts || opts.destroy !== false
this._forwardEnd = !opts || opts.end !== false
this._corked = 1 // start corked
this._ondrain = null
this._drained = false
this._forwarding = false
this._unwrite = null
this._unread = null
this._ended = false
this.destroyed = false
if (writable) this.setWritable(writable)
if (readable) this.setReadable(readable)
}
inherits(Duplexify, stream.Duplex)
Duplexify.obj = function(writable, readable, opts) {
if (!opts) opts = {}
opts.objectMode = true
opts.highWaterMark = 16
return new Duplexify(writable, readable, opts)
}
Duplexify.prototype.cork = function() {
if (++this._corked === 1) this.emit('cork')
}
Duplexify.prototype.uncork = function() {
if (this._corked && --this._corked === 0) this.emit('uncork')
}
Duplexify.prototype.setWritable = function(writable) {
if (this._unwrite) this._unwrite()
if (this.destroyed) {
if (writable && writable.destroy) writable.destroy()
return
}
if (writable === null || writable === false) {
this.end()
return
}
var self = this
var unend = eos(writable, {writable:true, readable:false}, destroyer(this, this._forwardEnd))
var ondrain = function() {
var ondrain = self._ondrain
self._ondrain = null
if (ondrain) ondrain()
}
var clear = function() {
self._writable.removeListener('drain', ondrain)
unend()
}
if (this._unwrite) process.nextTick(ondrain) // force a drain on stream reset to avoid livelocks
this._writable = writable
this._writable.on('drain', ondrain)
this._unwrite = clear
this.uncork() // always uncork setWritable
}
Duplexify.prototype.setReadable = function(readable) {
if (this._unread) this._unread()
if (this.destroyed) {
if (readable && readable.destroy) readable.destroy()
return
}
if (readable === null || readable === false) {
this.push(null)
this.resume()
return
}
var self = this
var unend = eos(readable, {writable:false, readable:true}, destroyer(this))
var onreadable = function() {
self._forward()
}
var onend = function() {
self.push(null)
}
var clear = function() {
self._readable2.removeListener('readable', onreadable)
self._readable2.removeListener('end', onend)
unend()
}
this._drained = true
this._readable = readable
this._readable2 = readable._readableState ? readable : toStreams2(readable)
this._readable2.on('readable', onreadable)
this._readable2.on('end', onend)
this._unread = clear
this._forward()
}
Duplexify.prototype._read = function() {
this._drained = true
this._forward()
}
Duplexify.prototype._forward = function() {
if (this._forwarding || !this._readable2 || !this._drained) return
this._forwarding = true
var data
while (this._drained && (data = shift(this._readable2)) !== null) {
if (this.destroyed) continue
this._drained = this.push(data)
}
this._forwarding = false
}
Duplexify.prototype.destroy = function(err) {
if (this.destroyed) return
this.destroyed = true
var self = this
process.nextTick(function() {
self._destroy(err)
})
}
Duplexify.prototype._destroy = function(err) {
if (err) {
var ondrain = this._ondrain
this._ondrain = null
if (ondrain) ondrain(err)
else this.emit('error', err)
}
if (this._forwardDestroy) {
if (this._readable && this._readable.destroy) this._readable.destroy()
if (this._writable && this._writable.destroy) this._writable.destroy()
}
this.emit('close')
}
Duplexify.prototype._write = function(data, enc, cb) {
if (this.destroyed) return cb()
if (this._corked) return onuncork(this, this._write.bind(this, data, enc, cb))
if (data === SIGNAL_FLUSH) return this._finish(cb)
if (!this._writable) return cb()
if (this._writable.write(data) === false) this._ondrain = cb
else cb()
}
Duplexify.prototype._finish = function(cb) {
var self = this
this.emit('preend')
onuncork(this, function() {
end(self._forwardEnd && self._writable, function() {
// haxx to not emit prefinish twice
if (self._writableState.prefinished === false) self._writableState.prefinished = true
self.emit('prefinish')
onuncork(self, cb)
})
})
}
Duplexify.prototype.end = function(data, enc, cb) {
if (typeof data === 'function') return this.end(null, null, data)
if (typeof enc === 'function') return this.end(data, null, enc)
this._ended = true
if (data) this.write(data)
if (!this._writableState.ending) this.write(SIGNAL_FLUSH)
return stream.Writable.prototype.end.call(this, cb)
}
module.exports = Duplexify
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