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Mini Shell
'use strict'
const EE = require('events')
const Yallist = require('yallist')
const EOF = Symbol('EOF')
const MAYBE_EMIT_END = Symbol('maybeEmitEnd')
const EMITTED_END = Symbol('emittedEnd')
const CLOSED = Symbol('closed')
const READ = Symbol('read')
const FLUSH = Symbol('flush')
const doIter = process.env._MP_NO_ITERATOR_SYMBOLS_ !== '1'
const ASYNCITERATOR = doIter && Symbol.asyncIterator || Symbol('asyncIterator not implemented')
const ITERATOR = doIter && Symbol.iterator || Symbol('iterator not implemented')
const FLUSHCHUNK = Symbol('flushChunk')
const SD = require('string_decoder').StringDecoder
const ENCODING = Symbol('encoding')
const DECODER = Symbol('decoder')
const FLOWING = Symbol('flowing')
const RESUME = Symbol('resume')
const BUFFERLENGTH = Symbol('bufferLength')
const BUFFERPUSH = Symbol('bufferPush')
const BUFFERSHIFT = Symbol('bufferShift')
const OBJECTMODE = Symbol('objectMode')
const SILENT_END = Symbol('silentEnd')
// Buffer in node 4.x < 4.5.0 doesn't have working Buffer.from
// or Buffer.alloc, and Buffer in node 10 deprecated the ctor.
// .M, this is fine .\^/M..
let B = Buffer
/* istanbul ignore next */
if (!B.alloc) {
B = require('safe-buffer').Buffer
}
module.exports = class MiniPass extends EE {
constructor (options) {
super()
this[SILENT_END] = false
this[FLOWING] = false
this.pipes = new Yallist()
this.buffer = new Yallist()
this[OBJECTMODE] = options && options.objectMode || false
if (this[OBJECTMODE])
this[ENCODING] = null
else
this[ENCODING] = options && options.encoding || null
if (this[ENCODING] === 'buffer')
this[ENCODING] = null
this[DECODER] = this[ENCODING] ? new SD(this[ENCODING]) : null
this[EOF] = false
this[EMITTED_END] = false
this[CLOSED] = false
this.writable = true
this.readable = true
this[BUFFERLENGTH] = 0
}
get bufferLength () { return this[BUFFERLENGTH] }
get encoding () { return this[ENCODING] }
set encoding (enc) {
if (this[OBJECTMODE])
throw new Error('cannot set encoding in objectMode')
if (this[ENCODING] && enc !== this[ENCODING] &&
(this[DECODER] && this[DECODER].lastNeed || this[BUFFERLENGTH]))
throw new Error('cannot change encoding')
if (this[ENCODING] !== enc) {
this[DECODER] = enc ? new SD(enc) : null
if (this.buffer.length)
this.buffer = this.buffer.map(chunk => this[DECODER].write(chunk))
}
this[ENCODING] = enc
}
setEncoding (enc) {
this.encoding = enc
}
write (chunk, encoding, cb) {
if (this[EOF])
throw new Error('write after end')
if (typeof encoding === 'function')
cb = encoding, encoding = 'utf8'
if (!encoding)
encoding = 'utf8'
// fast-path writing strings of same encoding to a stream with
// an empty buffer, skipping the buffer/decoder dance
if (typeof chunk === 'string' && !this[OBJECTMODE] &&
// unless it is a string already ready for us to use
!(encoding === this[ENCODING] && !this[DECODER].lastNeed)) {
chunk = B.from(chunk, encoding)
}
if (B.isBuffer(chunk) && this[ENCODING])
chunk = this[DECODER].write(chunk)
try {
return this.flowing
? (this.emit('data', chunk), this.flowing)
: (this[BUFFERPUSH](chunk), false)
} finally {
this.emit('readable')
if (cb)
cb()
}
}
read (n) {
try {
if (this[BUFFERLENGTH] === 0 || n === 0 || n > this[BUFFERLENGTH])
return null
if (this[OBJECTMODE])
n = null
if (this.buffer.length > 1 && !this[OBJECTMODE]) {
if (this.encoding)
this.buffer = new Yallist([
Array.from(this.buffer).join('')
])
else
this.buffer = new Yallist([
B.concat(Array.from(this.buffer), this[BUFFERLENGTH])
])
}
return this[READ](n || null, this.buffer.head.value)
} finally {
this[MAYBE_EMIT_END]()
}
}
[READ] (n, chunk) {
if (n === chunk.length || n === null)
this[BUFFERSHIFT]()
else {
this.buffer.head.value = chunk.slice(n)
chunk = chunk.slice(0, n)
this[BUFFERLENGTH] -= n
}
this.emit('data', chunk)
if (!this.buffer.length && !this[EOF])
this.emit('drain')
return chunk
}
end (chunk, encoding, cb) {
if (typeof chunk === 'function')
cb = chunk, chunk = null
if (typeof encoding === 'function')
cb = encoding, encoding = 'utf8'
if (chunk)
this.write(chunk, encoding)
if (cb)
this.once('end', cb)
this[EOF] = true
this.writable = false
if (this.flowing)
this[MAYBE_EMIT_END]()
}
// don't let the internal resume be overwritten
[RESUME] () {
this[FLOWING] = true
this.emit('resume')
if (this.buffer.length)
this[FLUSH]()
else if (this[EOF])
this[MAYBE_EMIT_END]()
else
this.emit('drain')
}
resume () {
return this[RESUME]()
}
pause () {
this[FLOWING] = false
}
get flowing () {
return this[FLOWING]
}
[BUFFERPUSH] (chunk) {
if (this[OBJECTMODE])
this[BUFFERLENGTH] += 1
else
this[BUFFERLENGTH] += chunk.length
return this.buffer.push(chunk)
}
[BUFFERSHIFT] () {
if (this.buffer.length) {
if (this[OBJECTMODE])
this[BUFFERLENGTH] -= 1
else
this[BUFFERLENGTH] -= this.buffer.head.value.length
}
return this.buffer.shift()
}
[FLUSH] () {
do {} while (this[FLUSHCHUNK](this[BUFFERSHIFT]()))
if (!this.buffer.length && !this[EOF])
this.emit('drain')
}
[FLUSHCHUNK] (chunk) {
return chunk ? (this.emit('data', chunk), this.flowing) : false
}
pipe (dest, opts) {
if (dest === process.stdout || dest === process.stderr)
(opts = opts || {}).end = false
const p = { dest: dest, opts: opts, ondrain: _ => this[RESUME]() }
this.pipes.push(p)
dest.on('drain', p.ondrain)
this[RESUME]()
return dest
}
addListener (ev, fn) {
return this.on(ev, fn)
}
on (ev, fn) {
try {
return super.on(ev, fn)
} finally {
if (ev === 'data' && !this.pipes.length && !this.flowing)
this[RESUME]()
else if (ev === 'end' && this[SILENT_END] && this[EMITTED_END]) {
this[SILENT_END] = false
super.emit('end')
}
}
}
get emittedEnd () {
return this[EMITTED_END]
}
[MAYBE_EMIT_END] () {
if (!this[EMITTED_END] && this.buffer.length === 0 && this[EOF]) {
this.emit('end')
this.emit('prefinish')
this.emit('finish')
if (this[CLOSED])
this.emit('close')
}
}
emit (ev, data) {
if (ev === 'data') {
if (!data)
return
if (this.pipes.length)
this.pipes.forEach(p => p.dest.write(data) || this.pause())
} else if (ev === 'end') {
if (this[EMITTED_END] === true)
return
this[EMITTED_END] = true
this.readable = false
if (this[DECODER]) {
data = this[DECODER].end()
if (data) {
this.pipes.forEach(p => p.dest.write(data))
super.emit('data', data)
}
}
this.pipes.forEach(p => {
p.dest.removeListener('drain', p.ondrain)
if (!p.opts || p.opts.end !== false)
p.dest.end()
})
} else if (ev === 'close') {
this[CLOSED] = true
// don't emit close before 'end' and 'finish'
if (!this[EMITTED_END])
return
}
const args = new Array(arguments.length)
args[0] = ev
args[1] = data
if (arguments.length > 2) {
for (let i = 2; i < arguments.length; i++) {
args[i] = arguments[i]
}
}
try {
const ret = super.emit.apply(this, args)
if (ev === 'end' && ret === false)
this[SILENT_END] = true
return ret
} finally {
if (ev !== 'end')
this[MAYBE_EMIT_END]()
}
}
// const all = await stream.collect()
collect () {
return new Promise((resolve, reject) => {
const buf = []
this.on('data', c => buf.push(c))
this.on('end', () => resolve(buf))
this.on('error', reject)
})
}
// for await (let chunk of stream)
[ASYNCITERATOR] () {
const next = () => {
const res = this.read()
if (res !== null)
return Promise.resolve({ done: false, value: res })
if (this[EOF])
return Promise.resolve({ done: true })
let resolve = null
let reject = null
const onerr = er => {
this.removeListener('data', ondata)
this.removeListener('end', onend)
reject(er)
}
const ondata = value => {
this.removeListener('error', onerr)
this.removeListener('end', onend)
this.pause()
resolve({ value: value, done: !!this[EOF] })
}
const onend = () => {
this.removeListener('error', onerr)
this.removeListener('data', ondata)
resolve({ done: true })
}
return new Promise((res, rej) => {
reject = rej
resolve = res
this.once('error', onerr)
this.once('end', onend)
this.once('data', ondata)
this.resume()
})
}
return { next }
}
// for (let chunk of stream)
[ITERATOR] () {
const next = () => {
const value = this.read()
const done = value === null
return { value, done }
}
return { next }
}
}
Zerion Mini Shell 1.0