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1/*2Copyright (c) 2014-2018, Matteo Collina <hello@matteocollina.com>3 4Permission to use, copy, modify, and/or distribute this software for any5purpose with or without fee is hereby granted, provided that the above6copyright notice and this permission notice appear in all copies.7 8THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES9WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF10MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR11ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES12WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN13ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR14IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.15*/16 17'use strict'18 19const { Transform } = require('readable-stream')20const { StringDecoder } = require('string_decoder')21const kLast = Symbol('last')22const kDecoder = Symbol('decoder')23 24function transform (chunk, enc, cb) {25  var list26  if (this.overflow) { // Line buffer is full. Skip to start of next line.27    var buf = this[kDecoder].write(chunk)28    list = buf.split(this.matcher)29 30    if (list.length === 1) return cb() // Line ending not found. Discard entire chunk.31 32    // Line ending found. Discard trailing fragment of previous line and reset overflow state.33    list.shift()34    this.overflow = false35  } else {36    this[kLast] += this[kDecoder].write(chunk)37    list = this[kLast].split(this.matcher)38  }39 40  this[kLast] = list.pop()41 42  for (var i = 0; i < list.length; i++) {43    try {44      push(this, this.mapper(list[i]))45    } catch (error) {46      return cb(error)47    }48  }49 50  this.overflow = this[kLast].length > this.maxLength51  if (this.overflow && !this.skipOverflow) return cb(new Error('maximum buffer reached'))52 53  cb()54}55 56function flush (cb) {57  // forward any gibberish left in there58  this[kLast] += this[kDecoder].end()59 60  if (this[kLast]) {61    try {62      push(this, this.mapper(this[kLast]))63    } catch (error) {64      return cb(error)65    }66  }67 68  cb()69}70 71function push (self, val) {72  if (val !== undefined) {73    self.push(val)74  }75}76 77function noop (incoming) {78  return incoming79}80 81function split (matcher, mapper, options) {82  // Set defaults for any arguments not supplied.83  matcher = matcher || /\r?\n/84  mapper = mapper || noop85  options = options || {}86 87  // Test arguments explicitly.88  switch (arguments.length) {89    case 1:90      // If mapper is only argument.91      if (typeof matcher === 'function') {92        mapper = matcher93        matcher = /\r?\n/94      // If options is only argument.95      } else if (typeof matcher === 'object' && !(matcher instanceof RegExp)) {96        options = matcher97        matcher = /\r?\n/98      }99      break100 101    case 2:102      // If mapper and options are arguments.103      if (typeof matcher === 'function') {104        options = mapper105        mapper = matcher106        matcher = /\r?\n/107      // If matcher and options are arguments.108      } else if (typeof mapper === 'object') {109        options = mapper110        mapper = noop111      }112  }113 114  options = Object.assign({}, options)115  options.transform = transform116  options.flush = flush117  options.readableObjectMode = true118 119  const stream = new Transform(options)120 121  stream[kLast] = ''122  stream[kDecoder] = new StringDecoder('utf8')123  stream.matcher = matcher124  stream.mapper = mapper125  stream.maxLength = options.maxLength126  stream.skipOverflow = options.skipOverflow127  stream.overflow = false128 129  return stream130}131 132module.exports = split133