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1var Writable = require('readable-stream').Writable2var inherits = require('inherits')3var bufferFrom = require('buffer-from')4 5if (typeof Uint8Array === 'undefined') {6  var U8 = require('typedarray').Uint8Array7} else {8  var U8 = Uint8Array9}10 11function ConcatStream(opts, cb) {12  if (!(this instanceof ConcatStream)) return new ConcatStream(opts, cb)13 14  if (typeof opts === 'function') {15    cb = opts16    opts = {}17  }18  if (!opts) opts = {}19 20  var encoding = opts.encoding21  var shouldInferEncoding = false22 23  if (!encoding) {24    shouldInferEncoding = true25  } else {26    encoding =  String(encoding).toLowerCase()27    if (encoding === 'u8' || encoding === 'uint8') {28      encoding = 'uint8array'29    }30  }31 32  Writable.call(this, { objectMode: true })33 34  this.encoding = encoding35  this.shouldInferEncoding = shouldInferEncoding36 37  if (cb) this.on('finish', function () { cb(this.getBody()) })38  this.body = []39}40 41module.exports = ConcatStream42inherits(ConcatStream, Writable)43 44ConcatStream.prototype._write = function(chunk, enc, next) {45  this.body.push(chunk)46  next()47}48 49ConcatStream.prototype.inferEncoding = function (buff) {50  var firstBuffer = buff === undefined ? this.body[0] : buff;51  if (Buffer.isBuffer(firstBuffer)) return 'buffer'52  if (typeof Uint8Array !== 'undefined' && firstBuffer instanceof Uint8Array) return 'uint8array'53  if (Array.isArray(firstBuffer)) return 'array'54  if (typeof firstBuffer === 'string') return 'string'55  if (Object.prototype.toString.call(firstBuffer) === "[object Object]") return 'object'56  return 'buffer'57}58 59ConcatStream.prototype.getBody = function () {60  if (!this.encoding && this.body.length === 0) return []61  if (this.shouldInferEncoding) this.encoding = this.inferEncoding()62  if (this.encoding === 'array') return arrayConcat(this.body)63  if (this.encoding === 'string') return stringConcat(this.body)64  if (this.encoding === 'buffer') return bufferConcat(this.body)65  if (this.encoding === 'uint8array') return u8Concat(this.body)66  return this.body67}68 69var isArray = Array.isArray || function (arr) {70  return Object.prototype.toString.call(arr) == '[object Array]'71}72 73function isArrayish (arr) {74  return /Array\]$/.test(Object.prototype.toString.call(arr))75}76 77function isBufferish (p) {78  return typeof p === 'string' || isArrayish(p) || (p && typeof p.subarray === 'function')79}80 81function stringConcat (parts) {82  var strings = []83  var needsToString = false84  for (var i = 0; i < parts.length; i++) {85    var p = parts[i]86    if (typeof p === 'string') {87      strings.push(p)88    } else if (Buffer.isBuffer(p)) {89      strings.push(p)90    } else if (isBufferish(p)) {91      strings.push(bufferFrom(p))92    } else {93      strings.push(bufferFrom(String(p)))94    }95  }96  if (Buffer.isBuffer(parts[0])) {97    strings = Buffer.concat(strings)98    strings = strings.toString('utf8')99  } else {100    strings = strings.join('')101  }102  return strings103}104 105function bufferConcat (parts) {106  var bufs = []107  for (var i = 0; i < parts.length; i++) {108    var p = parts[i]109    if (Buffer.isBuffer(p)) {110      bufs.push(p)111    } else if (isBufferish(p)) {112      bufs.push(bufferFrom(p))113    } else {114      bufs.push(bufferFrom(String(p)))115    }116  }117  return Buffer.concat(bufs)118}119 120function arrayConcat (parts) {121  var res = []122  for (var i = 0; i < parts.length; i++) {123    res.push.apply(res, parts[i])124  }125  return res126}127 128function u8Concat (parts) {129  var len = 0130  for (var i = 0; i < parts.length; i++) {131    if (typeof parts[i] === 'string') {132      parts[i] = bufferFrom(parts[i])133    }134    len += parts[i].length135  }136  var u8 = new U8(len)137  for (var i = 0, offset = 0; i < parts.length; i++) {138    var part = parts[i]139    for (var j = 0; j < part.length; j++) {140      u8[offset++] = part[j]141    }142  }143  return u8144}145