www.aleph1.co.uk Git - yaffs-website/blob - node_modules/duplexer/index.js

   1 var Stream = require("stream")
   2 var writeMethods = ["write", "end", "destroy"]
   3 var readMethods = ["resume", "pause"]
   4 var readEvents = ["data", "close"]
   5 var slice = Array.prototype.slice
   6
   7 module.exports = duplex
   8
   9 function forEach (arr, fn) {
  10     if (arr.forEach) {
  11         return arr.forEach(fn)
  12     }
  13
  14     for (var i = 0; i < arr.length; i++) {
  15         fn(arr[i], i)
  16     }
  17 }
  18
  19 function duplex(writer, reader) {
  20     var stream = new Stream()
  21     var ended = false
  22
  23     forEach(writeMethods, proxyWriter)
  24
  25     forEach(readMethods, proxyReader)
  26
  27     forEach(readEvents, proxyStream)
  28
  29     reader.on("end", handleEnd)
  30
  31     writer.on("drain", function() {
  32       stream.emit("drain")
  33     })
  34
  35     writer.on("error", reemit)
  36     reader.on("error", reemit)
  37
  38     stream.writable = writer.writable
  39     stream.readable = reader.readable
  40
  41     return stream
  42
  43     function proxyWriter(methodName) {
  44         stream[methodName] = method
  45
  46         function method() {
  47             return writer[methodName].apply(writer, arguments)
  48         }
  49     }
  50
  51     function proxyReader(methodName) {
  52         stream[methodName] = method
  53
  54         function method() {
  55             stream.emit(methodName)
  56             var func = reader[methodName]
  57             if (func) {
  58                 return func.apply(reader, arguments)
  59             }
  60             reader.emit(methodName)
  61         }
  62     }
  63
  64     function proxyStream(methodName) {
  65         reader.on(methodName, reemit)
  66
  67         function reemit() {
  68             var args = slice.call(arguments)
  69             args.unshift(methodName)
  70             stream.emit.apply(stream, args)
  71         }
  72     }
  73
  74     function handleEnd() {
  75         if (ended) {
  76             return
  77         }
  78         ended = true
  79         var args = slice.call(arguments)
  80         args.unshift("end")
  81         stream.emit.apply(stream, args)
  82     }
  83
  84     function reemit(err) {
  85         stream.emit("error", err)
  86     }
  87 }