lib/filter_stream.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # Copyright 2006 Floréal Morandat <morandat@lirmm.fr>
   4 # Copyright 2009 Jean-Sebastien Gelinas <calestar@gmail.com>
   5 #
   6 # This file is free software, which comes along with NIT.  This software is
   7 # distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
   8 # without  even  the implied warranty of  MERCHANTABILITY or  FITNESS FOR A
   9 # PARTICULAR PURPOSE.  You can modify it is you want,  provided this header
  10 # is kept unaltered, and a notification of the changes is added.
  11 # You  are  allowed  to  redistribute it and sell it, alone or is a part of
  12 # another product.
  13
  14 class FilterReader
  15         super Reader
  16         # Filter readed elements
  17         var stream: nullable Reader = null
  18
  19         redef fun eof: Bool
  20         do
  21                 assert stream != null
  22                 return stream.eof
  23         end
  24 end
  25
  26 class FilterWriter
  27         super Writer
  28         # Filter outputed elements
  29         var stream: nullable Writer = null
  30
  31         # Can the stream be used to write
  32         redef fun is_writable: Bool
  33         do
  34                 assert stream != null
  35                 return stream.is_writable
  36         end
  37 end
  38
  39 class StreamCat
  40         super FilterReader
  41         private var streams: Iterator[Reader]
  42
  43         redef fun eof: Bool
  44         do
  45                 if stream == null then
  46                         return true
  47                 else if stream.eof then
  48                         stream.close
  49                         stream = null
  50                         return eof
  51                 else
  52                         return false
  53                 end
  54         end
  55
  56         redef fun stream: nullable Reader
  57         do
  58                 var res = super
  59                 if res == null and _streams.is_ok then
  60                         res = _streams.item
  61                         stream = res
  62                         assert stream != null
  63                         _streams.next
  64                 end
  65                 return res
  66         end
  67
  68         redef fun read_char: Int
  69         do
  70                 assert not eof
  71                 return stream.read_char
  72         end
  73
  74         redef fun close
  75         do
  76                 while stream != null do
  77                         stream.close
  78                         stream = null
  79                 end
  80         end
  81
  82         init with_streams(streams: Array[Reader])
  83         do
  84                 _streams = streams.iterator
  85         end
  86
  87         init(streams: Reader ...) is old_style_init do
  88                 _streams = streams.iterator
  89         end
  90 end
  91
  92 class StreamDemux
  93         super FilterWriter
  94         private var streams: Array[Writer]
  95
  96         redef fun is_writable: Bool
  97         do
  98                 if stream.is_writable then
  99                         return true
 100                 else
 101                         for i in _streams
 102                         do
 103                                 if i.is_writable then
 104                                         return true
 105                                 end
 106                         end
 107                         return false
 108                 end
 109         end
 110
 111         redef fun write(s: Text)
 112         do
 113                 for i in _streams
 114                 do
 115                         stream = i
 116                         if stream.is_writable then
 117                                 stream.write(s)
 118                         end
 119                 end
 120         end
 121
 122         redef fun close
 123         do
 124                 for i in _streams
 125                 do
 126                         stream = i
 127                         stream.close
 128                 end
 129         end
 130
 131         init with_streams(streams: Array[Writer])
 132         do
 133                 _streams = streams
 134         end
 135
 136         init(streams: Writer ...) is old_style_init do
 137                 _streams = streams
 138         end
 139 end