mcs/class/corlib/System.Text/EncoderReplacementFallbackBuffer.cs

   1 //
   2 // EncoderReplacementFallbackBuffer.cs
   3 //
   4 // Author:
   5 //      Atsushi Enomoto <atsushi@ximian.com>
   6 //
   7
   8 //
   9 // Copyright (C) 2005 Novell, Inc (http://www.novell.com)
  10 // Copyright 2011 Xamarin Inc (http://www.xamarin.com).
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31
  32 namespace System.Text
  33 {
  34         // This EncoderFallbackBuffer is simple. It ignores the input buffers.
  35         // EncoderFallbackBuffer users could implement their own complex
  36         // fallback buffers.
  37
  38         public sealed class EncoderReplacementFallbackBuffer
  39                 : EncoderFallbackBuffer
  40         {
  41                 string replacement;
  42                 int current;
  43                 bool fallback_assigned;
  44
  45                 public EncoderReplacementFallbackBuffer (
  46                         EncoderReplacementFallback fallback)
  47                 {
  48                         if (fallback == null)
  49                                 throw new ArgumentNullException ("fallback");
  50                         replacement = fallback.DefaultString;
  51                         current = 0;
  52                 }
  53
  54                 public override int Remaining {
  55                         get { return replacement.Length - current; }
  56                 }
  57
  58                 public override bool Fallback (char charUnknown, int index)
  59                 {
  60                         return Fallback (index);
  61                 }
  62
  63                 public override bool Fallback (char charUnknownHigh, char charUnknownLow, int index)
  64                 {
  65                         return Fallback (index);
  66                 }
  67
  68                 // hmm, what is this index for???
  69                 private bool Fallback (int index)
  70                 {
  71                         if (fallback_assigned && Remaining != 0)
  72                                 throw new ArgumentException ("Reentrant Fallback method invocation occured. It might be because either this FallbackBuffer is incorrectly shared by multiple threads, invoked inside Encoding recursively, or Reset invocation is forgotten.");
  73                         if (index < 0)
  74                                 throw new ArgumentOutOfRangeException ("index");
  75                         fallback_assigned = true;
  76                         current = 0;
  77
  78                         return replacement.Length > 0;
  79                 }
  80
  81                 public override char GetNextChar ()
  82                 {
  83                         if (current >= replacement.Length)
  84                                 return char.MinValue;
  85                         return replacement [current++];
  86                 }
  87
  88                 public override bool MovePrevious ()
  89                 {
  90                         if (current == 0)
  91                                 return false;
  92                         current--;
  93                         return true;
  94                 }
  95
  96                 public override void Reset ()
  97                 {
  98                         fallback_assigned = false;
  99                         current = 0;
 100                 }
 101         }
 102 }
 103