mcs/class/corlib/System.IO/UnexceptionalStreamReader.cs

   1 //
   2 // System.IO.UnexceptionalStreamReader.cs
   3 //
   4 // Authors:
   5 //   Dietmar Maurer (dietmar@ximian.com)
   6 //   Miguel de Icaza (miguel@ximian.com)
   7 //   Dick Porter (dick@ximian.com)
   8 //   Sebastien Pouliot  <sebastien@ximian.com>
   9 //
  10 // (C) Ximian, Inc.  http://www.ximian.com
  11 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining
  14 // a copy of this software and associated documentation files (the
  15 // "Software"), to deal in the Software without restriction, including
  16 // without limitation the rights to use, copy, modify, merge, publish,
  17 // distribute, sublicense, and/or sell copies of the Software, and to
  18 // permit persons to whom the Software is furnished to do so, subject to
  19 // the following conditions:
  20 //
  21 // The above copyright notice and this permission notice shall be
  22 // included in all copies or substantial portions of the Software.
  23 //
  24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31 //
  32
  33
  34 // This is a wrapper around StreamReader used by System.Console that
  35 // catches IOException so that graphical applications don't suddenly
  36 // get IO errors when their terminal vanishes.  See
  37 // UnexceptionalStreamWriter too.
  38
  39 using System.Text;
  40 using System.Runtime.InteropServices;
  41
  42 namespace System.IO {
  43         internal class UnexceptionalStreamReader : StreamReader {
  44
  45                 private static bool[] newline = new bool [Environment.NewLine.Length];
  46
  47                 private static char newlineChar;
  48
  49                 static UnexceptionalStreamReader () {
  50                         string n = Environment.NewLine;
  51                         if (n.Length == 1)
  52                                 newlineChar = n [0];
  53                 }
  54 /*
  55                 public UnexceptionalStreamReader(Stream stream)
  56                         : base (stream)
  57                 {
  58                 }
  59
  60                 public UnexceptionalStreamReader(Stream stream, bool detect_encoding_from_bytemarks)
  61                         : base (stream, detect_encoding_from_bytemarks)
  62                 {
  63                 }
  64 */
  65                 public UnexceptionalStreamReader(Stream stream, Encoding encoding)
  66                         : base (stream, encoding)
  67                 {
  68                 }
  69 /*
  70                 public UnexceptionalStreamReader(Stream stream, Encoding encoding, bool detect_encoding_from_bytemarks)
  71                         : base (stream, encoding, detect_encoding_from_bytemarks)
  72                 {
  73                 }
  74
  75                 public UnexceptionalStreamReader(Stream stream, Encoding encoding, bool detect_encoding_from_bytemarks, int buffer_size)
  76                         : base (stream, encoding, detect_encoding_from_bytemarks, buffer_size)
  77                 {
  78                 }
  79
  80                 public UnexceptionalStreamReader(string path)
  81                         : base (path)
  82                 {
  83                 }
  84
  85                 public UnexceptionalStreamReader(string path, bool detect_encoding_from_bytemarks)
  86                         : base (path, detect_encoding_from_bytemarks)
  87                 {
  88                 }
  89
  90                 public UnexceptionalStreamReader(string path, Encoding encoding)
  91                         : base (path, encoding)
  92                 {
  93                 }
  94
  95                 public UnexceptionalStreamReader(string path, Encoding encoding, bool detect_encoding_from_bytemarks)
  96                         : base (path, encoding, detect_encoding_from_bytemarks)
  97                 {
  98                 }
  99
 100                 public UnexceptionalStreamReader(string path, Encoding encoding, bool detect_encoding_from_bytemarks, int buffer_size)
 101                         : base (path, encoding, detect_encoding_from_bytemarks, buffer_size)
 102                 {
 103                 }
 104 */
 105                 public override int Peek ()
 106                 {
 107                         try {
 108                                 return(base.Peek ());
 109                         } catch (IOException) {
 110                         }
 111
 112                         return(-1);
 113                 }
 114
 115                 public override int Read ()
 116                 {
 117                         try {
 118                                 return(base.Read ());
 119                         } catch (IOException) {
 120                         }
 121
 122                         return(-1);
 123                 }
 124
 125                 public override int Read ([In, Out] char[] dest_buffer,
 126                                           int index, int count)
 127                 {
 128                         if (dest_buffer == null)
 129                                 throw new ArgumentNullException ("dest_buffer");
 130                         if (index < 0)
 131                                 throw new ArgumentOutOfRangeException ("index", "< 0");
 132                         if (count < 0)
 133                                 throw new ArgumentOutOfRangeException ("count", "< 0");
 134                         // ordered to avoid possible integer overflow
 135                         if (index > dest_buffer.Length - count)
 136                                 throw new ArgumentException ("index + count > dest_buffer.Length");
 137
 138                         int chars_read = 0;
 139                         char nl = newlineChar;
 140                         try {
 141                                 while (count > 0) {
 142                                         int c = base.Read ();
 143                                         if (c < 0)
 144                                                 break;
 145                                         chars_read++;
 146                                         count--;
 147
 148                                         dest_buffer [index] = (char) c;
 149                                         // shortcut when a new line is only one character (e.g. Linux, Mac)
 150                                         if (nl != (char)0) {
 151                                                 if ((char)c == nl)
 152                                                         return chars_read;
 153                                         } else {
 154                                                 if (CheckEOL ((char)c))
 155                                                         return chars_read;
 156                                         }
 157                                         index ++;
 158                                 }
 159                         } catch (IOException) {
 160                         }
 161
 162                         return chars_read;
 163                 }
 164
 165                 private bool CheckEOL (char current)
 166                 {
 167                         // general case for any length (e.g. Windows)
 168                         for (int i=0; i < newline.Length; i++) {
 169                                 if (!newline [i]) {
 170                                         if (current == Environment.NewLine [i]) {
 171                                                 newline [i] = true;
 172                                                 return (i == newline.Length - 1);
 173                                         }
 174                                         break;
 175                                 }
 176                         }
 177                         for (int j=0; j < newline.Length; j++)
 178                                 newline [j] = false;
 179                         return false;
 180                 }
 181
 182                 public override string ReadLine()
 183                 {
 184                         try {
 185                                 return(base.ReadLine ());
 186                         } catch (IOException) {
 187                         }
 188
 189                         return(null);
 190                 }
 191
 192                 public override string ReadToEnd()
 193                 {
 194                         try {
 195                                 return(base.ReadToEnd ());
 196                         } catch (IOException) {
 197                         }
 198
 199                         return(null);
 200                 }
 201         }
 202 }