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

   1 //\r
   2 // System.IO.StreamReader.cs\r
   3 //\r
   4 // Author:\r
   5 //   Dietmar Maurer (dietmar@ximian.com)\r
   6 //\r
   7 // (C) Ximian, Inc.  http://www.ximian.com\r
   8 //\r
   9 \r
  10 using System;\r
  11 using System.Text;\r
  12 \r
  13 namespace System.IO {\r
  14         [Serializable]\r
  15         public class StreamReader : TextReader {\r
  16 \r
  17                 private const int DefaultBufferSize = 1024;\r
  18                 private const int DefaultFileBufferSize = 4096;\r
  19                 private const int MinimumBufferSize = 128;\r
  20 \r
  21                 // buffering members\r
  22                 private byte [] rgbEncoded;\r
  23 //              private int cbEncoded;\r
  24                 private char [] rgchDecoded;\r
  25                 private int cchDecoded;\r
  26 \r
  27                 private int pos;\r
  28 \r
  29 \r
  30                 private Encoding internalEncoding;\r
  31                 private Decoder decoder;\r
  32 \r
  33                 private Stream internalStream;\r
  34 \r
  35                 [MonoTODO("Make Read methods return 0, etc.")]\r
  36                 private class NullStreamReader : StreamReader {\r
  37                 }\r
  38 \r
  39                 public new static readonly StreamReader Null = (StreamReader)(new NullStreamReader());\r
  40 \r
  41                 internal StreamReader() {}\r
  42 \r
  43                 public StreamReader(Stream stream)\r
  44                         : this (stream, null, false, DefaultBufferSize) { }\r
  45 \r
  46                 public StreamReader(Stream stream, bool detectEncodingFromByteOrderMarks)\r
  47                         : this (stream, null, detectEncodingFromByteOrderMarks, DefaultBufferSize) { }\r
  48 \r
  49                 public StreamReader(Stream stream, Encoding encoding)\r
  50                         : this (stream, encoding, false, DefaultBufferSize) { }\r
  51 \r
  52                 public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks)\r
  53                         : this (stream, encoding, detectEncodingFromByteOrderMarks, DefaultBufferSize) { }\r
  54                 \r
  55                 public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)\r
  56                 {\r
  57                         Initialize (stream, encoding, detectEncodingFromByteOrderMarks, bufferSize);\r
  58                 }\r
  59 \r
  60                 public StreamReader(string path)\r
  61                         : this (path, null, false, DefaultFileBufferSize) { }\r
  62 \r
  63                 public StreamReader(string path, bool detectEncodingFromByteOrderMarks)\r
  64                         : this (path, null, detectEncodingFromByteOrderMarks, DefaultFileBufferSize) { }\r
  65 \r
  66                 public StreamReader(string path, Encoding encoding)\r
  67                         : this (path, encoding, false, DefaultFileBufferSize) { }\r
  68 \r
  69                 public StreamReader(string path, Encoding encoding, bool detectEncodingFromByteOrderMarks)\r
  70                         : this (path, encoding, detectEncodingFromByteOrderMarks, DefaultFileBufferSize) { }\r
  71                 \r
  72                 [MonoTODO]\r
  73                 public StreamReader(string path, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)\r
  74                 {\r
  75                         if (null == path)\r
  76                                 throw new ArgumentNullException();\r
  77                         if (String.Empty == path)\r
  78                                 throw new ArgumentException();\r
  79                         if (path.IndexOfAny (Path.InvalidPathChars) != -1)\r
  80                                 throw new ArgumentException("path contains invalid characters");\r
  81 \r
  82                         string DirName = Path.GetDirectoryName(path);\r
  83                         if (DirName != String.Empty && !Directory.Exists(DirName))\r
  84                                 throw new DirectoryNotFoundException();\r
  85                         if (!File.Exists(path))\r
  86                                 throw new FileNotFoundException(path);\r
  87 \r
  88                         Stream stream = (Stream) File.OpenRead (path);\r
  89                         Initialize (stream, encoding, detectEncodingFromByteOrderMarks, bufferSize);\r
  90                 }\r
  91 \r
  92                 [MonoTODO]\r
  93                 protected void Initialize (Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)\r
  94                 {\r
  95                         if (null == stream)\r
  96                                 throw new ArgumentNullException();\r
  97                         if (!stream.CanRead)\r
  98                                 throw new ArgumentException("Cannot read stream");\r
  99 \r
 100                         internalStream = stream;\r
 101 \r
 102                         // use detect encoding flag\r
 103                         if (encoding == null) {\r
 104                                 internalEncoding = Encoding.UTF8;\r
 105                                 decoder = Encoding.UTF8.GetDecoder ();\r
 106                         } else {\r
 107                                 internalEncoding = encoding;\r
 108                                 decoder = encoding.GetDecoder ();\r
 109                         }\r
 110 \r
 111                         if (bufferSize < MinimumBufferSize)\r
 112                                 bufferSize = MinimumBufferSize;\r
 113 \r
 114                         rgbEncoded = new byte [bufferSize];\r
 115                         rgchDecoded = new char [internalEncoding.GetMaxCharCount (bufferSize)];\r
 116                         pos = 0;\r
 117                         cchDecoded = 0;\r
 118                 }\r
 119 \r
 120                 public virtual Stream BaseStream\r
 121                 {\r
 122                         get {\r
 123                                 return internalStream;\r
 124                         }\r
 125                 }\r
 126 \r
 127                 public virtual Encoding CurrentEncoding\r
 128                 {\r
 129                         get {\r
 130                                 return internalEncoding;\r
 131                         }\r
 132                 }\r
 133 \r
 134                 public override void Close ()\r
 135                 {\r
 136                         Dispose (true);\r
 137                 }\r
 138 \r
 139                 public void DiscardBufferedData ()\r
 140                 {\r
 141                         pos = 0;\r
 142                         cchDecoded = 0;\r
 143 \r
 144 /* I'm sure there's no need to do all this\r
 145                         if ((cchDecoded == null) || (pos == cchDecoded.Length))\r
 146                                 return;\r
 147 \r
 148                         if (!internalStream.CanSeek)\r
 149                                 return;\r
 150 \r
 151                         int seek_back = pos - cchDecoded.Length;\r
 152                         internalStream.Seek (seek_back, SeekOrigin.Current);\r
 153 */\r
 154                 }\r
 155 \r
 156 \r
 157                 // the buffer is empty, fill it again\r
 158                 [MonoTODO ("handle byte order marks here")]\r
 159                 private int ReadBuffer ()\r
 160                 {\r
 161                         pos = 0;\r
 162                         int cbEncoded = 0;\r
 163                         cchDecoded = 0;\r
 164                         do      // keep looping until the decoder gives us some chars\r
 165                         {\r
 166                                 cbEncoded = internalStream.Read (rgbEncoded, 0, rgbEncoded.Length);\r
 167                                 // TODO: remove this line when iconv is fixed\r
 168                                 int bufcnt = decoder.GetCharCount (rgbEncoded, 0, cbEncoded);\r
 169 \r
 170                                 if (cbEncoded == 0)\r
 171                                         return 0;\r
 172                                 // TODO: remove byte order marks here\r
 173                                 cchDecoded += decoder.GetChars (rgbEncoded, 0, cbEncoded, rgchDecoded, 0);\r
 174                         } while (cchDecoded == 0);\r
 175 \r
 176                         return cchDecoded;\r
 177                 }\r
 178 \r
 179                 public override int Peek ()\r
 180                 {\r
 181                         if (!internalStream.CanSeek)\r
 182                                 return -1;\r
 183 \r
 184                         if (pos >= cchDecoded && ReadBuffer () == 0)\r
 185                                 return -1;\r
 186 \r
 187                         return rgchDecoded [pos];\r
 188                 }\r
 189 \r
 190                 public override int Read ()\r
 191                 {\r
 192                         if (pos >= cchDecoded && ReadBuffer () == 0)\r
 193                                 return -1;\r
 194 \r
 195                         return rgchDecoded [pos++];\r
 196                 }\r
 197 \r
 198                 public override int Read (char[] dest_buffer, int index, int count)\r
 199                 {\r
 200                         if (dest_buffer == null)\r
 201                                 throw new ArgumentException ();\r
 202 \r
 203                         if ((index < 0) || (count < 0))\r
 204                                 throw new ArgumentOutOfRangeException ();\r
 205 \r
 206                         if (index + count > dest_buffer.Length)\r
 207                                 throw new ArgumentException ();\r
 208 \r
 209                         int cchRead = 0;\r
 210                         while (count > 0)\r
 211                         {\r
 212                                 if (pos >= cchDecoded && ReadBuffer () == 0)\r
 213                                         return cchRead > 0? cchRead: -1;\r
 214 \r
 215                                 int cch = Math.Min (cchDecoded - pos, count);\r
 216                                 Array.Copy (rgchDecoded, pos, dest_buffer, index, cch);\r
 217                                 pos += cch;\r
 218                                 index += cch;\r
 219                                 count -= cch;\r
 220                                 cchRead += cch;\r
 221                         }\r
 222                         return cchRead;\r
 223                 }\r
 224 \r
 225                 public override string ReadLine()\r
 226                 {\r
 227                         StringBuilder text = new StringBuilder ();\r
 228 \r
 229                         while (true) {\r
 230                                 int c = Read ();\r
 231 \r
 232                                 if (c == -1) {                          // end of stream\r
 233                                         if (text.Length == 0)\r
 234                                                 return null;\r
 235 \r
 236                                         break;\r
 237                                 }\r
 238 \r
 239                                 if (c == '\n')                          // newline\r
 240                                         break;\r
 241 \r
 242                                 if (c == '\r' && Peek () == '\n') {     // cr, newline\r
 243                                         Read ();\r
 244                                         break;\r
 245                                 }\r
 246 \r
 247                                 text.Append ((char) c);\r
 248                         }\r
 249 \r
 250                         return text.ToString ();\r
 251                 }\r
 252 \r
 253                 public override string ReadToEnd()\r
 254                 {\r
 255                         StringBuilder text = new StringBuilder ();\r
 256 \r
 257                         int c;\r
 258                         while ((c = Read ()) != -1) {\r
 259                                 text.Append ((char) c);\r
 260                         }\r
 261 \r
 262                         if (text.Length == 0)\r
 263                                 return String.Empty;\r
 264                         return text.ToString ();\r
 265                 }\r
 266         }\r
 267 }\r