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                 internal 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 \r
  80                         Stream stream = (Stream) File.OpenRead (path);\r
  81                         Initialize (stream, encoding, detectEncodingFromByteOrderMarks, bufferSize);\r
  82                 }\r
  83 \r
  84                 [MonoTODO]\r
  85                 protected void Initialize (Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)\r
  86                 {\r
  87                         if (null == stream)\r
  88                                 throw new ArgumentNullException();\r
  89                         if (!stream.CanRead)\r
  90                                 throw new ArgumentException("Cannot read stream");\r
  91 \r
  92                         internalStream = stream;\r
  93 \r
  94                         // use detect encoding flag\r
  95                         if (encoding == null) {\r
  96                                 internalEncoding = Encoding.UTF8;\r
  97                                 decoder = Encoding.UTF8.GetDecoder ();\r
  98                         } else {\r
  99                                 internalEncoding = encoding;\r
 100                                 decoder = encoding.GetDecoder ();\r
 101                         }\r
 102 \r
 103                         if (bufferSize < MinimumBufferSize)\r
 104                                 bufferSize = MinimumBufferSize;\r
 105 \r
 106                         rgbEncoded = new byte [bufferSize];\r
 107                         rgchDecoded = new char [internalEncoding.GetMaxCharCount (bufferSize)];\r
 108                         pos = 0;\r
 109                         cchDecoded = 0;\r
 110                 }\r
 111 \r
 112                 public virtual Stream BaseStream\r
 113                 {\r
 114                         get {\r
 115                                 return internalStream;\r
 116                         }\r
 117                 }\r
 118 \r
 119                 public virtual Encoding CurrentEncoding\r
 120                 {\r
 121                         get {\r
 122                                 return internalEncoding;\r
 123                         }\r
 124                 }\r
 125 \r
 126                 public override void Close ()\r
 127                 {\r
 128                         Dispose (true);\r
 129                 }\r
 130 \r
 131                 public void DiscardBufferedData ()\r
 132                 {\r
 133                         pos = 0;\r
 134                         cchDecoded = 0;\r
 135 \r
 136 /* I'm sure there's no need to do all this\r
 137                         if ((cchDecoded == null) || (pos == cchDecoded.Length))\r
 138                                 return;\r
 139 \r
 140                         if (!internalStream.CanSeek)\r
 141                                 return;\r
 142 \r
 143                         int seek_back = pos - cchDecoded.Length;\r
 144                         internalStream.Seek (seek_back, SeekOrigin.Current);\r
 145 */\r
 146                 }\r
 147 \r
 148 \r
 149                 // the buffer is empty, fill it again\r
 150                 [MonoTODO ("handle byte order marks here")]\r
 151                 private int ReadBuffer ()\r
 152                 {\r
 153                         pos = 0;\r
 154                         int cbEncoded = 0;\r
 155                         cchDecoded = 0;\r
 156                         do      // keep looping until the decoder gives us some chars\r
 157                         {\r
 158                                 cbEncoded = internalStream.Read (rgbEncoded, 0, rgbEncoded.Length);\r
 159                                 // TODO: remove this line when iconv is fixed\r
 160                                 int bufcnt = decoder.GetCharCount (rgbEncoded, 0, cbEncoded);\r
 161 \r
 162                                 if (cbEncoded == 0)\r
 163                                         return 0;\r
 164                                 // TODO: remove byte order marks here\r
 165                                 cchDecoded += decoder.GetChars (rgbEncoded, 0, cbEncoded, rgchDecoded, 0);\r
 166                         } while (cchDecoded == 0);\r
 167 \r
 168                         return cchDecoded;\r
 169                 }\r
 170 \r
 171                 public override int Peek ()\r
 172                 {\r
 173                         if (!internalStream.CanSeek)\r
 174                                 return -1;\r
 175 \r
 176                         if (pos >= cchDecoded && ReadBuffer () == 0)\r
 177                                 return -1;\r
 178 \r
 179                         return rgchDecoded [pos];\r
 180                 }\r
 181 \r
 182                 public override int Read ()\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 (char[] dest_buffer, int index, int count)\r
 191                 {\r
 192                         if (dest_buffer == null)\r
 193                                 throw new ArgumentException ();\r
 194 \r
 195                         if ((index < 0) || (count < 0))\r
 196                                 throw new ArgumentOutOfRangeException ();\r
 197 \r
 198                         if (index + count > dest_buffer.Length)\r
 199                                 throw new ArgumentException ();\r
 200 \r
 201                         int cchRead = 0;\r
 202                         while (count > 0)\r
 203                         {\r
 204                                 if (pos >= cchDecoded && ReadBuffer () == 0)\r
 205                                         return -1;\r
 206 \r
 207                                 int cch = Math.Min (cchDecoded - pos, count);\r
 208                                 Array.Copy (rgchDecoded, pos, dest_buffer, index, cch);\r
 209                                 pos += cch;\r
 210                                 index += cch;\r
 211                                 count -= cch;\r
 212                                 cchRead += cch;\r
 213                         }\r
 214                         return cchRead;\r
 215                 }\r
 216 \r
 217                 public override string ReadLine()\r
 218                 {\r
 219                         StringBuilder text = new StringBuilder ();\r
 220 \r
 221                         while (true) {\r
 222                                 int c = Read ();\r
 223 \r
 224                                 if (c == -1) {                          // end of stream\r
 225                                         if (text.Length == 0)\r
 226                                                 return null;\r
 227 \r
 228                                         break;\r
 229                                 }\r
 230 \r
 231                                 if (c == '\n')                          // newline\r
 232                                         break;\r
 233 \r
 234                                 if (c == '\r' && Peek () == '\n') {     // cr, newline\r
 235                                         Read ();\r
 236                                         break;\r
 237                                 }\r
 238 \r
 239                                 text.Append ((char) c);\r
 240                         }\r
 241 \r
 242                         return text.ToString ();\r
 243                 }\r
 244 \r
 245                 public override string ReadToEnd()\r
 246                 {\r
 247                         StringBuilder text = new StringBuilder ();\r
 248 \r
 249                         int c;\r
 250                         while ((c = Read ()) != -1) {\r
 251                                 text.Append ((char) c);\r
 252                         }\r
 253 \r
 254                         if (text.Length == 0)\r
 255                                 return String.Empty;\r
 256                         return text.ToString ();\r
 257                 }\r
 258         }\r
 259 }\r