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

   1 //\r
   2 // System.IO.StreamWriter.cs\r
   3 //\r
   4 // Authors:\r
   5 //   Dietmar Maurer (dietmar@ximian.com)\r
   6 //   Paolo Molaro (lupus@ximian.com)\r
   7 //\r
   8 // (C) Ximian, Inc.  http://www.ximian.com\r
   9 //\r
  10 \r
  11 //\r
  12 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)\r
  13 //\r
  14 // Permission is hereby granted, free of charge, to any person obtaining\r
  15 // a copy of this software and associated documentation files (the\r
  16 // "Software"), to deal in the Software without restriction, including\r
  17 // without limitation the rights to use, copy, modify, merge, publish,\r
  18 // distribute, sublicense, and/or sell copies of the Software, and to\r
  19 // permit persons to whom the Software is furnished to do so, subject to\r
  20 // the following conditions:\r
  21 // \r
  22 // The above copyright notice and this permission notice shall be\r
  23 // included in all copies or substantial portions of the Software.\r
  24 // \r
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,\r
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF\r
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND\r
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE\r
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION\r
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION\r
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.\r
  32 //\r
  33 \r
  34 using System.Text;\r
  35 using System;\r
  36 \r
  37 using System.Runtime.InteropServices;\r
  38 \r
  39 namespace System.IO {\r
  40         \r
  41         [Serializable]\r
  42         [ComVisible (true)]\r
  43         public class StreamWriter : TextWriter {\r
  44 \r
  45                 private Encoding internalEncoding;\r
  46 \r
  47                 private Stream internalStream;\r
  48 \r
  49                 private const int DefaultBufferSize = 1024;\r
  50                 private const int DefaultFileBufferSize = 4096;\r
  51                 private const int MinimumBufferSize = 256;\r
  52 \r
  53                 private byte[] byte_buf;\r
  54                 private char[] decode_buf;\r
  55                 private int byte_pos;\r
  56                 private int decode_pos;\r
  57 \r
  58                 private bool iflush;\r
  59                 private bool DisposedAlready;\r
  60                 private bool preamble_done;\r
  61 \r
  62                 public new static readonly StreamWriter Null = new StreamWriter (Stream.Null, Encoding.UTF8Unmarked, 1);\r
  63 \r
  64                 public StreamWriter (Stream stream)\r
  65                         : this (stream, Encoding.UTF8Unmarked, DefaultBufferSize) {}\r
  66 \r
  67                 public StreamWriter (Stream stream, Encoding encoding)\r
  68                         : this (stream, encoding, DefaultBufferSize) {}\r
  69 \r
  70                 internal void Initialize(Encoding encoding, int bufferSize) {\r
  71                         internalEncoding = encoding;\r
  72                         decode_pos = byte_pos = 0;\r
  73                         int BufferSize = Math.Max(bufferSize, MinimumBufferSize);\r
  74                         decode_buf = new char [BufferSize];\r
  75                         byte_buf = new byte [encoding.GetMaxByteCount (BufferSize)];\r
  76 \r
  77                         // Fixes bug http://bugzilla.ximian.com/show_bug.cgi?id=74513\r
  78                         if (internalStream.CanSeek && internalStream.Position > 0)\r
  79                                 preamble_done = true;\r
  80                 }\r
  81 \r
  82                 public StreamWriter (Stream stream, Encoding encoding, int bufferSize) {\r
  83                         if (null == stream)\r
  84                                 throw new ArgumentNullException("stream");\r
  85                         if (null == encoding)\r
  86                                 throw new ArgumentNullException("encoding");\r
  87                         if (bufferSize <= 0)\r
  88                                 throw new ArgumentOutOfRangeException("bufferSize");\r
  89                         if (!stream.CanWrite)\r
  90                                 throw new ArgumentException ("Can not write to stream");\r
  91 \r
  92                         internalStream = stream;\r
  93 \r
  94                         Initialize(encoding, bufferSize);\r
  95                 }\r
  96 \r
  97                 public StreamWriter (string path)\r
  98                         : this (path, false, Encoding.UTF8Unmarked, DefaultFileBufferSize) {}\r
  99 \r
 100                 public StreamWriter (string path, bool append)\r
 101                         : this (path, append, Encoding.UTF8Unmarked, DefaultFileBufferSize) {}\r
 102 \r
 103                 public StreamWriter (string path, bool append, Encoding encoding)\r
 104                         : this (path, append, encoding, DefaultFileBufferSize) {}\r
 105                 \r
 106                 public StreamWriter (string path, bool append, Encoding encoding, int bufferSize) {\r
 107                         if (null == encoding)\r
 108                                 throw new ArgumentNullException("encoding");\r
 109                         if (bufferSize <= 0)\r
 110                                 throw new ArgumentOutOfRangeException("bufferSize");\r
 111 \r
 112                         FileMode mode;\r
 113 \r
 114                         if (append)\r
 115                                 mode = FileMode.Append;\r
 116                         else\r
 117                                 mode = FileMode.Create;\r
 118                         \r
 119                         internalStream = new FileStream (path, mode, FileAccess.Write, FileShare.Read);\r
 120 \r
 121                         if (append)\r
 122                                 internalStream.Position = internalStream.Length;\r
 123                         else\r
 124                                 internalStream.SetLength (0);\r
 125 \r
 126                         Initialize(encoding, bufferSize);\r
 127                 }\r
 128 \r
 129                 public virtual bool AutoFlush {\r
 130                         get {\r
 131                                 return iflush;\r
 132                         }\r
 133                         set {\r
 134                                 iflush = value;\r
 135                                 if (iflush)\r
 136                                         Flush ();\r
 137                         }\r
 138                 }\r
 139 \r
 140                 public virtual Stream BaseStream {\r
 141                         get {\r
 142                                 return internalStream;\r
 143                         }\r
 144                 }\r
 145 \r
 146                 public override Encoding Encoding {\r
 147                         get {\r
 148                                 return internalEncoding;\r
 149                         }\r
 150                 }\r
 151 \r
 152                 protected override void Dispose (bool disposing) \r
 153                 {\r
 154                         Exception exc = null;\r
 155                         if (!DisposedAlready && disposing && internalStream != null) {\r
 156                                 try {\r
 157                                         Flush();\r
 158                                 } catch (Exception e) {\r
 159                                         exc = e;\r
 160                                 }\r
 161                                 DisposedAlready = true;\r
 162                                 try {\r
 163                                         internalStream.Close ();\r
 164                                 } catch (Exception e) {\r
 165                                         if (exc == null)\r
 166                                                 exc = e;\r
 167                                 }\r
 168                         }\r
 169 \r
 170                         internalStream = null;\r
 171                         byte_buf = null;\r
 172                         internalEncoding = null;\r
 173                         decode_buf = null;\r
 174                         if (exc != null)\r
 175                                 throw exc;\r
 176                 }\r
 177 \r
 178                 public override void Flush ()\r
 179                 {\r
 180                         if (DisposedAlready)\r
 181                                 throw new ObjectDisposedException("StreamWriter");\r
 182 \r
 183                         Decode ();\r
 184                         if (byte_pos > 0) {\r
 185                                 FlushBytes ();\r
 186                                 internalStream.Flush ();\r
 187                         }\r
 188                 }\r
 189 \r
 190                 // how the speedup works:\r
 191                 // the Write () methods simply copy the characters in a buffer of chars (decode_buf)\r
 192                 // Decode () is called when the buffer is full or we need to flash.\r
 193                 // Decode () will use the encoding to get the bytes and but them inside\r
 194                 // byte_buf. From byte_buf the data is finally outputted to the stream.\r
 195                 void FlushBytes () \r
 196                 {\r
 197                         // write the encoding preamble only at the start of the stream\r
 198                         if (!preamble_done && byte_pos > 0) {\r
 199                                 byte[] preamble = internalEncoding.GetPreamble ();\r
 200                                 if (preamble.Length > 0)\r
 201                                         internalStream.Write (preamble, 0, preamble.Length);\r
 202                                 preamble_done = true;\r
 203                         }\r
 204                         internalStream.Write (byte_buf, 0, byte_pos);\r
 205                         byte_pos = 0;\r
 206                 }\r
 207                 \r
 208                 void Decode () \r
 209                 {\r
 210                         if (byte_pos > 0)\r
 211                                 FlushBytes ();\r
 212                         if (decode_pos > 0) {\r
 213                                 int len = internalEncoding.GetBytes (decode_buf, 0, decode_pos, byte_buf, byte_pos);\r
 214                                 byte_pos += len;\r
 215                                 decode_pos = 0;\r
 216                         }\r
 217                 }\r
 218                 \r
 219                 public override void Write (char[] buffer, int index, int count) \r
 220                 {\r
 221                         if (DisposedAlready)\r
 222                                 throw new ObjectDisposedException("StreamWriter");\r
 223                         if (buffer == null)\r
 224                                 throw new ArgumentNullException ("buffer");\r
 225                         if (index < 0)\r
 226                                 throw new ArgumentOutOfRangeException ("index", "< 0");\r
 227                         if (count < 0)\r
 228                                 throw new ArgumentOutOfRangeException ("count", "< 0");\r
 229                         // re-ordered to avoid possible integer overflow\r
 230                         if (index > buffer.Length - count)\r
 231                                 throw new ArgumentException ("index + count > buffer.Length");\r
 232 \r
 233                         LowLevelWrite (buffer, index, count);\r
 234                         if (iflush)\r
 235                                 Flush();\r
 236                 }\r
 237                 \r
 238                 void LowLevelWrite (char[] buffer, int index, int count)\r
 239                 {\r
 240                         while (count > 0) {\r
 241                                 int todo = decode_buf.Length - decode_pos;\r
 242                                 if (todo == 0) {\r
 243                                         Decode ();\r
 244                                         todo = decode_buf.Length;\r
 245                                 }\r
 246                                 if (todo > count)\r
 247                                         todo = count;\r
 248                                 Buffer.BlockCopy (buffer, index * 2, decode_buf, decode_pos * 2, todo * 2);\r
 249                                 count -= todo;\r
 250                                 index += todo;\r
 251                                 decode_pos += todo;\r
 252                         }\r
 253                 }\r
 254                 \r
 255                 void LowLevelWrite (string s)\r
 256                 {\r
 257                         int count = s.Length;\r
 258                         int index = 0;\r
 259                         while (count > 0) {\r
 260                                 int todo = decode_buf.Length - decode_pos;\r
 261                                 if (todo == 0) {\r
 262                                         Decode ();\r
 263                                         todo = decode_buf.Length;\r
 264                                 }\r
 265                                 if (todo > count)\r
 266                                         todo = count;\r
 267                                 \r
 268                                 for (int i = 0; i < todo; i ++)\r
 269                                         decode_buf [i + decode_pos] = s [i + index];\r
 270                                 \r
 271                                 count -= todo;\r
 272                                 index += todo;\r
 273                                 decode_pos += todo;\r
 274                         }\r
 275                 }\r
 276 \r
 277                 public override void Write (char value)\r
 278                 {\r
 279                         if (DisposedAlready)\r
 280                                 throw new ObjectDisposedException("StreamWriter");\r
 281 \r
 282                         // the size of decode_buf is always > 0 and\r
 283                         // we check for overflow right away\r
 284                         if (decode_pos >= decode_buf.Length)\r
 285                                 Decode ();\r
 286                         decode_buf [decode_pos++] = value;\r
 287                         if (iflush)\r
 288                                 Flush ();\r
 289                 }\r
 290 \r
 291                 public override void Write (char[] buffer)\r
 292                 {\r
 293                         if (DisposedAlready)\r
 294                                 throw new ObjectDisposedException ("StreamWriter");\r
 295 \r
 296                         if (buffer != null)\r
 297                                 LowLevelWrite (buffer, 0, buffer.Length);\r
 298                         if (iflush)\r
 299                                 Flush ();\r
 300                 }\r
 301 \r
 302                 public override void Write (string value) \r
 303                 {\r
 304                         if (DisposedAlready)\r
 305                                 throw new ObjectDisposedException("StreamWriter");\r
 306 \r
 307                         if (value != null)\r
 308                                 LowLevelWrite (value);\r
 309                         \r
 310                         if (iflush)\r
 311                                 Flush ();\r
 312                 }\r
 313 \r
 314                 public override void Close()\r
 315                 {\r
 316                         Dispose (true);\r
 317                 }\r
 318 \r
 319                 ~StreamWriter ()\r
 320                 {\r
 321                         Dispose(false);\r
 322                 }\r
 323         }\r
 324 }\r