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

   1 //
   2 // System.IO.StringReader
   3 //
   4 // Author: Marcin Szczepanski (marcins@zipworld.com.au)
   5 //
   6 // Copyright (C) 2004 Novell (http://www.novell.com)
   7 //
   8
   9 //
  10 // Copyright (C) 2004 Novell, Inc (http://www.novell.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 using System;
  33 using System.Globalization;
  34 using System.Runtime.InteropServices;
  35
  36 namespace System.IO {
  37         [Serializable]
  38         public class StringReader : TextReader {
  39
  40                 string source;
  41                 int nextChar;
  42                 int sourceLength;
  43
  44                 public StringReader( string s ) {
  45
  46                         if (s == null)
  47                                 throw new ArgumentNullException ("s");
  48
  49                         this.source = s;
  50                         nextChar = 0;
  51                         sourceLength = s.Length;
  52                 }
  53
  54                 public override void Close ()
  55                 {
  56                         Dispose (true);
  57                 }
  58
  59                 protected override void Dispose (bool disposing)
  60                 {
  61                         source = null;
  62                         base.Dispose (disposing);
  63                 }
  64
  65                 public override int Peek() {
  66
  67                         CheckObjectDisposedException ();
  68
  69                         if( nextChar >= sourceLength ) {
  70                                 return -1;
  71                         } else {
  72                                 return (int)source[ nextChar ];
  73                         }
  74                 }
  75
  76                 public override int Read() {
  77
  78                         CheckObjectDisposedException ();
  79
  80                         if( nextChar >= sourceLength ) {
  81                                 return -1;
  82                         } else {
  83                                 return (int)source[ nextChar++ ];
  84                         }
  85                 }
  86
  87
  88                 // The method will read up to count characters from the StringReader
  89                 // into the buffer character array starting at position index. Returns
  90                 // the actual number of characters read, or zero if the end of the string
  91                 // has been reached and no characters are read.
  92
  93                 public override int Read ([In, Out] char[] buffer, int index, int count)
  94                 {
  95                         CheckObjectDisposedException ();
  96
  97                         if (buffer == null)
  98                                 throw new ArgumentNullException ("buffer");
  99                         if (buffer.Length - index < count)
 100                                 throw new ArgumentException ();
 101                         if (index < 0 || count < 0)
 102                                 throw new ArgumentOutOfRangeException ();
 103
 104                         int charsToRead;
 105
 106                         // reordered to avoir possible integer overflow
 107                         if (nextChar > sourceLength - count)
 108                                 charsToRead = sourceLength - nextChar;
 109                         else
 110                                 charsToRead = count;
 111
 112                         source.CopyTo (nextChar, buffer, index, charsToRead);
 113
 114                         nextChar += charsToRead;
 115
 116                         return charsToRead;
 117                 }
 118
 119                 public override string ReadLine ()
 120                 {
 121                         // Reads until next \r or \n or \r\n, otherwise return null
 122
 123                         // LAMESPEC:
 124                         // The Beta 2 SDK help says that the ReadLine method
 125                         // returns "The next line from the input stream [...] A
 126                         // line is defined as a sequence of characters followed by
 127                         // a carriage return (\r), a line feed (\n), or a carriage
 128                         // return immediately followed by a line feed (\r\n).
 129                         // [...] The returned value is a null reference if the end
 130                         // of the input stream has been reached."
 131                         //
 132                         // HOWEVER, the MS implementation returns the rest of
 133                         // the string if no \r and/or \n is found in the string
 134
 135                         CheckObjectDisposedException ();
 136
 137                         if (nextChar >= source.Length)
 138                                 return null;
 139
 140                         int nextCR = source.IndexOf ('\r', nextChar);
 141                         int nextLF = source.IndexOf ('\n', nextChar);
 142                         int readTo;
 143                         bool consecutive = false;
 144
 145                         if (nextCR == -1) {
 146                                 if (nextLF == -1)
 147                                         return ReadToEnd ();
 148
 149                                 readTo = nextLF;
 150                         } else if (nextLF == -1) {
 151                                 readTo = nextCR;
 152                         } else {
 153                                 readTo = (nextCR > nextLF) ? nextLF : nextCR;
 154                                 consecutive = (nextCR + 1 == nextLF || nextLF + 1 == nextCR);
 155                         }
 156
 157                         string nextLine = source.Substring (nextChar, readTo - nextChar);
 158                         nextChar = readTo + ((consecutive) ? 2 : 1);
 159                         return nextLine;
 160                 }
 161
 162                 public override string ReadToEnd() {
 163
 164                         CheckObjectDisposedException ();
 165                         string toEnd = source.Substring( nextChar, sourceLength - nextChar );
 166                         nextChar = sourceLength;
 167                         return toEnd;
 168                 }
 169
 170                 private void CheckObjectDisposedException ()
 171                 {
 172                         if (source == null)
 173                                 throw new ObjectDisposedException ("StringReader",
 174                                         Locale.GetText ("Cannot read from a closed StringReader"));
 175                 }
 176         }
 177 }