mcs/ilasm/scanner/StringHelper.cs

   1 // StringHelper.cs\r
   2 // Author: Sergey Chaban (serge@wildwestsoftware.com)\r
   3 \r
   4 using System;\r
   5 using System.Text;\r
   6 \r
   7 namespace Mono.ILASM {\r
   8 \r
   9         /// <summary>\r
  10         /// </summary>\r
  11         internal class StringHelper : StringHelperBase {\r
  12 \r
  13                 private static readonly string startIdChars = "#$@_";\r
  14                 private static readonly string idChars = "_$@?`";\r
  15 \r
  16                 /// <summary>\r
  17                 /// </summary>\r
  18                 /// <param name="host"></param>\r
  19                 public StringHelper (ILTokenizer host) : base (host)\r
  20                 {\r
  21                 }\r
  22 \r
  23 \r
  24                 /// <summary>\r
  25                 /// </summary>\r
  26                 /// <returns></returns>\r
  27                 public override bool Start (char ch)\r
  28                 {\r
  29                         mode = Token.UNKNOWN;\r
  30 \r
  31                         if (Char.IsLetter (ch) || startIdChars.IndexOf (ch) != -1) {\r
  32                                 mode = Token.ID;\r
  33                         } else if (ch == '\'') {\r
  34                                 mode = Token.SQSTRING;\r
  35                         } else if (ch == '"') {\r
  36                                 mode = Token.QSTRING;\r
  37                         }\r
  38 \r
  39                         return (mode != Token.UNKNOWN);\r
  40                 }\r
  41 \r
  42 \r
  43                 private static bool IsIdChar (int c)\r
  44                 {\r
  45                         char ch = (char) c;\r
  46                         return (Char.IsLetterOrDigit(ch) || idChars.IndexOf (ch) != -1);\r
  47                 }\r
  48 \r
  49                 /// <summary>\r
  50                 /// </summary>\r
  51                 /// <returns></returns>\r
  52                 public override string Build ()\r
  53                 {\r
  54                         if (mode == Token.UNKNOWN) return String.Empty;\r
  55                         int ch = 0;\r
  56 \r
  57                         ILReader reader = host.Reader;\r
  58 \r
  59                         StringBuilder idsb = new StringBuilder ();\r
  60                         if (mode == Token.SQSTRING || mode == Token.QSTRING) {\r
  61                                 int term = (mode == Token.SQSTRING) ? '\'' : '"';\r
  62                                 reader.Read (); // skip quote\r
  63                                 for (ch = reader.Read (); ch != -1; ch = reader.Read ()) {\r
  64                                         if (ch == term) {\r
  65                                                 break;\r
  66                                         }\r
  67 \r
  68                                         if (ch == '\\') {\r
  69                                                 ch = reader.Read ();\r
  70 \r
  71                                                 /*\r
  72                                                  * Long string can be broken across multiple lines\r
  73                                                  * by using '\' as the last char in line.\r
  74                                                  * Any white space chars between '\' and the first\r
  75                                                  * char on the next line are ignored.\r
  76                                                  */\r
  77                                                 if (ch == '\n') {\r
  78                                                         reader.SkipWhitespace ();\r
  79                                                         continue;\r
  80                                                 }\r
  81 \r
  82                                                 int escaped = Escape (reader, ch);\r
  83                                                 if (escaped == -1) {\r
  84                                                         reader.Unread (ch);\r
  85                                                         ch = '\\';\r
  86                                                 } else {\r
  87                                                         ch = escaped;\r
  88                                                 }\r
  89                                         }\r
  90 \r
  91                                         idsb.Append((char)ch);\r
  92                                 }\r
  93                         } else { // ID\r
  94                                 while ((ch = reader.Read ()) != -1) {\r
  95                                         if (IsIdChar (ch)) {\r
  96                                                 idsb.Append ((char) ch);\r
  97                                         } else {\r
  98                                                 reader.Unread (ch);\r
  99                                                 break;\r
 100                                         }\r
 101                                 }\r
 102                         }\r
 103                         return idsb.ToString ();\r
 104                 }\r
 105 \r
 106 \r
 107 \r
 108 \r
 109                 /// <summary>\r
 110                 /// </summary>\r
 111                 /// <param name="ch"></param>\r
 112                 /// <returns></returns>\r
 113                 public static int Escape (ILReader reader, int ch)\r
 114                 {\r
 115                         int res = -1;\r
 116 \r
 117                         if (ch >= '0' && ch <='7') {\r
 118                                 StringBuilder octal = new StringBuilder ();\r
 119                                 octal.Append ((char)ch);\r
 120                                 int possibleOctalChar = reader.Peek ();\r
 121                                 if (possibleOctalChar >= '0' && possibleOctalChar <='7') {\r
 122                                         octal.Append ((char)reader.Read ());\r
 123                                         possibleOctalChar = reader.Peek ();\r
 124                                         if (possibleOctalChar >= '0' && possibleOctalChar <='7')\r
 125                                                 octal.Append ((char)reader.Read ());\r
 126                                 }\r
 127                                 res = Convert.ToInt32(octal.ToString (), 8);\r
 128                         } else {\r
 129                                 int id = "abfnrtv\"'\\".IndexOf ((char)ch);\r
 130                                 if (id != -1) {\r
 131                                         res = "\a\b\f\n\r\t\v\"'\\" [id];\r
 132                                 }\r
 133                         }\r
 134 \r
 135                         return res;\r
 136                 }\r
 137 \r
 138         }\r
 139 \r
 140 \r
 141 }\r
 142 \r