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