mcs/ilasm/scanner/StringHelper.cs

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