lexer/comment.cpp

   1 #include <fridh/lexer.hpp>
   2
   3 namespace fridh
   4 {
   5         void lexer::parse_comment()
   6         {
   7                 std::string const
   8                         multi_line_comment = ";;",
   9                         nested_comment_start = ";.",
  10                         nested_comment_end = ".;",
  11
  12                         multiline_comment_prefix = "In multi-line comment: ",
  13                         nested_comment_prefix = "In nested comment: ";
  14
  15                 uword start_of_comment = line;
  16
  17                 if(string_match(multi_line_comment))
  18                 {
  19                         bool got_end = false;
  20                         for(i += multi_line_comment.size(); !got_end && i < end;)
  21                         {
  22                                 char byte = input[i];
  23                                 switch(byte)
  24                                 {
  25                                         case '\n':
  26                                                 process_newline();
  27                                                 continue;
  28
  29                                         case ';':
  30                                                 if(string_match(multi_line_comment))
  31                                                 {
  32                                                         got_end = true;
  33                                                         i++;
  34                                                 }
  35                                                 break;
  36                                 }
  37                                 i++;
  38                         }
  39                         if(!got_end)
  40                                 lexer_error("Unable to find the end of a multi-line comment", start_of_comment);
  41                 }
  42                 else if(string_match(nested_comment_start))
  43                 {
  44                         uword comment_depth = 1;
  45                         for(i += nested_comment_start.size(); comment_depth > 0 && i < end;)
  46                         {
  47                                 char byte = input[i];
  48                                 if(byte == '\n')
  49                                 {
  50                                         process_newline();
  51                                         continue;
  52                                 }
  53                                 else if(string_match(nested_comment_start))
  54                                 {
  55                                         comment_depth++;
  56                                         i += nested_comment_start.size();
  57                                         continue;
  58                                 }
  59                                 else if(string_match(nested_comment_end))
  60                                 {
  61                                         comment_depth--;
  62                                         i += nested_comment_end.size();
  63                                         continue;
  64                                 }
  65                                 i++;
  66                         }
  67
  68                         if(comment_depth != 0)
  69                                 lexer_error("Unable to find the end of a nested comment", start_of_comment);
  70                 }
  71                 else
  72                 {
  73                         std::size_t offset = input.find('\n', i);
  74                         if(offset == std::string::npos)
  75                                 lexer_error("Unable to find the end of a multi-line comment", start_of_comment);
  76                         i = offset;
  77                         process_newline();
  78                 }
  79         }
  80 }