lexer/comment.cpp

   1 #include <fridh/lexer.hpp>
   2
   3 namespace fridh
   4 {
   5                 bool lexer::parse_comment(std::string & error_message)
   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                         {
  41                                 error_message = lexer_error("Unable to find the end of a multi-line comment", start_of_comment);
  42                                 return false;
  43                         }
  44                 }
  45                 else if(string_match(nested_comment_start))
  46                 {
  47                         uword comment_depth = 1;
  48                         for(i += nested_comment_start.size(); comment_depth > 0 && i < end;)
  49                         {
  50                                 char byte = input[i];
  51                                 if(byte == '\n')
  52                                 {
  53                                         process_newline();
  54                                         continue;
  55                                 }
  56                                 else if(string_match(nested_comment_start))
  57                                 {
  58                                         comment_depth++;
  59                                         i += nested_comment_start.size();
  60                                         continue;
  61                                 }
  62                                 else if(string_match(nested_comment_end))
  63                                 {
  64                                         comment_depth--;
  65                                         i += nested_comment_end.size();
  66                                         continue;
  67                                 }
  68                                 i++;
  69                         }
  70
  71                         if(comment_depth != 0)
  72                         {
  73                                 error_message = lexer_error("Unable to find the end of a nested comment", start_of_comment);
  74                                 return false;
  75                         }
  76                 }
  77                 else
  78                 {
  79                         std::size_t offset = input.find('\n', i);
  80                         if(offset == std::string::npos)
  81                         {
  82                                 error_message = lexer_error("Unable to find the end of a multi-line comment", start_of_comment);
  83                                 return false;
  84                         }
  85                         i = offset;
  86                         process_newline();
  87                 }
  88                 return true;
  89         }
  90 }