lexer/string.cpp

   1 #include <fridh/lexer.hpp>
   2 #include <ail/string.hpp>
   3
   4 namespace fridh
   5 {
   6         void lexer::parse_string(line_of_code & output)
   7         {
   8                 std::string string;
   9                 char string_character = input[i];
  10                 i++;
  11                 std::size_t start = i;
  12                 for(; i < end; i++)
  13                 {
  14                         char byte = input[i];
  15                         switch(byte)
  16                         {
  17                                 case '\\':
  18                                 {
  19                                         if(end - i < 2)
  20                                                 lexer_error("Backslash at the end of the input");
  21
  22                                         i++;
  23
  24                                         char next_byte = input[i];
  25
  26                                         switch(next_byte)
  27                                         {
  28                                                 case 'r':
  29                                                         string.push_back('\r');
  30                                                         continue;
  31
  32                                                 case 'n':
  33                                                         string.push_back('\n');
  34                                                         continue;
  35                                         }
  36
  37                                         if(ail::is_hex_digit(next_byte))
  38                                         {
  39                                                 if(end - i < 2)
  40                                                         lexer_error("Incomplete hex number escape sequence at the end of the input");
  41
  42                                                 if(!ail::is_hex_digit(input[i + 1]))
  43                                                         lexer_error("Invalid hex number escape sequence");
  44
  45                                                 std::string hex_string = input.substr(i, 2);
  46                                                 i++;
  47                                                 char new_byte = ail::string_to_number<char>(hex_string, std::ios_base::hex);
  48                                                 string.push_back(new_byte);
  49                                         }
  50                                         else
  51                                                 lexer_error("Invalid escape sequence: " + ail::hex_string_8(static_cast<uchar>(next_byte)));
  52                                         break;
  53                                 }
  54
  55                                 case '\n':
  56                                         lexer_error("Detected a newline in a string");
  57                                         break;
  58
  59                                 case '\'':
  60                                 case '"':
  61                                         if(byte == string_character)
  62                                         {
  63                                                 output.lexemes.push_back(lexeme(string));
  64                                                 i++;
  65                                                 return;
  66                                         }
  67                                         string.push_back(byte);
  68                                         break;
  69
  70                                 default:
  71                                         string.push_back(byte);
  72                                         break;
  73                         }
  74                 }
  75                 lexer_error("String lacks terminator");
  76         }
  77 }