lexer.rl

%%{
  machine Lexer;

  main := |*

    '(' => {
      CAPTURE_TOKEN_TYPE(Open);
      fbreak;
    };

    ')' => {
      CAPTURE_TOKEN_TYPE(Close);
      fbreak;
    };

    ';' [^\n]* => {
      CAPTURE_TOKEN(Comment);
      fbreak;
    };

    "nil" => {
      CAPTURE_TOKEN_TYPE(Nil);
      fbreak;
    };

    '"' ([^"] | '\\"')* '"' => {
      CAPTURE_TOKEN_TYPE(String);
      size_t len = static_cast<size_t>(te - ts) - 2;
      if (Unescape(std::string_view{ts + 1, len}, &tok.value)) {
        tok.type = TokenType::Error;
        tok.value = "Invalid string escape sequence";
      }
      fbreak;
    };

    ['`,@#~.[\]] => {
      CAPTURE_TOKEN(Punct);
      fbreak;
    };

    ('+' | '-')? digit+ => {
      CAPTURE_TOKEN(Int);
      fbreak;
    };

    ('+' | '-')? digit+ '.' digit* => {
      CAPTURE_TOKEN(Float);
      fbreak;
    };

    (alpha | digit | '-' | [+~:?!/]) * => {
      CAPTURE_TOKEN(Sym);
      fbreak;
    };

    space+;
  *|;
}%%