stela/lexer.l

%{
    #include <iostream>
    #include <cstdlib>
    #include "lexer.hpp"
    #include "interpreter.hpp"
    #include "parser.hpp"
    #include "location.hh"
    
    // Original yyterminate() macro returns int. Since we're using Bison 3 variants
    // as tokens, we must redefine it to change type from `int` to `Parser::semantic_type`
    #define yyterminate() stela::Parser::make_END(stela::location());

    // This will track current scanner location.
    // Action is called when length of the token is known.
    #define YY_USER_ACTION this->interpreter.increase_location(yyleng);

    // !!!WARNING!!!
    // Location API is used, but the location is not initialized, 'cause I'm lazy. When making
    // a token with make_{something} method you can pass detailed token location. Current location
    // is accessible with m_driver.location() method. All puzzle elements are there - just
    // pass location value in every action code block below. I'm going to waste more time writing
    // this excuse than putting this boilerplate below...
    //
    // Location class can be found in location.hh and posistion.hh files. It's just a bit too much
    // boilerplate for this small example. Bummer.
%}

%option nodefault noyywrap noyylineno c++ yyclass="Lexer" prefix="stela_"

%%

[a-z]+ {
    std::cout << "Scanner: identifier [" << yytext << "]\n";
    return stela::Parser::make_STRING(yytext, stela::location()); 
}

\( {
    std::cout << "Scanner: '('\n";
    return stela::Parser::make_LEFTPAR(stela::location());
}

\) {
    std::cout << "Scanner: ')'\n";
    return stela::Parser::make_RIGHTPAR(stela::location());
}

; {
    std::cout << "Scanner: ';'\n";
    return stela::Parser::make_SEMICOLON(stela::location());
}

, {
    std::cout << "Scanner: ','\n";
    return stela::Parser::make_COMMA(stela::location());
}

[\n\t ] {
    //cout << "Scanner: whitechar (ignored)" << endl;
}

[1-9][0-9]* {
    std::cout << "Scanner: decimal number: " << yytext << '\n';
    uint64_t number = strtoull(yytext, 0, 10);
    return stela::Parser::make_NUMBER(number, stela::location());
}

. {
    std::cout << "Scanner: unknown character [" << yytext << "]\n";
}

<<EOF>> { return yyterminate(); }


%%