//LEX
%x MULTILINE_COMMENT

CHAR        [a-zA-Z]
IDEN        [_a-zA-Z][_a-zA-Z0-9]*
NUM         [0-9]+

%%

"/*" BEGIN(MULTILINE_COMMENT);

<MULTILINE_COMMENT> {
    "*/" BEGIN(INITIAL);
    .
}

"func"      return FUNC;
"int"       retrun INT;
"string"    return STRING;
"fmt.Println(" return PRINT;
"retrun"    return RETURN;
{IDEN}      return IDENTIFIER;
"\"{CHAR}+\""       yylval.str = yytext; return LITERAL;
{NUM}       yylval.num = atoi(yytext); return DEC;
.
%%

//BISON
%union {
    char* str;
    int num;
}

%token FUNC IDENTIFIER
%token INT STRING
%token PRINT RETURN
%token DEC LITERAL

%%
program: program expr '\n'
    |
    ;
expr: def_f
    ;

def_f: header_f body_f
    ;

header_f: FUNC IDENTIFIER '(' arg_f ')' ret_f
    ;

arg_f: IDENTIFIER type
    | IDENTIFIER ',' arg_f
    | arg_f ',' arg_f
    |
    ;

ret_f: type
    | '(' a ')'
    ;

a : type ',' type
    | type ',' a
    ;

type: STRING
    | INT
    ;

body_f: '{' exp '}'

exp: PRINT LITERAL ')'
    | PRINT IDENTIFIER ')'
    | RETURN b

b: calc
    | calc ',' b
    ;

calc: DEC
    | LITERAL
    | calc '+' calc
    | calc '-' calc
    | calc '%' calc
    | calc '*' calc
    | calc '/' calc

%%