%{
    #include <stdio.h>
    extern void yyerror(const char *);
    extern int yylex(void);

%}

%token BEGAN CANDY ROUND SEMICOLON TRICK TREAT COLON WORD WENT HOME
%define parse.error verbose
%start candy_round

%%

candy_round : BEGAN CANDY ROUND SEMICOLON trick_or_treat_list WENT HOME SEMICOLON
    ;

trick_or_treat_list: trick_or_treat trick_or_treat_list
          | /* empty */
          ;

trick_or_treat : TRICK COLON word_list SEMICOLON
	| TREAT COLON word_list SEMICOLON
        ;

word_list : WORD
         | WORD word_list
         ;

%%

int main() {
    printf("Enter a complete candy round. Finsih with EOF.\n");
    yyparse();
    printf("Done!\n");
    return 0;
}

void yyerror(const char *s) {
    printf("Invalid candy round! Error message: %s\n", s);
}

int yywrap(void) {
    return 1;
}