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%{
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<ctype.h>
void three_address_code();
char add_to_table(char ,char, char);
int yyerror(char *);
int yylex();
int idx = 0;
char tvar = '1';
struct instruction {
char op1;
char op2;
char opr;
};
%}
%token IDENT NUM
%type expr
%left '+'
%left '*''/'
%left '-'
%%
statement: IDENT '=' expr ';' { add_to_table((char)$1, (char)$3, '='); }
| expr ';'
;
expr: expr '+' expr {$$ = add_to_table((char)$1, (char)$3, '+');}
| expr '-' expr {$$ = add_to_table((char)$1, (char)$3, '-');}
| expr '*' expr {$$ = add_to_table((char)$1, (char)$3, '*');}
| expr '/' expr {$$ = add_to_table((char)$1, (char)$3, '/');}
| '(' expr ')' {$$ = (char)$2;}
| NUM {$$ = (char)$1;}
| IDENT {$$ = (char)$1;}
| '-' expr {$$ = add_to_table((char)$2, (char)'\t', '-');}
;
%%
int yyerror(char *s) {
printf("ERROR: %s",s);
exit(0);
}
struct instruction ops[20];
char add_to_table(char op1, char op2, char opr) {
ops[idx].op1 = op1;
ops[idx].op2 = op2;
ops[idx].opr = opr;
idx++;
return tvar++;
}
void three_address_code() {
int count = 0;
char temp = '1';
while(count < idx) {
if(ops[count].opr != '=') {
printf("t%c=", temp++);
}
if(isalpha(ops[count].op1)) {
printf("%c",ops[count].op1);
} else if(ops[count].op1 >='1' && ops[count].op1 <='9') {
printf("t%c",ops[count].op1);
}
printf("%c",ops[count].opr);
if(isalpha(ops[count].op2)) {
printf(" %c\n",ops[count].op2);
} else if(ops[count].op2 >='1' && ops[count].op2 <='9') {
printf("t%c\n",ops[count].op2);
}
count++;
}
}
int main() {
yyparse();
three_address_code();
}
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