BSD 4_1c_2 release

[unix-history] / usr / src / usr.bin / m4 / m4y.y

/* @(#)m4y.y    1.1 (Berkeley) 12/15/82 */
%{
extern long     evalval;
#define YYSTYPE long
%}

%term DIGITS
%left '|'
%left '&'
%right '!'
%nonassoc GT GE LT LE NE EQ
%left '+' '-'
%left '*' '/' '%'
%right POWER
%right UMINUS
%%

s       : e     ={ evalval = $1; }
       |       ={ evalval = 0; }
       ;

e       : e '|' e       ={ $$ = ($1!=0 || $3!=0) ? 1 : 0; }
       | e '&' e       ={ $$ = ($1!=0 && $3!=0) ? 1 : 0; }
       | '!' e         ={ $$ = $2 == 0; }
       | e EQ e        ={ $$ = $1 == $3; }
       | e NE e        ={ $$ = $1 != $3; }
       | e GT e        ={ $$ = $1 > $3; }
       | e GE e        ={ $$ = $1 >= $3; }
       | e LT e        ={ $$ = $1 < $3; }
       | e LE e        ={ $$ = $1 <= $3; }
       | e '+' e       ={ $$ = ($1+$3); }
       | e '-' e       ={ $$ = ($1-$3); }
       | e '*' e       ={ $$ = ($1*$3); }
       | e '/' e       ={ $$ = ($1/$3); }
       | e '%' e       ={ $$ = ($1%$3); }
       | '(' e ')'     ={ $$ = ($2); }
       | e POWER e     ={ for ($$=1; $3-->0; $$ *= $1); }      
       | '-' e %prec UMINUS    ={ $$ = $2-1; $$ = -$2; }
       | '+' e %prec UMINUS    ={ $$ = $2-1; $$ = $2; }
       | DIGITS        ={ $$ = evalval; }
       ;

%%

yylex() {
       extern char *pe;

       while (*pe==' ' || *pe=='\t' || *pe=='\n')
               pe++;
       switch(*pe) {
       case '\0':
       case '+':
       case '-':
       case '/':
       case '%':
       case '(':
       case ')':
               return(*pe++);
       case '^':
               pe++;
               return(POWER);
       case '*':
               return(peek('*', POWER, '*'));
       case '>':
               return(peek('=', GE, GT));
       case '<':
               return(peek('=', LE, LT));
       case '=':
               return(peek('=', EQ, EQ));
       case '|':
               return(peek('|', '|', '|'));
       case '&':
               return(peek('&', '&', '&'));
       case '!':
               return(peek('=', NE, '!'));
       default:
               evalval = 0;
               while (*pe >= '0' && *pe <= '9')
                       evalval = evalval*10 + *pe++ - '0';
               return(DIGITS);
       }
}

peek(c, r1, r2)
{
       if (*++pe != c)
               return(r2);
       ++pe;
       return(r1);
}

yyerror(s)
char *s;
{
}