4.3BSD - /usr/src/usr.bin/m4/m4y.y

   1: /* @(#)m4y.y	1.1 (Berkeley) 12/15/82 */
   2: %{
   3: extern long evalval;
   4: #define YYSTYPE long
   5: %}
   6: 
   7: %term DIGITS
   8: %left '|'
   9: %left '&'
  10: %right '!'
  11: %nonassoc GT GE LT LE NE EQ
  12: %left '+' '-'
  13: %left '*' '/' '%'
  14: %right POWER
  15: %right UMINUS
  16: %%
  17: 
  18: s   : e ={ evalval = $1; }
  19:     |   ={ evalval = 0; }
  20:     ;
  21: 
  22: e   : e '|' e   ={ $$ = ($1!=0 || $3!=0) ? 1 : 0; }
  23:     | e '&' e   ={ $$ = ($1!=0 && $3!=0) ? 1 : 0; }
  24:     | '!' e     ={ $$ = $2 == 0; }
  25:     | e EQ e    ={ $$ = $1 == $3; }
  26:     | e NE e    ={ $$ = $1 != $3; }
  27:     | e GT e    ={ $$ = $1 > $3; }
  28:     | e GE e    ={ $$ = $1 >= $3; }
  29:     | e LT e    ={ $$ = $1 < $3; }
  30:     | e LE e    ={ $$ = $1 <= $3; }
  31:     | e '+' e   ={ $$ = ($1+$3); }
  32:     | e '-' e   ={ $$ = ($1-$3); }
  33:     | e '*' e   ={ $$ = ($1*$3); }
  34:     | e '/' e   ={ $$ = ($1/$3); }
  35:     | e '%' e   ={ $$ = ($1%$3); }
  36:     | '(' e ')' ={ $$ = ($2); }
  37:     | e POWER e ={ for ($$=1; $3-->0; $$ *= $1); }
  38:     | '-' e %prec UMINUS    ={ $$ = $2-1; $$ = -$2; }
  39:     | '+' e %prec UMINUS    ={ $$ = $2-1; $$ = $2; }
  40:     | DIGITS    ={ $$ = evalval; }
  41:     ;
  42: 
  43: %%
  44: 
  45: yylex() {
  46:     extern char *pe;
  47: 
  48:     while (*pe==' ' || *pe=='\t' || *pe=='\n')
  49:         pe++;
  50:     switch(*pe) {
  51:     case '\0':
  52:     case '+':
  53:     case '-':
  54:     case '/':
  55:     case '%':
  56:     case '(':
  57:     case ')':
  58:         return(*pe++);
  59:     case '^':
  60:         pe++;
  61:         return(POWER);
  62:     case '*':
  63:         return(peek('*', POWER, '*'));
  64:     case '>':
  65:         return(peek('=', GE, GT));
  66:     case '<':
  67:         return(peek('=', LE, LT));
  68:     case '=':
  69:         return(peek('=', EQ, EQ));
  70:     case '|':
  71:         return(peek('|', '|', '|'));
  72:     case '&':
  73:         return(peek('&', '&', '&'));
  74:     case '!':
  75:         return(peek('=', NE, '!'));
  76:     default:
  77:         evalval = 0;
  78:         while (*pe >= '0' && *pe <= '9')
  79:             evalval = evalval*10 + *pe++ - '0';
  80:         return(DIGITS);
  81:     }
  82: }
  83: 
  84: peek(c, r1, r2)
  85: {
  86:     if (*++pe != c)
  87:         return(r2);
  88:     ++pe;
  89:     return(r1);
  90: }
  91: 
  92: yyerror(s)
  93: char *s;
  94: {
  95: }

Defined functions

Defined macros