external/bsd/byacc/dist/test/pure_calc.y

   1 /*      $NetBSD: pure_calc.y,v 1.1.1.4 2013/04/06 14:45:27 christos Exp $       */
   2
   3 %{
   4 # include <stdio.h>
   5 # include <ctype.h>
   6
   7 int regs[26];
   8 int base;
   9
  10 #ifdef YYBISON
  11 #define YYSTYPE int
  12 #define YYLEX_PARAM &yylval
  13 #define YYLEX_DECL() yylex(YYSTYPE *yylval)
  14 #define YYERROR_DECL() yyerror(const char *s)
  15 int YYLEX_DECL();
  16 static void YYERROR_DECL();
  17 #endif
  18
  19 %}
  20
  21 %start list
  22
  23 %token DIGIT LETTER
  24
  25 %left '|'
  26 %left '&'
  27 %left '+' '-'
  28 %left '*' '/' '%'
  29 %left UMINUS   /* supplies precedence for unary minus */
  30
  31 %% /* beginning of rules section */
  32
  33 list  :  /* empty */
  34       |  list stat '\n'
  35       |  list error '\n'
  36             {  yyerrok ; }
  37       ;
  38
  39 stat  :  expr
  40             {  printf("%d\n",$1);}
  41       |  LETTER '=' expr
  42             {  regs[$1] = $3; }
  43       ;
  44
  45 expr  :  '(' expr ')'
  46             {  $$ = $2; }
  47       |  expr '+' expr
  48             {  $$ = $1 + $3; }
  49       |  expr '-' expr
  50             {  $$ = $1 - $3; }
  51       |  expr '*' expr
  52             {  $$ = $1 * $3; }
  53       |  expr '/' expr
  54             {  $$ = $1 / $3; }
  55       |  expr '%' expr
  56             {  $$ = $1 % $3; }
  57       |  expr '&' expr
  58             {  $$ = $1 & $3; }
  59       |  expr '|' expr
  60             {  $$ = $1 | $3; }
  61       |  '-' expr %prec UMINUS
  62             {  $$ = - $2; }
  63       |  LETTER
  64             {  $$ = regs[$1]; }
  65       |  number
  66       ;
  67
  68 number:  DIGIT
  69          {  $$ = $1; base = ($1==0) ? 8 : 10; }
  70       |  number DIGIT
  71          {  $$ = base * $1 + $2; }
  72       ;
  73
  74 %% /* start of programs */
  75
  76 #ifdef YYBYACC
  77 static int YYLEX_DECL();
  78 #endif
  79
  80 int
  81 main (void)
  82 {
  83     while(!feof(stdin)) {
  84         yyparse();
  85     }
  86     return 0;
  87 }
  88
  89 static void
  90 YYERROR_DECL()
  91 {
  92     fprintf(stderr, "%s\n", s);
  93 }
  94
  95 int
  96 YYLEX_DECL()
  97 {
  98         /* lexical analysis routine */
  99         /* returns LETTER for a lower case letter, yylval = 0 through 25 */
 100         /* return DIGIT for a digit, yylval = 0 through 9 */
 101         /* all other characters are returned immediately */
 102
 103     int c;
 104
 105     while( (c=getchar()) == ' ' )   { /* skip blanks */ }
 106
 107     /* c is now nonblank */
 108
 109     if( islower( c )) {
 110         *yylval = c - 'a';
 111         return ( LETTER );
 112     }
 113     if( isdigit( c )) {
 114         *yylval = c - '0';
 115         return ( DIGIT );
 116     }
 117     return( c );
 118 }