external/bsd/byacc/dist/test/quote_calc2.y

   1 /*      $NetBSD: quote_calc2.y,v 1.1.1.1 2013/04/06 14:45:28 christos Exp $     */
   2
   3 %{
   4 # include <stdio.h>
   5 # include <ctype.h>
   6
   7 int regs[26];
   8 int base;
   9
  10 int yylex(void);
  11 static void yyerror(const char *s);
  12
  13 %}
  14
  15 %start list
  16
  17 %token OP_ADD "ADD"
  18 %token OP_SUB "SUB"
  19 %token OP_MUL "MUL"
  20 %token OP_DIV "DIV"
  21 %token OP_MOD "MOD"
  22 %token OP_AND "AND"
  23
  24 %token DIGIT LETTER
  25
  26 %left '|'
  27 %left '&'
  28 %left '+' '-'
  29 %left '*' '/' '%'
  30 %left UMINUS   /* supplies precedence for unary minus */
  31
  32 %% /* beginning of rules section */
  33
  34 list  :  /* empty */
  35       |  list stat '\n'
  36       |  list error '\n'
  37             {  yyerrok ; }
  38       ;
  39
  40 stat  :  expr
  41             {  printf("%d\n",$1);}
  42       |  LETTER '=' expr
  43             {  regs[$1] = $3; }
  44       ;
  45
  46 expr  :  '(' expr ')'
  47             {  $$ = $2; }
  48       |  expr "ADD" expr
  49             {  $$ = $1 + $3; }
  50       |  expr "SUB" expr
  51             {  $$ = $1 - $3; }
  52       |  expr "MUL" expr
  53             {  $$ = $1 * $3; }
  54       |  expr "DIV" expr
  55             {  $$ = $1 / $3; }
  56       |  expr "MOD" expr
  57             {  $$ = $1 % $3; }
  58       |  expr "AND" expr
  59             {  $$ = $1 & $3; }
  60       |  expr '|' expr
  61             {  $$ = $1 | $3; }
  62       |  "SUB" expr %prec UMINUS
  63             {  $$ = - $2; }
  64       |  LETTER
  65             {  $$ = regs[$1]; }
  66       |  number
  67       ;
  68
  69 number:  DIGIT
  70          {  $$ = $1; base = ($1==0) ? 8 : 10; }
  71       |  number DIGIT
  72          {  $$ = base * $1 + $2; }
  73       ;
  74
  75 %% /* start of programs */
  76
  77 int
  78 main (void)
  79 {
  80     while(!feof(stdin)) {
  81         yyparse();
  82     }
  83     return 0;
  84 }
  85
  86 static void
  87 yyerror(const char *s)
  88 {
  89     fprintf(stderr, "%s\n", s);
  90 }
  91
  92 int
  93 yylex(void) {
  94         /* lexical analysis routine */
  95         /* returns LETTER for a lower case letter, yylval = 0 through 25 */
  96         /* return DIGIT for a digit, yylval = 0 through 9 */
  97         /* all other characters are returned immediately */
  98
  99     int c;
 100
 101     while( (c=getchar()) == ' ' )   { /* skip blanks */ }
 102
 103     /* c is now nonblank */
 104
 105     if( islower( c )) {
 106         yylval = c - 'a';
 107         return ( LETTER );
 108     }
 109     if( isdigit( c )) {
 110         yylval = c - '0';
 111         return ( DIGIT );
 112     }
 113     return( c );
 114 }