freebsd-dev/contrib/byacc/test/pure_calc.y
Baptiste Daroussin 98e903e7a0 Import byacc from invisible island, it brings us lots of compatibilities with
bison, keeping full compatibility with our previous yacc implementation.

Also bring the ability to create reentrant parser

This fix bin/140309 [1]

PR:		bin/140309 [1]
Submitted by:	Philippe Pepiot <ksh@philpep.org> [1]
Approved by:	des (mentor)
MFC after:	1 month
2012-05-21 13:31:26 +00:00

117 lines
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%{
# include <stdio.h>
# include <ctype.h>
int regs[26];
int base;
#ifdef YYBISON
#define YYSTYPE int
#define YYLEX_PARAM &yylval
#define YYLEX_DECL() yylex(YYSTYPE *yylval)
#define YYERROR_DECL() yyerror(const char *s)
int YYLEX_DECL();
static void YYERROR_DECL();
#endif
%}
%start list
%token DIGIT LETTER
%left '|'
%left '&'
%left '+' '-'
%left '*' '/' '%'
%left UMINUS /* supplies precedence for unary minus */
%% /* beginning of rules section */
list : /* empty */
| list stat '\n'
| list error '\n'
{ yyerrok ; }
;
stat : expr
{ printf("%d\n",$1);}
| LETTER '=' expr
{ regs[$1] = $3; }
;
expr : '(' expr ')'
{ $$ = $2; }
| expr '+' expr
{ $$ = $1 + $3; }
| expr '-' expr
{ $$ = $1 - $3; }
| expr '*' expr
{ $$ = $1 * $3; }
| expr '/' expr
{ $$ = $1 / $3; }
| expr '%' expr
{ $$ = $1 % $3; }
| expr '&' expr
{ $$ = $1 & $3; }
| expr '|' expr
{ $$ = $1 | $3; }
| '-' expr %prec UMINUS
{ $$ = - $2; }
| LETTER
{ $$ = regs[$1]; }
| number
;
number: DIGIT
{ $$ = $1; base = ($1==0) ? 8 : 10; }
| number DIGIT
{ $$ = base * $1 + $2; }
;
%% /* start of programs */
#ifdef YYBYACC
static int YYLEX_DECL();
#endif
int
main (void)
{
while(!feof(stdin)) {
yyparse();
}
return 0;
}
static void
YYERROR_DECL()
{
fprintf(stderr, "%s\n", s);
}
int
YYLEX_DECL()
{
/* lexical analysis routine */
/* returns LETTER for a lower case letter, yylval = 0 through 25 */
/* return DIGIT for a digit, yylval = 0 through 9 */
/* all other characters are returned immediately */
int c;
while( (c=getchar()) == ' ' ) { /* skip blanks */ }
/* c is now nonblank */
if( islower( c )) {
*yylval = c - 'a';
return ( LETTER );
}
if( isdigit( c )) {
*yylval = c - '0';
return ( DIGIT );
}
return( c );
}