freebsd-dev/contrib/byacc/test/quote_calc4.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

113 lines
2.1 KiB
Plaintext

%{
# include <stdio.h>
# include <ctype.h>
int regs[26];
int base;
int yylex(void);
static void yyerror(const char *s);
%}
%start list
%token OP_ADD "ADD-operator"
%token OP_SUB "SUB-operator"
%token OP_MUL "MUL-operator"
%token OP_DIV "DIV-operator"
%token OP_MOD "MOD-operator"
%token OP_AND "AND-operator"
%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 ')'
{ $$ = $2; }
| expr "ADD-operator" expr
{ $$ = $1 + $3; }
| expr "SUB-operator" expr
{ $$ = $1 - $3; }
| expr "MUL-operator" expr
{ $$ = $1 * $3; }
| expr "DIV-operator" expr
{ $$ = $1 / $3; }
| expr "MOD-operator" expr
{ $$ = $1 % $3; }
| expr "AND-operator" expr
{ $$ = $1 & $3; }
| expr '|' expr
{ $$ = $1 | $3; }
| "SUB-operator" expr %prec UMINUS
{ $$ = - $2; }
| LETTER
{ $$ = regs[$1]; }
| number
;
number: DIGIT
{ $$ = $1; base = ($1==0) ? 8 : 10; }
| number DIGIT
{ $$ = base * $1 + $2; }
;
%% /* start of programs */
int
main (void)
{
while(!feof(stdin)) {
yyparse();
}
return 0;
}
static void
yyerror(const char *s)
{
fprintf(stderr, "%s\n", s);
}
int
yylex(void) {
/* 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 );
}