/usr/share/doc/bison-doc/examples/rpcalc/rpcalc.y is in bison-doc 1:3.0.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 | /* Reverse polish notation calculator. */
%{
#include <stdio.h>
#include <math.h>
int yylex (void);
void yyerror (char const *);
%}
%define api.value.type {double}
%token NUM
%% /* Grammar rules and actions follow. */
input:
%empty
| input line
;
line:
'\n'
| exp '\n' { printf ("%.10g\n", $1); }
;
exp:
NUM { $$ = $1; }
| exp exp '+' { $$ = $1 + $2; }
| exp exp '-' { $$ = $1 - $2; }
| exp exp '*' { $$ = $1 * $2; }
| exp exp '/' { $$ = $1 / $2; }
| exp exp '^' { $$ = pow ($1, $2); } /* Exponentiation */
| exp 'n' { $$ = -$1; } /* Unary minus */
;
%%
/* The lexical analyzer returns a double floating point
number on the stack and the token NUM, or the numeric code
of the character read if not a number. It skips all blanks
and tabs, and returns 0 for end-of-input. */
#include <ctype.h>
int
yylex (void)
{
int c;
/* Skip white space. */
while ((c = getchar ()) == ' ' || c == '\t')
continue;
/* Process numbers. */
if (c == '.' || isdigit (c))
{
ungetc (c, stdin);
scanf ("%lf", &yylval);
return NUM;
}
/* Return end-of-input. */
if (c == EOF)
return 0;
/* Return a single char. */
return c;
}
int
main (void)
{
return yyparse ();
}
#include <stdio.h>
/* Called by yyparse on error. */
void
yyerror (char const *s)
{
fprintf (stderr, "%s\n", s);
}
|