/usr/share/doc/flex/examples/manual/expr.y is in flex 2.6.4-6.
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 | /*
* expr.y : A simple yacc expression parser
* Based on the Bison manual example.
*/
%{
#include <stdio.h>
#include <math.h>
%}
%union {
float val;
}
%token NUMBER
%token PLUS MINUS MULT DIV EXPON
%token EOL
%token LB RB
%left MINUS PLUS
%left MULT DIV
%right EXPON
%type <val> exp NUMBER
%%
input :
| input line
;
line : EOL
| exp EOL { printf("%g\n",$1);}
exp : NUMBER { $$ = $1; }
| exp PLUS exp { $$ = $1 + $3; }
| exp MINUS exp { $$ = $1 - $3; }
| exp MULT exp { $$ = $1 * $3; }
| exp DIV exp { $$ = $1 / $3; }
| MINUS exp %prec MINUS { $$ = -$2; }
| exp EXPON exp { $$ = pow($1,$3);}
| LB exp RB { $$ = $2; }
;
%%
yyerror(char *message)
{
printf("%s\n",message);
}
int main(int argc, char *argv[])
{
yyparse();
return(0);
}
|