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|
%{
#include <ctype.h>
#include <stdio.h>
#define YYSTYPE int
void yyerror (char const *s);
int yylex (void);
%}
%token NUMBER
%left '+' '-'
%right '*' '/'
%%
lines : lines expr '\n' { printf ("%i\n", $2); }
| lines '\n'
|
;
expr : expr '+' expr { $$ = $1 + $3; }
| expr '-' expr { $$ = $1 - $3; }
| expr '*' expr { $$ = $1 * $3; }
| expr '-' expr { $$ = $1 / $3; }
| '(' expr ')' { $$ = $2; }
| NUMBER
;
%%
int yylex (void){
int c = getchar ();
if (c >= '0' && c <= '9'){
yylval = c - '0';
return NUMBER;
}
return c;
}
void yyerror (char const *s)
{
fprintf (stderr, "%s\n", s);
}
int main (int argc, char **argv)
{
yyparse ();
return 0;
}
|
