Well, this is not C. And it is not an interpeter. So, yeah, pretty much totally inappropriate for this question.
But what it is, is, a perfectly portable brainfuck compiler using C++0x variadic templates. You have to #define PROGRAM as a comma-separated sequence of C-syntax characters, because I could not extract them from the string at compile-time. But otherwise it is legit. I think.
Tested with g++ 4.5.2, using g++ -std=c++0x -O2 -Wall.
#include <cstdio>
#include <vector>
#define PROGRAM '+', '+', '+', '+', '+', '+', '+', '+', '[', '-', '>', \
'-', '[', '-', '>', '-', '[', '-', '>', '-', '[', '-', ']', '<', \
']', '<', ']', '<', ']', '>', '+', '+', '+', '+', '+', '+', '+', \
'+', '[', '<', '+', '+', '+', '+', '+', '+', '+', '+', '+', '+', \
'>', '-', ']', '<', '[', '>', '+', '>', '+', '<', '<', '-', ']', \
'>', '-', '.', '>', '-', '-', '-', '-', '-', '.', '>'
template<char... all>
struct C;
template<char... rest>
struct C<'>', rest...> {
typedef C<rest...> rest_t;
typedef typename rest_t::remainder remainder;
static char *body(char *p) {
return rest_t::body(p+1);
}
};
template<char... rest>
struct C<'<', rest...> {
typedef C<rest...> rest_t;
typedef typename rest_t::remainder remainder;
static char *body(char *p) {
return rest_t::body(p-1);
}
};
template<char... rest>
struct C<'+', rest...> {
typedef C<rest...> rest_t;
typedef typename rest_t::remainder remainder;
static char *body(char *p) {
++*p;
return rest_t::body(p);
}
};
template<char... rest>
struct C<'-', rest...> {
typedef C<rest...> rest_t;
typedef typename rest_t::remainder remainder;
static char *body(char *p) {
--*p;
return rest_t::body(p);
}
};
template<char... rest>
struct C<'.', rest...> {
typedef C<rest...> rest_t;
typedef typename rest_t::remainder remainder;
static char *body(char *p) {
putchar(*p);
return rest_t::body(p);
}
};
template<char... rest>
struct C<',', rest...> {
typedef C<rest...> rest_t;
typedef typename rest_t::remainder remainder;
static char *body(char *p) {
*p = getchar();
return rest_t::body(p);
}
};
template<char... rest>
struct C<'[', rest...> {
typedef C<rest...> rest_t;
typedef typename rest_t::remainder::remainder remainder;
static char *body(char *p) {
while (*p) {
p = rest_t::body(p);
}
return rest_t::remainder::body(p);
}
};
template<char... rest>
struct C<']', rest...> {
typedef C<rest...> rest_t;
struct remainder_hack {
typedef typename rest_t::remainder remainder;
static char *body(char *p) {
return rest_t::body(p);
}
};
typedef remainder_hack remainder;
static char *body(char *p) {
return p;
}
};
template<>
struct C<> {
static char *body(char *p) {
return p;
}
struct remainder {
static char *body(char *p) {
return p;
}
};
};
int
main(int argc, char *argv[])
{
std::vector<char> v(30000, 0);
C<PROGRAM> thing;
thing.body(&v[0]);
return 0;
}