Viewing file:  variadic-mem_fn.C (1 KB) -rw-r--r--
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// { dg-do run { target c++11 } }
// A basic implementation of TR1's mem_fn using variadic teplates
// Contributed by Douglas Gregor <doug.gregor@gmail.com>
#include <cassert>
template<typename R, typename Class, typename... Args>
class Mem_fn
{
public:
explicit Mem_fn(R (Class::*pmf)(Args...)) : pmf(pmf) { }
R operator()(Class& object, Args... args)
{
return (object.*pmf)(args...);
}
R operator()(Class* object, Args... args)
{
return (object->*pmf)(args...);
}
R (Class::*pmf)(Args...);
};
template<typename R, typename Class, typename... Args>
inline Mem_fn<R, Class, Args...>
mem_fn(R (Class::* pmf)(Args...))
{
return Mem_fn<R, Class, Args...>(pmf);
}
class X {
public:
int negate(int x) { return -x; }
int plus(int x, int y) { return x + y; }
};
int main()
{
X x;
X* xp = &x;
assert(mem_fn(&X::negate)(x, 17) == -17);
assert(mem_fn(&X::negate)(xp, 17) == -17);
assert(mem_fn(&X::plus)(x, 17, 25) == 42);
assert(mem_fn(&X::plus)(xp, 17, 25) == 42);
return 0;
}
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