Viewing file:  sfinae6.C (1.9 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
// DR 339
//
// Test of the use of the function call operator with SFINAE
typedef char yes_type;
struct no_type { char data[2]; };
template<typename T> T create_a();
template<typename T> struct type { };
template<bool, typename T = void> struct enable_if { typedef T type; };
template<typename T> struct enable_if<false, T> { };
template<typename F, typename T1, typename T2>
typename enable_if<sizeof(create_a<F>()(create_a<T1>(), create_a<T2>()), 1),
yes_type>::type
check_is_callable2(type<F>, type<T1>, type<T2>);
no_type check_is_callable2(...);
template<typename F, typename T1, typename T2 = T1>
struct is_callable2
{
static const bool value =
(sizeof(check_is_callable2(type<F>(), type<T1>(), type<T2>()))
== sizeof(yes_type));
};
#define JOIN( X, Y ) DO_JOIN( X, Y )
#define DO_JOIN( X, Y ) DO_JOIN2(X,Y)
#define DO_JOIN2( X, Y ) X##Y
#ifdef __GXX_EXPERIMENTAL_CXX0X__
# define STATIC_ASSERT(Expr) static_assert(Expr, #Expr)
#else
# define STATIC_ASSERT(Expr) int JOIN(a,__LINE__)[Expr? 1 : -1]
#endif
struct A;
struct B;
struct A {
A(B);
};
struct B {
B(A);
};
struct F1 { };
struct F2 {
bool operator()(int, float);
};
struct F3 {
bool operator()(int);
};
struct F4 {
void operator()(A, A);
void operator()(B, B);
};
struct F5 {
void operator()(A, A);
private:
void operator()(B, B);
};
STATIC_ASSERT((is_callable2<int(*)(int, int), long, int>::value));
STATIC_ASSERT((!is_callable2<int(*)(int, int), int*, int>::value));
STATIC_ASSERT((!is_callable2<F1, int, int>::value));
STATIC_ASSERT((is_callable2<F2, int, int>::value));
STATIC_ASSERT((!is_callable2<F2, int*, int>::value));
STATIC_ASSERT((!is_callable2<F3, int, int>::value));
STATIC_ASSERT((is_callable2<F4, A, A>::value));
STATIC_ASSERT((is_callable2<F4, B, B>::value));
STATIC_ASSERT((!is_callable2<F4, A, B>::value));
STATIC_ASSERT((is_callable2<F5, A, A>::value));
STATIC_ASSERT((!is_callable2<F5, A, B>::value));
|
