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minor tweaks in has_* helpers

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This commit is contained in:
Gael Guennebaud 2016-08-31 23:04:14 +02:00
parent 7ae819123c
commit 84cf6e42ca
1 changed files with 10 additions and 13 deletions
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23
Eigen/src/Core/util/Meta.h
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@ -368,29 +368,26 @@ struct result_of<Func(ArgType0,ArgType1,ArgType2)> {
}; };
#endif #endif
struct meta_yes { char a[1]; };
struct meta_no { char a[2]; };
// Check whether T::ReturnType does exist // Check whether T::ReturnType does exist
template <typename T> template <typename T>
struct has_ReturnType struct has_ReturnType
{ {
typedef char yes[1]; template <typename C> static meta_yes testFunctor(typename C::ReturnType const *);
typedef char no[2]; template <typename C> static meta_no testFunctor(...);
template <typename C> static yes& testFunctor(typename C::ReturnType const *); enum { value = sizeof(testFunctor<T>(0)) == sizeof(meta_yes) };
template <typename C> static no& testFunctor(...);
enum { value = sizeof(testFunctor<T>(0)) == sizeof(yes) };
}; };
template<int> struct any_int {}; template<int Val> struct integral_constant { static const int value = Val; };
template<typename T> const T& return_ref(); template<typename T> const T& return_ref();
struct meta_yes { char data[1]; };
struct meta_no { char data[2]; };
template <typename T> template <typename T>
struct has_nullary_operator struct has_nullary_operator
{ {
template <typename C> static meta_yes testFunctor(C const *,any_int< sizeof(return_ref<C>()()) > * = 0); template <typename C> static meta_yes testFunctor(C const *,integral_constant< sizeof(return_ref<C>()()) > * = 0);
static meta_no testFunctor(...); static meta_no testFunctor(...);
enum { value = sizeof(testFunctor(static_cast<T*>(0))) == sizeof(meta_yes) }; enum { value = sizeof(testFunctor(static_cast<T*>(0))) == sizeof(meta_yes) };
@ -399,7 +396,7 @@ struct has_nullary_operator
template <typename T> template <typename T>
struct has_unary_operator struct has_unary_operator
{ {
template <typename C> static meta_yes testFunctor(C const *,any_int< sizeof(return_ref<C>()(Index(0))) > * = 0); template <typename C> static meta_yes testFunctor(C const *,integral_constant< sizeof(return_ref<C>()(Index(0))) > * = 0);
static meta_no testFunctor(...); static meta_no testFunctor(...);
enum { value = sizeof(testFunctor(static_cast<T*>(0))) == sizeof(meta_yes) }; enum { value = sizeof(testFunctor(static_cast<T*>(0))) == sizeof(meta_yes) };
@ -408,7 +405,7 @@ struct has_unary_operator
template <typename T> template <typename T>
struct has_binary_operator struct has_binary_operator
{ {
template <typename C> static meta_yes testFunctor(C const *,any_int< sizeof(return_ref<C>()(Index(0),Index(0))) > * = 0); template <typename C> static meta_yes testFunctor(C const *,integral_constant< sizeof(return_ref<C>()(Index(0),Index(0))) > * = 0);
static meta_no testFunctor(...); static meta_no testFunctor(...);
enum { value = sizeof(testFunctor(static_cast<T*>(0))) == sizeof(meta_yes) }; enum { value = sizeof(testFunctor(static_cast<T*>(0))) == sizeof(meta_yes) };