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Library: better use a dedicated detector metafunction

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...and check for presence of *all three* standard type bindings

 - value_type
 - reference
 - pointer
This commit is contained in:
Fischlurch 2017-11-30 22:39:43 +01:00
parent 6bb288bf20
commit dce09ebe0d
1 changed files with 23 additions and 3 deletions
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26
src/lib/meta/value-type-binding.hpp
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@ -40,7 +40,7 @@
#include "lib/error.hpp"
#include "lib/meta/duck-detector.hpp" ////////TODO
//#include "lib/meta/duck-detector.hpp" ////////TODO
#include "lib/meta/util.hpp" ////////TODO
@ -53,7 +53,27 @@ namespace std {
namespace lib {
namespace meta {
META_DETECT_NESTED (value_type);
namespace {
template<typename TY>
class has_nested_ValueTypeBindings
{
template<typename X, int i = sizeof(typename X::value_type)
, int j = sizeof(typename X::reference)
, int k = sizeof(typename X::pointer)
>
struct Probe
{ };
template<class X>
static Yes_t check(Probe<X> * );
template<class>
static No_t check(...);
public:
static const bool value = (sizeof(Yes_t)==sizeof(check<TY>(0)));
};
}
/**
* Type re-binding helper template for creating nested typedefs
@ -108,7 +128,7 @@ namespace meta {
* STL style type binding definitions themselves
*/
template<typename TY>
struct TypeBinding<TY, enable_if<HasNested_value_type<TY>> >
struct TypeBinding<TY, enable_if<has_nested_ValueTypeBindings<TY>> >
{
typedef typename TY::pointer pointer;
typedef typename TY::reference reference;