iterators.h

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#ifndef __utl_concepts_iterator_h__
#define __utl_concepts_iterator_h__

#include <utl/core/impl.h>
#include <utl/concepts/defines.h>
#include <utl/concepts/stl.h>

namespace utl {

   #if CXX_CONCEPTS
   template <class I>
   _utlConcept WeaklyIncrementable =
      Semiregular<I> &&
      requires(I i) {
         { ++i } -> Same<I>&; // not required to be equality preserving
         i++;                 // not required to be equality preserving
      };
   #else
   namespace detail {
      template <typename I> using try_ppI = decltype (++(std::declval<I>()));
      template <typename I> using try_Ipp = decltype (std::declval<I>()++);
   }
   template <class I>
   _utlConcept WeaklyIncrementable =
      Semiregular<I>
      && Same<_ref_t<I>, meta::detected_t<detail::try_ppI, _ref_t<I>>>
      && meta::is_detected<detail::try_Ipp, _ref_t<I>>::value;
   #endif

   #if CXX_CONCEPTS
   template <class I>
   _utlConcept DeviceIterator =
      requires(I i) {
         { *i } -> auto&&; // Requires: i is dereferenceable
      } &&
      WeaklyIncrementable<I>;

   #else

   #endif

}

#endif /* __utl_concepts_iterator_h__ */