projected.hpp

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//
// Created by cosge on 2023-12-29.
//
 
#ifndef VCCC_ITERATOR_PROJECTED_HPP
#define VCCC_ITERATOR_PROJECTED_HPP
 
#include "vccc/__core/ignore_dumb_diagnostics_push.hpp"
 
#include "vccc/__iterator/indirect_result_t.hpp"
#include "vccc/__iterator/indirectly_readable.hpp"
#include "vccc/__iterator/indirectly_regular_unary_invocable.hpp"
#include "vccc/__iterator/iter_difference_t.hpp"
#include "vccc/__iterator/weakly_incrementable.hpp"
#include "vccc/__type_traits/conjunction.hpp"
#include "vccc/__type_traits/has_typename_type.hpp"
#include "vccc/__type_traits/remove_cvref.hpp"
 
namespace vccc {
namespace detail {
 
template<typename I, bool = weakly_incrementable<I>::value /* true */>
struct projected_impl_difference_type {
  using difference_type = iter_difference_t<I>;
};
template<typename I>
struct projected_impl_difference_type<I, false> {};
 
template<
    typename I,
    typename Proj,
    bool = conjunction<
               indirectly_readable<I>,
               indirectly_regular_unary_invocable<Proj, I>
           >::value /* true */
>
struct projected_impl {
  struct type : projected_impl_difference_type<I> {
    using value_type = remove_cvref_t<indirect_result_t<Proj, I>>;
 
    indirect_result_t<Proj&, I> operator*() const;
  };
};
 
template<typename I, typename Proj>
struct projected_impl<I, Proj, false> {};
 
} // namespace detail
 
template<typename I, typename Proj>
using projected = typename detail::projected_impl<I, Proj>::type;
 
template<typename I, typename Proj>
using projectable = has_typename_type<detail::projected_impl<I, Proj>>;
 
 
} // namespace vccc
 
#include "vccc/__core/ignore_dumb_diagnostics_pop.hpp"
#endif // VCCC_ITERATOR_PROJECTED_HPP