emulation.hpp

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// SPDX-License-Identifier: BSL-1.0
 
#ifndef TETL_CONCEPTS_EMULATION_HPP
#define TETL_CONCEPTS_EMULATION_HPP
 
#include <etl/_iterator/begin.hpp>
#include <etl/_iterator/end.hpp>
#include <etl/_iterator/iterator_traits.hpp>
#include <etl/_type_traits/bool_constant.hpp>
#include <etl/_type_traits/declval.hpp>
#include <etl/_type_traits/is_assignable.hpp>
#include <etl/_type_traits/is_convertible.hpp>
#include <etl/_type_traits/is_move_constructible.hpp>
#include <etl/_type_traits/is_object.hpp>
#include <etl/_type_traits/is_swappable.hpp>
#include <etl/_type_traits/void_t.hpp>
 
namespace etl::detail {
 
// Concepts (poor-man emulation using type traits)
 
template <typename T>
inline constexpr bool is_movable_v
    = is_object_v<T> and is_assignable_v<T&, T> and is_move_constructible_v<T> and is_swappable_v<T&>;
 
template <typename Rng>
using range_iterator_t = decltype(etl::begin(etl::declval<Rng>()));
 
template <typename T>
using iterator_reference_t = typename iterator_traits<T>::reference;
 
template <typename T>
using iterator_category_t = typename iterator_traits<T>::iterator_category;
 
template <typename T, typename Category, typename = void>
struct IteratorConcept : false_type { };
 
template <typename T, typename Category>
struct IteratorConcept<T, Category, void_t<iterator_category_t<T>>>
    : bool_constant<is_convertible_v<iterator_category_t<T>, Category>> { };
 
// clang-format off
template <typename T> inline constexpr bool InputIterator           = IteratorConcept<T, input_iterator_tag> {};
template <typename T> inline constexpr bool ForwardIterator         = IteratorConcept<T, forward_iterator_tag> {};
template <typename T> inline constexpr bool OutputIterator          = IteratorConcept<T, output_iterator_tag> {} || ForwardIterator<T>;
template <typename T> inline constexpr bool BidirectionalIterator   = IteratorConcept<T, bidirectional_iterator_tag> {};
template <typename T> inline constexpr bool RandomAccessIterator    = IteratorConcept<T, random_access_iterator_tag> {};
template <typename T> inline constexpr bool RandomAccessRange       = RandomAccessIterator<range_iterator_t<T>>;
// clang-format on
 
} // namespace etl::detail
 
#endif // TETL_CONCEPTS_EMULATION_HPP