iterator_traits.hpp

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// SPDX-FileCopyrightText: 2006-2025 Knut Reinert & Freie Universität Berlin
// SPDX-FileCopyrightText: 2016-2025 Knut Reinert & MPI für molekulare Genetik
// SPDX-License-Identifier: BSD-3-Clause

 
#pragma once
 
#include <iterator>
#include <type_traits>
 
#include <seqan3/core/platform.hpp>
 
namespace seqan3::detail
{
template <typename underlying_iterator_t>
struct maybe_iterator_category
{
#if SEQAN3_DOXYGEN_ONLY(1) 0
    using iterator_category = MAYBE_PRESENT(std::iterator_traits<underlying_iterator_t>::iterator_category);
#endif // SEQAN3_DOXYGEN_ONLY(1)0
};

template <typename t>
concept has_iterator_category = requires () { typename t::iterator_category; };

template <typename underlying_iterator_t>
    requires has_iterator_category<std::iterator_traits<underlying_iterator_t>>
struct maybe_iterator_category<underlying_iterator_t>
{
    using iterator_category = typename std::iterator_traits<underlying_iterator_t>::iterator_category;
};

template <typename underling_iterator_t>
struct maybe_inherited_iterator_category : public maybe_iterator_category<underling_iterator_t>
{};

template <typename underling_iterator_t>
    requires has_iterator_category<underling_iterator_t>
struct maybe_inherited_iterator_category<underling_iterator_t>
{
    // underling_iterator_t::iterator_category is already defined
};

template <typename it_t>
    requires std::input_or_output_iterator<it_t>
using iterator_concept_tag_t = std::conditional_t<
    std::contiguous_iterator<it_t>,
    std::contiguous_iterator_tag,
    std::conditional_t<std::random_access_iterator<it_t>,
                       std::random_access_iterator_tag,
                       std::conditional_t<std::bidirectional_iterator<it_t>,
                                          std::bidirectional_iterator_tag,
                                          std::conditional_t<std::forward_iterator<it_t>,
                                                             std::forward_iterator_tag,
                                                             std::conditional_t<std::input_iterator<it_t>,
                                                                                std::input_iterator_tag,
                                                                                std::output_iterator_tag>>>>>;
 
} // namespace seqan3::detail
 
namespace seqan3::detail
{
// ----------------------------------------------------------------------------
// iter_pointer
// ----------------------------------------------------------------------------

template <typename it_t>
struct iter_pointer
{
    using type = void;
};

template <typename it_t>
    requires requires { typename std::iterator_traits<it_t>::pointer; }
struct iter_pointer<it_t>
{
    using type = typename std::iterator_traits<it_t>::pointer;
};

template <typename it_t>
using iter_pointer_t = typename iter_pointer<it_t>::type;
 
} // namespace seqan3::detail