iterator_traits.hpp

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// -----------------------------------------------------------------------------------------------------
// Copyright (c) 2006-2021, Knut Reinert & Freie Universität Berlin
// Copyright (c) 2016-2021, Knut Reinert & MPI für molekulare Genetik
// This file may be used, modified and/or redistributed under the terms of the 3-clause BSD-License
// shipped with this file and also available at: https://github.com/seqan/seqan3/blob/master/LICENSE.md
// -----------------------------------------------------------------------------------------------------
 
#pragma once
 
#include <seqan3/std/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>
SEQAN3_CONCEPT has_iterator_category = requires ()
{
    typename t::iterator_category;
};
 
#if SEQAN3_WORKAROUND_GCC_96070
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 = void;
};
#endif // SEQAN3_WORKAROUND_GCC_96070
 
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