transfer_type_modifier_onto.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/type_traits>
 
#include <seqan3/core/platform.hpp>
 
namespace seqan3::detail
{
 
template <typename source_t, typename target_t>
struct transfer_type_modifier_onto
{
private:
    using maybe_const_target_t = std::conditional_t<std::is_const_v<std::remove_reference_t<source_t>> ||
                                                    std::is_const_v<std::remove_reference_t<target_t>>,
                                                    std::add_const_t<std::remove_cvref_t<target_t>>,
                                                    std::remove_cvref_t<target_t>>;
 
    using maybe_rvalue_reference_t = std::conditional_t<std::is_rvalue_reference_v<source_t> ||
                                                        std::is_rvalue_reference_v<target_t>,
                                                        std::add_rvalue_reference_t<maybe_const_target_t>,
                                                        maybe_const_target_t>;
 
    using maybe_lvalue_reference_target_t = std::conditional_t<std::is_lvalue_reference_v<source_t> ||
                                                               std::is_lvalue_reference_v<target_t>,
                                                               std::add_lvalue_reference_t<maybe_rvalue_reference_t>,
                                                               maybe_rvalue_reference_t>;
public:
 
    using type = maybe_lvalue_reference_target_t;
};
 
template <typename source_t, typename target_t>
using transfer_type_modifier_onto_t = typename transfer_type_modifier_onto<source_t, target_t>::type;
 
} // namespace seqan3::detail