transformation_trait_or.hpp

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// -----------------------------------------------------------------------------------------------------
// Copyright (c) 2006-2019, Knut Reinert & Freie Universität Berlin
// Copyright (c) 2016-2019, 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 <type_traits>

#include <meta/meta.hpp>

#include <seqan3/core/platform.hpp>
#include <seqan3/std/type_traits>

namespace seqan3::detail
{

template <typename type_t, typename default_t>
using transformation_trait_or = std::conditional_t<meta::is_trait<type_t>::value,   // check if type_t::type exists
                                                   type_t,                          // if yes, return type_t
                                                   std::type_identity<default_t>>;  // else return default_t as trait

template <typename type_t, typename default_t>
using transformation_trait_or_t = typename transformation_trait_or<type_t, default_t>::type;

} // namespace seqan3::detail