template_inspection.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/concepts>
 
#include <seqan3/utility/type_traits/detail/transformation_trait_or.hpp>
 
namespace seqan3::detail
{
 
// ----------------------------------------------------------------------------
// transfer_template_args_onto
// ----------------------------------------------------------------------------
 
template <typename source_type, template <typename ...> typename target_template>
struct transfer_template_args_onto
{};
 
template <template <typename ...> typename source_template,
          template <typename ...> typename target_template,
          typename ...source_arg_types>
    requires requires ()
    {
        typename target_template<source_arg_types...>;
    }
struct transfer_template_args_onto<source_template<source_arg_types...>, target_template>
{
    using type = target_template<source_arg_types...>;
};
 
template <typename source_type, template <typename ...> typename target_template>
using transfer_template_args_onto_t = typename transfer_template_args_onto<source_type, target_template>::type;
 
// ----------------------------------------------------------------------------
// transfer_template_vargs_onto
// ----------------------------------------------------------------------------
 
template <typename source_type, template <auto ...> typename target_template>
struct transfer_template_vargs_onto
{};
 
template <template <auto ...> typename source_template,
          template <auto ...> typename target_template,
          auto ... source_varg_types>
    requires requires ()
    {
        typename target_template<source_varg_types...>;
    }
struct transfer_template_vargs_onto<source_template<source_varg_types...>, target_template>
{
    using type = target_template<source_varg_types...>;
};
 
template <typename source_type, template <auto ...> typename target_template>
using transfer_template_vargs_onto_t = typename transfer_template_vargs_onto<source_type, target_template>::type;
 
// ----------------------------------------------------------------------------
// is_type_specialisation_of_v
// ----------------------------------------------------------------------------
 
template <typename source_t, template <typename ...> typename target_template>
struct is_type_specialisation_of : public std::false_type
{};
 
template <typename source_t, template <typename ...> typename target_template>
    requires (!std::same_as<transformation_trait_or_t<transfer_template_args_onto<source_t, target_template>, void>,
                            void>)
struct is_type_specialisation_of<source_t, target_template> :
        std::is_same<source_t, transfer_template_args_onto_t<source_t, target_template>>
{};
 
template <typename source_t, template <typename ...> typename target_template>
inline constexpr bool is_type_specialisation_of_v = is_type_specialisation_of<source_t, target_template>::value;
 
// ----------------------------------------------------------------------------
// is_value_specialisation_of_v
// ----------------------------------------------------------------------------
 
template <typename source_t, template <auto ...> typename target_template>
struct is_value_specialisation_of : std::false_type
{};
 
template <typename source_t, template <auto ...> typename target_template>
    requires (!std::same_as<transformation_trait_or_t<transfer_template_vargs_onto<source_t, target_template>, void>,
                            void>)
struct is_value_specialisation_of<source_t, target_template> :
    std::is_same<source_t, transfer_template_vargs_onto_t<source_t, target_template>>
{};
 
template <typename source_t, template <auto ...> typename target_template>
inline constexpr bool is_value_specialisation_of_v = is_value_specialisation_of<source_t, target_template>::value;
 
template <typename fallback_t, template <typename ...> typename templ_t, typename ...spec_t>
struct valid_template_spec_or
{
    using type = fallback_t;
};
 
template <typename fallback_t, template <typename ...> typename templ_t, typename ...spec_t>
    requires requires { typename templ_t<spec_t...>; }
struct valid_template_spec_or<fallback_t, templ_t, spec_t...>
{
    using type = templ_t<spec_t...>;
};
 
template <typename fallback_t, template <typename ...> typename templ_t, typename ...spec_t>
using valid_template_spec_or_t = typename valid_template_spec_or<fallback_t, templ_t, spec_t...>::type;
 
// ----------------------------------------------------------------------------
// template_specialisation_of
// ----------------------------------------------------------------------------
 
template <typename mytype, template <typename ...> typename type_template>
SEQAN3_CONCEPT template_specialisation_of = is_type_specialisation_of_v<mytype, type_template>;
 
 
// ----------------------------------------------------------------------------
// strip_type_identity
// ----------------------------------------------------------------------------
 
template <typename t>
using strip_type_identity_t = std::conditional_t<is_type_specialisation_of_v<t, std::type_identity>,
                                                 transformation_trait_or_t<t, void>,
                                                 t>;
} // namespace seqan3::detail