typetreefallback.hh

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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
 
// SPDX-FileCopyrightText: Copyright © DUNE-FUFEM Project contributors, see file AUTHORS.md
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception OR LGPL-3.0-or-later
 
#ifndef DUNE_FUFEM_TYPETREEFALLBACK_HH
#define DUNE_FUFEM_TYPETREEFALLBACK_HH
 
#include <concepts>
#include <type_traits>
#include <utility>
 
#include <dune/common/typetraits.hh>
#include <dune/common/indices.hh>
#include <dune/common/version.hh>
 
#if DUNE_VERSION_GTE(DUNE_FUNCTIONS, 2, 11)
#include <dune/common/typetree/childaccess.hh>
#include <dune/common/typetree/nodeconcepts.hh>
#include <dune/common/typetree/treepath.hh>
#else
#include <dune/typetree/childextraction.hh>
#include <dune/typetree/treepath.hh>
#endif
 
 
namespace Dune::Fufem::Impl {
 
  namespace Concept {
 
#if DUNE_VERSION_GTE(DUNE_FUNCTIONS, 2, 11)
 
    template<class Node>
    concept TreeNode = Dune::TypeTree::Concept::TreeNode<Node>;
 
    template<class Node>
    concept StaticDegreeInnerTreeNode = Dune::TypeTree::Concept::StaticDegreeInnerTreeNode<Node>;
 
    template<class Node>
    concept UniformInnerTreeNode = Dune::TypeTree::Concept::UniformInnerTreeNode<Node>;
 
    template<class Node>
    concept InnerTreeNode = Dune::TypeTree::Concept::InnerTreeNode<Node>;
 
    template<class Node>
    concept LeafTreeNode = Dune::TypeTree::Concept::LeafTreeNode<Node>;
 
#else
 
    template<class Node>
    concept HasConstExprDegree = requires(Node node)
    {
      std::bool_constant<(std::remove_cvref_t<Node>::degree(), true)>();
    };
 
    template<class Node>
    concept HasPositiveDegree = ( std::remove_cvref_t<Node>::degree() > 0);
 
 
    template<class Node>
    concept TreeNode = requires(Node node)
    {
      { std::as_const(node).degree() } -> std::convertible_to<std::size_t>;
    };
 
    template<class Node>
    concept StaticDegreeInnerTreeNode = TreeNode<Node> && requires(Node node)
    {
      std::remove_cvref_t<Node>::degree();
      requires IsCompileTimeConstant<decltype(std::remove_cvref_t<Node>::degree())>::value;
      requires HasConstExprDegree<Node> and HasPositiveDegree<Node>;
      node.child(index_constant<0>());
      node.child(index_constant<(std::remove_cvref_t<Node>::degree()-1)>());
    };
 
    template<class Node>
    concept UniformInnerTreeNode = TreeNode<Node> && requires(Node node, std::size_t index)
    {
      node.child(index);
    };
 
    template<class Node>
    concept InnerTreeNode = StaticDegreeInnerTreeNode<Node> || UniformInnerTreeNode<Node>;
 
    template<class Node>
    concept LeafTreeNode = TreeNode<Node> && not InnerTreeNode<Node>;
 
#endif
 
  } // namespace Concept (in Dune::Fufem::Impl::)
 
#if DUNE_VERSION_GTE(DUNE_FUNCTIONS, 2, 11)
 
  template<class N>
  using Children = Dune::TypeTree::Impl::Children<N>;
 
  template<typename... T>
  using TreePath = Dune::TypeTree::TreePath<T...>;
 
#else
 
  template<typename... T>
  using TreePath = Dune::TypeTree::HybridTreePath<T...>;
 
  template<class N>
  static constexpr auto childTypes()
  {
    if constexpr (Dune::Fufem::Impl::Concept::StaticDegreeInnerTreeNode<N>)
    {
      return Dune::unpackIntegerSequence([&](auto... i) {
        return Dune::MetaType<std::tuple<Dune::TypeTree::Child<N, i>...>>{};
      }, std::make_index_sequence<N::degree()>{});
    }
    else
      return Dune::MetaType<void>{};
  }
 
 
  template<class N>
  using Children = typename decltype(childTypes<N>())::type;
 
#endif
 
} // namespace Dune::Fufem::Impl
 
 
#endif // DUNE_FUFEM_TYPETREEFALLBACK_HH