proxynode.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-FileCopyrightInfo: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-GPL-2.0-only-with-PDELab-exception
 
#ifndef DUNE_TYPETREE_PROXYNODE_HH
#define DUNE_TYPETREE_PROXYNODE_HH
 
#include <type_traits>
#include <dune/typetree/nodeinterface.hh>
#include <dune/typetree/nodetags.hh>
#include <dune/common/shared_ptr.hh>
#include <dune/common/indices.hh>
#include <dune/common/std/type_traits.hh>
 
namespace Dune {
  namespace TypeTree {
 
    template<typename Node>
    class ProxyNode;
 
    template<typename ProxiedNode>
    class StaticChildAccessors
    {
 
      static const bool proxiedNodeIsConst = std::is_const<typename std::remove_reference<ProxiedNode>::type>::value;
 
      template<std::size_t k>
      struct lazy_enabled
      {
        static const bool value = !proxiedNodeIsConst;
      };
 
      typedef ProxyNode<ProxiedNode> Node;
 
      template<bool enabled = !proxiedNodeIsConst>
      typename std::enable_if<enabled,Node&>::type
      node ()
      {
        return static_cast<Node&>(*this);
      }
 
      const Node& node () const
      {
        return static_cast<const Node&>(*this);
      }
 
    public:
 
      template<std::size_t k>
      struct Child
        : public ProxiedNode::template Child<k>
      {};
 
 
 
      template<std::size_t k,
        typename std::enable_if<lazy_enabled<k>::value, int>::type = 0>
      auto& child (index_constant<k> = {})
      {
        return node().proxiedNode().template child<k>();
      }
 
 
      template<std::size_t k>
      const auto& child (index_constant<k> = {}) const
      {
        return node().proxiedNode().template child<k>();
      }
 
 
      template<std::size_t k,
        typename std::enable_if<lazy_enabled<k>::value, int>::type = 0>
      auto childStorage (index_constant<k> = {})
      {
        return node().proxiedNode().template childStorage<k>();
      }
 
 
      template<std::size_t k>
      auto childStorage (index_constant<k> = {}) const
      {
        return node().proxiedNode().template childStorage<k>();
      }
 
      template<std::size_t k, class ProxyChild>
      void setChild (ProxyChild&& child, typename std::enable_if<lazy_enabled<k>::value,void*>::type = 0)
      {
        node().proxiedNode().template setChild<k>(std::forward<ProxyChild>(child));
      }
 
      const typename ProxiedNode::NodeStorage& nodeStorage () const
      {
        return node().proxiedNode().nodeStorage();
      }
 
    };
 
 
    template<typename ProxiedNode>
    class DynamicChildAccessors
      : public StaticChildAccessors<ProxiedNode>
    {
 
      typedef ProxyNode<ProxiedNode> Node;
 
      static const bool proxiedNodeIsConst = std::is_const<typename std::remove_reference<ProxiedNode>::type>::value;
 
      template<bool enabled = !proxiedNodeIsConst>
      typename std::enable_if<enabled,Node&>::type
      node ()
      {
        return static_cast<Node&>(*this);
      }
 
      const Node& node () const
      {
        return static_cast<const Node&>(*this);
      }
 
    public:
 
 
 
      template<bool enabled = !proxiedNodeIsConst,
        typename std::enable_if<enabled, int>::type = 0>
      auto& child (std::size_t i)
      {
        return node().proxiedNode().child(i);
      }
 
 
      const auto& child (std::size_t i) const
      {
        return node().proxiedNode().child(i);
      }
 
 
      template<bool enabled = !proxiedNodeIsConst,
        typename std::enable_if<enabled, int>::type = 0>
      auto childStorage (std::size_t i)
      {
        return node().proxiedNode().childStorage(i);
      }
 
 
      auto childStorage (std::size_t i) const
      {
        return node().proxiedNode().childStorage(i);
      }
 
      template<class ProxyChild, bool enabled = !proxiedNodeIsConst>
      void setChild (std::size_t i, ProxyChild&& child, typename std::enable_if<enabled,void*>::type = 0)
      {
        node().proxiedNode().setChild(i, std::forward<ProxyChild>(child));
      }
 
    };
 
    template<typename Node, typename NodeTag>
    struct ProxyNodeBase;
 
    template<typename Node>
    struct ProxyNodeBase<Node,LeafNodeTag>
    {
    };
 
    template<typename Node>
    struct ProxyNodeBase<Node,CompositeNodeTag>
      : public StaticChildAccessors<Node>
    {
      typedef typename Node::ChildTypes ChildTypes;
      typedef typename Node::NodeStorage NodeStorage;
    };
 
    template<typename Node>
    struct ProxyNodeBase<Node,PowerNodeTag>
      : public DynamicChildAccessors<Node>
    {
      typedef typename Node::ChildType ChildType;
      typedef typename Node::NodeStorage NodeStorage;
    };
 
    template<typename Node>
    struct ProxyNodeBase<Node,DynamicPowerNodeTag>
      : public DynamicChildAccessors<Node>
    {
      typedef typename Node::ChildType ChildType;
      typedef typename Node::NodeStorage NodeStorage;
    };
 
 
    template<typename Node>
    class ProxyNode
      : public ProxyNodeBase<Node,NodeTag<Node>>
    {
      static const bool proxiedNodeIsConst = std::is_const<typename std::remove_reference<Node>::type>::value;
 
      template <class N>
      using HasStaticDegree = index_constant<N::degree()>;
 
      template <class N>
      static constexpr bool hasStaticDegree = Std::is_detected<HasStaticDegree, N>::value;
 
      // accessor mixins need to be friends for access to proxiedNode()
      friend class StaticChildAccessors<Node>;
      friend class DynamicChildAccessors<Node>;
 
    public:
 
      typedef Node ProxiedNode;
 
      typedef Dune::TypeTree::NodeTag<Node> NodeTag;
 
      static const bool isLeaf = Node::isLeaf;
 
      static const bool isPower = Node::isPower;
 
      static const bool isComposite = Node::isComposite;
 
      template <class N = Node,
        std::enable_if_t<hasStaticDegree<N>, int> = 0>
      static constexpr auto degree ()
      {
        return N::degree();
      }
 
      template <class N = Node,
        std::enable_if_t<not hasStaticDegree<N>, int> = 0>
      auto degree () const
      {
        return proxiedNode().degree();
      }
 
 
    protected:
 
 
      template<bool enabled = !proxiedNodeIsConst>
      typename std::enable_if<enabled,Node&>::type
      proxiedNode ()
      {
        return *_node;
      }
 
      const Node& proxiedNode () const
      {
        return *_node;
      }
 
      template<bool enabled = !proxiedNodeIsConst>
      typename std::enable_if<enabled,std::shared_ptr<Node> >::type
      proxiedNodeStorage ()
      {
        return _node;
      }
 
      std::shared_ptr<const Node> proxiedNodeStorage () const
      {
        return _node;
      }
 
 
 
      ProxyNode (Node& node)
        : _node(stackobject_to_shared_ptr(node))
      {}
 
      ProxyNode (std::shared_ptr<Node> node)
        : _node(std::move(node))
      {}
 
 
    private:
 
      std::shared_ptr<Node> _node;
    };
 
 
  } // namespace TypeTree
} //namespace Dune
 
#endif // DUNE_TYPETREE_PROXYNODE_HH