pairtraversal.hh

// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
 
#ifndef DUNE_TYPETREE_PAIRTRAVERSAL_HH
#define DUNE_TYPETREE_PAIRTRAVERSAL_HH
 
#include <dune/common/std/type_traits.hh>
 
#include <dune/typetree/nodeinterface.hh>
#include <dune/typetree/nodetags.hh>
#include <dune/typetree/treepath.hh>
#include <dune/typetree/visitor.hh>
#include <dune/typetree/traversal.hh>
 
namespace Dune {
  namespace TypeTree {
 
    namespace Detail {
 
      /* The signature is the same as for the public applyToTreePair
       * function in Dune::Typtree, despite the additionally passed
       * treePath argument. The path passed here is associated to
       * the tree and the relative paths of the children (wrt. to tree)
       * are appended to this.  Hence the behavior of the public function
       * is resembled by passing an empty treePath.
       */
 
      /*
       * This is the overload for leaf traversal
       */
      template<class T1, class T2, class TreePath, class V,
        std::enable_if_t<(std::decay_t<T1>::isLeaf or std::decay_t<T2>::isLeaf), int> = 0>
      void applyToTreePair(T1&& tree1, T2&& tree2, TreePath treePath, V&& visitor)
      {
        visitor.leaf(tree1, tree2, treePath);
      }
 
      /*
       * This is the general overload doing static child traversal.
       */
      template<class T1, class T2, class TreePath, class V,
        std::enable_if_t<not(std::decay_t<T1>::isLeaf or std::decay_t<T2>::isLeaf), int> = 0>
      void applyToTreePair(T1&& tree1, T2&& tree2, TreePath treePath, V&& visitor)
      {
        // Do we really want to take care for const-ness of the Tree
        // when instanciating VisitChild below? I'd rather expect this:
        // using Tree1 = std::decay_t<T1>;
        // using Tree2 = std::decay_t<T2>;
        // using Visitor = std::decay_t<V>;
        using Tree1 = std::remove_reference_t<T1>;
        using Tree2 = std::remove_reference_t<T2>;
        using Visitor = std::remove_reference_t<V>;
        visitor.pre(tree1, tree2, treePath);
 
        // Use statically encoded degree unless both trees
        // are power nodes and dynamic traversal is requested.
        constexpr auto useDynamicTraversal = (Tree1::isPower and Tree2::isPower and Visitor::treePathType==TreePathType::dynamic);
        auto degree = conditionalValue<useDynamicTraversal>(Tree1::degree(), Dune::index_constant<Tree1::degree()>{});
 
        auto indices = Dune::range(degree);
        Dune::Hybrid::forEach(indices, [&](auto i) {
          auto childTreePath = Dune::TypeTree::push_back(treePath, i);
          auto&& child1 = tree1.child(i);
          auto&& child2 = tree2.child(i);
          using Child1 = std::decay_t<decltype(child1)>;
          using Child2 = std::decay_t<decltype(child2)>;
 
          visitor.beforeChild(tree1, child1, tree2, child2, treePath, i);
 
          // This requires that visiotor.in(...) can always be instantiated,
          // even if there's a single child only.
          if (i>0)
            visitor.in(tree1, tree2, treePath);
          static const auto visitChild = Visitor::template VisitChild<Tree1,Child1,Tree2,Child2,TreePath>::value;
          Dune::Hybrid::ifElse(Dune::Std::bool_constant<visitChild>{}, [&] (auto id) {
            applyToTreePair(child1, child2, childTreePath, visitor);
          });
 
          visitor.afterChild(tree1, child1, tree2, child2, treePath, i);
        });
        visitor.post(tree1, tree2, treePath);
      }
 
    } // namespace Detail
 
 
    template<typename Tree1, typename Tree2, typename Visitor>
    void applyToTreePair(Tree1&& tree1, Tree2&& tree2, Visitor&& visitor)
    {
      Detail::applyToTreePair(tree1, tree2, hybridTreePath(), visitor);
    }
 
 
  } // namespace TypeTree
} //namespace Dune
 
#endif // DUNE_TYPETREE_PAIRTRAVERSAL_HH