topologyfactory.hh

// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_GEOMETRY_TOPOLOGYFACTORY_HH
#define DUNE_GEOMETRY_TOPOLOGYFACTORY_HH
 
#include <cassert>
 
#include <array>
#include <map>
#include <memory>
#include <type_traits>
#include <vector>
 
#include <dune/geometry/type.hh>
 
namespace Dune
{
 
  template <class Traits>
  struct TopologyFactory
  {
    // extract types from Traits class
    static const unsigned int dimension = Traits::dimension;
    typedef typename Traits::Key Key;
    typedef typename Traits::Object Object;
    typedef typename Traits::Factory Factory;
 
    static Object *create ( const Dune::GeometryType &gt, const Key &key )
    {
      return Impl::IfTopology< Maker, dimension >::apply( gt.id(), key );
    }
 
    template< class Topology >
    static Object *create ( const Key &key )
    {
      return Factory::template createObject< Topology >( key );
    }
 
    static void release( Object *object ) { delete object; }
 
  private:
    // Internal maker class used in ifTopology helper
    template< class Topology >
    struct Maker
    {
      static Object *apply ( const Key &key )
      {
        return create< Topology >( key );
      };
    };
  };
 
 
 
  template <class Factory>
  struct TopologySingletonFactory
  {
    static const unsigned int dimension = Factory::dimension;
    typedef typename Factory::Key Key;
    typedef const typename Factory::Object Object;
 
    static Object *create ( const Dune::GeometryType &gt, const Key &key )
    {
      assert( gt.id() < numTopologies );
      return instance().getObject( gt, key );
    }
 
    template< class Topology >
    static auto create ( const Key &key )
      -> std::enable_if_t< Topology::dimension == dimension, Object * >
    {
      return instance().template getObject< Topology >( key );
    }
 
    static void release ( Object *object )
    {}
 
  private:
    struct ObjectDeleter
    {
      void operator() ( Object *ptr ) const { Factory::release( ptr ); }
    };
 
    static TopologySingletonFactory &instance ()
    {
      static TopologySingletonFactory instance;
      return instance;
    }
 
    static const unsigned int numTopologies = (1 << dimension);
    typedef std::array< std::unique_ptr< Object, ObjectDeleter >, numTopologies > Array;
    typedef std::map< Key, Array > Storage;
 
    TopologySingletonFactory () = default;
 
    std::unique_ptr< Object, ObjectDeleter > &find ( const unsigned int topologyId, const Key &key )
    {
      return storage_[ key ][ topologyId ];
    }
 
    Object *getObject ( const Dune::GeometryType &gt, const Key &key )
    {
      auto &object = find( gt.id(), key );
      if( !object )
        object.reset( Factory::create( gt, key ) );
      return object.get();
    }
 
    template< class Topology >
    Object *getObject ( const Key &key )
    {
      auto &object = find( Topology::id, key );
      if( !object )
        object.reset( Factory::template create< Topology >( key ) );
      return object.get();
    }
 
    Storage storage_;
  };
 
}
 
#endif // #ifndef DUNE_GEOMETRY_TOPOLOGYFACTORY_HH