gridmanager_sub.hh

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#ifndef DUMUX_IO_GRID_MANAGER_SUB_HH
#define DUMUX_IO_GRID_MANAGER_SUB_HH
 
#include <memory>
 
#include <dune/common/shared_ptr.hh>
#include <dune/common/concept.hh>
 
// SubGrid specific includes
#if HAVE_DUNE_SUBGRID
#include <dune/subgrid/subgrid.hh>
#include <dumux/io/rasterimagereader.hh>
#endif
 
#ifndef DUMUX_IO_GRID_MANAGER_HH
#include <dumux/io/grid/gridmanager.hh>
#endif
 
#include <dumux/common/parameters.hh>
#include <dumux/common/boundaryflag.hh>
 
#if HAVE_DUNE_SUBGRID
namespace Dumux {
namespace Concept {

template<class Element>
struct ElementSelector
{
    template<class F>
    auto require(F&& f) -> decltype(
        bool(f(std::declval<const Element&>()))
    );
};
} // end namespace Concept

template <class HostGrid, class HostGridManager = GridManager<HostGrid>>
class SubGridManagerBase
: public GridManagerBase<Dune::SubGrid<HostGrid::dimension, HostGrid>>
{
    static constexpr int dim = HostGrid::dimension;
    using HostElement = typename HostGrid::template Codim<0>::Entity;
 
public:
    using Grid = Dune::SubGrid<dim, HostGrid>;

    template<class ES,
             typename std::enable_if_t<Dune::models<Concept::ElementSelector<HostElement>, ES>(), int> = 0>
    void init(HostGrid& hostGrid,
              const ES& selector,
              const std::string& paramGroup = "")
    {
        this->gridPtr() = createGrid_(hostGrid, selector, paramGroup);
        loadBalance();
    }

    template<class ES,
             typename std::enable_if_t<Dune::models<Concept::ElementSelector<HostElement>, ES>(), int> = 0>
    void init(const ES& selector,
              const std::string& paramGroup = "")
    {
        initHostGrid_(paramGroup);
        this->gridPtr() = createGrid_(hostGridManager_->grid(), selector, paramGroup);
        loadBalance();
    }

    void loadBalance()
    {
        if (Dune::MPIHelper::getCollectiveCommunication().size() > 1)
            this->grid().loadBalance();
    }
 
protected:

    template<class ES,
             typename std::enable_if_t<Dune::models<Concept::ElementSelector<HostElement>, ES>(), int> = 0>
    static std::unique_ptr<Grid> createGrid_(HostGrid& hostGrid,
                                             const ES& selector,
                                             const std::string& paramGroup = "")
    {
        // A unique pointer to the subgrid.
        auto subgridPtr = std::make_unique<Grid>(hostGrid);
 
        // A container to store the host grid elements' ids.
        std::set<typename HostGrid::Traits::GlobalIdSet::IdType> elementsForSubgrid;
        const auto& globalIDset = subgridPtr->getHostGrid().globalIdSet();
 
        // Construct the subgrid.
        subgridPtr->createBegin();
 
        // Loop over all elements of the host grid and use the selector to
        // choose which elements to add to the subgrid.
        auto hostGridView = subgridPtr->getHostGrid().leafGridView();
        for (const auto& e : elements(hostGridView))
            if (selector(e))
                elementsForSubgrid.insert(globalIDset.template id<0>(e));
 
        if (elementsForSubgrid.empty())
            DUNE_THROW(Dune::GridError, "No elements in subgrid");
 
        subgridPtr->insertSetPartial(elementsForSubgrid);
        subgridPtr->createEnd();
 
        // Return a unique pointer to the subgrid.
        return subgridPtr;
    }
 
    void initHostGrid_(const std::string& paramGroup)
    {
        hostGridManager_ = std::make_unique<HostGridManager>();
        hostGridManager_->init(paramGroup);
    }

    HostGrid& hostGrid_()
    {
        return hostGridManager_->grid();
    }
 
    std::unique_ptr<HostGridManager> hostGridManager_;
};

template<int dim, class HostGrid>
class GridManager<Dune::SubGrid<dim, HostGrid>>
: public SubGridManagerBase<HostGrid, GridManager<HostGrid>>
{};

template<int dim, class Coordinates>
class GridManager<Dune::SubGrid<dim, Dune::YaspGrid<dim, Coordinates>>>
: public SubGridManagerBase<Dune::YaspGrid<dim, Coordinates>, GridManager<Dune::YaspGrid<dim, Coordinates>>>
{
    using ParentType = SubGridManagerBase<Dune::YaspGrid<dim, Coordinates>,
                                          GridManager<Dune::YaspGrid<dim, Coordinates>>>;
public:
    using typename ParentType::Grid;
    using ParentType::init;

    void init(const std::string& paramGroup = "")
    {
        // check if there is an image file we can construct the element selector from
        if (hasParamInGroup(paramGroup, "Grid.Image"))
        {
            const auto imgFileName = getParamFromGroup<std::string>(paramGroup, "Grid.Image");
            const auto ext = this->getFileExtension(imgFileName);
            if (ext == "pbm")
            {
                if (dim != 2)
                    DUNE_THROW(Dune::GridError, "Portable Bitmap Format only supports dim == 2");
 
                // read image
                const auto img = NetPBMReader::readPBM(imgFileName);
                createGridFromImage_(img, paramGroup);
            }
            else
                DUNE_THROW(Dune::IOError, "The SubGridManager doesn't support image files with extension: *." << ext);
 
        }
        else
            DUNE_THROW(Dune::IOError, "SubGridManager couldn't construct element selector. Specify Grid.Image in the input file!");
    }
 
private:
    template<class Img>
    void createGridFromImage_(const Img& img, const std::string& paramGroup)
    {
        // check if the number of cells matches
        std::array<int, dim> cells; cells.fill(1);
        cells = getParamFromGroup<std::array<int, dim>>(paramGroup, "Grid.Cells", cells);
 
        if (img.header().nCols != cells[0])
            DUNE_THROW(Dune::GridError, "Host grid has wrong number of cells in x-direction. Expected "
                         << img.header().nCols << ", got " << cells[0]);
        if (img.header().nRows != cells[1])
            DUNE_THROW(Dune::GridError, "Host grid has wrong number of cells in y-direction. Expected "
                         << img.header().nRows << ", got " << cells[1]);
 
 
        // construct the host grid
        this->initHostGrid_(paramGroup);
 
        // check if the marker is customized, per default
        // we mark all cells that are encoded as 0
        const bool marked = getParamFromGroup<bool>(paramGroup, "Grid.Marker", 0);
 
        // Create the selector
        auto elementSelector = [this, &img, &marked](const auto& element)
        {
            const auto eIdx = this->hostGrid_().leafGridView().indexSet().index(element);
            return img[eIdx] == marked;
        };
 
        // create the grid
        this->gridPtr() = this->createGrid_(this->hostGrid_(), elementSelector, paramGroup);
        this->loadBalance();
    }
};

template<int dim, class HostGrid>
class BoundaryFlag<Dune::SubGrid<dim, HostGrid>>
{
public:
    BoundaryFlag() : flag_(-1) {}
 
    template<class Intersection>
    BoundaryFlag(const Intersection& i) : flag_(-1) {}
 
    using value_type = int;
 
    value_type get() const
    { DUNE_THROW(Dune::NotImplemented, "Sub-grid doesn't implement boundary segment indices!"); }
 
private:
    int flag_;
};
 
} // end namespace Dumux
#endif // HAVE_DUNE_SUBGRID
#endif