GridB.h

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/* Author: Ioan Sucan */

#ifndef OMPL_DATASTRUCTURES_GRID_B_
#define OMPL_DATASTRUCTURES_GRID_B_

#include "ompl/datastructures/GridN.h"
#include "ompl/datastructures/BinaryHeap.h"

namespace ompl
{

    template < typename _T,
               class LessThanExternal = std::less<_T>,
               class LessThanInternal = LessThanExternal >
    class GridB : public GridN<_T>
    {
    public:

        typedef typename GridN<_T>::Cell      Cell;

        typedef typename GridN<_T>::CellArray CellArray;

        typedef typename GridN<_T>::Coord     Coord;

    protected:

        // the type of cell here needs an extra pointer to allow the updatable heap to work fast
        // however, this stays hidden from the user
        struct CellX : public Cell
        {
            CellX() : Cell()
            {
            }

            virtual ~CellX()
            {
            }

            void *heapElement;
        };


    public:

        typedef void (*EventCellUpdate)(Cell*, void*);

        explicit
        GridB(unsigned int dimension) : GridN<_T>(dimension)
        {
            setupHeaps();
        }

        virtual ~GridB()
        {
            clearHeaps();
        }

        void onCellUpdate(EventCellUpdate event, void *arg)
        {
            eventCellUpdate_ = event;
            eventCellUpdateData_ = arg;
        }

        Cell* topInternal() const
        {
            Cell* top = static_cast<Cell*>(internal_.top()->data);
            return top ? top : topExternal();
        }

        Cell* topExternal() const
        {
            Cell* top = static_cast<Cell*>(external_.top()->data);
            return top ? top : topInternal();
        }

        unsigned int countInternal() const
        {
            return internal_.size();
        }

        unsigned int countExternal() const
        {
            return external_.size();
        }

        double fracExternal() const
        {
            return external_.empty() ? 0.0 : (double)(external_.size()) / (double)(external_.size() + internal_.size());
        }

        double fracInternal() const
        {
            return 1.0 - fracExternal();
        }

        void update(Cell* cell)
        {
            eventCellUpdate_(cell, eventCellUpdateData_);
            if (cell->border)
                external_.update(reinterpret_cast<typename externalBHeap::Element*>
                                  (static_cast<CellX*>(cell)->heapElement));
            else
                internal_.update(reinterpret_cast<typename internalBHeap::Element*>
                                  (static_cast<CellX*>(cell)->heapElement));
        }

        void updateAll()
        {
            std::vector< Cell* > cells;
            this->getCells(cells);
            for (int i = cells.size() - 1 ; i >= 0 ; --i)
                eventCellUpdate_(cells[i], eventCellUpdateData_);
            external_.rebuild();
            internal_.rebuild();
        }

        virtual Cell* createCell(const Coord& coord, CellArray *nbh = nullptr)
        {
            CellX* cell = new CellX();
            cell->coord = coord;

            CellArray *list = nbh ? nbh : new CellArray();
            this->neighbors(cell->coord, *list);

            for (typename CellArray::iterator cl = list->begin() ; cl != list->end() ; ++cl)
            {
                CellX* c = static_cast<CellX*>(*cl);
                bool wasBorder = c->border;
                c->neighbors++;
                if (c->border && c->neighbors >= GridN<_T>::interiorCellNeighborsLimit_)
                    c->border = false;

                eventCellUpdate_(c, eventCellUpdateData_);

                if (c->border)
                    external_.update(reinterpret_cast<typename externalBHeap::Element*>(c->heapElement));
                else
                {
                    if (wasBorder)
                    {
                        external_.remove(reinterpret_cast<typename externalBHeap::Element*>(c->heapElement));
                        internal_.insert(c);
                    }
                    else
                        internal_.update(reinterpret_cast<typename internalBHeap::Element*>(c->heapElement));
                }
            }

            cell->neighbors = GridN<_T>::numberOfBoundaryDimensions(cell->coord) + list->size();
            if (cell->border && cell->neighbors >= GridN<_T>::interiorCellNeighborsLimit_)
                cell->border = false;

            if (!nbh)
                delete list;

            return static_cast<Cell*>(cell);
        }

        virtual void add(Cell* cell)
        {
            CellX* ccell = static_cast<CellX*>(cell);
            eventCellUpdate_(ccell, eventCellUpdateData_);

            GridN<_T>::add(cell);

            if (cell->border)
                external_.insert(ccell);
            else
                internal_.insert(ccell);
        }

        virtual bool remove(Cell* cell)
        {
            if (cell)
            {
                CellArray *list = new CellArray();
                this->neighbors(cell->coord, *list);

                for (typename CellArray::iterator cl = list->begin() ; cl != list->end() ; ++cl)
                {
                    CellX* c = static_cast<CellX*>(*cl);
                    bool wasBorder = c->border;
                    c->neighbors--;
                    if (!c->border && c->neighbors < GridN<_T>::interiorCellNeighborsLimit_)
                        c->border = true;

                    eventCellUpdate_(c, eventCellUpdateData_);

                    if (c->border)
                    {
                        if (wasBorder)
                            external_.update(reinterpret_cast<typename externalBHeap::Element*>(c->heapElement));
                        else
                        {
                            internal_.remove(reinterpret_cast<typename internalBHeap::Element*>(c->heapElement));
                            external_.insert(c);
                        }
                    }
                    else
                        internal_.update(reinterpret_cast<typename internalBHeap::Element*>(c->heapElement));
                }

                delete list;

                typename GridN<_T>::CoordHash::iterator pos = GridN<_T>::hash_.find(&cell->coord);
                if (pos != GridN<_T>::hash_.end())
                {
                    GridN<_T>::hash_.erase(pos);
                    CellX* cx = static_cast<CellX*>(cell);
                    if (cx->border)
                        external_.remove(reinterpret_cast<typename externalBHeap::Element*>(cx->heapElement));
                    else
                        internal_.remove(reinterpret_cast<typename internalBHeap::Element*>(cx->heapElement));
                    return true;
                }
            }
            return false;
        }

        virtual void clear()
        {
            GridN<_T>::clear();
            clearHeaps();
        }

        virtual void status(std::ostream &out = std::cout) const
        {
            GridN<_T>::status(out);
            out << countInternal() << " internal cells" << std::endl;
            out << countExternal() << " external cells" << std::endl;
        }

    protected:

        EventCellUpdate          eventCellUpdate_;

        void                    *eventCellUpdateData_;

        static void noCellUpdate(Cell*, void*)
        {
        }

        void setupHeaps()
        {
            eventCellUpdate_     = &noCellUpdate;
            eventCellUpdateData_ = nullptr;
            internal_.onAfterInsert(&setHeapElementI, nullptr);
            external_.onAfterInsert(&setHeapElementE, nullptr);
        }

        void clearHeaps()
        {
            internal_.clear();
            external_.clear();
        }

        struct LessThanInternalCell
        {
            bool operator()(const CellX* const a, const CellX* const b) const
            {
                return lt_(a->data, b->data);
            }

        private:
            LessThanInternal lt_;
        };

        struct LessThanExternalCell
        {
            bool operator()(const CellX* const a, const CellX* const b) const
            {
                return lt_(a->data, b->data);
            }
        private:
            LessThanExternal lt_;
        };

        typedef BinaryHeap< CellX*, LessThanInternalCell > internalBHeap;

        typedef BinaryHeap< CellX*, LessThanExternalCell > externalBHeap;

        static void setHeapElementI(typename internalBHeap::Element *element, void*)
        {
            element->data->heapElement = reinterpret_cast<void*>(element);
        }

        static void setHeapElementE(typename externalBHeap::Element *element, void*)
        {
            element->data->heapElement = reinterpret_cast<void*>(element);
        }

        internalBHeap internal_;

        externalBHeap external_;
    };

}

#endif