Added utility for querying (only) active cells.

This will relieve us from building up a full EclipseGrid
just for filtering well connections.

opm/common/utility/ActiveGridCells.hpp

@@ -0,0 +1,79 @@
+/*
+  Copyright 2019 Equinor ASA
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#ifndef ACTIVEGRIDCELLS_HPP
+#define ACTIVEGRIDCELLS_HPP
+
+#include <opm/parser/eclipse/EclipseState/Grid/GridDims.hpp>
+
+#include <array>
+
+namespace Opm
+{
+
+/**
+ * \brief Simple class capturing active cells of a grid
+ *
+ */
+class ActiveGridCells
+    : public GridDims
+{
+public:
+    /// \brief Constructs mapping of active cells.
+    /// \param xyz The cartesian dimensions of the grid
+    /// \param globalCell Pointer to first entry of contiguous
+    ///        array mapping local index to cartesian one.
+    /// \param nc The number of cells of a grid.
+    ActiveGridCells(std::array<int, 3> xyz,
+                    const int* globalCell, std::size_t nc);
+
+    /// \brief Constructs mapping of active cells.
+    /// \param nx Number of cells in x
+    /// \param ny Number of cells in y
+    /// \param nz Number of cells in z
+    /// \param globalCell Pointer to first entry of contiguous
+    ///        array mapping local index to cartesian one.
+    /// \param nc The number of cells of a grid.
+    ActiveGridCells(std::size_t nx, std::size_t ny, std::size_t nz,
+                    const int* globalCell, std::size_t nc);
+
+    bool cellActive(std::size_t i, std::size_t j, std::size_t k) const;
+
+    bool cellActive(std::size_t cartesianIndex) const;
+
+    std::vector<int> actNum() const;
+
+    /// \brief Get the local index of a cell
+    /// \param cartesianIndex The cartesian index of the cell
+    /// \return The local index or -1 if the cell is inactive
+    int localCell(std::size_t cartesianIndex) const;
+    
+    /// \brief Get the local index of a cell
+    /// \param i The index in the i direction
+    /// \param j The index in the j direction
+    /// \param k The index in the k direction
+    /// \return The local index or -1 if the cell is inactive
+    int localCell(std::size_t i, std::size_t j, std::size_t k) const;
+protected:
+    /// \brief Maps the cartesian index to a compressed local index.
+    ///
+    /// nonactive cells are marked with -1.
+    std::vector<int> localCell_;
+};
+} // end namespace Opm
+#endif //  ACTIVEGRIDCELLS_HPP