Factored out DofStoragePolicy and related classes to own file

[[Imported from SVN: r2798]]

fem/space/dofstorage.hh

+// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+// vi: set et ts=4 sw=2 sts=2:
+#ifndef DUNE_DOFSTORAGE_HH
+#define DUNE_DOFSTORAGE_HH
+
+namespace Dune {
+
+  //! Indicates how the dofs shall be stored in the discrete functions
+  //! Point based means that all dofs belonging to one local degree in a
+  //! contained spaced are stored consecutively, whereas in the variable based
+  //! approach all dofs belonging to one subspace are stored consecutively
+  enum DofStoragePolicy { PointBased, VariableBased };
+
+  //! Utility class that helps in the transformation between dofs in the
+  //! combined space and its enclosed spaces
+  template <DofStoragePolicy p>
+  class DofConversionUtility {
+  public:
+    DofConversionUtility(int size);
+
+    void newSize(int size);
+
+    int component(int combinedIndex) const;
+    int containedDof(int combinedIndex) const;
+
+    int combinedDof(int enclosedIndex, int component) const;
+  private:
+    int size_;
+  };
+
+  template <>
+  class DofConversionUtility<PointBased> {
+  public:
+    DofConversionUtility(int numComponents) :
+      numComponents_(numComponents)
+    {}
+
+    static DofStoragePolicy policy() { return PointBased; }
+
+    void newSize(int size) {} // just do nothing
+
+    int component(int combinedIndex) const {
+      return combinedIndex%numComponents_;
+    }
+    int containedDof(int combinedIndex) const {
+      return combinedIndex/numComponents_;
+    }
+
+    int combinedDof(int containedIndex, int component) const {
+      return containedIndex*numComponents_ + component;
+    }
+
+  private:
+    const int numComponents_;
+  };
+
+  template <>
+  class DofConversionUtility<VariableBased> {
+  public:
+    DofConversionUtility(int size) :
+      size_(size)
+    {}
+
+    static DofStoragePolicy policy() { return VariableBased; }
+
+    void newSize(int size) { size_ = size; }
+
+    int component(int combinedIndex) const {
+      return combinedIndex/size_;
+    }
+    int containedDof(int combinedIndex) const {
+      return combinedIndex%size_;
+    }
+
+    int combinedDof(int containedIndex, int component) const {
+      return containedIndex + component*size_;
+    }
+
+  private:
+    int size_;
+  };
+
+} // end namespace Dune
+
+#endif