bcrspattern.hh

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// -*- tab-width: 4; indent-tabs-mode: nil -*-
#ifndef DUNE_PDELAB_BACKEND_ISTL_BCRSPATTERN_HH
#define DUNE_PDELAB_BACKEND_ISTL_BCRSPATTERN_HH
 
#include <utility>
#include <vector>
#include <algorithm>
#include <set>
 
#include <dune/common/iteratorfacades.hh>
 
#include <dune/pdelab/backend/common/tags.hh>
#include <dune/pdelab/backend/common/uncachedmatrixview.hh>
#include <dune/pdelab/backend/istl/matrixhelpers.hh>
#include <dune/pdelab/backend/istl/descriptors.hh>
 
namespace Dune {
  namespace PDELab {
    namespace ISTL {
 
 
      template<typename RowOrdering, typename ColOrdering>
      class BCRSPattern
      {
 
      public:
 
        typedef typename RowOrdering::Traits::size_type size_type;
 
        typedef void SubPattern;
 
      private:
 
        static const size_type empty = ~static_cast<size_type>(0);
 
 
        struct PaddedColumnCriterion
        {
 
          bool operator()(size_type k) const
          {
            return k == _j || k == empty;
          }
 
          PaddedColumnCriterion(size_type j)
            : _j(j)
          {}
 
          const size_type _j;
 
        };
 
 
        typedef typename std::vector<size_type>::iterator IndicesIterator;
        typedef typename std::set<std::pair<size_type,size_type> >::iterator OverflowIterator;
 
        typedef typename std::vector<size_type>::const_iterator ConstIndicesIterator;
        typedef typename std::set<std::pair<size_type,size_type> >::const_iterator ConstOverflowIterator;
 
      public:
 
        template<typename RI, typename CI>
        void add_link(const RI& ri, const CI& ci)
        {
          // extract block indices for current level
          size_type i = ri.back();
          size_type j = ci.back();
 
          IndicesIterator start = _indices.begin();
          IndicesIterator begin = start + _entries_per_row*i;
          IndicesIterator end = start + _entries_per_row*(i+1);
 
          // Does the entry (i,j) already exist?
          IndicesIterator it = std::find_if(begin,end,PaddedColumnCriterion(j));
          if (it != end)
            {
              // Yes, just write out j. This does the right thing regardless of whether
              // it points at the correct column value or at an empty entry.
              *it = j;
            }
          else
            {
              // The row is already full -> spill into map
              _overflow.insert(std::make_pair(i,j));
            }
        }
 
#ifndef DOXYGEN
 
        // implementation detail for nested patterns
        template<typename RI, typename CI>
        void recursive_add_entry(const RI& ri, const CI& ci)
        {
          add_link(ri,ci);
        }
 
#endif //DOXYGEN
 
        template<typename I>
        void sizes(I rit) const
        {
          ConstIndicesIterator it = _indices.begin();
          ConstIndicesIterator end = _indices.begin() + _entries_per_row;
          ConstOverflowIterator oit = _overflow.begin();
          ConstOverflowIterator oend = _overflow.end();
          for (size_type i = 0; i < _row_ordering.blockCount(); ++i, ++rit, end+=_entries_per_row)
            {
              size_type s = 0;
              // count non-empty column entries, break when first empty one is found.
              for (; it != end; ++it)
                {
                  if (*it == empty)
                    break;
                  ++s;
                }
              it = end;
              // add overflow entries
              for (; oit != oend && oit->first == i; ++oit)
                ++s;
              *rit = s;
            }
        }
 
        std::vector<size_type> sizes() const
        {
          std::vector<size_type> r(_row_ordering.blockCount());
          sizes(r.begin());
          return r;
        }
 
        struct iterator
          : public ForwardIteratorFacade<iterator, const size_type>
        {
 
#ifndef DOXYGEN
 
          const size_type& dereference() const
          {
            if (_in_overflow)
              return _oit->second;
            else
              return *_it;
          }
 
          void increment()
          {
            if (_in_overflow)
              {
                if (++_oit == _oend or _oit->first != _row)
                  {
                    // we have exhausted the row, invalidate iterator
                    _at_end = true;
                  }
              }
            else
              {
                if (_it != _end)
                  ++_it;
                if (_it == _end || *_it == empty)
                  {
                    _in_overflow = true;
                    // we have exhausted the row, invalidate iterator
                    if (_oit == _oend || _oit->first > _row)
                      _at_end = true;
                  }
              }
          }
 
          bool equals(const iterator& other) const
          {
            if (_row != other._row)
              return false;
            if (_at_end || other._at_end)
              return _at_end && other._at_end;
            if (_in_overflow)
              return _oit == other._oit;
            else
              return _it == other._it;
          }
 
          iterator(const BCRSPattern& p, size_type row, bool at_end)
            : _row(row)
            , _in_overflow(false)
            , _at_end(at_end)
            , _it(p._indices.begin() + row * p._entries_per_row)
            , _end(p._indices.begin() + (row+1) * p._entries_per_row)
            , _oit(p._overflow.lower_bound(std::make_pair(row,0)))
            , _oend(p._overflow.end())
          {
            // catch corner case with completely empty row
            if ((!_at_end) && (_it == _end || *_it == empty))
              {
                _in_overflow = true;
                _at_end = _oit == _oend || _oit->first != _row;
              }
          }
 
          size_type _row;
          bool _in_overflow;
          bool _at_end;
          typename std::vector<size_type>::const_iterator _it;
          typename std::vector<size_type>::const_iterator _end;
          typename std::set<std::pair<size_type,size_type> >::const_iterator _oit;
          const typename std::set<std::pair<size_type,size_type> >::const_iterator _oend;
 
#endif // DOXYGEN
 
        };
 
        iterator begin(size_type i) const
        {
          return iterator(*this,i,false);
        }
 
        iterator end(size_type i) const
        {
          return iterator(*this,i,true);
        }
 
 
        BCRSPattern(const RowOrdering& row_ordering, const ColOrdering& col_ordering, size_type entries_per_row)
          : _row_ordering(row_ordering)
          , _col_ordering(col_ordering)
          , _entries_per_row(entries_per_row)
          , _indices(row_ordering.blockCount()*entries_per_row,size_type(empty))
        {}
 
        const RowOrdering& rowOrdering() const
        {
          return _row_ordering;
        }
 
        const ColOrdering& colOrdering() const
        {
          return _row_ordering;
        }
 
 
        void clear()
        {
          _indices = std::vector<size_type>();
          _overflow = std::set<std::pair<size_type,size_type> >();
        }
 
        size_type entriesPerRow() const
        {
          return _entries_per_row;
        }
 
        size_type overflowCount() const
        {
          return _overflow.size();
        }
 
      private:
 
        const RowOrdering& _row_ordering;
        const ColOrdering& _col_ordering;
        const size_type _entries_per_row;
 
        std::vector<size_type> _indices;
        std::set<std::pair<size_type,size_type> > _overflow;
 
      };
 
 
 
      template<typename RowOrdering, typename ColOrdering, typename SubPattern_>
      class NestedPattern
      {
 
      public:
 
        typedef SubPattern_ SubPattern;
 
        typedef typename SubPattern::size_type size_type;
 
 
        template<typename RI, typename CI>
        void add_link(const RI& ri, const CI& ci)
        {
          recursive_add_entry(ri.view(),ci.view());
        }
 
#ifndef DOXYGEN
 
        template<typename RI, typename CI>
        void recursive_add_entry(const RI& ri, const CI& ci)
        {
          _sub_patterns[ri.back() * _col_ordering.blockCount() + ci.back()].recursive_add_entry(ri.back_popped(),ci.back_popped());
        }
 
#endif // DOXYGEN
 
        template<typename EntriesPerRow>
        NestedPattern(const RowOrdering& row_ordering, const ColOrdering& col_ordering, const EntriesPerRow& entries_per_row)
          : _row_ordering(row_ordering)
          , _col_ordering(col_ordering)
        {
          size_type rows = row_ordering.blockCount();
          size_type cols = col_ordering.blockCount();
          for (size_type i = 0; i < rows; ++i)
            for (size_type j = 0; j < cols; ++j)
              _sub_patterns.push_back(
                SubPattern(
                  _row_ordering.childOrdering(i),
                  _col_ordering.childOrdering(j),
                  entries_per_row[i][j]
                  )
                );
        }
 
        NestedPattern(const RowOrdering& row_ordering, const ColOrdering& col_ordering, size_type entries_per_row)
          : _row_ordering(row_ordering)
          , _col_ordering(col_ordering)
        {
          size_type rows = row_ordering.blockCount();
          size_type cols = col_ordering.blockCount();
          for (size_type i = 0; i < rows; ++i)
            for (size_type j = 0; j < cols; ++j)
              _sub_patterns.push_back(
                SubPattern(
                  _row_ordering.childOrdering(i),
                  _col_ordering.childOrdering(j),
                  entries_per_row
                  )
                );
        }
 
        SubPattern& subPattern(size_type i, size_type j)
        {
          return _sub_patterns[i * _col_ordering.blockCount() + j];
        }
 
      private:
 
        const RowOrdering& _row_ordering;
        const ColOrdering& _col_ordering;
        std::vector<SubPattern> _sub_patterns;
 
      };
 
 
    } // namespace ISTL
  } // namespace PDELab
} // namespace Dune
 
#endif // DUNE_PDELAB_BACKEND_ISTL_BCRSPATTERN_HH