Selection of indices in an index set.

[[Imported from SVN: r135]]

istl/selection.hh

+// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+// vi: set et ts=4 sw=2 sts=2:
+// $Id$
+#ifndef DUNE_SELECTION_HH
+#define DUNE_SELECTION_HH
+
+#include "indexset.hh"
+#include <dune/common/iteratorfacades.hh>
+
+namespace Dune
+{
+  /** @addtogroup ISTL_Comm
+   *
+   * @{
+   */
+  /**
+   * @file
+   * @brief Provides classes for selecting
+   * indices base on attribute flags.
+   * @author Markus Blatt
+   */
+
+  /**
+   * @brief A const iterator over an uncached selection.
+   */
+  template<typename TS, typename TG, typename TL>
+  class SelectionIterator
+  {
+  public:
+    /**
+     * @brief The type of the Set of attributes.
+     *
+     * It has to provide a static method
+     * <pre> bool contains(AttributeType a);</pre>
+     * that returns true if a is in the set.
+     * Such types are EnumItem, EnumRange, Combine.
+     */
+    typedef TS AttributeSet;
+
+    /**
+     * @brief The type of the underlying index set.
+     */
+    typedef IndexSet<TG,TL> IndexSet;
+
+    //typedef typename IndexSet::const_iterator IndexSetIterator;
+
+    typedef ConstArrayListIterator<IndexPair<TG,TL>,100, std::allocator<Dune::IndexPair<TG,TL> > > IndexSetIterator;
+    /**
+     * @brief Constructor.
+     * @param iter The iterator over the index set.
+     * @param end The iterator over the index set positioned at the end.
+     */
+    SelectionIterator(const IndexSetIterator& iter, const IndexSetIterator& end)
+      : iter_(iter), end_(end)
+    {
+      // Step to the first valid entry
+      while(iter_!=end_ && !AttributeSet::contains(iter_->local().attribute()))
+        ++iter_;
+    }
+
+    void operator++()
+    {
+      assert(iter_!=end_);
+      for(++iter_; iter_!=end_; ++iter_)
+        if(AttributeSet::contains(iter_->local().attribute()))
+          break;
+    }
+
+
+    const uint32_t operator*() const
+    {
+      return iter_->local().local();
+    }
+
+    bool operator==(const SelectionIterator<TS,TG,TL>& other) const
+    {
+      return iter_ == other.iter_;
+    }
+
+    bool operator!=(const SelectionIterator<TS,TG,TL>& other) const
+    {
+      return iter_ != other.iter_;
+    }
+
+  private:
+    IndexSetIterator iter_;
+    const IndexSetIterator& end_;
+  };
+
+
+  /**
+   * @brief An uncached selection of indices.
+   */
+  template<typename TS, typename TG, typename TL>
+  class UncachedSelection
+  {
+  public:
+    /**
+     * @brief The type of the Set of attributes.
+     *
+     * It has to provide a static method
+     * <pre> bool contains(AttributeType a);</pre>
+     * that returns true if a is in the set.
+     * Such types are EnumItem, EnumRange, Combine.
+     */
+    typedef TS AttributeSet;
+
+    /**
+     * @brief The type of the global index of the underlying index set.
+     */
+    typedef TG GlobalIndex;
+
+    /**
+     * @brief The type of the local index of the underlying index set.
+     *
+     * It has to provide a function
+     * <pre>AttributeType attribute();</pre>
+     */
+    typedef TL LocalIndex;
+
+    /**
+     * @brief The type of the underlying index set.
+     */
+    typedef IndexSet<GlobalIndex,LocalIndex> IndexSet;
+
+    /**
+     * @brief The type of the iterator of the selected indices.
+     */
+    typedef SelectionIterator<TS,TG,TL> iterator;
+
+    /**
+     * @brief The type of the iterator of the selected indices.
+     */
+    typedef iterator const_iterator;
+
+    UncachedSelection()
+      : indexSet_()
+    {}
+
+    UncachedSelection(const IndexSet& indexset)
+      : indexSet_(&indexset)
+    {}
+    /**
+     * @brief Set the index set of the selection.
+     * @param indexset The index set to use.
+     */
+    void setIndexSet(const IndexSet& indexset);
+
+    /**
+     * @brief Get the index set we are a selection for.
+     */
+    //const IndexSet& indexSet() const;
+
+    /**
+     * @brief Get an iterator over the selected indices.
+     * @return An iterator positioned at the first selected index.
+     */
+    const_iterator begin() const;
+
+    /**
+     * @brief Get an iterator over the selected indices.
+     * @return An iterator positioned at the first selected index.
+     */
+    const_iterator end() const;
+
+
+  private:
+    const IndexSet* indexSet_;
+
+  };
+
+
+
+  /**
+   * @brief An cached selection of indices.
+   */
+  template<typename TS, typename TG, typename TL>
+  class Selection
+  {
+  public:
+    /**
+     * @brief The type of the Set of attributes.
+     *
+     * It has to provide a static method
+     * <pre> bool contains(AttributeType a);</pre>
+     * that returns true if a is in the set.
+     * Such types are EnumItem, EnumRange, Combine.
+     */
+    typedef TS AttributeSet;
+
+    /**
+     * @brief The type of the global index of the underlying index set.
+     */
+    typedef TG GlobalIndex;
+
+    /**
+     * @brief The type of the local index of the underlying index set.
+     *
+     * It has to provide a function
+     * <pre>AttributeType attribute();</pre>
+     */
+    typedef TL LocalIndex;
+
+    /**
+     * @brief The type of the underlying index set.
+     */
+    typedef IndexSet<GlobalIndex,LocalIndex> IndexSet;
+
+    /**
+     * @brief The type of the iterator of the selected indices.
+     */
+    typedef uint32_t* iterator;
+
+    /**
+     * @brief The type of the iterator of the selected indices.
+     */
+    typedef uint32_t* const_iterator;
+
+    Selection()
+      : selected_()
+    {}
+
+    Selection(const IndexSet& indexset)
+      : selected_(), size_(0), built_(false)
+    {
+      setIndexSet(indexset);
+    }
+
+    ~Selection();
+
+    /**
+     * @brief Set the index set of the selection.
+     * @param indexset The index set to use.
+     */
+    void setIndexSet(const IndexSet& indexset);
+
+    /**
+     * @brief Free allocated memory.
+     */
+    void free();
+
+    /**
+     * @brief Get the index set we are a selection for.
+     */
+    //IndexSet indexSet() const;
+
+    /**
+     * @brief Get an iterator over the selected indices.
+     * @return An iterator positioned at the first selected index.
+     */
+    const_iterator begin() const;
+
+    /**
+     * @brief Get an iterator over the selected indices.
+     * @return An iterator positioned at the first selected index.
+     */
+    const_iterator end() const;
+
+
+  private:
+    uint32_t* selected_;
+    size_t size_;
+    bool built_;
+
+  };
+
+  template<typename TS, typename TG, typename TL>
+  inline void Selection<TS,TG,TL>::setIndexSet(const IndexSet& indexset)
+  {
+    if(built_)
+      free();
+
+    // Count the number of entries the selection has to hold
+    typedef typename IndexSet::const_iterator const_iterator;
+    const const_iterator end = indexset.end();
+    int entries = 0;
+
+    for(const_iterator index = indexset.begin(); index != end; ++index)
+      if(AttributeSet::contains(index->local().attribute()))
+        ++entries;
+
+    selected_ = new uint32_t[entries];
+    built_ = true;
+
+    entries = 0;
+    for(const_iterator index = indexset.begin(); index != end; ++index)
+      if(AttributeSet::contains(index->local().attribute()))
+        selected_[entries++]= index->local().local();
+
+    size_=entries;
+    built_=true;
+  }
+
+  template<typename TS, typename TG, typename TL>
+  uint32_t* Selection<TS,TG,TL>::begin() const
+  {
+    return selected_;
+  }
+
+  template<typename TS, typename TG, typename TL>
+  uint32_t* Selection<TS,TG,TL>::end() const
+  {
+    return selected_+size_;
+  }
+
+  template<typename TS, typename TG, typename TL>
+  inline void Selection<TS,TG,TL>::free()
+  {
+    delete[] selected_;
+    size_=0;
+    built_=false;
+  }
+
+  template<typename TS, typename TG, typename TL>
+  inline Selection<TS,TG,TL>::~Selection()
+  {
+    if(built_)
+      free();
+  }
+
+  template<typename TS, typename TG, typename TL>
+  SelectionIterator<TS,TG,TL> UncachedSelection<TS,TG,TL>::begin() const
+  {
+    return SelectionIterator<TS,TG,TL>(indexSet_->begin(),
+                                       indexSet_->end());
+  }
+
+  template<typename TS, typename TG, typename TL>
+  SelectionIterator<TS,TG,TL> UncachedSelection<TS,TG,TL>::end() const
+  {
+    return SelectionIterator<TS,TG,TL>(indexSet_->end(),
+                                       indexSet_->end());
+  }
+  template<typename TS, typename TG, typename TL>
+  void UncachedSelection<TS,TG,TL>::setIndexSet(const IndexSet& indexset)
+  {
+    indexSet_ = &indexset;
+  }
+
+  /** @} */
+
+
+}
+#endif