# HG changeset patch
# User alpar
# Date 1094221563 0
# Node ID a76d8d52b25cbd2a8a53249d9898d1b62f415b1b
# Parent  b0a427f60edb90243fc1eca5991a39411d49a434
Skeleton for paths.

diff -r b0a427f60edb -r a76d8d52b25c src/hugo/skeletons/path.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hugo/skeletons/path.h	Fri Sep 03 14:26:03 2004 +0000
@@ -0,0 +1,1172 @@
+// -*- c++ -*- //
+
+/**
+@defgroup paths Path Structures
+@ingroup datas
+\brief Path structures implemented in Hugo.
+
+Hugolib provides flexible data structures
+to work with paths.
+
+All of them have the same interface, especially they can be built or extended
+using a standard Builder subclass. This make is easy to have e.g. the Dijkstra
+algorithm to store its result in any kind of path structure.
+
+*/
+
+///\ingroup paths
+///\file
+///\brief Classes for representing paths in graphs.
+
+#ifndef HUGO_PATH_H
+#define HUGO_PATH_H
+
+#include <deque>
+#include <vector>
+#include <algorithm>
+
+#include <hugo/invalid.h>
+#include <hugo/error.h>
+#include <debug.h>
+
+namespace hugo {
+
+  /// \addtogroup paths
+  /// @{
+
+
+  //! \brief A structure for representing directed path in a graph.
+  //!
+  //! A structure for representing directed path in a graph.
+  //! \param Graph The graph type in which the path is.
+  //! \param DM DebugMode, defaults to DefaultDebugMode.
+  //! 
+  //! In a sense, the path can be treated as a graph, for is has \c NodeIt
+  //! and \c EdgeIt with the same usage. These types converts to the \c Node
+  //! and \c Edge of the original graph.
+  //!
+  //! \todo Thoroughfully check all the range and consistency tests.
+  template<typename Graph, typename DM = DefaultDebugMode>
+  class DirPath {
+  public:
+    /// Edge type of the underlying graph.
+    typedef typename Graph::Edge GraphEdge; 
+    /// Node type of the underlying graph.
+    typedef typename Graph::Node GraphNode;
+    class NodeIt;
+    class EdgeIt;
+
+  protected:
+    const Graph *gr;
+    typedef std::vector<GraphEdge> Container;
+    Container edges;
+
+  public:
+
+    /// \param _G The graph in which the path is.
+    ///
+    DirPath(const Graph &_G) : gr(&_G) {}
+
+    /// \brief Subpath constructor.
+    ///
+    /// Subpath defined by two nodes.
+    /// \warning It is an error if the two edges are not in order!
+    DirPath(const DirPath &P, const NodeIt &a, const NodeIt &b) {
+      if( DM::range_check && (!a.valid() || !b.valid) ) {
+	// FIXME: this check should be more elaborate...
+	fault("DirPath, subpath ctor: invalid bounding nodes");
+      }
+      gr = P.gr;
+      edges.insert(edges.end(), P.edges.begin()+a.idx, P.edges.begin()+b.idx);
+    }
+
+    /// \brief Subpath constructor.
+    ///
+    /// Subpath defined by two edges. Contains edges in [a,b)
+    /// \warning It is an error if the two edges are not in order!
+    DirPath(const DirPath &P, const EdgeIt &a, const EdgeIt &b) {
+      if( DM::range_check && (!a.valid() || !b.valid) ) {
+	// FIXME: this check should be more elaborate...
+	fault("DirPath, subpath ctor: invalid bounding nodes");
+      }
+      gr = P.gr;
+      edges.insert(edges.end(), P.edges.begin()+a.idx, P.edges.begin()+b.idx);
+    }
+
+    /// Length of the path.
+    size_t length() const { return edges.size(); }
+    /// Returns whether the path is empty.
+    bool empty() const { return edges.empty(); }
+
+    /// Resets the path to an empty path.
+    void clear() { edges.clear(); }
+
+    /// \brief Starting point of the path.
+    ///
+    /// Starting point of the path.
+    /// Returns INVALID if the path is empty.
+    GraphNode from() const {
+      return empty() ? INVALID : gr->tail(edges[0]);
+    }
+    /// \brief End point of the path.
+    ///
+    /// End point of the path.
+    /// Returns INVALID if the path is empty.
+    GraphNode to() const {
+      return empty() ? INVALID : gr->head(edges[length()-1]);
+    }
+
+    /// \brief Initializes node or edge iterator to point to the first
+    /// node or edge.
+    ///
+    /// \sa nth
+    template<typename It>
+    It& first(It &i) const { return i=It(*this); }
+
+    /// \brief Initializes node iterator to point to the node of a given index.
+    NodeIt& nth(NodeIt &i, int n) const {
+      if( DM::range_check && (n<0 || n>int(length())) )
+	fault("DirPath::nth: index out of range");
+      return i=NodeIt(*this, n);
+    }
+
+    /// \brief Initializes edge iterator to point to the edge of a given index.
+    EdgeIt& nth(EdgeIt &i, int n) const {
+      if( DM::range_check && (n<0 || n>=int(length())) )
+	fault("DirPath::nth: index out of range");
+      return i=EdgeIt(*this, n);
+    }
+
+    /// Checks validity of a node or edge iterator.
+    template<typename It>
+    static
+    bool valid(const It &i) { return i.valid(); }
+
+    /// Steps the given node or edge iterator.
+    template<typename It>
+    static
+    It& next(It &e) {
+      if( DM::range_check && !e.valid() )
+	fault("DirPath::next() on invalid iterator");
+      return ++e;
+    }
+
+    /// \brief Returns node iterator pointing to the head node of the
+    /// given edge iterator.
+    NodeIt head(const EdgeIt& e) const {
+      if( DM::range_check && !e.valid() )
+	fault("DirPath::head() on invalid iterator");
+      return NodeIt(*this, e.idx+1);
+    }
+
+    /// \brief Returns node iterator pointing to the tail node of the
+    /// given edge iterator.
+    NodeIt tail(const EdgeIt& e) const {
+      if( DM::range_check && !e.valid() )
+	fault("DirPath::tail() on invalid iterator");
+      return NodeIt(*this, e.idx);
+    }
+
+
+    /* Iterator classes */
+
+    /**
+     * \brief Iterator class to iterate on the edges of the paths
+     * 
+     * \ingroup paths
+     * This class is used to iterate on the edges of the paths
+     *
+     * Of course it converts to Graph::Edge
+     * 
+     * \todo Its interface differs from the standard edge iterator.
+     * Yes, it shouldn't.
+     */
+    class EdgeIt {
+      friend class DirPath;
+
+      int idx;
+      const DirPath *p;
+    public:
+      /// Default constructor
+      EdgeIt() {}
+      /// Invalid constructor
+      EdgeIt(Invalid) : idx(-1), p(0) {}
+      /// Constructor with starting point
+      EdgeIt(const DirPath &_p, int _idx = 0) :
+	idx(_idx), p(&_p) { validate(); }
+
+      ///Validity check
+      bool valid() const { return idx!=-1; }
+
+      ///Conversion to Graph::Edge
+      operator GraphEdge () const {
+	return valid() ? p->edges[idx] : INVALID;
+      }
+
+      /// Next edge
+      EdgeIt& operator++() { ++idx; validate(); return *this; }
+
+      /// Comparison operator
+      bool operator==(const EdgeIt& e) const { return idx==e.idx; }
+      /// Comparison operator
+      bool operator!=(const EdgeIt& e) const { return idx!=e.idx; }
+      /// Comparison operator
+      bool operator<(const EdgeIt& e) const { return idx<e.idx; }
+
+    private:
+      // FIXME: comparison between signed and unsigned...
+      // Jo ez igy? Vagy esetleg legyen a length() int?
+      void validate() { if( size_t(idx) >= p->length() ) idx=-1; }
+    };
+
+    /**
+     * \brief Iterator class to iterate on the nodes of the paths
+     * 
+     * \ingroup paths
+     * This class is used to iterate on the nodes of the paths
+     *
+     * Of course it converts to Graph::Node
+     * 
+     * \todo Its interface differs from the standard node iterator.
+     * Yes, it shouldn't.
+     */
+    class NodeIt {
+      friend class DirPath;
+
+      int idx;
+      const DirPath *p;
+    public:
+      /// Default constructor
+      NodeIt() {}
+      /// Invalid constructor
+      NodeIt(Invalid) : idx(-1), p(0) {}
+      /// Constructor with starting point
+      NodeIt(const DirPath &_p, int _idx = 0) :
+	idx(_idx), p(&_p) { validate(); }
+
+      ///Validity check
+      bool valid() const { return idx!=-1; }
+
+      ///Conversion to Graph::Node
+      operator const GraphNode& () const {
+	if(idx >= p->length())
+	  return p->to();
+	else if(idx >= 0)
+	  return p->gr->tail(p->edges[idx]);
+	else
+	  return INVALID;
+      }
+      /// Next node
+      NodeIt& operator++() { ++idx; validate(); return *this; }
+
+      /// Comparison operator
+      bool operator==(const NodeIt& e) const { return idx==e.idx; }
+      /// Comparison operator
+      bool operator!=(const NodeIt& e) const { return idx!=e.idx; }
+      /// Comparison operator
+      bool operator<(const NodeIt& e) const { return idx<e.idx; }
+
+    private:
+      void validate() { if( size_t(idx) > p->length() ) idx=-1; }
+    };
+
+    friend class Builder;    
+
+    /**
+     * \brief Class to build paths
+     * 
+     * \ingroup paths
+     * This class is used to fill a path with edges.
+     *
+     * You can push new edges to the front and to the back of the path in
+     * arbitrary order then you should commit these changes to the graph.
+     *
+     * Fundamentally, for most "Paths" (classes fulfilling the
+     * PathConcept) while the builder is active (after the first modifying
+     * operation and until the commit()) the original Path is in a
+     * "transitional" state (operations on it have undefined result). But
+     * in the case of DirPath the original path remains unchanged until the
+     * commit. However we don't recomend that you use this feature.
+     */
+    class Builder {
+      DirPath &P;
+      Container front, back;
+
+    public:
+      ///\param _P the path you want to fill in.
+      ///
+      Builder(DirPath &_P) : P(_P) {}
+
+      /// Sets the starting node of the path.
+      
+      /// Sets the starting node of the path. Edge added to the path
+      /// afterwards have to be incident to this node.
+      /// It should be called iff the path is empty and before any call to
+      /// \ref pushFront() or \ref pushBack()
+      void setStart(const GraphNode &) {}
+
+      ///Push a new edge to the front of the path
+
+      ///Push a new edge to the front of the path.
+      ///\sa setStart
+      void pushFront(const GraphEdge& e) {
+	if( DM::consistensy_check && !empty() && P.gr->head(e)!=from() ) {
+	  fault("DirPath::Builder::pushFront: nonincident edge");
+	}
+	front.push_back(e);
+      }
+
+      ///Push a new edge to the back of the path
+
+      ///Push a new edge to the back of the path.
+      ///\sa setStart
+      void pushBack(const GraphEdge& e) {
+	if( DM::consistensy_check && !empty() && P.gr->tail(e)!=to() ) {
+	  fault("DirPath::Builder::pushBack: nonincident edge");
+	}
+	back.push_back(e);
+      }
+
+      ///Commit the changes to the path.
+      void commit() {
+	if( !(front.empty() && back.empty()) ) {
+	  Container tmp;
+	  tmp.reserve(front.size()+back.size()+P.length());
+	  tmp.insert(tmp.end(), front.rbegin(), front.rend());
+	  tmp.insert(tmp.end(), P.edges.begin(), P.edges.end());
+	  tmp.insert(tmp.end(), back.begin(), back.end());
+	  P.edges.swap(tmp);
+	  front.clear();
+	  back.clear();
+	}
+      }
+
+      // FIXME: Hmm, pontosan hogy is kene ezt csinalni?
+      // Hogy kenyelmes egy ilyet hasznalni?
+  
+      ///Reserve storage in advance for the builder
+
+      ///If you know an reasonable upper bound of the number of the edges
+      ///to add, using this function you can speed up the building.
+      void reserve(size_t r) {
+	front.reserve(r);
+	back.reserve(r);
+      }
+
+    private:
+      bool empty() {
+	return front.empty() && back.empty() && P.empty();
+      }
+
+      GraphNode from() const {
+	if( ! front.empty() )
+	  return P.gr->tail(front[front.size()-1]);
+	else if( ! P.empty() )
+	  return P.gr->tail(P.edges[0]);
+	else if( ! back.empty() )
+	  return P.gr->tail(back[0]);
+	else
+	  return INVALID;
+      }
+      GraphNode to() const {
+	if( ! back.empty() )
+	  return P.gr->head(back[back.size()-1]);
+	else if( ! P.empty() )
+	  return P.gr->head(P.edges[P.length()-1]);
+	else if( ! front.empty() )
+	  return P.gr->head(front[0]);
+	else
+	  return INVALID;
+      }
+
+    };
+
+  };
+
+
+
+
+
+
+
+
+
+
+  /**********************************************************************/
+
+
+  //! \brief A structure for representing undirected path in a graph.
+  //!
+  //! A structure for representing undirected path in a graph. Ie. this is
+  //! a path in a \e directed graph but the edges should not be directed
+  //! forward.
+  //!
+  //! \param Graph The graph type in which the path is.
+  //! \param DM DebugMode, defaults to DefaultDebugMode.
+  //! 
+  //! In a sense, the path can be treated as a graph, for is has \c NodeIt
+  //! and \c EdgeIt with the same usage. These types converts to the \c Node
+  //! and \c Edge of the original graph.
+  //!
+  //! \todo Thoroughfully check all the range and consistency tests.
+  template<typename Graph, typename DM = DefaultDebugMode>
+  class UndirPath {
+  public:
+    /// Edge type of the underlying graph.
+    typedef typename Graph::Edge GraphEdge;
+     /// Node type of the underlying graph.
+   typedef typename Graph::Node GraphNode;
+    class NodeIt;
+    class EdgeIt;
+
+  protected:
+    const Graph *gr;
+    typedef std::vector<GraphEdge> Container;
+    Container edges;
+
+  public:
+
+    /// \param _G The graph in which the path is.
+    ///
+    UndirPath(const Graph &_G) : gr(&_G) {}
+
+    /// \brief Subpath constructor.
+    ///
+    /// Subpath defined by two nodes.
+    /// \warning It is an error if the two edges are not in order!
+    UndirPath(const UndirPath &P, const NodeIt &a, const NodeIt &b) {
+      if( DM::range_check && (!a.valid() || !b.valid) ) {
+	// FIXME: this check should be more elaborate...
+	fault("UndirPath, subpath ctor: invalid bounding nodes");
+      }
+      gr = P.gr;
+      edges.insert(edges.end(), P.edges.begin()+a.idx, P.edges.begin()+b.idx);
+    }
+
+    /// \brief Subpath constructor.
+    ///
+    /// Subpath defined by two edges. Contains edges in [a,b)
+    /// \warning It is an error if the two edges are not in order!
+    UndirPath(const UndirPath &P, const EdgeIt &a, const EdgeIt &b) {
+      if( DM::range_check && (!a.valid() || !b.valid) ) {
+	// FIXME: this check should be more elaborate...
+	fault("UndirPath, subpath ctor: invalid bounding nodes");
+      }
+      gr = P.gr;
+      edges.insert(edges.end(), P.edges.begin()+a.idx, P.edges.begin()+b.idx);
+    }
+
+    /// Length of the path.
+    size_t length() const { return edges.size(); }
+    /// Returns whether the path is empty.
+    bool empty() const { return edges.empty(); }
+
+    /// Resets the path to an empty path.
+    void clear() { edges.clear(); }
+
+    /// \brief Starting point of the path.
+    ///
+    /// Starting point of the path.
+    /// Returns INVALID if the path is empty.
+    GraphNode from() const {
+      return empty() ? INVALID : gr->tail(edges[0]);
+    }
+    /// \brief End point of the path.
+    ///
+    /// End point of the path.
+    /// Returns INVALID if the path is empty.
+    GraphNode to() const {
+      return empty() ? INVALID : gr->head(edges[length()-1]);
+    }
+
+    /// \brief Initializes node or edge iterator to point to the first
+    /// node or edge.
+    ///
+    /// \sa nth
+    template<typename It>
+    It& first(It &i) const { return i=It(*this); }
+
+    /// \brief Initializes node iterator to point to the node of a given index.
+    NodeIt& nth(NodeIt &i, int n) const {
+      if( DM::range_check && (n<0 || n>int(length())) )
+	fault("UndirPath::nth: index out of range");
+      return i=NodeIt(*this, n);
+    }
+
+    /// \brief Initializes edge iterator to point to the edge of a given index.
+    EdgeIt& nth(EdgeIt &i, int n) const {
+      if( DM::range_check && (n<0 || n>=int(length())) )
+	fault("UndirPath::nth: index out of range");
+      return i=EdgeIt(*this, n);
+    }
+
+    /// Checks validity of a node or edge iterator.
+    template<typename It>
+    static
+    bool valid(const It &i) { return i.valid(); }
+
+    /// Steps the given node or edge iterator.
+    template<typename It>
+    static
+    It& next(It &e) {
+      if( DM::range_check && !e.valid() )
+	fault("UndirPath::next() on invalid iterator");
+      return ++e;
+    }
+
+    /// \brief Returns node iterator pointing to the head node of the
+    /// given edge iterator.
+    NodeIt head(const EdgeIt& e) const {
+      if( DM::range_check && !e.valid() )
+	fault("UndirPath::head() on invalid iterator");
+      return NodeIt(*this, e.idx+1);
+    }
+
+    /// \brief Returns node iterator pointing to the tail node of the
+    /// given edge iterator.
+    NodeIt tail(const EdgeIt& e) const {
+      if( DM::range_check && !e.valid() )
+	fault("UndirPath::tail() on invalid iterator");
+      return NodeIt(*this, e.idx);
+    }
+
+
+
+    /**
+     * \brief Iterator class to iterate on the edges of the paths
+     * 
+     * \ingroup paths
+     * This class is used to iterate on the edges of the paths
+     *
+     * Of course it converts to Graph::Edge
+     * 
+     * \todo Its interface differs from the standard edge iterator.
+     * Yes, it shouldn't.
+     */
+    class EdgeIt {
+      friend class UndirPath;
+
+      int idx;
+      const UndirPath *p;
+    public:
+      /// Default constructor
+      EdgeIt() {}
+      /// Invalid constructor
+      EdgeIt(Invalid) : idx(-1), p(0) {}
+      /// Constructor with starting point
+      EdgeIt(const UndirPath &_p, int _idx = 0) :
+	idx(_idx), p(&_p) { validate(); }
+
+      ///Validity check
+      bool valid() const { return idx!=-1; }
+
+      ///Conversion to Graph::Edge
+      operator GraphEdge () const {
+	return valid() ? p->edges[idx] : INVALID;
+      }
+      /// Next edge
+     EdgeIt& operator++() { ++idx; validate(); return *this; }
+
+      /// Comparison operator
+      bool operator==(const EdgeIt& e) const { return idx==e.idx; }
+      /// Comparison operator
+      bool operator!=(const EdgeIt& e) const { return idx!=e.idx; }
+      /// Comparison operator
+      bool operator<(const EdgeIt& e) const { return idx<e.idx; }
+
+    private:
+      // FIXME: comparison between signed and unsigned...
+      // Jo ez igy? Vagy esetleg legyen a length() int?
+      void validate() { if( size_t(idx) >= p->length() ) idx=-1; }
+    };
+
+    /**
+     * \brief Iterator class to iterate on the nodes of the paths
+     * 
+     * \ingroup paths
+     * This class is used to iterate on the nodes of the paths
+     *
+     * Of course it converts to Graph::Node
+     * 
+     * \todo Its interface differs from the standard node iterator.
+     * Yes, it shouldn't.
+     */
+    class NodeIt {
+      friend class UndirPath;
+
+      int idx;
+      const UndirPath *p;
+    public:
+      /// Default constructor
+      NodeIt() {}
+      /// Invalid constructor
+      NodeIt(Invalid) : idx(-1), p(0) {}
+      /// Constructor with starting point
+      NodeIt(const UndirPath &_p, int _idx = 0) :
+	idx(_idx), p(&_p) { validate(); }
+
+      ///Validity check
+      bool valid() const { return idx!=-1; }
+
+      ///Conversion to Graph::Node
+      operator const GraphNode& () const {
+	if(idx >= p->length())
+	  return p->to();
+	else if(idx >= 0)
+	  return p->gr->tail(p->edges[idx]);
+	else
+	  return INVALID;
+      }
+      /// Next node
+      NodeIt& operator++() { ++idx; validate(); return *this; }
+
+      /// Comparison operator
+      bool operator==(const NodeIt& e) const { return idx==e.idx; }
+      /// Comparison operator
+      bool operator!=(const NodeIt& e) const { return idx!=e.idx; }
+       /// Comparison operator
+     bool operator<(const NodeIt& e) const { return idx<e.idx; }
+
+    private:
+      void validate() { if( size_t(idx) > p->length() ) idx=-1; }
+    };
+
+    friend class Builder;    
+
+    /**
+     * \brief Class to build paths
+     * 
+     * \ingroup paths
+     * This class is used to fill a path with edges.
+     *
+     * You can push new edges to the front and to the back of the path in
+     * arbitrary order then you should commit these changes to the graph.
+     *
+     * Fundamentally, for most "Paths" (classes fulfilling the
+     * PathConcept) while the builder is active (after the first modifying
+     * operation and until the commit()) the original Path is in a
+     * "transitional" state (operations ot it have undefined result). But
+     * in the case of UndirPath the original path is unchanged until the
+     * commit. However we don't recomend that you use this feature.
+     */
+    class Builder {
+      UndirPath &P;
+      Container front, back;
+
+    public:
+      ///\param _P the path you want to fill in.
+      ///
+      Builder(UndirPath &_P) : P(_P) {}
+
+      /// Sets the starting node of the path.
+      
+      /// Sets the starting node of the path. Edge added to the path
+      /// afterwards have to be incident to this node.
+      /// It should be called iff the path is empty and before any call to
+      /// \ref pushFront() or \ref pushBack()
+      void setStart(const GraphNode &) {}
+
+      ///Push a new edge to the front of the path
+
+      ///Push a new edge to the front of the path.
+      ///\sa setStart
+      void pushFront(const GraphEdge& e) {
+	if( DM::consistensy_check && !empty() && P.gr->head(e)!=from() ) {
+	  fault("UndirPath::Builder::pushFront: nonincident edge");
+	}
+	front.push_back(e);
+      }
+
+      ///Push a new edge to the back of the path
+
+      ///Push a new edge to the back of the path.
+      ///\sa setStart
+      void pushBack(const GraphEdge& e) {
+	if( DM::consistensy_check && !empty() && P.gr->tail(e)!=to() ) {
+	  fault("UndirPath::Builder::pushBack: nonincident edge");
+	}
+	back.push_back(e);
+      }
+
+      ///Commit the changes to the path.
+      void commit() {
+	if( !(front.empty() && back.empty()) ) {
+	  Container tmp;
+	  tmp.reserve(front.size()+back.size()+P.length());
+	  tmp.insert(tmp.end(), front.rbegin(), front.rend());
+	  tmp.insert(tmp.end(), P.edges.begin(), P.edges.end());
+	  tmp.insert(tmp.end(), back.begin(), back.end());
+	  P.edges.swap(tmp);
+	  front.clear();
+	  back.clear();
+	}
+      }
+
+      // FIXME: Hmm, pontosan hogy is kene ezt csinalni?
+      // Hogy kenyelmes egy ilyet hasznalni?
+
+      ///Reserve storage in advance for the builder
+
+      ///If you know an reasonable upper bound of the number of the edges
+      ///to add, using this function you can speed up the building.
+       void reserve(size_t r) {
+	front.reserve(r);
+	back.reserve(r);
+      }
+
+    private:
+      bool empty() {
+	return front.empty() && back.empty() && P.empty();
+      }
+
+      GraphNode from() const {
+	if( ! front.empty() )
+	  return P.gr->tail(front[front.size()-1]);
+	else if( ! P.empty() )
+	  return P.gr->tail(P.edges[0]);
+	else if( ! back.empty() )
+	  return P.gr->tail(back[0]);
+	else
+	  return INVALID;
+      }
+      GraphNode to() const {
+	if( ! back.empty() )
+	  return P.gr->head(back[back.size()-1]);
+	else if( ! P.empty() )
+	  return P.gr->head(P.edges[P.length()-1]);
+	else if( ! front.empty() )
+	  return P.gr->head(front[0]);
+	else
+	  return INVALID;
+      }
+
+    };
+
+  };
+
+
+
+
+
+
+
+
+
+
+  /**********************************************************************/
+
+
+  /* Ennek az allocatorosdinak sokkal jobban utana kene nezni a hasznalata
+     elott. Eleg bonyinak nez ki, ahogyan azokat az STL-ben hasznaljak. */
+
+  template<typename Graph>
+  class DynamicPath {
+
+  public:
+    typedef typename Graph::Edge GraphEdge;
+    typedef typename Graph::Node GraphNode;
+    class NodeIt;
+    class EdgeIt;
+
+  protected:
+    Graph& G;
+    // FIXME: ehelyett eleg lenne tarolni ket boolt: a ket szelso el
+    // iranyitasat:
+    GraphNode _first, _last;
+    typedef std::deque<GraphEdge> Container;
+    Container edges;
+
+  public:
+
+    DynamicPath(Graph &_G) : G(_G), _first(INVALID), _last(INVALID) {}
+
+    /// Subpath defined by two nodes.
+    /// Nodes may be in reversed order, then
+    /// we contstruct the reversed path.
+    DynamicPath(const DynamicPath &P, const NodeIt &a, const NodeIt &b);
+    /// Subpath defined by two edges. Contains edges in [a,b)
+    /// It is an error if the two edges are not in order!
+    DynamicPath(const DynamicPath &P, const EdgeIt &a, const EdgeIt &b);
+    
+    size_t length() const { return edges.size(); }
+    GraphNode from() const { return _first; }
+    GraphNode to() const { return _last; }
+
+    NodeIt& first(NodeIt &n) const { return nth(n, 0); }
+    EdgeIt& first(EdgeIt &e) const { return nth(e, 0); }
+    template<typename It>
+    It first() const { 
+      It e;
+      first(e);
+      return e; 
+    }
+
+    NodeIt& nth(NodeIt &, size_t) const;
+    EdgeIt& nth(EdgeIt &, size_t) const;
+    template<typename It>
+    It nth(size_t n) const { 
+      It e;
+      nth(e, n);
+      return e; 
+    }
+
+    bool valid(const NodeIt &n) const { return n.idx <= length(); }
+    bool valid(const EdgeIt &e) const { return e.it < edges.end(); }
+
+    bool isForward(const EdgeIt &e) const { return e.forw; }
+
+    /// index of a node on the path. Returns length+2 for the invalid NodeIt
+    int index(const NodeIt &n) const { return n.idx; }
+    /// index of an edge on the path. Returns length+1 for the invalid EdgeIt
+    int index(const EdgeIt &e) const { return e.it - edges.begin(); }
+
+    EdgeIt& next(EdgeIt &e) const;
+    NodeIt& next(NodeIt &n) const;
+    template <typename It>
+    It getNext(It it) const {
+      It tmp(it); return next(tmp);
+    }
+
+    // A path is constructed using the following four functions.
+    // They return false if the requested operation is inconsistent
+    // with the path constructed so far.
+    // If your path has only one edge you MUST set either "from" or "to"!
+    // So you probably SHOULD call it in any case to be safe (and check the
+    // returned value to check if your path is consistent with your idea).
+    bool pushFront(const GraphEdge &e);
+    bool pushBack(const GraphEdge &e);
+    bool setFrom(const GraphNode &n);
+    bool setTo(const GraphNode &n);
+
+    // WARNING: these two functions return the head/tail of an edge with
+    // respect to the direction of the path!
+    // So G.head(P.graphEdge(e)) == P.graphNode(P.head(e)) holds only if 
+    // P.forward(e) is true (or the edge is a loop)!
+    NodeIt head(const EdgeIt& e) const;
+    NodeIt tail(const EdgeIt& e) const;
+
+    // FIXME: ezeknek valami jobb nev kellene!!!
+    GraphEdge graphEdge(const EdgeIt& e) const;
+    GraphNode graphNode(const NodeIt& n) const;
+
+
+    /*** Iterator classes ***/
+    class EdgeIt {
+      friend class DynamicPath;
+
+      typename Container::const_iterator it;
+      bool forw;
+    public:
+      // FIXME: jarna neki ilyen is...
+      // EdgeIt(Invalid);
+
+      bool forward() const { return forw; }
+
+      bool operator==(const EdgeIt& e) const { return it==e.it; }
+      bool operator!=(const EdgeIt& e) const { return it!=e.it; }
+      bool operator<(const EdgeIt& e) const { return it<e.it; }
+    };
+
+    class NodeIt {
+      friend class DynamicPath;
+
+      size_t idx;
+      bool tail;  // Is this node the tail of the edge with same idx?
+
+    public:
+      // FIXME: jarna neki ilyen is...
+      // NodeIt(Invalid);
+
+      bool operator==(const NodeIt& n) const { return idx==n.idx; }
+      bool operator!=(const NodeIt& n) const { return idx!=n.idx; }
+      bool operator<(const NodeIt& n) const { return idx<n.idx; }
+    };
+
+  private:
+    bool edgeIncident(const GraphEdge &e, const GraphNode &a,
+		      GraphNode &b);
+    bool connectTwoEdges(const GraphEdge &e, const GraphEdge &f);
+  };
+
+  template<typename Gr>
+  typename DynamicPath<Gr>::EdgeIt&
+  DynamicPath<Gr>::next(DynamicPath::EdgeIt &e) const {
+    if( e.it == edges.end() ) 
+      return e;
+
+    GraphNode common_node = ( e.forw ? G.head(*e.it) : G.tail(*e.it) );
+    ++e.it;
+
+    // Invalid edgeit is always forward :)
+    if( e.it == edges.end() ) {
+      e.forw = true;
+      return e;
+    }
+
+    e.forw = ( G.tail(*e.it) == common_node );
+    return e;
+  }
+
+  template<typename Gr>
+  typename DynamicPath<Gr>::NodeIt& DynamicPath<Gr>::next(NodeIt &n) const {
+    if( n.idx >= length() ) {
+      // FIXME: invalid
+      n.idx = length()+1;
+      return n;
+    }
+
+    
+    GraphNode next_node = ( n.tail ? G.head(edges[n.idx]) :
+			      G.tail(edges[n.idx]) );
+    ++n.idx;
+    if( n.idx < length() ) {
+      n.tail = ( next_node == G.tail(edges[n.idx]) );
+    }
+    else {
+      n.tail = true;
+    }
+
+    return n;
+  }
+
+  template<typename Gr>
+  bool DynamicPath<Gr>::edgeIncident(const GraphEdge &e, const GraphNode &a,
+			  GraphNode &b) {
+    if( G.tail(e) == a ) {
+      b=G.head(e);
+      return true;
+    }
+    if( G.head(e) == a ) {
+      b=G.tail(e);
+      return true;
+    }
+    return false;
+  }
+
+  template<typename Gr>
+  bool DynamicPath<Gr>::connectTwoEdges(const GraphEdge &e,
+			     const GraphEdge &f) {
+    if( edgeIncident(f, G.tail(e), _last) ) {
+      _first = G.head(e);
+      return true;
+    }
+    if( edgeIncident(f, G.head(e), _last) ) {
+      _first = G.tail(e);
+      return true;
+    }
+    return false;
+  }
+
+  template<typename Gr>
+  bool DynamicPath<Gr>::pushFront(const GraphEdge &e) {
+    if( G.valid(_first) ) {
+	if( edgeIncident(e, _first, _first) ) {
+	  edges.push_front(e);
+	  return true;
+	}
+	else
+	  return false;
+    }
+    else if( length() < 1 || connectTwoEdges(e, edges[0]) ) {
+      edges.push_front(e);
+      return true;
+    }
+    else
+      return false;
+  }
+
+  template<typename Gr>
+  bool DynamicPath<Gr>::pushBack(const GraphEdge &e) {
+    if( G.valid(_last) ) {
+	if( edgeIncident(e, _last, _last) ) {
+	  edges.push_back(e);
+	  return true;
+	}
+	else
+	  return false;
+    }
+    else if( length() < 1 || connectTwoEdges(edges[0], e) ) {
+      edges.push_back(e);
+      return true;
+    }
+    else
+      return false;
+  }
+
+
+  template<typename Gr>
+  bool DynamicPath<Gr>::setFrom(const GraphNode &n) {
+    if( G.valid(_first) ) {
+      return _first == n;
+    }
+    else {
+      if( length() > 0) {
+	if( edgeIncident(edges[0], n, _last) ) {
+	  _first = n;
+	  return true;
+	}
+	else return false;
+      }
+      else {
+	_first = _last = n;
+	return true;
+      }
+    }
+  }
+
+  template<typename Gr>
+  bool DynamicPath<Gr>::setTo(const GraphNode &n) {
+    if( G.valid(_last) ) {
+      return _last == n;
+    }
+    else {
+      if( length() > 0) {
+	if( edgeIncident(edges[0], n, _first) ) {
+	  _last = n;
+	  return true;
+	}
+	else return false;
+      }
+      else {
+	_first = _last = n;
+	return true;
+      }
+    }
+  }
+
+
+  template<typename Gr>
+  typename DynamicPath<Gr>::NodeIt
+  DynamicPath<Gr>::tail(const EdgeIt& e) const {
+    NodeIt n;
+
+    if( e.it == edges.end() ) {
+      // FIXME: invalid-> invalid
+      n.idx = length() + 1;
+      n.tail = true;
+      return n;
+    }
+
+    n.idx = e.it-edges.begin();
+    n.tail = e.forw;
+    return n;
+  }
+
+  template<typename Gr>
+  typename DynamicPath<Gr>::NodeIt
+  DynamicPath<Gr>::head(const EdgeIt& e) const {
+    if( e.it == edges.end()-1 ) {
+      return _last;
+    }
+
+    EdgeIt next_edge = e;
+    next(next_edge);
+    return tail(next_edge);
+  }
+      
+  template<typename Gr>
+  typename DynamicPath<Gr>::GraphEdge
+  DynamicPath<Gr>::graphEdge(const EdgeIt& e) const {
+    if( e.it != edges.end() ) {
+      return *e.it;
+    }
+    else {
+      return INVALID;
+    }
+  }
+  
+  template<typename Gr>
+  typename DynamicPath<Gr>::GraphNode
+  DynamicPath<Gr>::graphNode(const NodeIt& n) const {
+    if( n.idx < length() ) {
+      return n.tail ? G.tail(edges[n.idx]) : G.head(edges[n.idx]);
+    }
+    else if( n.idx == length() ) {
+      return _last;
+    }
+    else {
+      return INVALID;
+    }
+  }
+
+  template<typename Gr>
+  typename DynamicPath<Gr>::EdgeIt&
+  DynamicPath<Gr>::nth(EdgeIt &e, size_t k) const {
+    if( k>=length() ) {
+      // FIXME: invalid EdgeIt
+      e.it = edges.end();
+      e.forw = true;
+      return e;
+    }
+
+    e.it = edges.begin()+k;
+    if(k==0) {
+      e.forw = ( G.tail(*e.it) == _first );
+    }
+    else {
+      e.forw = ( G.tail(*e.it) == G.tail(edges[k-1]) ||
+		 G.tail(*e.it) == G.head(edges[k-1]) );
+    }
+    return e;
+  }
+    
+  template<typename Gr>
+  typename DynamicPath<Gr>::NodeIt&
+  DynamicPath<Gr>::nth(NodeIt &n, size_t k) const {
+    if( k>length() ) {
+      // FIXME: invalid NodeIt
+      n.idx = length()+1;
+      n.tail = true;
+      return n;
+    }
+    if( k==length() ) {
+      n.idx = length();
+      n.tail = true;
+      return n;
+    }
+    n = tail(nth<EdgeIt>(k));
+    return n;
+  }
+
+  // Reszut konstruktorok:
+
+
+  template<typename Gr>
+  DynamicPath<Gr>::DynamicPath(const DynamicPath &P, const EdgeIt &a,
+			       const EdgeIt &b) :
+    G(P.G), edges(a.it, b.it)    // WARNING: if b.it < a.it this will blow up! 
+  {
+    if( G.valid(P._first) && a.it < P.edges.end() ) {
+      _first = ( a.forw ? G.tail(*a.it) : G.head(*a.it) );
+      if( b.it < P.edges.end() ) {
+	_last = ( b.forw ? G.tail(*b.it) : G.head(*b.it) );
+      }
+      else {
+	_last = P._last;
+      }
+    }
+  }
+
+  template<typename Gr>
+  DynamicPath<Gr>::DynamicPath(const DynamicPath &P, const NodeIt &a,
+			       const NodeIt &b) : G(P.G)
+  {
+    if( !P.valid(a) || !P.valid(b) )
+      return;
+
+    int ai = a.idx, bi = b.idx;
+    if( bi<ai )
+      std::swap(ai,bi);
+    
+    edges.resize(bi-ai);
+    copy(P.edges.begin()+ai, P.edges.begin()+bi, edges.begin());
+
+    _first = P.graphNode(a);
+    _last = P.graphNode(b);
+  }
+
+  ///@}
+
+} // namespace hugo
+
+#endif // HUGO_PATH_H