/* -*- C++ -*-

 * src/lemon/dijkstra.h - Part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Combinatorial Optimization Research Group, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#ifndef LEMON_DIJKSTRA_H

#define LEMON_DIJKSTRA_H

///\ingroup flowalgs

///\file

///\brief Dijkstra algorithm.

#include <lemon/list_graph.h>

#include <lemon/bin_heap.h>

#include <lemon/invalid.h>

#include <lemon/error.h>

#include <lemon/maps.h>

namespace lemon {

  ///Default traits class of Dijkstra class.

  ///Default traits class of Dijkstra class.

  ///\param GR Graph type.

  ///\param LM Type of length map.

  template<class GR, class LM>

  struct DijkstraDefaultTraits

  {

    ///The graph type the algorithm runs on. 

    typedef GR Graph;

    ///The type of the map that stores the edge lengths.

    ///The type of the map that stores the edge lengths.

    ///It must meet the \ref concept::ReadMap "ReadMap" concept.

    typedef LM LengthMap;

    //The type of the length of the edges.

    typedef typename LM::Value Value;

    ///The heap type used by Dijkstra algorithm.

    ///The heap type used by Dijkstra algorithm.

    ///

    ///\sa BinHeap

    ///\sa Dijkstra

    typedef BinHeap<typename Graph::Node,

		    typename LM::Value,

		    typename GR::template NodeMap<int>,

		    std::less<Value> > Heap;

    ///\brief The type of the map that stores the last

    ///edges of the shortest paths.

    /// 

    ///The type of the map that stores the last

    ///edges of the shortest paths.

    ///It must meet the \ref concept::WriteMap "WriteMap" concept.

    ///

    typedef typename Graph::template NodeMap<typename GR::Edge> PredMap;

    ///Instantiates a PredMap.

    ///This function instantiates a \ref PredMap. 

    ///\param G is the graph, to which we would like to define the PredMap.

    ///\todo The graph alone may be insufficient for the initialization

    static PredMap *createPredMap(const GR &G) 

    {

      return new PredMap(G);

    }

    ///\brief The type of the map that stores the last but one

    ///nodes of the shortest paths.

    ///

    ///The type of the map that stores the last but one

    ///nodes of the shortest paths.

    ///It must meet the \ref concept::WriteMap "WriteMap" concept.

    ///

    typedef NullMap<typename Graph::Node,typename Graph::Node> PredNodeMap;

    ///Instantiates a PredNodeMap.

    ///This function instantiates a \ref PredNodeMap. 

    ///\param G is the graph, to which

    ///we would like to define the \ref PredNodeMap

    static PredNodeMap *createPredNodeMap(const GR &G)

    {

      return new PredNodeMap();

    }

    ///The type of the map that stores whether a nodes is reached.

    ///The type of the map that stores whether a nodes is reached.

    ///It must meet the \ref concept::WriteMap "WriteMap" concept.

    ///By default it is a NullMap.

    ///\todo If it is set to a real map, Dijkstra::reached() should read this.

    ///\todo named parameter to set this type, function to read and write.

    typedef NullMap<typename Graph::Node,bool> ReachedMap;

    ///Instantiates a ReachedMap.

    ///This function instantiates a \ref ReachedMap. 

    ///\param G is the graph, to which

    ///we would like to define the \ref ReachedMap

    static ReachedMap *createReachedMap(const GR &G)

    {

      return new ReachedMap();

    }

    ///The type of the map that stores the dists of the nodes.

    ///The type of the map that stores the dists of the nodes.

    ///It must meet the \ref concept::WriteMap "WriteMap" concept.

    ///

    typedef typename Graph::template NodeMap<typename LM::Value> DistMap;

    ///Instantiates a DistMap.

    ///This function instantiates a \ref DistMap. 

    ///\param G is the graph, to which we would like to define the \ref DistMap

    static DistMap *createDistMap(const GR &G)

    {

      return new DistMap(G);

    }

  };

  ///%Dijkstra algorithm class.

  /// \ingroup flowalgs

  ///This class provides an efficient implementation of %Dijkstra algorithm.

  ///The edge lengths are passed to the algorithm using a

  ///\ref concept::ReadMap "ReadMap",

  ///so it is easy to change it to any kind of length.

  ///

  ///The type of the length is determined by the

  ///\ref concept::ReadMap::Value "Value" of the length map.

  ///

  ///It is also possible to change the underlying priority heap.

  ///

  ///\param GR The graph type the algorithm runs on. The default value is

  ///\ref ListGraph. The value of GR is not used directly by Dijkstra, it

  ///is only passed to \ref DijkstraDefaultTraits.

  ///\param LM This read-only

  ///EdgeMap

  ///determines the

  ///lengths of the edges. It is read once for each edge, so the map

  ///may involve in relatively time consuming process to compute the edge

  ///length if it is necessary. The default map type is

  ///\ref concept::StaticGraph::EdgeMap "Graph::EdgeMap<int>".

  ///The value of LM is not used directly by Dijkstra, it

  ///is only passed to \ref DijkstraDefaultTraits.

  ///\param TR Traits class to set various data types used by the algorithm.

  ///The default traits class is

  ///\ref DijkstraDefaultTraits "DijkstraDefaultTraits<GR,LM>".

  ///See \ref DijkstraDefaultTraits for the documentation of

  ///a Dijkstra traits class.

  ///

  ///\author Jacint Szabo and Alpar Juttner

  ///\todo A compare object would be nice.

#ifdef DOXYGEN

  template <typename GR,

	    typename LM,

	    typename TR>

#else

  template <typename GR=ListGraph,

	    typename LM=typename GR::template EdgeMap<int>,

	    typename TR=DijkstraDefaultTraits<GR,LM> >

#endif

  class Dijkstra {

  public:

    /**

     * \brief \ref Exception for uninitialized parameters.

     *

     * This error represents problems in the initialization

     * of the parameters of the algorithms.

     */

    class UninitializedParameter : public lemon::UninitializedParameter {

    public:

      virtual const char* exceptionName() const {

	return "lemon::Dijsktra::UninitializedParameter";

      }

    };

    typedef TR Traits;

    ///The type of the underlying graph.

    typedef typename TR::Graph Graph;

    ///\e

    typedef typename Graph::Node Node;

    ///\e

    typedef typename Graph::NodeIt NodeIt;

    ///\e

    typedef typename Graph::Edge Edge;

    ///\e

    typedef typename Graph::OutEdgeIt OutEdgeIt;

    ///The type of the length of the edges.

    typedef typename TR::LengthMap::Value Value;

    ///The type of the map that stores the edge lengths.

    typedef typename TR::LengthMap LengthMap;

    ///\brief The type of the map that stores the last

    ///edges of the shortest paths.

    typedef typename TR::PredMap PredMap;

    ///\brief The type of the map that stores the last but one

    ///nodes of the shortest paths.

    typedef typename TR::PredNodeMap PredNodeMap;

    ///The type of the map indicating if a node is reached.

    typedef typename TR::ReachedMap ReachedMap;

    ///The type of the map that stores the dists of the nodes.

    typedef typename TR::DistMap DistMap;

    ///The heap type used by the dijkstra algorithm.

    typedef typename TR::Heap Heap;

  private:

    /// Pointer to the underlying graph.

    const Graph *G;

    /// Pointer to the length map

    const LengthMap *length;

    ///Pointer to the map of predecessors edges.

    PredMap *_pred;

    ///Indicates if \ref _pred is locally allocated (\c true) or not.

    bool local_pred;

    ///Pointer to the map of predecessors nodes.

    PredNodeMap *_predNode;

    ///Indicates if \ref _predNode is locally allocated (\c true) or not.

    bool local_predNode;

    ///Pointer to the map of distances.

    DistMap *_dist;

    ///Indicates if \ref _dist is locally allocated (\c true) or not.

    bool local_dist;

    ///Pointer to the map of reached status of the nodes.

    ReachedMap *_reached;

    ///Indicates if \ref _reached is locally allocated (\c true) or not.

    bool local_reached;

    ///The source node of the last execution.

    Node source;

    ///Creates the maps if necessary.

    ///\todo Error if \c G or are \c NULL. What about \c length?

    ///\todo Better memory allocation (instead of new).

    void create_maps() 

    {

      if(!_pred) {

	local_pred = true;

	_pred = Traits::createPredMap(*G);

      }

      if(!_predNode) {

	local_predNode = true;

	_predNode = Traits::createPredNodeMap(*G);

      }

      if(!_dist) {

	local_dist = true;

	_dist = Traits::createDistMap(*G);

      }

      if(!_reached) {

	local_reached = true;

	_reached = Traits::createReachedMap(*G);

      }

    }

  public :

    ///\name Named template parameters

    ///@{

    template <class T>

    struct DefPredMapTraits : public Traits {

      typedef T PredMap;

      static PredMap *createPredMap(const Graph &G) 

      {

	throw UninitializedParameter();

      }

    };

    ///\ref named-templ-param "Named parameter" for setting PredMap type

    ///\ref named-templ-param "Named parameter" for setting PredMap type

    ///

    template <class T>

    class DefPredMap : public Dijkstra< Graph,

					LengthMap,

					DefPredMapTraits<T> > { };

    template <class T>

    struct DefPredNodeMapTraits : public Traits {

      typedef T PredNodeMap;

      static PredNodeMap *createPredNodeMap(const Graph &G) 

      {

	throw UninitializedParameter();

      }

    };

    ///\ref named-templ-param "Named parameter" for setting PredNodeMap type

    ///\ref named-templ-param "Named parameter" for setting PredNodeMap type

    ///

    template <class T>

    class DefPredNodeMap : public Dijkstra< Graph,

					    LengthMap,

					    DefPredNodeMapTraits<T> > { };

    template <class T>

    struct DefDistMapTraits : public Traits {

      typedef T DistMap;

      static DistMap *createDistMap(const Graph &G) 

      {

	throw UninitializedParameter();

      }

    };

    ///\ref named-templ-param "Named parameter" for setting DistMap type

    ///\ref named-templ-param "Named parameter" for setting DistMap type

    ///

    template <class T>

    class DefDistMap : public Dijkstra< Graph,

					LengthMap,

					DefDistMapTraits<T> > { };

    template <class T>

    struct DefReachedMapTraits : public Traits {

      typedef T ReachedMap;

      static ReachedMap *createReachedMap(const Graph &G) 

      {

	throw UninitializedParameter();

      }

    };

    ///\ref named-templ-param "Named parameter" for setting ReachedMap type

    ///\ref named-templ-param "Named parameter" for setting ReachedMap type

    ///

    template <class T>

    class DefReachedMap : public Dijkstra< Graph,

					LengthMap,

					DefReachedMapTraits<T> > { };

    struct DefGraphReachedMapTraits : public Traits {

      typedef typename Graph::NodeMap<bool> ReachedMap;

      static ReachedMap *createReachedMap(const Graph &G) 

      {

	return new ReachedMap(G);

      }

    };

    ///\brief \ref named-templ-param "Named parameter"

    ///for setting the ReachedMap type to be Graph::NodeMap<bool>.

    ///

    ///\ref named-templ-param "Named parameter"

    ///for setting the ReachedMap type to be Graph::NodeMap<bool>.

    ///If you don't set it explicitely, it will be automatically allocated.

    template <class T>

    class DefReachedMapToBeDefaultMap :

      public Dijkstra< Graph,

		       LengthMap,

		       DefGraphReachedMapTraits> { };

    ///@}

  private:

    typename Graph::template NodeMap<int> _heap_map;

    Heap _heap;

  public:      

    ///Constructor.

    ///\param _G the graph the algorithm will run on.

    ///\param _length the length map used by the algorithm.

    Dijkstra(const Graph& _G, const LengthMap& _length) :

      G(&_G), length(&_length),

      _pred(NULL), local_pred(false),

      _predNode(NULL), local_predNode(false),

      _dist(NULL), local_dist(false),

      _reached(NULL), local_reached(false),

      _heap_map(*G,-1),_heap(_heap_map)

    { }

    ///Destructor.

    ~Dijkstra() 

    {

      if(local_pred) delete _pred;

      if(local_predNode) delete _predNode;

      if(local_dist) delete _dist;

      if(local_reached) delete _reached;

    }

    ///Sets the length map.

    ///Sets the length map.

    ///\return <tt> (*this) </tt>

    Dijkstra &lengthMap(const LengthMap &m) 

    {

      length = &m;

      return *this;

    }

    ///Sets the map storing the predecessor edges.

    ///Sets the map storing the predecessor edges.

    ///If you don't use this function before calling \ref run(),

    ///it will allocate one. The destuctor deallocates this

    ///automatically allocated map, of course.

    ///\return <tt> (*this) </tt>

    Dijkstra &predMap(PredMap &m) 

    {

      if(local_pred) {

	delete _pred;

	local_pred=false;

      }

      _pred = &m;

      return *this;

    }

    ///Sets the map storing the predecessor nodes.

    ///Sets the map storing the predecessor nodes.

    ///If you don't use this function before calling \ref run(),

    ///it will allocate one. The destuctor deallocates this

    ///automatically allocated map, of course.

    ///\return <tt> (*this) </tt>

    Dijkstra &predNodeMap(PredNodeMap &m) 

    {

      if(local_predNode) {

	delete _predNode;

	local_predNode=false;

      }

      _predNode = &m;

      return *this;

    }

    ///Sets the map storing the distances calculated by the algorithm.

    ///Sets the map storing the distances calculated by the algorithm.

    ///If you don't use this function before calling \ref run(),

    ///it will allocate one. The destuctor deallocates this

    ///automatically allocated map, of course.

    ///\return <tt> (*this) </tt>

    Dijkstra &distMap(DistMap &m) 

    {

      if(local_dist) {

	delete _dist;

	local_dist=false;

      }

      _dist = &m;

      return *this;

    }

  private:

    void finalizeNodeData(Node v,Value dst)

    {

      _reached->set(v,true);

      _dist->set(v, dst);

      _predNode->set(v,G->source((*_pred)[v]));

    }

  public:

    ///\name Excetution control

    ///The simplest way to execute the algorithm is to use

    ///one of the member functions called \c run(...).

    ///\n

    ///It you need more control on the execution,

    ///first you must call \ref init(), then you can add several source nodes

    ///with \ref addSource(). Finally \ref start() will perform the actual path

    ///computation.

    ///@{

    ///Initializes the internal data structures.

    ///Initializes the internal data structures.

    ///

    ///\todo _heap_map's type could also be in the traits class.

    void init()

    {

      create_maps();

      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {

	_pred->set(u,INVALID);

	_predNode->set(u,INVALID);

	///\todo *_reached is not set to false.

	_heap_map.set(u,Heap::PRE_HEAP);

      }

    }

    ///Adds a new source node.

    ///Adds a new source node to the priority heap.

    ///

    ///The optional second parameter is the initial distance of the node.

    ///

    ///It checks if the node has already been added to the heap and

    ///It is pushed to the heap only if either it was not in the heap

    ///or the shortest path found till then is longer then \c dst.

    void addSource(Node s,Value dst=0)

    {

      source = s;

      if(_heap.state(s) != Heap::IN_HEAP) _heap.push(s,dst);

      else if(_heap[s]<dst) {

	_heap.push(s,dst);

	_pred->set(s,INVALID);

      }

    }

    ///Processes the next node in the priority heap

    ///Processes the next node in the priority heap.

    ///

    ///\warning The priority heap must not be empty!

    void processNextNode()

    {

      Node v=_heap.top(); 

      Value oldvalue=_heap[v];

      _heap.pop();

      finalizeNodeData(v,oldvalue);

      for(OutEdgeIt e(*G,v); e!=INVALID; ++e) {

	Node w=G->target(e); 

	switch(_heap.state(w)) {

	case Heap::PRE_HEAP:

	  _heap.push(w,oldvalue+(*length)[e]); 

	  _pred->set(w,e);

//  	  _predNode->set(w,v);

	  break;

	case Heap::IN_HEAP:

	  if ( oldvalue+(*length)[e] < _heap[w] ) {

	    _heap.decrease(w, oldvalue+(*length)[e]); 

	    _pred->set(w,e);

// 	    _predNode->set(w,v);

	  }

	  break;

	case Heap::POST_HEAP:

	  break;

	}

      }

    }

    ///Returns \c false if there are nodes to be processed in the priority heap

    ///Returns \c false if there are nodes to be processed in the priority heap

    ///

    bool emptyHeap() { return heap.empty(); }

    ///Returns the number of the nodes to be processed in the priority heap

    ///Returns the number of the nodes to be processed in the priority heap

    ///

    int heapSize() { return heap.size(); }

    ///Executes the algorithm.

    ///Executes the algorithm.

    ///

    ///\pre init() must be called and at least one node should be added

    ///with addSource() before using this function.

    ///

    ///This method runs the %Dijkstra algorithm from the root node(s)

    ///in order to

    ///compute the

    ///shortest path to each node. The algorithm computes

    ///- The shortest path tree.

    ///- The distance of each node from the root(s).

    ///

    void start()

    {

      while ( !_heap.empty() ) processNextNode();

    }

    ///Executes the algorithm until \c dest is reached.

    ///Executes the algorithm until \c dest is reached.

    ///

    ///\pre init() must be called and at least one node should be added

    ///with addSource() before using this function.

    ///

    ///This method runs the %Dijkstra algorithm from the root node(s)

    ///in order to

    ///compute the

    ///shortest path to \c dest. The algorithm computes

    ///- The shortest path to \c  dest.

    ///- The distance of \c dest from the root(s).

    ///

    void start(Node dest)

    {

      while ( !_heap.empty() && _heap.top()!=dest ) processNextNode();

      if ( _heap.top()==dest ) finalizeNodeData(_heap.top());

    }

    ///Executes the algorithm until a condition is met.

    ///Executes the algorithm until a condition is met.

    ///

    ///\pre init() must be called and at least one node should be added

    ///with addSource() before using this function.

    ///

    ///\param nm must be a bool (or convertible) node map. The algorithm

    ///will stop when it reaches a node \c v with <tt>nm[v]==true</tt>.

    template<class NM>

    void start(const NM &nm)

    {

      while ( !_heap.empty() && !mn[_heap.top()] ) processNextNode();

      if ( !_heap.empty() ) finalizeNodeData(_heap.top());

    }

    ///Runs %Dijkstra algorithm from node \c s.

    ///This method runs the %Dijkstra algorithm from a root node \c s

    ///in order to

    ///compute the

    ///shortest path to each node. The algorithm computes

    ///- The shortest path tree.

    ///- The distance of each node from the root.

    ///

    ///\note d.run(s) is just a shortcut of the following code.

    ///\code

    ///  d.init();

    ///  d.addSource(s);

    ///  d.start();

    ///\endcode

    void run(Node s) {

      init();

      addSource(s);

      start();

    }

    ///Finds the shortest path between \c s and \c t.

    ///Finds the shortest path between \c s and \c t.

    ///

    ///\return The length of the shortest s---t path if there exists one,

    ///0 otherwise.

    ///\note Apart from the return value, d.run(s) is

    ///just a shortcut of the following code.

    ///\code

    ///  d.init();

    ///  d.addSource(s);

    ///  d.start(t);

    ///\endcode

    Value run(Node s,Node t) {

      init();

      addSource(s);

      start(t);

      return (*_pred)[t]==INVALID?0:(*_dist)[t];

    }

    ///@}

    ///\name Query Functions

    ///The result of the %Dijkstra algorithm can be obtained using these

    ///functions.\n

    ///Before the use of these functions,

    ///either run() or start() must be called.

    ///@{

    ///The distance of a node from the root.

    ///Returns the distance of a node from the root.

    ///\pre \ref run() must be called before using this function.

    ///\warning If node \c v in unreachable from the root the return value

    ///of this funcion is undefined.

    Value dist(Node v) const { return (*_dist)[v]; }

    ///Returns the 'previous edge' of the shortest path tree.

    ///For a node \c v it returns the 'previous edge' of the shortest path tree,

    ///i.e. it returns the last edge of a shortest path from the root to \c

    ///v. It is \ref INVALID

    ///if \c v is unreachable from the root or if \c v=s. The

    ///shortest path tree used here is equal to the shortest path tree used in

    ///\ref predNode(Node v).  \pre \ref run() must be called before using

    ///this function.

    ///\todo predEdge could be a better name.

    Edge pred(Node v) const { return (*_pred)[v]; }

    ///Returns the 'previous node' of the shortest path tree.

    ///For a node \c v it returns the 'previous node' of the shortest path tree,

    ///i.e. it returns the last but one node from a shortest path from the

    ///root to \c /v. It is INVALID if \c v is unreachable from the root or if

    ///\c v=s. The shortest path tree used here is equal to the shortest path

    ///tree used in \ref pred(Node v).  \pre \ref run() must be called before

    ///using this function.

    Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID:

				  G->source((*_pred)[v]); }

    ///Returns a reference to the NodeMap of distances.

    ///Returns a reference to the NodeMap of distances. \pre \ref run() must

    ///be called before using this function.

    const DistMap &distMap() const { return *_dist;}

    ///Returns a reference to the shortest path tree map.

    ///Returns a reference to the NodeMap of the edges of the

    ///shortest path tree.

    ///\pre \ref run() must be called before using this function.

    const PredMap &predMap() const { return *_pred;}

    ///Returns a reference to the map of nodes of shortest paths.

    ///Returns a reference to the NodeMap of the last but one nodes of the

    ///shortest path tree.

    ///\pre \ref run() must be called before using this function.

    const PredNodeMap &predNodeMap() const { return *_predNode;}

    ///Checks if a node is reachable from the root.

    ///Returns \c true if \c v is reachable from the root.

    ///\warning If the algorithm is started from multiple nodes,

    ///this function may give false result for the source nodes.

    ///\pre \ref run() must be called before using this function.

    ///

    bool reached(Node v) { return v==source || (*_pred)[v]!=INVALID; }

    ///@}

  };

  /// Default traits used by \ref DijkstraWizard

  /// To make it easier to use Dijkstra algorithm

  ///we have created a wizard class.

  /// This \ref DijkstraWizard class needs default traits,

  ///as well as the \ref Dijkstra class.

  /// The \ref DijkstraWizardBase is a class to be the default traits of the

  /// \ref DijkstraWizard class.

  template<class GR,class LM>

  class DijkstraWizardBase : public DijkstraDefaultTraits<GR,LM>

  {

    typedef DijkstraDefaultTraits<GR,LM> Base;

  protected:

    /// Pointer to the underlying graph.

    void *_g;

    /// Pointer to the length map

    void *_length;

    ///Pointer to the map of predecessors edges.

    void *_pred;

    ///Pointer to the map of predecessors nodes.

    void *_predNode;

    ///Pointer to the map of distances.

    void *_dist;

    ///Pointer to the source node.

    void *_source;

    /// Type of the nodes in the graph.

    typedef typename Base::Graph::Node Node;

    public:

    /// Constructor.

    /// This constructor does not require parameters, therefore it initiates

    /// all of the attributes to default values (0, INVALID).

    DijkstraWizardBase() : _g(0), _length(0), _pred(0), _predNode(0),

		       _dist(0), _source(INVALID) {}

    /// Constructor.

    /// This constructor requires some parameters,

    /// listed in the parameters list.

    /// Others are initiated to 0.

    /// \param g is the initial value of  \ref _g

    /// \param l is the initial value of  \ref _length

    /// \param s is the initial value of  \ref _source

    DijkstraWizardBase(const GR &g,const LM &l, Node s=INVALID) :

      _g((void *)&g), _length((void *)&l), _pred(0), _predNode(0),

		  _dist(0), _source((void *)&s) {}

  };

  /// A class to make easier the usage of Dijkstra algorithm

  /// \ingroup flowalgs

  /// This class is created to make it easier to use Dijkstra algorithm.

  /// It uses the functions and features of the plain \ref Dijkstra,

  /// but it is much simpler to use it.

  ///

  /// Simplicity means that the way to change the types defined

  /// in the traits class is based on functions that returns the new class

  /// and not on templatable built-in classes.

  /// When using the plain \ref Dijkstra

  /// the new class with the modified type comes from

  /// the original class by using the ::

  /// operator. In the case of \ref DijkstraWizard only

  /// a function have to be called and it will

  /// return the needed class.

  ///

  /// It does not have own \ref run method. When its \ref run method is called

  /// it initiates a plain \ref Dijkstra class, and calls the \ref Dijkstra::run

  /// method of it.

  template<class TR>

  class DijkstraWizard : public TR

  {

    typedef TR Base;

    ///The type of the underlying graph.

    typedef typename TR::Graph Graph;

    //\e

    typedef typename Graph::Node Node;

    //\e

    typedef typename Graph::NodeIt NodeIt;

    //\e

    typedef typename Graph::Edge Edge;

    //\e

    typedef typename Graph::OutEdgeIt OutEdgeIt;

    ///The type of the map that stores the edge lengths.

    typedef typename TR::LengthMap LengthMap;

    ///The type of the length of the edges.

    typedef typename LengthMap::Value Value;

    ///\brief The type of the map that stores the last

    ///edges of the shortest paths.

    typedef typename TR::PredMap PredMap;

    ///\brief The type of the map that stores the last but one

    ///nodes of the shortest paths.

    typedef typename TR::PredNodeMap PredNodeMap;

    ///The type of the map that stores the dists of the nodes.

    typedef typename TR::DistMap DistMap;

    ///The heap type used by the dijkstra algorithm.

    typedef typename TR::Heap Heap;

public:

    /// Constructor.

    DijkstraWizard() : TR() {}

    /// Constructor that requires parameters.

    /// Constructor that requires parameters.

    /// These parameters will be the default values for the traits class.

    DijkstraWizard(const Graph &g,const LengthMap &l, Node s=INVALID) :

      TR(g,l,s) {}

    ///Copy constructor

    DijkstraWizard(const TR &b) : TR(b) {}

    ~DijkstraWizard() {}

    ///Runs Dijkstra algorithm from a given node.

    ///Runs Dijkstra algorithm from a given node.

    ///The node can be given by the \ref source function.

    void run()

    {

      if(_source==0) throw UninitializedParameter();

      Dijkstra<Graph,LengthMap,TR> Dij(*(Graph*)_g,*(LengthMap*)_length);

      if(_pred) Dij.predMap(*(PredMap*)_pred);

      if(_predNode) Dij.predNodeMap(*(PredNodeMap*)_predNode);

      if(_dist) Dij.distMap(*(DistMap*)_dist);

      Dij.run(*(Node*)_source);

    }

    ///Runs Dijkstra algorithm from the given node.

    ///Runs Dijkstra algorithm from the given node.

    ///\param s is the given source.

    void run(Node s)

    {

      _source=(void *)&s;

      run();

    }

    template<class T>

    struct DefPredMapBase : public Base {

      typedef T PredMap;

      static PredMap *createPredMap(const Graph &G) { return 0; };

      DefPredMapBase(const Base &b) : Base(b) {}

    };

    ///\brief \ref named-templ-param "Named parameter"

    ///function for setting PredMap type

    ///

    /// \ref named-templ-param "Named parameter"

    ///function for setting PredMap type

    ///

    template<class T>

    DijkstraWizard<DefPredMapBase<T> > predMap(const T &t) 

    {

      _pred=(void *)&t;

      return DijkstraWizard<DefPredMapBase<T> >(*this);

    }

    template<class T>

    struct DefPredNodeMapBase : public Base {

      typedef T PredNodeMap;

      static PredNodeMap *createPredNodeMap(const Graph &G) { return 0; };

      DefPredNodeMapBase(const Base &b) : Base(b) {}

    };

    ///\brief \ref named-templ-param "Named parameter"

    ///function for setting PredNodeMap type

    ///

    /// \ref named-templ-param "Named parameter"

    ///function for setting PredNodeMap type

    ///

    template<class T>

    DijkstraWizard<DefPredNodeMapBase<T> > predNodeMap(const T &t) 

    {

      _predNode=(void *)&t;

      return DijkstraWizard<DefPredNodeMapBase<T> >(*this);

    }

    template<class T>

    struct DefDistMapBase : public Base {

      typedef T DistMap;

      static DistMap *createDistMap(const Graph &G) { return 0; };

      DefDistMapBase(const Base &b) : Base(b) {}

    };

    ///\brief \ref named-templ-param "Named parameter"

    ///function for setting DistMap type

    ///

    /// \ref named-templ-param "Named parameter"

    ///function for setting DistMap type

    ///

    template<class T>

    DijkstraWizard<DefDistMapBase<T> > distMap(const T &t) 

    {

      _dist=(void *)&t;

      return DijkstraWizard<DefDistMapBase<T> >(*this);

    }

    /// Sets the source node, from which the Dijkstra algorithm runs.

    /// Sets the source node, from which the Dijkstra algorithm runs.

    /// \param s is the source node.

    DijkstraWizard<TR> &source(Node s) 

    {

      source=(void *)&s;

      return *this;

    }

  };

  ///\e

  /// \ingroup flowalgs

  ///\todo Please document...

  ///

  template<class GR, class LM>

  DijkstraWizard<DijkstraWizardBase<GR,LM> >

  dijkstra(const GR &g,const LM &l,typename GR::Node s=INVALID)

  {

    return DijkstraWizard<DijkstraWizardBase<GR,LM> >(g,l,s);

  }

/// @}

} //END OF NAMESPACE LEMON

#endif