/* -*- C++ -*-

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

  *

  * Copyright (C) 2005 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::template 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);

       if((*_pred)[v]!=INVALID) _predNode->set(v,G->source((*_pred)[v])); ///\todo What to do?

     }

   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() && !nm[_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(0) {}

     /// 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((s==INVALID)?0:(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(Base::_source==0) throw UninitializedParameter();

       Dijkstra<Graph,LengthMap,TR> 

 	Dij(*(Graph*)Base::_g,*(LengthMap*)Base::_length);

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

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

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

       Dij.run(*(Node*)Base::_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)

     {

       Base::_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) 

     {

       Base::_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) 

     {

       Base::_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) 

     {

       Base::_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) 

     {

       Base::_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