/* -*- C++ -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2003-2006

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, 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_PRIM_H

#define LEMON_PRIM_H

///\ingroup spantree

///\file

///\brief Prim algorithm to compute minimum spanning tree.

#include <lemon/list_graph.h>

#include <lemon/bin_heap.h>

#include <lemon/bits/invalid.h>

#include <lemon/error.h>

#include <lemon/maps.h>

#include <lemon/bits/traits.h>

#include <lemon/concepts/ugraph.h>

namespace lemon {

  ///Default traits class of Prim class.

  ///Default traits class of Prim class.

  ///\param GR Graph type.

  ///\param CM Type of cost map.

  template<class GR, class CM>

  struct PrimDefaultTraits{

    ///The graph type the algorithm runs on. 

    typedef GR UGraph;

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

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

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

    typedef CM CostMap;

    //The type of the cost of the edges.

    typedef typename CM::Value Value;

    /// The cross reference type used by heap.

    /// The cross reference type used by heap.

    /// Usually it is \c UGraph::NodeMap<int>.

    typedef typename UGraph::template NodeMap<int> HeapCrossRef;

    ///Instantiates a HeapCrossRef.

    ///This function instantiates a \ref HeapCrossRef. 

    /// \param _graph is the graph, to which we would like to define the 

    /// HeapCrossRef.

    static HeapCrossRef *createHeapCrossRef(const GR &_graph){

      return new HeapCrossRef(_graph);

    }

    ///The heap type used by Prim algorithm.

    ///The heap type used by Prim algorithm.

    ///

    ///\sa BinHeap

    ///\sa Prim

    typedef BinHeap<typename CM::Value,

		    HeapCrossRef, std::less<Value> > Heap;

    static Heap *createHeap(HeapCrossRef& _ref){

      return new Heap(_ref);

    }

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

    ///edges of the minimum spanning tree.

    /// 

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

    ///edges of the minimum spanning tree.

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

    ///

    typedef typename UGraph::template NodeMap<typename GR::UEdge> PredMap;

    ///Instantiates a PredMap.

    ///This function instantiates a \ref PredMap. 

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

    static PredMap *createPredMap(const GR &_graph){

      return new PredMap(_graph);

    }

    ///The type of the map that stores whether an edge is in the

    ///spanning tree or not.

    ///The type of the map that stores whether an edge is in the

    ///spanning tree or not.

    ///By default it is a NullMap.

    typedef NullMap<typename UGraph::UEdge,bool> TreeMap;

    ///Instantiates a TreeMap.

    ///This function instantiates a \ref TreeMap.

    ///

    ///The first parameter is the graph, to which

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

    static TreeMap *createTreeMap(const GR &){

      return new TreeMap();

    }

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

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

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

    ///By default it is a NodeMap<bool>.

    typedef NullMap<typename UGraph::Node,bool> ProcessedMap;

    ///Instantiates a ProcessedMap.

    ///This function instantiates a \ref ProcessedMap. 

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

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

#ifdef DOXYGEN

    static ProcessedMap *createProcessedMap(const GR &_graph)

#else

    static ProcessedMap *createProcessedMap(const GR &)

#endif

    {

      return new ProcessedMap();

    }

  };

  ///%Prim algorithm class to find a minimum spanning tree.

  /// \ingroup spantree

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

  ///

  ///The running time is \f$ O(e\log(n)) \f$ where e is the number of edges and

  ///n is the number of nodes in the graph.

  ///

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

  ///\ref concepts::ReadMap "ReadMap",

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

  ///

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

  ///\ref concepts::ReadMap::Value "Value" of the cost 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 ListUGraph. The value of GR is not used directly by

  ///Prim, it is only passed to \ref PrimDefaultTraits.

  ///

  ///\param CM This read-only UEdgeMap determines the costs of the

  ///edges. It is read once for each edge, so the map may involve in

  ///relatively time consuming process to compute the edge cost if

  ///it is necessary. The default map type is \ref

  ///concepts::UGraph::UEdgeMap "UGraph::UEdgeMap<int>".  The value

  ///of CM is not used directly by Prim, it is only passed to \ref

  ///PrimDefaultTraits.

  ///

  ///\param TR Traits class to set

  ///various data types used by the algorithm.  The default traits

  ///class is \ref PrimDefaultTraits

  ///"PrimDefaultTraits<GR,CM>".  See \ref

  ///PrimDefaultTraits for the documentation of a Prim traits

  ///class.

  ///

  ///\author Balazs Attila Mihaly

#ifdef DOXYGEN

  template <typename GR,

	    typename CM,

	    typename TR>

#else

  template <typename GR=ListUGraph,

	    typename CM=typename GR::template UEdgeMap<int>,

	    typename TR=PrimDefaultTraits<GR,CM> >

#endif

  class Prim {

  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* what() const throw() {

	return "lemon::Prim::UninitializedParameter";

      }

    };

    typedef TR Traits;

    ///The type of the underlying graph.

    typedef typename TR::UGraph UGraph;

    ///\e

    typedef typename UGraph::Node Node;

    ///\e

    typedef typename UGraph::NodeIt NodeIt;

    ///\e

    typedef typename UGraph::UEdge UEdge;

    ///\e

    typedef typename UGraph::IncEdgeIt IncEdgeIt;

    ///The type of the cost of the edges.

    typedef typename TR::CostMap::Value Value;

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

    typedef typename TR::CostMap CostMap;

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

    ///predecessor edges of the spanning tree.

    typedef typename TR::PredMap PredMap;

    ///Edges of the spanning tree.

    typedef typename TR::TreeMap TreeMap;

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

    typedef typename TR::ProcessedMap ProcessedMap;

    ///The cross reference type used for the current heap.

    typedef typename TR::HeapCrossRef HeapCrossRef;

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

    typedef typename TR::Heap Heap;

  private:

    /// Pointer to the underlying graph.

    const UGraph *graph;

    /// Pointer to the cost map

    const CostMap *cost;

    ///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 tree edges.

    TreeMap *_tree;

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

    bool local_tree;

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

    ProcessedMap *_processed;

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

    bool local_processed;

    ///Pointer to the heap cross references.

    HeapCrossRef *_heap_cross_ref;

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

    bool local_heap_cross_ref;

    ///Pointer to the heap.

    Heap *_heap;

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

    bool local_heap;

    ///Creates the maps if necessary.

    void create_maps(){

      if(!_pred) {

	local_pred = true;

	_pred = Traits::createPredMap(*graph);

      }

      if(!_tree) {

	local_tree = true;

	_tree = Traits::createTreeMap(*graph);

      }

      if(!_processed) {

	local_processed = true;

	_processed = Traits::createProcessedMap(*graph);

      }

      if (!_heap_cross_ref) {

	local_heap_cross_ref = true;

	_heap_cross_ref = Traits::createHeapCrossRef(*graph);

      }

      if (!_heap) {

	local_heap = true;

	_heap = Traits::createHeap(*_heap_cross_ref);

      }

    }

  public :

    typedef Prim Create;

    ///\name Named template parameters

    ///@{

    template <class T>

    struct DefPredMapTraits : public Traits {

      typedef T PredMap;

      static PredMap *createPredMap(const UGraph &_graph){

	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>

    struct DefPredMap 

      : public Prim< UGraph, CostMap, DefPredMapTraits<T> > {

      typedef Prim< UGraph, CostMap, DefPredMapTraits<T> > Create;

    };

    template <class T>

    struct DefProcessedMapTraits : public Traits {

      typedef T ProcessedMap;

      static ProcessedMap *createProcessedMap(const UGraph &_graph){

	throw UninitializedParameter();

      }

    };

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

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

    ///

    template <class T>

    struct DefProcessedMap 

      : public Prim< UGraph, CostMap, DefProcessedMapTraits<T> > { 

      typedef Prim< UGraph, CostMap, DefProcessedMapTraits<T> > Create;

    };

    struct DefGraphProcessedMapTraits : public Traits {

      typedef typename UGraph::template NodeMap<bool> ProcessedMap;

      static ProcessedMap *createProcessedMap(const UGraph &_graph){

	return new ProcessedMap(_graph);

      }

    };

    template <class H, class CR>

    struct DefHeapTraits : public Traits {

      typedef CR HeapCrossRef;

      typedef H Heap;

      static HeapCrossRef *createHeapCrossRef(const UGraph &) {

	throw UninitializedParameter();

      }

      static Heap *createHeap(HeapCrossRef &){

	return UninitializedParameter();

      }

    };

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

    ///heap and cross reference type

    ///

    ///\ref named-templ-param "Named parameter" for setting heap and cross 

    ///reference type

    ///

    template <class H, class CR = typename UGraph::template NodeMap<int> >

    struct DefHeap

      : public Prim< UGraph, CostMap, DefHeapTraits<H, CR> > {

      typedef Prim< UGraph, CostMap, DefHeapTraits<H, CR> > Create;

    };

    template <class H, class CR>

    struct DefStandardHeapTraits : public Traits {

      typedef CR HeapCrossRef;

      typedef H Heap;

      static HeapCrossRef *createHeapCrossRef(const UGraph &_graph) {

	return new HeapCrossRef(_graph);

      }

      static Heap *createHeap(HeapCrossRef &ref){

	return new Heap(ref);

      }

    };

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

    ///heap and cross reference type with automatic allocation

    ///

    ///\ref named-templ-param "Named parameter" for setting heap and cross 

    ///reference type. It can allocate the heap and the cross reference 

    ///object if the cross reference's constructor waits for the graph as 

    ///parameter and the heap's constructor waits for the cross reference.

    template <class H, class CR = typename UGraph::template NodeMap<int> >

    struct DefStandardHeap

      : public Prim< UGraph, CostMap, DefStandardHeapTraits<H, CR> > { 

      typedef Prim< UGraph, CostMap, DefStandardHeapTraits<H, CR> > 

      Create;

    };

    template <class TM>

    struct DefTreeMapTraits : public Traits {

      typedef TM TreeMap;

      static TreeMap *createTreeMap(const UGraph &) {

        throw UninitializedParameter();

      }

    };

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

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

    ///

    template <class TM>

    struct DefTreeMap

      : public Prim< UGraph, CostMap, DefTreeMapTraits<TM> > {

      typedef Prim< UGraph, CostMap, DefTreeMapTraits<TM> > Create;

    };    

    struct DefGraphTreeMapTraits : public Traits {

      typedef typename UGraph::template NodeMap<bool> TreeMap;

      static TreeMap *createTreeMap(const UGraph &_graph){

	return new TreeMap(_graph);

      }

    };

    ///@}

  protected:

    Prim() {}

  public:      

    ///Constructor.

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

    ///\param _cost the cost map used by the algorithm.

    Prim(const UGraph& _graph, const CostMap& _cost) :

      graph(&_graph), cost(&_cost),

      _pred(NULL), local_pred(false),

      _tree(NULL), local_tree(false),

      _processed(NULL), local_processed(false),

      _heap_cross_ref(NULL), local_heap_cross_ref(false),

      _heap(NULL), local_heap(false)

    {

      checkConcept<concepts::UGraph, UGraph>();

    }

    ///Destructor.

    ~Prim(){

      if(local_pred) delete _pred;

      if(local_tree) delete _tree;

      if(local_processed) delete _processed;

      if(local_heap_cross_ref) delete _heap_cross_ref;

      if(local_heap) delete _heap;

    }

    ///\brief Sets the cost map.

    ///Sets the cost map.

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

    Prim &costMap(const CostMap &m){

      cost = &m;

      return *this;

    }

    ///\brief 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>

    Prim &predMap(PredMap &m){

      if(local_pred) {

	delete _pred;

	local_pred=false;

      }

      _pred = &m;

      return *this;

    }

    ///\brief Sets the map storing the tree edges.

    ///Sets the map storing the tree 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.

    ///By default this is a NullMap.

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

    Prim &treeMap(TreeMap &m){

      if(local_tree) {

	delete _tree;

	local_tree=false;

      }

      _tree = &m;

      return *this;

    }

    ///\brief Sets the heap and the cross reference used by algorithm.

    ///Sets the heap and the cross reference used by 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>

    Prim &heap(Heap& heap, HeapCrossRef &crossRef){

      if(local_heap_cross_ref) {

	delete _heap_cross_ref;

	local_heap_cross_ref=false;

      }

      _heap_cross_ref = &crossRef;

      if(local_heap) {

	delete _heap;

	local_heap=false;

      }

      _heap = &heap;

      return *this;

    }

  public:

    ///\name Execution control

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

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

    ///\n

    ///If 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.

    ///@{

    ///\brief Initializes the internal data structures.

    ///Initializes the internal data structures.

    ///

    void init(){

      create_maps();

      _heap->clear();

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

	_pred->set(u,INVALID);

	_processed->set(u,false);

	_heap_cross_ref->set(u,Heap::PRE_HEAP);

      }

    }

    ///\brief Adds a new source node.

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

    ///

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

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

    void addSource(Node s){

      if(_heap->state(s) != Heap::IN_HEAP) {

	_heap->push(s,Value());

      }

    }

    ///\brief Processes the next node in the priority heap

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

    ///

    ///\return The processed node.

    ///

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

    Node processNextNode(){

      Node v=_heap->top(); 

      _heap->pop();

      _processed->set(v,true);

      for(IncEdgeIt e(*graph,v); e!=INVALID; ++e) {

	Node w=graph->oppositeNode(v,e);

	switch(_heap->state(w)) {

	case Heap::PRE_HEAP:

	  _heap->push(w,(*cost)[e]);

	  _pred->set(w,e);

	  break;

	case Heap::IN_HEAP:

	  if ( (*cost)[e] < (*_heap)[w] ) {

	    _heap->decrease(w,(*cost)[e]); 

	    _pred->set(w,e);

	  }

	  break;

	case Heap::POST_HEAP:

	  break;

	}

      }

      if ((*_pred)[v]!=INVALID)_tree->set((*_pred)[v],true);

      return v;

    }

    ///\brief Next node to be processed.

    ///Next node to be processed.

    ///

    ///\return The next node to be processed or INVALID if the priority heap

    /// is empty.

    Node nextNode(){ 

      return _heap->empty()?_heap->top():INVALID;

    }

    ///\brief 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 emptyQueue() { return _heap->empty(); }

    ///\brief 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 queueSize() { return _heap->size(); }

    ///\brief 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 %Prim algorithm from the node(s)

    ///in order to compute the

    ///minimum spanning tree.

    ///

    void start(){

      while ( !_heap->empty() ) processNextNode();

    }

    ///\brief 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 NodeBoolMap>

    void start(const NodeBoolMap &nm){

      while ( !_heap->empty() && !nm[_heap->top()] ) processNextNode();

      if ( !_heap->empty() ) _processed->set(_heap->top(),true);

    }

    ///\brief Runs %Prim algorithm.

    ///This method runs the %Prim algorithm

    ///in order to compute the

    ///minimum spanning tree (or minimum spanning forest).

    ///The method also works on graphs that has more than one components.

    ///In this case it computes the minimum spanning forest.

    void run() {

      init();

      for(NodeIt it(*graph);it!=INVALID;++it){

	if(!processed(it)){

	  addSource(it);

	  start();

	}

      }

    }

    ///\brief Runs %Prim algorithm from node \c s.

    ///This method runs the %Prim algorithm from node \c s

    ///in order to

    ///compute the

    ///minimun spanning tree

    ///

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

    ///\code

    ///  d.init();

    ///  d.addSource(s);

    ///  d.start();

    ///\endcode

    ///\note If the graph has more than one components, the method

    ///will compute the minimun spanning tree for only one component.

    ///

    ///See \ref run() if you want to compute the minimal spanning forest.

    void run(Node s){

      init();

      addSource(s);

      start();

    }

    ///@}

    ///\name Query Functions

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

    ///functions.\n

    ///Before the use of these functions,

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

    ///@{

    ///\brief Returns the 'previous edge' of the minimum spanning tree.

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

    ///i.e. it returns the edge from where \c v was reached. For a source node

    ///or an unreachable node it is \ref INVALID.

    ///The minimum spanning tree used here is equal to the minimum spanning tree used

    ///in \ref predNode().  \pre \ref run() or \ref start() must be called before

    ///using this function.

    UEdge predEdge(Node v) const { return (*_pred)[v]; }

    ///\brief Returns the 'previous node' of the minimum spanning tree.

    ///For a node \c v it returns the 'previous node' of the minimum spanning tree,

    ///i.e. it returns the node from where \c v was reached. For a source node

    ///or an unreachable node it is \ref INVALID.

    //The minimum spanning tree used here is equal to the minimum spanning

    ///tree used in \ref predEdge().  \pre \ref run() or \ref start() must be called

    ///before using this function.

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

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

    ///\brief Returns a reference to the NodeMap of the edges of the minimum spanning tree.

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

    ///minimum spanning tree.

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

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

    ///\brief Returns a reference to the tree edges map.

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

    ///minimum spanning tree. The value of the map is \c true only if the edge is in

    ///the minimum spanning tree.

    ///\warning By default, the TreeEdgeMap is a NullMap.

    ///

    ///If it is not set before the execution of the algorithm, use the \ref

    ///treeMap(TreeMap&) function (after the execution) to set an UEdgeMap with the

    ///edges of the minimum spanning tree in O(n) time where n is the number of

    ///nodes in the graph.

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

    const TreeMap &treeMap() const { return *_tree;}

    ///\brief Sets the tree edges map.

    ///Sets the TreeMap of the edges of the minimum spanning tree.

    ///The map values belonging to the edges of the minimum

    ///spanning tree are set to \c tree_edge_value or \c true by default,

    ///the other map values remain untouched.

    ///

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

    template<class TreeMap>

    void quickTreeEdges(

        TreeMap& tree,

        const typename TreeMap::Value& tree_edge_value=true) const {

      for(NodeIt i(*graph);i!=INVALID;++i){

        if((*_pred)[i]!=INVALID) tree.set((*_pred)[i],tree_edge_value);

      }

    }

    ///\brief Sets the tree edges map.

    ///Sets the TreeMap of the edges of the minimum spanning tree.

    ///The map values belonging to the edges of the minimum

    ///spanning tree are set to \c tree_edge_value or \c true by default while

    ///the edge values not belonging to the minimum spanning tree are set to

    ///\c tree_default_value or \c false by default.

    ///

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

    template<class TreeMap>

    void treeEdges(

        TreeMap& tree,

        const typename TreeMap::Value& tree_edge_value=true,

        const typename TreeMap::Value& tree_default_value=false) const {

      for(typename ItemSetTraits<UGraph,UEdge>::ItemIt i(*graph);i!=INVALID;++i)

	tree.set(i,tree_default_value);

      for(NodeIt i(*graph);i!=INVALID;++i){

        if((*_pred)[i]!=INVALID) tree.set((*_pred)[i],tree_edge_value);

      }

    }

    ///\brief Checks if a node is reachable from the starting node.

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

    ///\warning The source nodes are inditated as unreached.

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

    ///

    bool reached(Node v) { return (*_heap_cross_ref)[v] != Heap::PRE_HEAP; }

    ///\brief Checks if a node is processed.

    ///Returns \c true if \c v is processed, i.e. \c v is already connencted to the

    ///minimum spanning tree.

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

    ///

    bool processed(Node v) { return (*_heap_cross_ref)[v] == Heap::POST_HEAP; }

    ///\brief Checks if an edge is in the spanning tree or not.

    ///Checks if an edge is in the spanning tree or not.

    ///\param e is the edge that will be checked

    ///\return \c true if e is in the spanning tree, \c false otherwise

    bool tree(UEdge e){

      return (*_pred)[*graph.source(e)]==e || (*_pred)[*graph.target(e)]==e;

    }

    ///@}

  };

  /// \ingroup spantree

  ///

  /// \brief Function type interface for Prim algorithm.

  ///

  /// Function type interface for Prim algorithm.

  /// \param graph the UGraph that the algorithm runs on

  /// \param cost the CostMap of the edges

  /// \retval tree the EdgeMap that contains whether an edge is in 

  /// the spanning tree or not

  ///

  ///\sa Prim

  template<class Graph,class CostMap,class TreeMap>

  void prim(const Graph& graph, const CostMap& cost,TreeMap& tree){

    typename Prim<Graph,CostMap>::template DefTreeMap<TreeMap>::

      Create prm(graph,cost);

    prm.treeMap(tree);

    prm.run();

  }

} //END OF NAMESPACE LEMON

#endif