RhodeCode

      return *this;

    }

    ///Sets the map that indicates which nodes are processed.

    ///Sets the map that indicates which nodes are processed.

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

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

    ///automatically allocated map, of course.

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

    Dfs &processedMap(ProcessedMap &m)

    {

      if(local_processed) {

        delete _processed;

        local_processed=false;

      }

      _processed = &m;

      return *this;

    }

    ///Sets the map that stores the distances of the nodes.

    ///Sets the map that stores the distances of the nodes calculated by

    ///the algorithm.

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

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

    ///automatically allocated map, of course.

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

    Dfs &distMap(DistMap &m)

    {

      if(local_dist) {

        delete _dist;

        local_dist=false;

      }

      _dist = &m;

      return *this;

    }

  public:

    ///\name Execution control

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

    ///one of the member functions called \ref lemon::Dfs::run() "run()".

    ///\n

    ///If you need more control on the execution, first you must call

    ///\ref lemon::Dfs::init() "init()", then you can add a source node

    ///with \ref lemon::Dfs::addSource() "addSource()".

    ///Finally \ref lemon::Dfs::start() "start()" will perform the

    ///actual path computation.

    ///@{

    ///Initializes the internal data structures.

    ///Initializes the internal data structures.

    ///

    void init()

    {

      create_maps();

      _stack.resize(countNodes(*G));

      _stack_head=-1;

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

        _pred->set(u,INVALID);

        _reached->set(u,false);

        _processed->set(u,false);

      }

    }

    ///Adds a new source node.

    ///Adds a new source node to the set of nodes to be processed.

    ///

    ///\pre The stack must be empty. (Otherwise the algorithm gives

    ///false results.)

    ///

    ///\warning Distances will be wrong (or at least strange) in case of

    ///multiple sources.

    void addSource(Node s)

    {

      LEMON_DEBUG(emptyQueue(), "The stack is not empty.");

      if(!(*_reached)[s])

        {

          _reached->set(s,true);

          _pred->set(s,INVALID);

          OutArcIt e(*G,s);

          if(e!=INVALID) {

            _stack[++_stack_head]=e;

            _dist->set(s,_stack_head);

          }

          else {

            _processed->set(s,true);

            _dist->set(s,0);

          }

        }

    }

    ///Processes the next arc.

    ///Processes the next arc.

    ///

    ///\return The processed arc.

    ///

    ///\pre The stack must not be empty.

    Arc processNextArc()

    {

      Node m;

      Arc e=_stack[_stack_head];

      if(!(*_reached)[m=G->target(e)]) {

        _pred->set(m,e);

        _reached->set(m,true);

        ++_stack_head;

        _stack[_stack_head] = OutArcIt(*G, m);

        _dist->set(m,_stack_head);

      }

      else {

        m=G->source(e);

        ++_stack[_stack_head];

      }

      while(_stack_head>=0 && _stack[_stack_head]==INVALID) {

        _processed->set(m,true);

        --_stack_head;

        if(_stack_head>=0) {

          m=G->source(_stack[_stack_head]);

          ++_stack[_stack_head];

        }

      }

      return e;

    }

    ///Next arc to be processed.

    ///Next arc to be processed.

    ///

    ///\return The next arc to be processed or \c INVALID if the stack

    ///is empty.

    OutArcIt nextArc() const

    {

      return _stack_head>=0?_stack[_stack_head]:INVALID;

    }

    ///\brief Returns \c false if there are nodes

    ///to be processed.

    ///

    ///Returns \c false if there are nodes

    ///to be processed in the queue (stack).

    bool emptyQueue() const { return _stack_head<0; }

    ///Returns the number of the nodes to be processed.

    ///Returns the number of the nodes to be processed in the queue (stack).

    int queueSize() const { return _stack_head+1; }

    ///Executes the algorithm.

    ///Executes the algorithm.

    ///

    ///This method runs the %DFS algorithm from the root node

    ///in order to compute the DFS path to each node.

    ///

    /// The algorithm computes

    ///- the %DFS tree,

    ///- the distance of each node from the root in the %DFS tree.

    ///

    ///\pre init() must be called and a root node should be

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

    ///

    ///\note <tt>d.start()</tt> is just a shortcut of the following code.

    ///\code

    ///  while ( !d.emptyQueue() ) {

    ///    d.processNextArc();

    ///  }

    ///\endcode

    void start()

    {

      while ( !emptyQueue() ) processNextArc();

    }

    ///Executes the algorithm until the given target node is reached.

    ///Executes the algorithm until the given target node is reached.

    ///

    ///This method runs the %DFS algorithm from the root node

    ///in order to compute the DFS path to \c t.

    ///

    ///The algorithm computes

    ///- the %DFS path to \c t,

    ///- the distance of \c t from the root in the %DFS tree.

    ///

    ///\pre init() must be called and a root node should be

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

    void start(Node t)

    {

        processNextArc();

    }

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

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

    ///

    ///This method runs the %DFS algorithm from the root node

    ///until an arc \c a with <tt>am[a]</tt> true is found.

    ///

    ///\param am A \c bool (or convertible) arc map. The algorithm

    ///will stop when it reaches an arc \c a with <tt>am[a]</tt> true.

    ///

    ///\return The reached arc \c a with <tt>am[a]</tt> true or

    ///\c INVALID if no such arc was found.

    ///

    ///\pre init() must be called and a root node should be

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

    ///

    ///\warning Contrary to \ref Bfs and \ref Dijkstra, \c am is an arc map,

    ///not a node map.

    template<class ArcBoolMap>

    Arc start(const ArcBoolMap &am)

    {

      while ( !emptyQueue() && !am[_stack[_stack_head]] )

        processNextArc();

      return emptyQueue() ? INVALID : _stack[_stack_head];

    }

    ///Runs the algorithm from the given source node.

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

    ///in order to compute the DFS path to each node.

    ///

    ///The algorithm computes

    ///- the %DFS tree,

    ///- the distance of each node from the root in the %DFS tree.

    ///

    ///\note <tt>d.run(s)</tt> 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 %DFS path between \c s and \c t.

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

    ///in order to compute the DFS path to node \c t

    ///(it stops searching when \c t is processed)

    ///

    ///\return \c true if \c t is reachable form \c s.

    ///

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

    ///just a shortcut of the following code.

    ///\code

    ///  d.init();

    ///  d.addSource(s);

    ///  d.start(t);

    ///\endcode

    bool run(Node s,Node t) {

      init();

      addSource(s);

      start(t);

      return reached(t);

    }

    ///Runs the algorithm to visit all nodes in the digraph.

    ///This method runs the %DFS algorithm in order to compute the

    ///%DFS path to each node.

    ///

    ///The algorithm computes

    ///- the %DFS tree,

    ///- the distance of each node from the root in the %DFS tree.

    ///

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

    ///\code

    ///  d.init();

    ///  for (NodeIt n(digraph); n != INVALID; ++n) {

    ///    if (!d.reached(n)) {

    ///      d.addSource(n);

    ///      d.start();

    ///    }

    ///  }

    ///\endcode

    void run() {

      init();

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

        if (!reached(it)) {

          addSource(it);

          start();

        }

      }

    }

    ///@}

    ///\name Query Functions

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

    ///functions.\n

    ///Either \ref lemon::Dfs::run() "run()" or \ref lemon::Dfs::start()

    ///"start()" must be called before using them.

    ///@{

    ///The DFS path to a node.

    ///Returns the DFS path to a node.

    ///

    ///\warning \c t should be reachable from the root.

    ///

    ///\pre Either \ref run() or \ref start() must be called before

    ///using this function.

    Path path(Node t) const { return Path(*G, *_pred, t); }

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

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

    ///

    ///\warning If node \c v is not reachable from the root, then

    ///the return value of this function is undefined.

    ///

    ///\pre Either \ref run() or \ref start() must be called before

    ///using this function.

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

    ///Returns the 'previous arc' of the %DFS tree for a node.

    ///This function returns the 'previous arc' of the %DFS tree for the

    ///node \c v, i.e. it returns the last arc of a %DFS path from the

    ///root to \c v. It is \c INVALID

    ///if \c v is not reachable from the root(s) or if \c v is a root.

    ///

    ///The %DFS tree used here is equal to the %DFS tree used in

    ///\ref predNode().

    ///

    ///\pre Either \ref run() or \ref start() must be called before using

    ///this function.

    Arc predArc(Node v) const { return (*_pred)[v];}

    ///Returns the 'previous node' of the %DFS tree.

    ///This function returns the 'previous node' of the %DFS

    ///tree for the node \c v, i.e. it returns the last but one node

    ///from a %DFS path from the root to \c v. It is \c INVALID

    ///if \c v is not reachable from the root(s) or if \c v is a root.

    ///

    ///The %DFS tree used here is equal to the %DFS tree used in

    ///\ref predArc().

    ///

    ///\pre Either \ref run() or \ref start() must be called before

    ///using this function.

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

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

    ///\brief Returns a const reference to the node map that stores the

    ///distances of the nodes.

    ///

    ///Returns a const reference to the node map that stores the

    ///distances of the nodes calculated by the algorithm.

    ///

    ///\pre Either \ref run() or \ref init()

    ///must be called before using this function.

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

    ///\brief Returns a const reference to the node map that stores the

    ///predecessor arcs.

    ///

    ///Returns a const reference to the node map that stores the predecessor

    ///arcs, which form the DFS tree.

    ///

    ///\pre Either \ref run() or \ref init()

    ///must be called before using this function.

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

    ///Checks if a node is reachable from the root(s).

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

    ///\pre Either \ref run() or \ref start()

    ///must be called before using this function.

    bool reached(Node v) const { return (*_reached)[v]; }

    ///@}

  };

  ///Default traits class of dfs() function.

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

    /// ReachedMap type.

    ///

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

    template <class T>

    struct SetReachedMap : public DfsVisit< Digraph, Visitor,

                                            SetReachedMapTraits<T> > {

      typedef DfsVisit< Digraph, Visitor, SetReachedMapTraits<T> > Create;

    };

    ///@}

  public:

    /// \brief Constructor.

    ///

    /// Constructor.

    ///

    /// \param digraph The digraph the algorithm runs on.

    /// \param visitor The visitor object of the algorithm.

    DfsVisit(const Digraph& digraph, Visitor& visitor)

      : _digraph(&digraph), _visitor(&visitor),

        _reached(0), local_reached(false) {}

    /// \brief Destructor.

    ~DfsVisit() {

      if(local_reached) delete _reached;

    }

    /// \brief Sets the map that indicates which nodes are reached.

    ///

    /// Sets the map that indicates which nodes are reached.

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

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

    /// automatically allocated map, of course.

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

    DfsVisit &reachedMap(ReachedMap &m) {

      if(local_reached) {

        delete _reached;

        local_reached=false;

      }

      _reached = &m;

      return *this;

    }

  public:

    /// \name Execution control

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

    /// one of the member functions called \ref lemon::DfsVisit::run()

    /// "run()".

    /// \n

    /// If you need more control on the execution, first you must call

    /// \ref lemon::DfsVisit::init() "init()", then you can add several

    /// source nodes with \ref lemon::DfsVisit::addSource() "addSource()".

    /// Finally \ref lemon::DfsVisit::start() "start()" will perform the

    /// actual path computation.

    /// @{

    /// \brief Initializes the internal data structures.

    ///

    /// Initializes the internal data structures.

    void init() {

      create_maps();

      _stack.resize(countNodes(*_digraph));

      _stack_head = -1;

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

        _reached->set(u, false);

      }

    }

    ///Adds a new source node.

    ///Adds a new source node to the set of nodes to be processed.

    ///

    ///\pre The stack must be empty. (Otherwise the algorithm gives

    ///false results.)

    ///

    ///\warning Distances will be wrong (or at least strange) in case of

    ///multiple sources.

    void addSource(Node s)

    {

      LEMON_DEBUG(emptyQueue(), "The stack is not empty.");

      if(!(*_reached)[s]) {

          _reached->set(s,true);

          _visitor->start(s);

          _visitor->reach(s);

          Arc e;

          _digraph->firstOut(e, s);

          if (e != INVALID) {

            _stack[++_stack_head] = e;

          } else {

            _visitor->leave(s);

            _visitor->stop(s);

          }

        }

    }

    /// \brief Processes the next arc.

    ///

    /// Processes the next arc.

    ///

    /// \return The processed arc.

    ///

    /// \pre The stack must not be empty.

    Arc processNextArc() {

      Arc e = _stack[_stack_head];

      Node m = _digraph->target(e);

      if(!(*_reached)[m]) {

        _visitor->discover(e);

        _visitor->reach(m);

        _reached->set(m, true);

        _digraph->firstOut(_stack[++_stack_head], m);

      } else {

        _visitor->examine(e);

        m = _digraph->source(e);

        _digraph->nextOut(_stack[_stack_head]);

      }

      while (_stack_head>=0 && _stack[_stack_head] == INVALID) {

        _visitor->leave(m);

        --_stack_head;

        if (_stack_head >= 0) {

          _visitor->backtrack(_stack[_stack_head]);

          m = _digraph->source(_stack[_stack_head]);

          _digraph->nextOut(_stack[_stack_head]);

        } else {

          _visitor->stop(m);

        }

      }

      return e;

    }

    /// \brief Next arc to be processed.

    ///

    /// Next arc to be processed.

    ///

    /// \return The next arc to be processed or INVALID if the stack is

    /// empty.

    Arc nextArc() const {

      return _stack_head >= 0 ? _stack[_stack_head] : INVALID;

    }

    /// \brief Returns \c false if there are nodes

    /// to be processed.

    ///

    /// Returns \c false if there are nodes

    /// to be processed in the queue (stack).

    bool emptyQueue() const { return _stack_head < 0; }

    /// \brief Returns the number of the nodes to be processed.

    ///

    /// Returns the number of the nodes to be processed in the queue (stack).

    int queueSize() const { return _stack_head + 1; }

    /// \brief Executes the algorithm.

    ///

    /// Executes the algorithm.

    ///

    /// This method runs the %DFS algorithm from the root node

    /// in order to compute the %DFS path to each node.

    ///

    /// The algorithm computes

    /// - the %DFS tree,

    /// - the distance of each node from the root in the %DFS tree.

    ///

    /// \pre init() must be called and a root node should be

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

    ///

    /// \note <tt>d.start()</tt> is just a shortcut of the following code.

    /// \code

    ///   while ( !d.emptyQueue() ) {

    ///     d.processNextArc();

    ///   }

    /// \endcode

    void start() {

      while ( !emptyQueue() ) processNextArc();

    }

    /// \brief Executes the algorithm until the given target node is reached.

    ///

    /// Executes the algorithm until the given target node is reached.

    ///

    /// This method runs the %DFS algorithm from the root node

    /// in order to compute the DFS path to \c t.

    ///

    /// The algorithm computes

    /// - the %DFS path to \c t,

    /// - the distance of \c t from the root in the %DFS tree.

    ///

    /// \pre init() must be called and a root node should be added

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

    void start(Node t) {

        processNextArc();

    }

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

    ///

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

    ///

    /// This method runs the %DFS algorithm from the root node

    /// until an arc \c a with <tt>am[a]</tt> true is found.

    ///

    /// \param am A \c bool (or convertible) arc map. The algorithm

    /// will stop when it reaches an arc \c a with <tt>am[a]</tt> true.

    ///

    /// \return The reached arc \c a with <tt>am[a]</tt> true or

    /// \c INVALID if no such arc was found.

    ///

    /// \pre init() must be called and a root node should be added

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

    ///

    /// \warning Contrary to \ref Bfs and \ref Dijkstra, \c am is an arc map,

    /// not a node map.

    template <typename AM>

    Arc start(const AM &am) {

      while ( !emptyQueue() && !am[_stack[_stack_head]] )

        processNextArc();

      return emptyQueue() ? INVALID : _stack[_stack_head];

    }

    /// \brief Runs the algorithm from the given source node.

    ///

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

    /// in order to compute the DFS path to each node.

    ///

    /// The algorithm computes

    /// - the %DFS tree,

    /// - the distance of each node from the root in the %DFS tree.

    ///

    /// \note <tt>d.run(s)</tt> 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();

    }

    /// \brief Finds the %DFS path between \c s and \c t.

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

    /// in order to compute the DFS path to node \c t

    /// (it stops searching when \c t is processed).

    ///

    /// \return \c true if \c t is reachable form \c s.

    ///

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

    /// just a shortcut of the following code.

    ///\code

    ///   d.init();

    ///   d.addSource(s);

    ///   d.start(t);

    ///\endcode

    bool run(Node s,Node t) {

      init();

      addSource(s);

      start(t);

      return reached(t);

    }

    /// \brief Runs the algorithm to visit all nodes in the digraph.

    /// This method runs the %DFS algorithm in order to

    /// compute the %DFS path to each node.

    ///

    /// The algorithm computes

    /// - the %DFS tree,

    /// - the distance of each node from the root in the %DFS tree.

    ///

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

    ///\code

    ///   d.init();

    ///   for (NodeIt n(digraph); n != INVALID; ++n) {

    ///     if (!d.reached(n)) {

    ///       d.addSource(n);

    ///       d.start();

    ///     }

    ///   }

    ///\endcode

    void run() {

      init();

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

        if (!reached(it)) {

          addSource(it);

          start();

        }

      }

    }

    ///@}

    /// \name Query Functions

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

    /// functions.\n

    /// Either \ref lemon::DfsVisit::run() "run()" or

    /// \ref lemon::DfsVisit::start() "start()" must be called before

    /// using them.

    ///@{

    /// \brief Checks if a node is reachable from the root(s).

    ///

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

    /// \pre Either \ref run() or \ref start()

    /// must be called before using this function.

    bool reached(Node v) { return (*_reached)[v]; }

    ///@}

  };

} //END OF NAMESPACE LEMON

#endif

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

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

 *

 * Copyright (C) 2003-2008

 * 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.

 *

 */

#include <lemon/concepts/digraph.h>

#include <lemon/smart_graph.h>

#include <lemon/list_graph.h>

#include <lemon/lgf_reader.h>

#include <lemon/dfs.h>

#include <lemon/path.h>

#include "graph_test.h"

#include "test_tools.h"

using namespace lemon;

char test_lgf[] =

  "@nodes\n"

  "label\n"

  "0\n"

  "1\n"

  "2\n"

  "3\n"

  "4\n"

  "5\n"

  "6\n"

  "@arcs\n"

  "     label\n"

  "0 1  0\n"

  "1 2  1\n"

  "2 3  2\n"

  "1 4  3\n"

  "4 2  4\n"

  "4 5  5\n"

  "5 0  6\n"

  "6 3  7\n"

  "@attributes\n"

  "source 0\n"

void checkDfsCompile()

{

  typedef concepts::Digraph Digraph;

  typedef Dfs<Digraph> DType;

  typedef Digraph::Node Node;

  typedef Digraph::Arc Arc;

  Digraph G;

  Node s, t;

  Arc e;

  int l;

  bool b;

  DType::DistMap d(G);

  DType::PredMap p(G);

  Path<Digraph> pp;

  {

    DType dfs_test(G);

    dfs_test.run(s);

    dfs_test.run(s,t);

    dfs_test.run();

    l  = dfs_test.dist(t);

    e  = dfs_test.predArc(t);

    s  = dfs_test.predNode(t);

    b  = dfs_test.reached(t);

    d  = dfs_test.distMap();

    p  = dfs_test.predMap();

    pp = dfs_test.path(t);

  }

  {

    DType

      ::SetPredMap<concepts::ReadWriteMap<Node,Arc> >

      ::SetDistMap<concepts::ReadWriteMap<Node,int> >

      ::SetReachedMap<concepts::ReadWriteMap<Node,bool> >

      ::SetProcessedMap<concepts::WriteMap<Node,bool> >

      ::SetStandardProcessedMap

      ::Create dfs_test(G);

    dfs_test.run(s);

    dfs_test.run(s,t);

    dfs_test.run();

    l  = dfs_test.dist(t);

    e  = dfs_test.predArc(t);

    s  = dfs_test.predNode(t);

    b  = dfs_test.reached(t);

    pp = dfs_test.path(t);

  }

}

void checkDfsFunctionCompile()

{

  typedef int VType;

  typedef concepts::Digraph Digraph;

  typedef Digraph::Arc Arc;

  typedef Digraph::Node Node;

  Digraph g;

  bool b;

  dfs(g).run(Node());

  b=dfs(g).run(Node(),Node());

  dfs(g).run();

  dfs(g)

    .predMap(concepts::ReadWriteMap<Node,Arc>())

    .distMap(concepts::ReadWriteMap<Node,VType>())

    .reachedMap(concepts::ReadWriteMap<Node,bool>())

    .processedMap(concepts::WriteMap<Node,bool>())

    .run(Node());

  b=dfs(g)

    .predMap(concepts::ReadWriteMap<Node,Arc>())

    .distMap(concepts::ReadWriteMap<Node,VType>())

    .reachedMap(concepts::ReadWriteMap<Node,bool>())

    .processedMap(concepts::WriteMap<Node,bool>())

    .path(concepts::Path<Digraph>())

    .dist(VType())

    .run(Node(),Node());

  dfs(g)

    .predMap(concepts::ReadWriteMap<Node,Arc>())

    .distMap(concepts::ReadWriteMap<Node,VType>())

    .reachedMap(concepts::ReadWriteMap<Node,bool>())

    .processedMap(concepts::WriteMap<Node,bool>())

    .run();

}

template <class Digraph>

void checkDfs() {

  TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);

  Digraph G;

  Node s, t;

  std::istringstream input(test_lgf);

  digraphReader(G, input).

    node("source", s).

    node("target", t).

    run();

  Dfs<Digraph> dfs_test(G);

  dfs_test.run(s);

  Path<Digraph> p = dfs_test.path(t);

  check(p.length() == dfs_test.dist(t),"path() found a wrong path.");

  check(checkPath(G, p),"path() found a wrong path.");

  check(pathSource(G, p) == s,"path() found a wrong path.");

  check(pathTarget(G, p) == t,"path() found a wrong path.");

  for(NodeIt v(G); v!=INVALID; ++v) {

    if (dfs_test.reached(v)) {

      check(v==s || dfs_test.predArc(v)!=INVALID, "Wrong tree.");

      if (dfs_test.predArc(v)!=INVALID ) {

        Arc e=dfs_test.predArc(v);

        Node u=G.source(e);

        check(u==dfs_test.predNode(v),"Wrong tree.");

        check(dfs_test.dist(v) - dfs_test.dist(u) == 1,

              "Wrong distance. (" << dfs_test.dist(u) << "->"

              << dfs_test.dist(v) << ")");

      }

    }

  }

  {

    NullMap<Node,Arc> myPredMap;

    dfs(G).predMap(myPredMap).run(s);

  }

}

int main()

{

  checkDfs<ListDigraph>();

  checkDfs<SmartDigraph>();

  return 0;

}