RhodeCode

        start=next;

        while(nedge[start]!=INVALID && visited[nedge[start]]) ++nedge[start];

      }

    }

    ///Arc Conversion

    operator Arc() const { return euler.empty()?INVALID:euler.front(); }

    ///Arc Conversion

    operator Edge() const { return euler.empty()?INVALID:euler.front(); }

    ///\e

    bool operator==(Invalid) const { return euler.empty(); }

    ///\e

    bool operator!=(Invalid) const { return !euler.empty(); }

    ///Next arc of the tour

    EulerIt &operator++() {

      Node s=g.target(euler.front());

      euler.pop_front();

      typename std::list<Arc>::iterator next=euler.begin();

      while(nedge[s]!=INVALID) {

        while(nedge[s]!=INVALID && visited[nedge[s]]) ++nedge[s];

        if(nedge[s]==INVALID) break;

        else {

          euler.insert(next,nedge[s]);

          visited[nedge[s]]=true;

          Node n=g.target(nedge[s]);

          ++nedge[s];

          s=n;

        }

      }

      return *this;

    }

    ///Postfix incrementation

    ///\warning This incrementation

    ///returns an \c Arc, not an \ref EulerIt, as one may

    ///expect.

    Arc operator++(int)

    {

      Arc e=*this;

      ++(*this);

      return e;

    }

  };

  /// \ingroup graph_prop

  ///graphs.

  ///and only if it is connected and the number of its incoming and outgoing

  ///arcs are the same for each node.

  ///and only if it is connected and the number of incident arcs is even

  ///\todo Test required

  template<class Digraph>

#ifdef DOXYGEN

  bool

#else

  typename enable_if<UndirectedTagIndicator<Digraph>,bool>::type

  {

    for(typename Digraph::NodeIt n(g);n!=INVALID;++n)

      if(countIncEdges(g,n)%2) return false;

    return connected(g);

  }

  template<class Digraph>

  typename disable_if<UndirectedTagIndicator<Digraph>,bool>::type

#endif

  {

    for(typename Digraph::NodeIt n(g);n!=INVALID;++n)

      if(countInArcs(g,n)!=countOutArcs(g,n)) return false;

    return connected(Undirector<const Digraph>(g));

  }

}

#endif