RhodeCode

    ///\param gr A digraph.

    ///\param start The starting point of the tour. If it is not given

    ///       the tour will start from the first node.

    DiEulerIt(const GR &gr, typename GR::Node start = INVALID)

      : g(gr), nedge(g)

    {

      for(NodeIt n(g);n!=INVALID;++n) nedge[n]=OutArcIt(g,n);

      while(nedge[start]!=INVALID) {

        euler.push_back(nedge[start]);

        Node next=g.target(nedge[start]);

        ++nedge[start];

        start=next;

      }

    }

    ///Arc Conversion

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

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

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

    ///\param gr An graph.

    ///\param start The starting point of the tour. If it is not given

    ///       the tour will start from the first node.

    EulerIt(const GR &gr, typename GR::Node start = INVALID)

      : g(gr), nedge(g), visited(g, false)

    {

      for(NodeIt n(g);n!=INVALID;++n) nedge[n]=OutArcIt(g,n);

      while(nedge[start]!=INVALID) {

        euler.push_back(nedge[start]);

        visited[nedge[start]]=true;

        Node next=g.target(nedge[start]);

        ++nedge[start];

        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