Boost C++ Libraries

boost/graph/visitors.hpp

//=======================================================================
// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================
//
// Revision History:
//   01 April 2001: Modified to use new <boost/limits.hpp> header. (JMaddock)
//
#ifndef BOOST_GRAPH_GRAPH_SEARCH_VISITORS_HPP
#define BOOST_GRAPH_GRAPH_SEARCH_VISITORS_HPP

#include <iosfwd>
#include <boost/config.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/property_map/property_map.hpp>
#include <boost/graph/graph_traits.hpp>
#include <boost/limits.hpp>

namespace boost {

  // This is a bit more convenient than std::numeric_limits because
  // you don't have to explicitly provide type T.
  template <class T>
  inline T numeric_limits_max(T) { return (std::numeric_limits<T>::max)(); }

  //========================================================================
  // Event Tags

  namespace detail {
    // For partial specialization workaround
    enum event_visitor_enum
    { on_no_event_num,
      on_initialize_vertex_num, on_start_vertex_num,
      on_discover_vertex_num, on_finish_vertex_num, on_examine_vertex_num,
      on_examine_edge_num, on_tree_edge_num, on_non_tree_edge_num,
      on_gray_target_num, on_black_target_num,
      on_forward_or_cross_edge_num, on_back_edge_num, on_finish_edge_num,
      on_edge_relaxed_num, on_edge_not_relaxed_num,
      on_edge_minimized_num, on_edge_not_minimized_num
    };

    template<typename Event, typename Visitor>
    struct functor_to_visitor : Visitor
    {
      typedef Event event_filter;
      functor_to_visitor(const Visitor& visitor) : Visitor(visitor) {}
    };

  } // namespace detail

  struct on_no_event { enum { num = detail::on_no_event_num }; };

  struct on_initialize_vertex {
    enum { num = detail::on_initialize_vertex_num }; };
  struct on_start_vertex { enum { num = detail::on_start_vertex_num }; };
  struct on_discover_vertex { enum { num = detail::on_discover_vertex_num }; };
  struct on_examine_vertex { enum { num = detail::on_examine_vertex_num }; };
  struct on_finish_vertex { enum { num = detail::on_finish_vertex_num }; };

  struct on_examine_edge { enum { num = detail::on_examine_edge_num }; };
  struct on_tree_edge { enum { num = detail::on_tree_edge_num }; };
  struct on_non_tree_edge { enum { num = detail::on_non_tree_edge_num }; };
  struct on_gray_target { enum { num = detail::on_gray_target_num }; };
  struct on_black_target { enum { num = detail::on_black_target_num }; };
  struct on_forward_or_cross_edge {
    enum { num = detail::on_forward_or_cross_edge_num }; };
  struct on_back_edge { enum { num = detail::on_back_edge_num }; };
  struct on_finish_edge { enum { num = detail::on_finish_edge_num }; };

  struct on_edge_relaxed { enum { num = detail::on_edge_relaxed_num }; };
  struct on_edge_not_relaxed {
    enum { num = detail::on_edge_not_relaxed_num }; };
  struct on_edge_minimized { enum { num = detail::on_edge_minimized_num }; };
  struct on_edge_not_minimized {
    enum { num = detail::on_edge_not_minimized_num }; };

  //========================================================================
  // base_visitor and null_visitor

  // needed for MSVC workaround
  template <class Visitor>
  struct base_visitor {
    typedef on_no_event event_filter;
    template <class T, class Graph>
    void operator()(T, Graph&) { }
  };

  struct null_visitor : public base_visitor<null_visitor> {
    typedef on_no_event event_filter;
    template <class T, class Graph>
    void operator()(T, Graph&) { }
  };

  //========================================================================
  // The invoke_visitors() function

  namespace detail {
    template <class Visitor, class T, class Graph>
    inline void invoke_dispatch(Visitor& v, T x, Graph& g, mpl::true_) {
       v(x, g);
    }

    template <class Visitor, class T, class Graph>
    inline void invoke_dispatch(Visitor&, T, Graph&, mpl::false_)
    { }
  } // namespace detail

  template <class Visitor, class Rest, class T, class Graph, class Tag>
  inline void
  invoke_visitors(std::pair<Visitor, Rest>& vlist, T x, Graph& g, Tag tag) {
    typedef typename Visitor::event_filter Category;
    typedef typename is_same<Category, Tag>::type IsSameTag;
    detail::invoke_dispatch(vlist.first, x, g, IsSameTag());
    invoke_visitors(vlist.second, x, g, tag);
  }
  template <class Visitor, class T, class Graph, class Tag>
  inline void
  invoke_visitors(Visitor& v, T x, Graph& g, Tag) {
    typedef typename Visitor::event_filter Category;
    typedef typename is_same<Category, Tag>::type IsSameTag;
    detail::invoke_dispatch(v, x, g, IsSameTag());
  }

  //========================================================================
  // predecessor_recorder

  template <class PredecessorMap, class Tag>
  struct predecessor_recorder
    : public base_visitor<predecessor_recorder<PredecessorMap, Tag> >
  {
    typedef Tag event_filter;
    predecessor_recorder(PredecessorMap pa) : m_predecessor(pa) { }
    template <class Edge, class Graph>
    void operator()(Edge e, const Graph& g) {
      put(m_predecessor, target(e, g), source(e, g));
    }
    PredecessorMap m_predecessor;
  };
  template <class PredecessorMap, class Tag>
  predecessor_recorder<PredecessorMap, Tag>
  record_predecessors(PredecessorMap pa, Tag) {
    return predecessor_recorder<PredecessorMap, Tag> (pa);
  }

  //========================================================================
  // edge_predecessor_recorder

  template <class PredEdgeMap, class Tag>
  struct edge_predecessor_recorder
    : public base_visitor<edge_predecessor_recorder<PredEdgeMap, Tag> >
  {
    typedef Tag event_filter;
    edge_predecessor_recorder(PredEdgeMap pa) : m_predecessor(pa) { }
    template <class Edge, class Graph>
    void operator()(Edge e, const Graph& g) {
      put(m_predecessor, target(e, g), e);
    }
    PredEdgeMap m_predecessor;
  };
  template <class PredEdgeMap, class Tag>
  edge_predecessor_recorder<PredEdgeMap, Tag>
  record_edge_predecessors(PredEdgeMap pa, Tag) {
    return edge_predecessor_recorder<PredEdgeMap, Tag> (pa);
  }

  //========================================================================
  // distance_recorder

  template <class DistanceMap, class Tag>
  struct distance_recorder
    : public base_visitor<distance_recorder<DistanceMap, Tag> >
  {
    typedef Tag event_filter;
    distance_recorder(DistanceMap pa) : m_distance(pa) { }
    template <class Edge, class Graph>
    void operator()(Edge e, const Graph& g) {
      typename graph_traits<Graph>::vertex_descriptor
        u = source(e, g), v = target(e, g);
      put(m_distance, v, get(m_distance, u) + 1);
    }
    DistanceMap m_distance;
  };
  template <class DistanceMap, class Tag>
  distance_recorder<DistanceMap, Tag>
  record_distances(DistanceMap pa, Tag) {
    return distance_recorder<DistanceMap, Tag> (pa);
  }

  //========================================================================
  // time_stamper


  template <class TimeMap, class TimeT, class Tag>
  struct time_stamper
    : public base_visitor<time_stamper<TimeMap, TimeT, Tag> >
  {
    typedef Tag event_filter;
    time_stamper(TimeMap pa, TimeT& t) : m_time_pa(pa), m_time(t) { }
    template <class Vertex, class Graph>
    void operator()(Vertex u, const Graph&) {
      put(m_time_pa, u, ++m_time);
    }
    TimeMap m_time_pa;
    TimeT& m_time;
  };
  template <class TimeMap, class TimeT, class Tag>
  time_stamper<TimeMap, TimeT, Tag>
  stamp_times(TimeMap pa, TimeT& time_counter, Tag) {
    return time_stamper<TimeMap, TimeT, Tag>(pa, time_counter);
  }

  //========================================================================
  // property_writer

  template <class PA, class OutputIterator, class Tag>
  struct property_writer
    : public base_visitor<property_writer<PA, OutputIterator, Tag> >
  {
    typedef Tag event_filter;

    property_writer(PA pa, OutputIterator out) : m_pa(pa), m_out(out) { }

    template <class T, class Graph>
    void operator()(T x, Graph&) { *m_out++ = get(m_pa, x); }
    PA m_pa;
    OutputIterator m_out;
  };
  template <class PA, class OutputIterator, class Tag>
  property_writer<PA, OutputIterator, Tag>
  write_property(PA pa, OutputIterator out, Tag) {
    return property_writer<PA, OutputIterator, Tag>(pa, out);
  }

  //========================================================================
  // property_put

    /**
     * Functor which just sets a given value to a vertex or edge in a property map.
     */

  template <typename PropertyMap, typename EventTag>
  struct property_put
  {
    typedef EventTag event_filter;
    
    property_put (PropertyMap property_map,
                  typename property_traits <PropertyMap>::value_type value) :
      property_map_ (property_map), value_ (value)
    {}

    template <typename VertexOrEdge, typename Graph>
    void operator() (VertexOrEdge v, const Graph&)
    {
      put (property_map_, v, value_);
    }

  private:
    PropertyMap property_map_;
    typename property_traits <PropertyMap>::value_type value_;
  };

  /**
   * Creates a property_put functor which just sets a given value to a vertex or edge.
   * 
   * @param property_map Given writeable property map 
   * @param value Fixed value of the map
   * @param tag Event Filter
   * @return The functor.
   */

    template <typename PropertyMap, typename EventTag>
    inline property_put <PropertyMap, EventTag>
    put_property (PropertyMap property_map,
                  typename property_traits <PropertyMap>::value_type value,
                  EventTag)
    {
      return property_put <PropertyMap, EventTag> (property_map, value);
    }

#define BOOST_GRAPH_EVENT_STUB(Event,Kind)                                 \
    typedef ::boost::Event Event##_type;                                   \
    template<typename Visitor>                                             \
    Kind##_visitor<std::pair<detail::functor_to_visitor<Event##_type,      \
                                                     Visitor>, Visitors> > \
    do_##Event(Visitor visitor)                                            \
    {                                                                      \
      typedef std::pair<detail::functor_to_visitor<Event##_type, Visitor>, \
                        Visitors> visitor_list;                            \
      typedef Kind##_visitor<visitor_list> result_type;                    \
      return result_type(visitor_list(visitor, m_vis));                    \
    }

} /* namespace boost */

#endif