108 lines
4.1 KiB
C++
108 lines
4.1 KiB
C++
//
|
|
//=======================================================================
|
|
// Copyright 1997-2001 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)
|
|
//=======================================================================
|
|
//
|
|
#ifndef BOOST_GRAPH_CONNECTED_COMPONENTS_HPP
|
|
#define BOOST_GRAPH_CONNECTED_COMPONENTS_HPP
|
|
|
|
#include <boost/config.hpp>
|
|
#include <boost/graph/depth_first_search.hpp>
|
|
#include <boost/graph/properties.hpp>
|
|
#include <boost/graph/graph_concepts.hpp>
|
|
#include <boost/graph/overloading.hpp>
|
|
#include <boost/static_assert.hpp>
|
|
#include <boost/concept/assert.hpp>
|
|
|
|
namespace boost {
|
|
|
|
namespace detail {
|
|
|
|
// This visitor is used both in the connected_components algorithm
|
|
// and in the kosaraju strong components algorithm during the
|
|
// second DFS traversal.
|
|
template <class ComponentsMap>
|
|
class components_recorder : public dfs_visitor<>
|
|
{
|
|
typedef typename property_traits<ComponentsMap>::value_type comp_type;
|
|
public:
|
|
components_recorder(ComponentsMap c,
|
|
comp_type& c_count)
|
|
: m_component(c), m_count(c_count) {}
|
|
|
|
template <class Vertex, class Graph>
|
|
void start_vertex(Vertex, Graph&) {
|
|
if (m_count == (std::numeric_limits<comp_type>::max)())
|
|
m_count = 0; // start counting components at zero
|
|
else
|
|
++m_count;
|
|
}
|
|
template <class Vertex, class Graph>
|
|
void discover_vertex(Vertex u, Graph&) {
|
|
put(m_component, u, m_count);
|
|
}
|
|
protected:
|
|
ComponentsMap m_component;
|
|
comp_type& m_count;
|
|
};
|
|
|
|
} // namespace detail
|
|
|
|
// This function computes the connected components of an undirected
|
|
// graph using a single application of depth first search.
|
|
|
|
template <class Graph, class ComponentMap, class P, class T, class R>
|
|
inline typename property_traits<ComponentMap>::value_type
|
|
connected_components(const Graph& g, ComponentMap c,
|
|
const bgl_named_params<P, T, R>& params
|
|
BOOST_GRAPH_ENABLE_IF_MODELS_PARM(Graph, vertex_list_graph_tag))
|
|
{
|
|
if (num_vertices(g) == 0) return 0;
|
|
|
|
typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
|
|
BOOST_CONCEPT_ASSERT(( WritablePropertyMapConcept<ComponentMap, Vertex> ));
|
|
typedef typename boost::graph_traits<Graph>::directed_category directed;
|
|
BOOST_STATIC_ASSERT((boost::is_same<directed, undirected_tag>::value));
|
|
|
|
typedef typename property_traits<ComponentMap>::value_type comp_type;
|
|
// c_count initialized to "nil" (with nil represented by (max)())
|
|
comp_type c_count((std::numeric_limits<comp_type>::max)());
|
|
detail::components_recorder<ComponentMap> vis(c, c_count);
|
|
depth_first_search(g, params.visitor(vis));
|
|
return c_count + 1;
|
|
}
|
|
|
|
template <class Graph, class ComponentMap>
|
|
inline typename property_traits<ComponentMap>::value_type
|
|
connected_components(const Graph& g, ComponentMap c
|
|
BOOST_GRAPH_ENABLE_IF_MODELS_PARM(Graph, vertex_list_graph_tag))
|
|
{
|
|
if (num_vertices(g) == 0) return 0;
|
|
|
|
typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
|
|
BOOST_CONCEPT_ASSERT(( WritablePropertyMapConcept<ComponentMap, Vertex> ));
|
|
// typedef typename boost::graph_traits<Graph>::directed_category directed;
|
|
// BOOST_STATIC_ASSERT((boost::is_same<directed, undirected_tag>::value));
|
|
|
|
typedef typename property_traits<ComponentMap>::value_type comp_type;
|
|
// c_count initialized to "nil" (with nil represented by (max)())
|
|
comp_type c_count((std::numeric_limits<comp_type>::max)());
|
|
detail::components_recorder<ComponentMap> vis(c, c_count);
|
|
depth_first_search(g, visitor(vis));
|
|
return c_count + 1;
|
|
}
|
|
|
|
|
|
} // namespace boost
|
|
|
|
#ifdef BOOST_GRAPH_USE_MPI
|
|
# include <boost/graph/distributed/connected_components.hpp>
|
|
#endif
|
|
|
|
#endif // BOOST_GRAPH_CONNECTED_COMPONENTS_HPP
|