// | |
//======================================================================= | |
// 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> | |
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; | |
function_requires< 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; | |
function_requires< 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 |