108 lines
4.1 KiB
C++
108 lines
4.1 KiB
C++
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//
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//=======================================================================
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// Copyright 1997-2001 University of Notre Dame.
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// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//=======================================================================
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//
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#ifndef BOOST_GRAPH_CONNECTED_COMPONENTS_HPP
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#define BOOST_GRAPH_CONNECTED_COMPONENTS_HPP
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#include <boost/config.hpp>
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#include <boost/graph/depth_first_search.hpp>
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#include <boost/graph/properties.hpp>
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#include <boost/graph/graph_concepts.hpp>
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#include <boost/graph/overloading.hpp>
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#include <boost/static_assert.hpp>
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#include <boost/concept/assert.hpp>
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namespace boost {
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namespace detail {
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// This visitor is used both in the connected_components algorithm
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// and in the kosaraju strong components algorithm during the
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// second DFS traversal.
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template <class ComponentsMap>
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class components_recorder : public dfs_visitor<>
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{
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typedef typename property_traits<ComponentsMap>::value_type comp_type;
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public:
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components_recorder(ComponentsMap c,
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comp_type& c_count)
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: m_component(c), m_count(c_count) {}
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template <class Vertex, class Graph>
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void start_vertex(Vertex, Graph&) {
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if (m_count == (std::numeric_limits<comp_type>::max)())
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m_count = 0; // start counting components at zero
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else
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++m_count;
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}
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template <class Vertex, class Graph>
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void discover_vertex(Vertex u, Graph&) {
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put(m_component, u, m_count);
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}
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protected:
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ComponentsMap m_component;
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comp_type& m_count;
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};
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} // namespace detail
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// This function computes the connected components of an undirected
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// graph using a single application of depth first search.
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template <class Graph, class ComponentMap, class P, class T, class R>
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inline typename property_traits<ComponentMap>::value_type
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connected_components(const Graph& g, ComponentMap c,
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const bgl_named_params<P, T, R>& params
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BOOST_GRAPH_ENABLE_IF_MODELS_PARM(Graph, vertex_list_graph_tag))
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{
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if (num_vertices(g) == 0) return 0;
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typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
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BOOST_CONCEPT_ASSERT(( WritablePropertyMapConcept<ComponentMap, Vertex> ));
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typedef typename boost::graph_traits<Graph>::directed_category directed;
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BOOST_STATIC_ASSERT((boost::is_same<directed, undirected_tag>::value));
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typedef typename property_traits<ComponentMap>::value_type comp_type;
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// c_count initialized to "nil" (with nil represented by (max)())
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comp_type c_count((std::numeric_limits<comp_type>::max)());
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detail::components_recorder<ComponentMap> vis(c, c_count);
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depth_first_search(g, params.visitor(vis));
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return c_count + 1;
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}
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template <class Graph, class ComponentMap>
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inline typename property_traits<ComponentMap>::value_type
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connected_components(const Graph& g, ComponentMap c
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BOOST_GRAPH_ENABLE_IF_MODELS_PARM(Graph, vertex_list_graph_tag))
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{
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if (num_vertices(g) == 0) return 0;
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typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
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BOOST_CONCEPT_ASSERT(( WritablePropertyMapConcept<ComponentMap, Vertex> ));
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// typedef typename boost::graph_traits<Graph>::directed_category directed;
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// BOOST_STATIC_ASSERT((boost::is_same<directed, undirected_tag>::value));
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typedef typename property_traits<ComponentMap>::value_type comp_type;
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// c_count initialized to "nil" (with nil represented by (max)())
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comp_type c_count((std::numeric_limits<comp_type>::max)());
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detail::components_recorder<ComponentMap> vis(c, c_count);
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depth_first_search(g, visitor(vis));
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return c_count + 1;
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}
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} // namespace boost
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#ifdef BOOST_GRAPH_USE_MPI
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# include <boost/graph/distributed/connected_components.hpp>
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#endif
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#endif // BOOST_GRAPH_CONNECTED_COMPONENTS_HPP
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