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106 lines
3.9 KiB
106 lines
3.9 KiB
// |
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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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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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function_requires< 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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function_requires< 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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