Added boost header

test/external/boost/graph/connected_components.hpp

@@ -0,0 +1,106 @@
+//
+//=======================================================================
+// 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