epoc32/include/stdapis/boost/graph/strong_components.hpp
author William Roberts <williamr@symbian.org>
Wed, 31 Mar 2010 12:33:34 +0100
branchSymbian3
changeset 4 837f303aceeb
permissions -rw-r--r--
Current Symbian^3 public API header files (from PDK 3.0.h)
This is the epoc32/include tree with the "platform" subtrees removed, and
all but a selected few mbg and rsg files removed.
     1 //
     2 //=======================================================================
     3 // Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
     4 // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
     5 //
     6 // Distributed under the Boost Software License, Version 1.0. (See
     7 // accompanying file LICENSE_1_0.txt or copy at
     8 // http://www.boost.org/LICENSE_1_0.txt)
     9 //=======================================================================
    10 //
    11 
    12 #ifndef BOOST_GRAPH_STRONG_COMPONENTS_HPP
    13 #define BOOST_GRAPH_STRONG_COMPONENTS_HPP
    14 
    15 #include <stack>
    16 #include <boost/config.hpp>
    17 #include <boost/graph/depth_first_search.hpp>
    18 #include <boost/type_traits/conversion_traits.hpp>
    19 #include <boost/static_assert.hpp>
    20 
    21 namespace boost {
    22 
    23   //==========================================================================
    24   // This is Tarjan's algorithm for strongly connected components
    25   // from his paper "Depth first search and linear graph algorithms".
    26   // It calculates the components in a single application of DFS.
    27   // We implement the algorithm as a dfs-visitor.
    28 
    29   namespace detail {
    30     
    31     template <typename ComponentMap, typename RootMap, typename DiscoverTime,
    32               typename Stack>
    33     class tarjan_scc_visitor : public dfs_visitor<> 
    34     {
    35       typedef typename property_traits<ComponentMap>::value_type comp_type;
    36       typedef typename property_traits<DiscoverTime>::value_type time_type;
    37     public:
    38       tarjan_scc_visitor(ComponentMap comp_map, RootMap r, DiscoverTime d, 
    39                          comp_type& c_, Stack& s_)
    40         : c(c_), comp(comp_map), root(r), discover_time(d),
    41           dfs_time(time_type()), s(s_) { }
    42 
    43       template <typename Graph>
    44       void discover_vertex(typename graph_traits<Graph>::vertex_descriptor v,
    45                            const Graph&) {
    46         put(root, v, v);
    47         put(comp, v, (std::numeric_limits<comp_type>::max)());
    48         put(discover_time, v, dfs_time++);
    49         s.push(v);
    50       }
    51       template <typename Graph>
    52       void finish_vertex(typename graph_traits<Graph>::vertex_descriptor v,
    53                          const Graph& g) {
    54         typename graph_traits<Graph>::vertex_descriptor w;
    55         typename graph_traits<Graph>::out_edge_iterator ei, ei_end;
    56         for (tie(ei, ei_end) = out_edges(v, g); ei != ei_end; ++ei) {
    57           w = target(*ei, g);
    58           if (get(comp, w) == (std::numeric_limits<comp_type>::max)())
    59             put(root, v, this->min_discover_time(get(root,v), get(root,w)));
    60         }
    61         if (get(root, v) == v) {
    62           do {
    63             w = s.top(); s.pop();
    64             put(comp, w, c);
    65           } while (w != v);
    66           ++c;
    67         }
    68       }
    69     private:
    70       template <typename Vertex>
    71       Vertex min_discover_time(Vertex u, Vertex v) {
    72         return get(discover_time, u) < get(discover_time,v) ? u : v;
    73       }
    74 
    75       comp_type& c;
    76       ComponentMap comp;
    77       RootMap root;
    78       DiscoverTime discover_time;
    79       time_type dfs_time;
    80       Stack& s;
    81     };
    82     
    83     template <class Graph, class ComponentMap, class RootMap,
    84               class DiscoverTime, class P, class T, class R>
    85     typename property_traits<ComponentMap>::value_type
    86     strong_components_impl
    87       (const Graph& g,    // Input
    88        ComponentMap comp, // Output
    89        // Internal record keeping
    90        RootMap root, 
    91        DiscoverTime discover_time,
    92        const bgl_named_params<P, T, R>& params)
    93     {
    94       typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
    95       function_requires< ReadWritePropertyMapConcept<ComponentMap, Vertex> >();
    96       function_requires< ReadWritePropertyMapConcept<RootMap, Vertex> >();
    97       typedef typename property_traits<RootMap>::value_type RootV;
    98       function_requires< ConvertibleConcept<RootV, Vertex> >();
    99       function_requires< ReadWritePropertyMapConcept<DiscoverTime, Vertex> >();
   100 
   101       typename property_traits<ComponentMap>::value_type total = 0;
   102 
   103       std::stack<Vertex> s;
   104       detail::tarjan_scc_visitor<ComponentMap, RootMap, DiscoverTime, 
   105         std::stack<Vertex> > 
   106         vis(comp, root, discover_time, total, s);
   107       depth_first_search(g, params.visitor(vis));
   108       return total;
   109     }
   110 
   111     //-------------------------------------------------------------------------
   112     // The dispatch functions handle the defaults for the rank and discover
   113     // time property maps.
   114     // dispatch with class specialization to avoid VC++ bug
   115 
   116     template <class DiscoverTimeMap>
   117     struct strong_comp_dispatch2 {
   118       template <class Graph, class ComponentMap, class RootMap, class P, class T, class R>
   119       inline static typename property_traits<ComponentMap>::value_type
   120       apply(const Graph& g,
   121             ComponentMap comp,
   122             RootMap r_map,
   123             const bgl_named_params<P, T, R>& params,
   124             DiscoverTimeMap time_map)
   125       {
   126         return strong_components_impl(g, comp, r_map, time_map, params);
   127       }
   128     };
   129 
   130 
   131     template <>
   132     struct strong_comp_dispatch2<detail::error_property_not_found> {
   133       template <class Graph, class ComponentMap, class RootMap,
   134                 class P, class T, class R>
   135       inline static typename property_traits<ComponentMap>::value_type
   136       apply(const Graph& g,
   137             ComponentMap comp,
   138             RootMap r_map,
   139             const bgl_named_params<P, T, R>& params,
   140             detail::error_property_not_found)
   141       {
   142         typedef typename graph_traits<Graph>::vertices_size_type size_type;
   143         size_type       n = num_vertices(g) > 0 ? num_vertices(g) : 1;
   144         std::vector<size_type> time_vec(n);
   145         return strong_components_impl
   146           (g, comp, r_map,
   147            make_iterator_property_map(time_vec.begin(), choose_const_pmap
   148                                       (get_param(params, vertex_index),
   149                                        g, vertex_index), time_vec[0]),
   150            params);
   151       }
   152     };
   153 
   154     template <class Graph, class ComponentMap, class RootMap,
   155               class P, class T, class R, class DiscoverTimeMap>
   156     inline typename property_traits<ComponentMap>::value_type
   157     scc_helper2(const Graph& g,
   158                 ComponentMap comp,
   159                 RootMap r_map,
   160                 const bgl_named_params<P, T, R>& params,
   161                 DiscoverTimeMap time_map)
   162     {
   163       return strong_comp_dispatch2<DiscoverTimeMap>::apply(g, comp, r_map, params, time_map);
   164     }
   165 
   166     template <class RootMap>
   167     struct strong_comp_dispatch1 {
   168 
   169       template <class Graph, class ComponentMap, class P, class T, class R>
   170       inline static typename property_traits<ComponentMap>::value_type
   171       apply(const Graph& g,
   172             ComponentMap comp,
   173             const bgl_named_params<P, T, R>& params,
   174             RootMap r_map)
   175       {
   176         return scc_helper2(g, comp, r_map, params, get_param(params, vertex_discover_time));
   177       }
   178     };
   179     template <>
   180     struct strong_comp_dispatch1<detail::error_property_not_found> {
   181 
   182       template <class Graph, class ComponentMap, 
   183                 class P, class T, class R>
   184       inline static typename property_traits<ComponentMap>::value_type
   185       apply(const Graph& g,
   186             ComponentMap comp,
   187             const bgl_named_params<P, T, R>& params,
   188             detail::error_property_not_found)
   189       {
   190         typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
   191         typename std::vector<Vertex>::size_type
   192           n = num_vertices(g) > 0 ? num_vertices(g) : 1;
   193         std::vector<Vertex> root_vec(n);
   194         return scc_helper2
   195           (g, comp, 
   196            make_iterator_property_map(root_vec.begin(), choose_const_pmap
   197                                       (get_param(params, vertex_index),
   198                                        g, vertex_index), root_vec[0]),
   199            params, 
   200            get_param(params, vertex_discover_time));
   201       }
   202     };
   203 
   204     template <class Graph, class ComponentMap, class RootMap,
   205               class P, class T, class R>
   206     inline typename property_traits<ComponentMap>::value_type
   207     scc_helper1(const Graph& g,
   208                ComponentMap comp,
   209                const bgl_named_params<P, T, R>& params,
   210                RootMap r_map)
   211     {
   212       return detail::strong_comp_dispatch1<RootMap>::apply(g, comp, params,
   213                                                            r_map);
   214     }
   215 
   216   } // namespace detail 
   217 
   218   template <class Graph, class ComponentMap, 
   219             class P, class T, class R>
   220   inline typename property_traits<ComponentMap>::value_type
   221   strong_components(const Graph& g, ComponentMap comp,
   222                     const bgl_named_params<P, T, R>& params)
   223   {
   224     typedef typename graph_traits<Graph>::directed_category DirCat;
   225     BOOST_STATIC_ASSERT((is_convertible<DirCat*, directed_tag*>::value == true));
   226     return detail::scc_helper1(g, comp, params, 
   227                                get_param(params, vertex_root_t()));
   228   }
   229 
   230   template <class Graph, class ComponentMap>
   231   inline typename property_traits<ComponentMap>::value_type
   232   strong_components(const Graph& g, ComponentMap comp)
   233   {
   234     typedef typename graph_traits<Graph>::directed_category DirCat;
   235     BOOST_STATIC_ASSERT((is_convertible<DirCat*, directed_tag*>::value == true));
   236     bgl_named_params<int, int> params(0);
   237     return strong_components(g, comp, params);
   238   }
   239 
   240   template <typename Graph, typename ComponentMap, typename ComponentLists>
   241   void build_component_lists
   242     (const Graph& g,
   243      typename graph_traits<Graph>::vertices_size_type num_scc,
   244      ComponentMap component_number,
   245      ComponentLists& components)
   246   {
   247     components.resize(num_scc);
   248     typename graph_traits<Graph>::vertex_iterator vi, vi_end;
   249     for (tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi)
   250       components[component_number[*vi]].push_back(*vi);
   251   }
   252 
   253 
   254 } // namespace boost
   255 
   256 #include <queue>
   257 #include <vector>
   258 #include <boost/graph/transpose_graph.hpp>
   259 #include <boost/pending/indirect_cmp.hpp>
   260 #include <boost/graph/connected_components.hpp> // for components_recorder
   261 
   262 namespace boost {
   263 
   264   //==========================================================================
   265   // This is the version of strongly connected components from
   266   // "Intro. to Algorithms" by Cormen, Leiserson, Rivest, which was
   267   // adapted from "Data Structure and Algorithms" by Aho, Hopcroft,
   268   // and Ullman, who credit the algorithm to S.R. Kosaraju and M. Sharir.
   269   // The algorithm is based on computing DFS forests the graph
   270   // and its transpose.
   271 
   272   // This algorithm is slower than Tarjan's by a constant factor, uses
   273   // more memory, and puts more requirements on the graph type.
   274 
   275   template <class Graph, class DFSVisitor, class ComponentsMap,
   276             class DiscoverTime, class FinishTime,
   277             class ColorMap>
   278   typename property_traits<ComponentsMap>::value_type
   279   kosaraju_strong_components(Graph& G, ComponentsMap c,
   280                              FinishTime finish_time, ColorMap color)
   281   {
   282     function_requires< MutableGraphConcept<Graph> >();
   283     // ...
   284     
   285     typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
   286     typedef typename property_traits<ColorMap>::value_type ColorValue;
   287     typedef color_traits<ColorValue> Color;
   288     typename property_traits<FinishTime>::value_type time = 0;
   289     depth_first_search
   290      (G, make_dfs_visitor(stamp_times(finish_time, time, on_finish_vertex())),
   291       color);
   292 
   293     Graph G_T(num_vertices(G));
   294     transpose_graph(G, G_T);
   295 
   296     typedef typename property_traits<ComponentsMap>::value_type count_type;
   297 
   298     count_type c_count(0);
   299     detail::components_recorder<ComponentsMap>
   300       vis(c, c_count);
   301 
   302     // initialize G_T
   303     typename graph_traits<Graph>::vertex_iterator ui, ui_end;
   304     for (tie(ui, ui_end) = vertices(G_T); ui != ui_end; ++ui)
   305       put(color, *ui, Color::white());
   306 
   307     typedef typename property_traits<FinishTime>::value_type D;
   308     typedef indirect_cmp< FinishTime, std::less<D> > Compare;
   309 
   310     Compare fl(finish_time);
   311     std::priority_queue<Vertex, std::vector<Vertex>, Compare > Q(fl);
   312 
   313     typename graph_traits<Graph>::vertex_iterator i, j, iend, jend;
   314     tie(i, iend) = vertices(G_T);
   315     tie(j, jend) = vertices(G);
   316     for ( ; i != iend; ++i, ++j) {
   317       put(finish_time, *i, get(finish_time, *j));
   318        Q.push(*i);
   319     }
   320 
   321     while ( !Q.empty() ) {
   322       Vertex u = Q.top();
   323       Q.pop();
   324       if  (get(color, u) == Color::white()) {
   325         depth_first_visit(G_T, u, vis, color);
   326         ++c_count; 
   327       }
   328     }
   329     return c_count;
   330   }
   331 
   332 } // namespace boost
   333 
   334 #endif // BOOST_GRAPH_STRONG_COMPONENTS_HPP