boost/graph/hawick_circuits.hpp

0001 // Copyright Louis Dionne 2013
0002
0003 // Use, modification and distribution is subject to the Boost Software
0004 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy
0005 // at http://www.boost.org/LICENSE_1_0.txt)
0006
0007 #ifndef BOOST_GRAPH_HAWICK_CIRCUITS_HPP
0008 #define BOOST_GRAPH_HAWICK_CIRCUITS_HPP
0009
0010 #include <algorithm>
0011 #include <boost/assert.hpp>
0012 #include <boost/foreach.hpp>
0013 #include <boost/graph/graph_traits.hpp>
0014 #include <boost/graph/one_bit_color_map.hpp>
0015 #include <boost/graph/properties.hpp>
0016 #include <boost/move/utility.hpp>
0017 #include <boost/property_map/property_map.hpp>
0018 #include <boost/range/begin.hpp>
0019 #include <boost/range/end.hpp>
0020 #include <boost/range/iterator.hpp>
0021 #include <boost/tuple/tuple.hpp> // for boost::tie
0022 #include <boost/type_traits/remove_reference.hpp>
0023 #include <boost/utility/result_of.hpp>
0024 #include <set>
0025 #include <utility> // for std::pair
0026 #include <vector>
0027
0028 namespace boost
0029 {
0030 namespace hawick_circuits_detail
0031 {
0032     //! @internal Functor returning all the vertices adjacent to a vertex.
0033     struct get_all_adjacent_vertices
0034     {
0035         template < typename Sig > struct result;
0036
0037         template < typename This, typename Vertex, typename Graph >
0038         struct result< This(Vertex, Graph) >
0039         {
0040         private:
0041             typedef typename remove_reference< Graph >::type RawGraph;
0042             typedef graph_traits< RawGraph > Traits;
0043             typedef typename Traits::adjacency_iterator AdjacencyIterator;
0044
0045         public:
0046             typedef std::pair< AdjacencyIterator, AdjacencyIterator > type;
0047         };
0048
0049         template < typename Vertex, typename Graph >
0050         typename result< get_all_adjacent_vertices(
0051             BOOST_FWD_REF(Vertex), BOOST_FWD_REF(Graph)) >::type
0052         operator()(BOOST_FWD_REF(Vertex) v, BOOST_FWD_REF(Graph) g) const
0053         {
0054             return adjacent_vertices(
0055                 boost::forward< Vertex >(v), boost::forward< Graph >(g));
0056         }
0057     };
0058
0059     //! @internal Functor returning a set of the vertices adjacent to a vertex.
0060     struct get_unique_adjacent_vertices
0061     {
0062         template < typename Sig > struct result;
0063
0064         template < typename This, typename Vertex, typename Graph >
0065         struct result< This(Vertex, Graph) >
0066         {
0067             typedef std::set< typename remove_reference< Vertex >::type > type;
0068         };
0069
0070         template < typename Vertex, typename Graph >
0071         typename result< get_unique_adjacent_vertices(
0072             Vertex, Graph const&) >::type
0073         operator()(Vertex v, Graph const& g) const
0074         {
0075             typedef typename result< get_unique_adjacent_vertices(
0076                 Vertex, Graph const&) >::type Set;
0077             return Set(
0078                 adjacent_vertices(v, g).first, adjacent_vertices(v, g).second);
0079         }
0080     };
0081
0082     //! @internal
0083     //! Return whether a container contains a given value.
0084     //! This is not meant as a general purpose membership testing function; it
0085     //! would have to be more clever about possible optimizations.
0086     template < typename Container, typename Value >
0087     bool contains(Container const& c, Value const& v)
0088     {
0089         return std::find(boost::begin(c), boost::end(c), v) != boost::end(c);
0090     }
0091
0092     /*!
0093      * @internal
0094      * Algorithm finding all the cycles starting from a given vertex.
0095      *
0096      * The search is only done in the subgraph induced by the starting vertex
0097      * and the vertices with an index higher than the starting vertex.
0098      */
0099     template < typename Graph, typename Visitor, typename VertexIndexMap,
0100         typename Stack, typename ClosedMatrix, typename GetAdjacentVertices >
0101     struct hawick_circuits_from
0102     {
0103     private:
0104         typedef graph_traits< Graph > Traits;
0105         typedef typename Traits::vertex_descriptor Vertex;
0106         typedef typename Traits::edge_descriptor Edge;
0107         typedef typename Traits::vertices_size_type VerticesSize;
0108         typedef
0109             typename property_traits< VertexIndexMap >::value_type VertexIndex;
0110
0111         typedef typename result_of< GetAdjacentVertices(
0112             Vertex, Graph const&) >::type AdjacentVertices;
0113         typedef typename range_iterator< AdjacentVertices const >::type
0114             AdjacencyIterator;
0115
0116         // The one_bit_color_map starts all white, i.e. not blocked.
0117         // Since we make that assumption (I looked at the implementation, but
0118         // I can't find anything that documents this behavior), we're gonna
0119         // assert it in the constructor.
0120         typedef one_bit_color_map< VertexIndexMap > BlockedMap;
0121         typedef typename property_traits< BlockedMap >::value_type BlockedColor;
0122
0123         static BlockedColor blocked_false_color()
0124         {
0125             return color_traits< BlockedColor >::white();
0126         }
0127
0128         static BlockedColor blocked_true_color()
0129         {
0130             return color_traits< BlockedColor >::black();
0131         }
0132
0133         // This is used by the constructor to secure the assumption
0134         // documented above.
0135         bool blocked_map_starts_all_unblocked() const
0136         {
0137             BOOST_FOREACH (Vertex v, vertices(graph_))
0138                 if (is_blocked(v))
0139                     return false;
0140             return true;
0141         }
0142
0143         // This is only used in the constructor to make sure the optimization of
0144         // sharing data structures between iterations does not break the code.
0145         bool all_closed_rows_are_empty() const
0146         {
0147             BOOST_FOREACH (typename ClosedMatrix::reference row, closed_)
0148                 if (!row.empty())
0149                     return false;
0150             return true;
0151         }
0152
0153     public:
0154         hawick_circuits_from(Graph const& graph, Visitor& visitor,
0155             VertexIndexMap const& vim, Stack& stack, ClosedMatrix& closed,
0156             VerticesSize n_vertices)
0157         : graph_(graph)
0158         , visitor_(visitor)
0159         , vim_(vim)
0160         , stack_(stack)
0161         , closed_(closed)
0162         , blocked_(n_vertices, vim_)
0163         {
0164             BOOST_ASSERT(blocked_map_starts_all_unblocked());
0165
0166             // Since sharing the data structures between iterations is
0167             // just an optimization, it must always be equivalent to
0168             // constructing new ones in this constructor.
0169             BOOST_ASSERT(stack_.empty());
0170             BOOST_ASSERT(closed_.size() == n_vertices);
0171             BOOST_ASSERT(all_closed_rows_are_empty());
0172         }
0173
0174     private:
0175         //! @internal Return the index of a given vertex.
0176         VertexIndex index_of(Vertex v) const { return get(vim_, v); }
0177
0178         //! @internal Return whether a vertex `v` is closed to a vertex `u`.
0179         bool is_closed_to(Vertex u, Vertex v) const
0180         {
0181             typedef typename ClosedMatrix::const_reference VertexList;
0182             VertexList closed_to_u = closed_[index_of(u)];
0183             return contains(closed_to_u, v);
0184         }
0185
0186         //! @internal Close a vertex `v` to a vertex `u`.
0187         void close_to(Vertex u, Vertex v)
0188         {
0189             BOOST_ASSERT(!is_closed_to(u, v));
0190             closed_[index_of(u)].push_back(v);
0191         }
0192
0193         //! @internal Return whether a given vertex is blocked.
0194         bool is_blocked(Vertex v) const
0195         {
0196             return get(blocked_, v) == blocked_true_color();
0197         }
0198
0199         //! @internal Block a given vertex.
0200         void block(Vertex v) { put(blocked_, v, blocked_true_color()); }
0201
0202         //! @internal Unblock a given vertex.
0203         void unblock(Vertex u)
0204         {
0205             typedef typename ClosedMatrix::reference VertexList;
0206
0207             put(blocked_, u, blocked_false_color());
0208             VertexList closed_to_u = closed_[index_of(u)];
0209
0210             while (!closed_to_u.empty())
0211             {
0212                 Vertex const w = closed_to_u.back();
0213                 closed_to_u.pop_back();
0214                 if (is_blocked(w))
0215                     unblock(w);
0216             }
0217             BOOST_ASSERT(closed_to_u.empty());
0218         }
0219
0220         //! @internal Main procedure as described in the paper.
0221         bool circuit(Vertex start, Vertex v)
0222         {
0223             bool found_circuit = false;
0224             stack_.push_back(v);
0225             block(v);
0226
0227             // Cache some values that are used more than once in the function.
0228             VertexIndex const index_of_start = index_of(start);
0229             AdjacentVertices const adj_vertices
0230                 = GetAdjacentVertices()(v, graph_);
0231             AdjacencyIterator const w_end = boost::end(adj_vertices);
0232
0233             for (AdjacencyIterator w_it = boost::begin(adj_vertices);
0234                  w_it != w_end; ++w_it)
0235             {
0236                 Vertex const w = *w_it;
0237                 // Since we're only looking in the subgraph induced by `start`
0238                 // and the vertices with an index higher than `start`, we skip
0239                 // any vertex that does not satisfy that.
0240                 if (index_of(w) < index_of_start)
0241                     continue;
0242
0243                 // If the last vertex is equal to `start`, we have a circuit.
0244                 else if (w == start)
0245                 {
0246                     // const_cast to ensure the visitor does not modify the
0247                     // stack
0248                     visitor_.cycle(const_cast< Stack const& >(stack_), graph_);
0249                     found_circuit = true;
0250                 }
0251
0252                 // If `w` is not blocked, we continue searching further down the
0253                 // same path for a cycle with `w` in it.
0254                 else if (!is_blocked(w) && circuit(start, w))
0255                     found_circuit = true;
0256             }
0257
0258             if (found_circuit)
0259                 unblock(v);
0260             else
0261                 for (AdjacencyIterator w_it = boost::begin(adj_vertices);
0262                      w_it != w_end; ++w_it)
0263                 {
0264                     Vertex const w = *w_it;
0265                     // Like above, we skip vertices that are not in the subgraph
0266                     // we're considering.
0267                     if (index_of(w) < index_of_start)
0268                         continue;
0269
0270                     // If `v` is not closed to `w`, we make it so.
0271                     if (!is_closed_to(w, v))
0272                         close_to(w, v);
0273                 }
0274
0275             BOOST_ASSERT(v == stack_.back());
0276             stack_.pop_back();
0277             return found_circuit;
0278         }
0279
0280     public:
0281         void operator()(Vertex start) { circuit(start, start); }
0282
0283     private:
0284         Graph const& graph_;
0285         Visitor& visitor_;
0286         VertexIndexMap const& vim_;
0287         Stack& stack_;
0288         ClosedMatrix& closed_;
0289         BlockedMap blocked_;
0290     };
0291
0292     template < typename GetAdjacentVertices, typename Graph, typename Visitor,
0293         typename VertexIndexMap >
0294     void call_hawick_circuits(Graph const& graph,
0295         Visitor /* by value */ visitor, VertexIndexMap const& vertex_index_map)
0296     {
0297         typedef graph_traits< Graph > Traits;
0298         typedef typename Traits::vertex_descriptor Vertex;
0299         typedef typename Traits::vertices_size_type VerticesSize;
0300         typedef typename Traits::vertex_iterator VertexIterator;
0301
0302         typedef std::vector< Vertex > Stack;
0303         typedef std::vector< std::vector< Vertex > > ClosedMatrix;
0304
0305         typedef hawick_circuits_from< Graph, Visitor, VertexIndexMap, Stack,
0306             ClosedMatrix, GetAdjacentVertices >
0307             SubAlgorithm;
0308
0309         VerticesSize const n_vertices = num_vertices(graph);
0310         Stack stack;
0311         stack.reserve(n_vertices);
0312         ClosedMatrix closed(n_vertices);
0313
0314         VertexIterator start, last;
0315         for (boost::tie(start, last) = vertices(graph); start != last; ++start)
0316         {
0317             // Note1: The sub algorithm may NOT be reused once it has been
0318             // called.
0319
0320             // Note2: We reuse the Stack and the ClosedMatrix (after clearing
0321             // them) in each iteration to avoid redundant destruction and
0322             // construction. It would be strictly equivalent to have these as
0323             // member variables of the sub algorithm.
0324             SubAlgorithm sub_algo(
0325                 graph, visitor, vertex_index_map, stack, closed, n_vertices);
0326             sub_algo(*start);
0327             stack.clear();
0328             typename ClosedMatrix::iterator row, last_row = closed.end();
0329             for (row = closed.begin(); row != last_row; ++row)
0330                 row->clear();
0331         }
0332     }
0333
0334     template < typename GetAdjacentVertices, typename Graph, typename Visitor >
0335     void call_hawick_circuits(
0336         Graph const& graph, BOOST_FWD_REF(Visitor) visitor)
0337     {
0338         call_hawick_circuits< GetAdjacentVertices >(graph,
0339             boost::forward< Visitor >(visitor), get(vertex_index, graph));
0340     }
0341 } // end namespace hawick_circuits_detail
0342
0343 //! Enumerate all the elementary circuits in a directed multigraph.
0344 template < typename Graph, typename Visitor, typename VertexIndexMap >
0345 void hawick_circuits(BOOST_FWD_REF(Graph) graph, BOOST_FWD_REF(Visitor) visitor,
0346     BOOST_FWD_REF(VertexIndexMap) vertex_index_map)
0347 {
0348     hawick_circuits_detail::call_hawick_circuits<
0349         hawick_circuits_detail::get_all_adjacent_vertices >(
0350         boost::forward< Graph >(graph), boost::forward< Visitor >(visitor),
0351         boost::forward< VertexIndexMap >(vertex_index_map));
0352 }
0353
0354 template < typename Graph, typename Visitor >
0355 void hawick_circuits(BOOST_FWD_REF(Graph) graph, BOOST_FWD_REF(Visitor) visitor)
0356 {
0357     hawick_circuits_detail::call_hawick_circuits<
0358         hawick_circuits_detail::get_all_adjacent_vertices >(
0359         boost::forward< Graph >(graph), boost::forward< Visitor >(visitor));
0360 }
0361
0362 /*!
0363  * Same as `boost::hawick_circuits`, but duplicate circuits caused by parallel
0364  * edges will not be considered. Each circuit will be considered only once.
0365  */
0366 template < typename Graph, typename Visitor, typename VertexIndexMap >
0367 void hawick_unique_circuits(BOOST_FWD_REF(Graph) graph,
0368     BOOST_FWD_REF(Visitor) visitor,
0369     BOOST_FWD_REF(VertexIndexMap) vertex_index_map)
0370 {
0371     hawick_circuits_detail::call_hawick_circuits<
0372         hawick_circuits_detail::get_unique_adjacent_vertices >(
0373         boost::forward< Graph >(graph), boost::forward< Visitor >(visitor),
0374         boost::forward< VertexIndexMap >(vertex_index_map));
0375 }
0376
0377 template < typename Graph, typename Visitor >
0378 void hawick_unique_circuits(
0379     BOOST_FWD_REF(Graph) graph, BOOST_FWD_REF(Visitor) visitor)
0380 {
0381     hawick_circuits_detail::call_hawick_circuits<
0382         hawick_circuits_detail::get_unique_adjacent_vertices >(
0383         boost::forward< Graph >(graph), boost::forward< Visitor >(visitor));
0384 }
0385 } // end namespace boost
0386
0387 #endif // !BOOST_GRAPH_HAWICK_CIRCUITS_HPP