1 | /* -*- C++ -*- |
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2 | * |
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3 | * This file is a part of LEMON, a generic C++ optimization library |
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4 | * |
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5 | * Copyright (C) 2003-2008 |
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6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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8 | * |
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9 | * Permission to use, modify and distribute this software is granted |
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10 | * provided that this copyright notice appears in all copies. For |
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11 | * precise terms see the accompanying LICENSE file. |
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12 | * |
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13 | * This software is provided "AS IS" with no warranty of any kind, |
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14 | * express or implied, and with no claim as to its suitability for any |
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15 | * purpose. |
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16 | * |
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17 | */ |
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18 | |
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19 | #ifndef LEMON_BFS_H |
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20 | #define LEMON_BFS_H |
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21 | |
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22 | ///\ingroup search |
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23 | ///\file |
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24 | ///\brief Bfs algorithm. |
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25 | |
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26 | #include <lemon/list_graph.h> |
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27 | #include <lemon/graph_utils.h> |
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28 | #include <lemon/bits/path_dump.h> |
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29 | #include <lemon/bits/invalid.h> |
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30 | #include <lemon/error.h> |
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31 | #include <lemon/maps.h> |
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32 | |
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33 | namespace lemon { |
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34 | |
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35 | |
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36 | |
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37 | ///Default traits class of Bfs class. |
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38 | |
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39 | ///Default traits class of Bfs class. |
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40 | ///\param GR Digraph type. |
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41 | template<class GR> |
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42 | struct BfsDefaultTraits |
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43 | { |
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44 | ///The digraph type the algorithm runs on. |
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45 | typedef GR Digraph; |
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46 | ///\brief The type of the map that stores the last |
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47 | ///arcs of the shortest paths. |
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48 | /// |
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49 | ///The type of the map that stores the last |
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50 | ///arcs of the shortest paths. |
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51 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
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52 | /// |
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53 | typedef typename Digraph::template NodeMap<typename GR::Arc> PredMap; |
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54 | ///Instantiates a PredMap. |
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55 | |
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56 | ///This function instantiates a \ref PredMap. |
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57 | ///\param G is the digraph, to which we would like to define the PredMap. |
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58 | ///\todo The digraph alone may be insufficient to initialize |
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59 | static PredMap *createPredMap(const GR &G) |
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60 | { |
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61 | return new PredMap(G); |
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62 | } |
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63 | ///The type of the map that indicates which nodes are processed. |
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64 | |
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65 | ///The type of the map that indicates which nodes are processed. |
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66 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
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67 | ///\todo named parameter to set this type, function to read and write. |
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68 | typedef NullMap<typename Digraph::Node,bool> ProcessedMap; |
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69 | ///Instantiates a ProcessedMap. |
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70 | |
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71 | ///This function instantiates a \ref ProcessedMap. |
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72 | ///\param g is the digraph, to which |
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73 | ///we would like to define the \ref ProcessedMap |
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74 | #ifdef DOXYGEN |
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75 | static ProcessedMap *createProcessedMap(const GR &g) |
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76 | #else |
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77 | static ProcessedMap *createProcessedMap(const GR &) |
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78 | #endif |
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79 | { |
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80 | return new ProcessedMap(); |
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81 | } |
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82 | ///The type of the map that indicates which nodes are reached. |
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83 | |
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84 | ///The type of the map that indicates which nodes are reached. |
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85 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
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86 | ///\todo named parameter to set this type, function to read and write. |
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87 | typedef typename Digraph::template NodeMap<bool> ReachedMap; |
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88 | ///Instantiates a ReachedMap. |
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89 | |
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90 | ///This function instantiates a \ref ReachedMap. |
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91 | ///\param G is the digraph, to which |
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92 | ///we would like to define the \ref ReachedMap. |
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93 | static ReachedMap *createReachedMap(const GR &G) |
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94 | { |
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95 | return new ReachedMap(G); |
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96 | } |
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97 | ///The type of the map that stores the dists of the nodes. |
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98 | |
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99 | ///The type of the map that stores the dists of the nodes. |
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100 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
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101 | /// |
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102 | typedef typename Digraph::template NodeMap<int> DistMap; |
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103 | ///Instantiates a DistMap. |
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104 | |
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105 | ///This function instantiates a \ref DistMap. |
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106 | ///\param G is the digraph, to which we would like to define the \ref DistMap |
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107 | static DistMap *createDistMap(const GR &G) |
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108 | { |
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109 | return new DistMap(G); |
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110 | } |
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111 | }; |
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112 | |
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113 | ///%BFS algorithm class. |
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114 | |
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115 | ///\ingroup search |
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116 | ///This class provides an efficient implementation of the %BFS algorithm. |
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117 | /// |
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118 | ///\param GR The digraph type the algorithm runs on. The default value is |
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119 | ///\ref ListDigraph. The value of GR is not used directly by Bfs, it |
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120 | ///is only passed to \ref BfsDefaultTraits. |
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121 | ///\param TR Traits class to set various data types used by the algorithm. |
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122 | ///The default traits class is |
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123 | ///\ref BfsDefaultTraits "BfsDefaultTraits<GR>". |
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124 | ///See \ref BfsDefaultTraits for the documentation of |
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125 | ///a Bfs traits class. |
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126 | /// |
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127 | ///\author Alpar Juttner |
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128 | |
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129 | #ifdef DOXYGEN |
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130 | template <typename GR, |
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131 | typename TR> |
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132 | #else |
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133 | template <typename GR=ListDigraph, |
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134 | typename TR=BfsDefaultTraits<GR> > |
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135 | #endif |
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136 | class Bfs { |
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137 | public: |
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138 | /** |
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139 | * \brief \ref Exception for uninitialized parameters. |
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140 | * |
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141 | * This error represents problems in the initialization |
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142 | * of the parameters of the algorithms. |
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143 | */ |
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144 | class UninitializedParameter : public lemon::UninitializedParameter { |
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145 | public: |
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146 | virtual const char* what() const throw() { |
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147 | return "lemon::Bfs::UninitializedParameter"; |
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148 | } |
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149 | }; |
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150 | |
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151 | typedef TR Traits; |
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152 | ///The type of the underlying digraph. |
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153 | typedef typename TR::Digraph Digraph; |
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154 | |
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155 | ///\brief The type of the map that stores the last |
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156 | ///arcs of the shortest paths. |
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157 | typedef typename TR::PredMap PredMap; |
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158 | ///The type of the map indicating which nodes are reached. |
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159 | typedef typename TR::ReachedMap ReachedMap; |
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160 | ///The type of the map indicating which nodes are processed. |
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161 | typedef typename TR::ProcessedMap ProcessedMap; |
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162 | ///The type of the map that stores the dists of the nodes. |
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163 | typedef typename TR::DistMap DistMap; |
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164 | private: |
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165 | |
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166 | typedef typename Digraph::Node Node; |
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167 | typedef typename Digraph::NodeIt NodeIt; |
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168 | typedef typename Digraph::Arc Arc; |
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169 | typedef typename Digraph::OutArcIt OutArcIt; |
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170 | |
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171 | /// Pointer to the underlying digraph. |
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172 | const Digraph *G; |
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173 | ///Pointer to the map of predecessors arcs. |
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174 | PredMap *_pred; |
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175 | ///Indicates if \ref _pred is locally allocated (\c true) or not. |
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176 | bool local_pred; |
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177 | ///Pointer to the map of distances. |
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178 | DistMap *_dist; |
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179 | ///Indicates if \ref _dist is locally allocated (\c true) or not. |
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180 | bool local_dist; |
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181 | ///Pointer to the map of reached status of the nodes. |
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182 | ReachedMap *_reached; |
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183 | ///Indicates if \ref _reached is locally allocated (\c true) or not. |
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184 | bool local_reached; |
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185 | ///Pointer to the map of processed status of the nodes. |
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186 | ProcessedMap *_processed; |
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187 | ///Indicates if \ref _processed is locally allocated (\c true) or not. |
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188 | bool local_processed; |
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189 | |
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190 | std::vector<typename Digraph::Node> _queue; |
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191 | int _queue_head,_queue_tail,_queue_next_dist; |
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192 | int _curr_dist; |
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193 | |
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194 | ///Creates the maps if necessary. |
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195 | |
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196 | ///\todo Better memory allocation (instead of new). |
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197 | void create_maps() |
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198 | { |
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199 | if(!_pred) { |
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200 | local_pred = true; |
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201 | _pred = Traits::createPredMap(*G); |
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202 | } |
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203 | if(!_dist) { |
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204 | local_dist = true; |
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205 | _dist = Traits::createDistMap(*G); |
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206 | } |
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207 | if(!_reached) { |
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208 | local_reached = true; |
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209 | _reached = Traits::createReachedMap(*G); |
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210 | } |
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211 | if(!_processed) { |
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212 | local_processed = true; |
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213 | _processed = Traits::createProcessedMap(*G); |
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214 | } |
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215 | } |
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216 | |
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217 | protected: |
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218 | |
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219 | Bfs() {} |
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220 | |
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221 | public: |
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222 | |
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223 | typedef Bfs Create; |
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224 | |
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225 | ///\name Named template parameters |
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226 | |
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227 | ///@{ |
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228 | |
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229 | template <class T> |
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230 | struct DefPredMapTraits : public Traits { |
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231 | typedef T PredMap; |
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232 | static PredMap *createPredMap(const Digraph &) |
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233 | { |
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234 | throw UninitializedParameter(); |
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235 | } |
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236 | }; |
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237 | ///\brief \ref named-templ-param "Named parameter" for setting |
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238 | ///PredMap type |
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239 | /// |
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240 | ///\ref named-templ-param "Named parameter" for setting PredMap type |
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241 | /// |
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242 | template <class T> |
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243 | struct DefPredMap : public Bfs< Digraph, DefPredMapTraits<T> > { |
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244 | typedef Bfs< Digraph, DefPredMapTraits<T> > Create; |
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245 | }; |
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246 | |
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247 | template <class T> |
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248 | struct DefDistMapTraits : public Traits { |
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249 | typedef T DistMap; |
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250 | static DistMap *createDistMap(const Digraph &) |
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251 | { |
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252 | throw UninitializedParameter(); |
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253 | } |
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254 | }; |
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255 | ///\brief \ref named-templ-param "Named parameter" for setting |
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256 | ///DistMap type |
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257 | /// |
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258 | ///\ref named-templ-param "Named parameter" for setting DistMap type |
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259 | /// |
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260 | template <class T> |
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261 | struct DefDistMap : public Bfs< Digraph, DefDistMapTraits<T> > { |
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262 | typedef Bfs< Digraph, DefDistMapTraits<T> > Create; |
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263 | }; |
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264 | |
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265 | template <class T> |
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266 | struct DefReachedMapTraits : public Traits { |
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267 | typedef T ReachedMap; |
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268 | static ReachedMap *createReachedMap(const Digraph &) |
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269 | { |
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270 | throw UninitializedParameter(); |
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271 | } |
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272 | }; |
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273 | ///\brief \ref named-templ-param "Named parameter" for setting |
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274 | ///ReachedMap type |
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275 | /// |
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276 | ///\ref named-templ-param "Named parameter" for setting ReachedMap type |
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277 | /// |
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278 | template <class T> |
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279 | struct DefReachedMap : public Bfs< Digraph, DefReachedMapTraits<T> > { |
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280 | typedef Bfs< Digraph, DefReachedMapTraits<T> > Create; |
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281 | }; |
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282 | |
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283 | template <class T> |
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284 | struct DefProcessedMapTraits : public Traits { |
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285 | typedef T ProcessedMap; |
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286 | static ProcessedMap *createProcessedMap(const Digraph &) |
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287 | { |
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288 | throw UninitializedParameter(); |
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289 | } |
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290 | }; |
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291 | ///\brief \ref named-templ-param "Named parameter" for setting |
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292 | ///ProcessedMap type |
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293 | /// |
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294 | ///\ref named-templ-param "Named parameter" for setting ProcessedMap type |
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295 | /// |
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296 | template <class T> |
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297 | struct DefProcessedMap : public Bfs< Digraph, DefProcessedMapTraits<T> > { |
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298 | typedef Bfs< Digraph, DefProcessedMapTraits<T> > Create; |
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299 | }; |
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300 | |
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301 | struct DefDigraphProcessedMapTraits : public Traits { |
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302 | typedef typename Digraph::template NodeMap<bool> ProcessedMap; |
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303 | static ProcessedMap *createProcessedMap(const Digraph &G) |
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304 | { |
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305 | return new ProcessedMap(G); |
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306 | } |
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307 | }; |
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308 | ///\brief \ref named-templ-param "Named parameter" |
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309 | ///for setting the ProcessedMap type to be Digraph::NodeMap<bool>. |
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310 | /// |
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311 | ///\ref named-templ-param "Named parameter" |
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312 | ///for setting the ProcessedMap type to be Digraph::NodeMap<bool>. |
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313 | ///If you don't set it explicitly, it will be automatically allocated. |
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314 | template <class T> |
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315 | struct DefProcessedMapToBeDefaultMap : |
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316 | public Bfs< Digraph, DefDigraphProcessedMapTraits> { |
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317 | typedef Bfs< Digraph, DefDigraphProcessedMapTraits> Create; |
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318 | }; |
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319 | |
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320 | ///@} |
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321 | |
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322 | public: |
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323 | |
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324 | ///Constructor. |
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325 | |
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326 | ///\param _G the digraph the algorithm will run on. |
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327 | /// |
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328 | Bfs(const Digraph& _G) : |
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329 | G(&_G), |
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330 | _pred(NULL), local_pred(false), |
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331 | _dist(NULL), local_dist(false), |
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332 | _reached(NULL), local_reached(false), |
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333 | _processed(NULL), local_processed(false) |
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334 | { } |
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335 | |
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336 | ///Destructor. |
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337 | ~Bfs() |
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338 | { |
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339 | if(local_pred) delete _pred; |
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340 | if(local_dist) delete _dist; |
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341 | if(local_reached) delete _reached; |
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342 | if(local_processed) delete _processed; |
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343 | } |
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344 | |
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345 | ///Sets the map storing the predecessor arcs. |
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346 | |
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347 | ///Sets the map storing the predecessor arcs. |
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348 | ///If you don't use this function before calling \ref run(), |
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349 | ///it will allocate one. The destructor deallocates this |
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350 | ///automatically allocated map, of course. |
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351 | ///\return <tt> (*this) </tt> |
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352 | Bfs &predMap(PredMap &m) |
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353 | { |
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354 | if(local_pred) { |
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355 | delete _pred; |
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356 | local_pred=false; |
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357 | } |
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358 | _pred = &m; |
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359 | return *this; |
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360 | } |
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361 | |
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362 | ///Sets the map indicating the reached nodes. |
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363 | |
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364 | ///Sets the map indicating the reached nodes. |
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365 | ///If you don't use this function before calling \ref run(), |
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366 | ///it will allocate one. The destructor deallocates this |
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367 | ///automatically allocated map, of course. |
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368 | ///\return <tt> (*this) </tt> |
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369 | Bfs &reachedMap(ReachedMap &m) |
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370 | { |
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371 | if(local_reached) { |
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372 | delete _reached; |
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373 | local_reached=false; |
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374 | } |
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375 | _reached = &m; |
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376 | return *this; |
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377 | } |
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378 | |
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379 | ///Sets the map indicating the processed nodes. |
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380 | |
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381 | ///Sets the map indicating the processed nodes. |
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382 | ///If you don't use this function before calling \ref run(), |
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383 | ///it will allocate one. The destructor deallocates this |
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384 | ///automatically allocated map, of course. |
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385 | ///\return <tt> (*this) </tt> |
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386 | Bfs &processedMap(ProcessedMap &m) |
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387 | { |
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388 | if(local_processed) { |
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389 | delete _processed; |
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390 | local_processed=false; |
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391 | } |
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392 | _processed = &m; |
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393 | return *this; |
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394 | } |
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395 | |
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396 | ///Sets the map storing the distances calculated by the algorithm. |
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397 | |
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398 | ///Sets the map storing the distances calculated by the algorithm. |
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399 | ///If you don't use this function before calling \ref run(), |
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400 | ///it will allocate one. The destructor deallocates this |
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401 | ///automatically allocated map, of course. |
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402 | ///\return <tt> (*this) </tt> |
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403 | Bfs &distMap(DistMap &m) |
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404 | { |
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405 | if(local_dist) { |
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406 | delete _dist; |
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407 | local_dist=false; |
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408 | } |
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409 | _dist = &m; |
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410 | return *this; |
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411 | } |
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412 | |
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413 | public: |
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414 | ///\name Execution control |
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415 | ///The simplest way to execute the algorithm is to use |
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416 | ///one of the member functions called \c run(...). |
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417 | ///\n |
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418 | ///If you need more control on the execution, |
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419 | ///first you must call \ref init(), then you can add several source nodes |
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420 | ///with \ref addSource(). |
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421 | ///Finally \ref start() will perform the actual path |
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422 | ///computation. |
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423 | |
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424 | ///@{ |
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425 | |
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426 | ///\brief Initializes the internal data structures. |
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427 | /// |
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428 | ///Initializes the internal data structures. |
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429 | /// |
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430 | void init() |
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431 | { |
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432 | create_maps(); |
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433 | _queue.resize(countNodes(*G)); |
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434 | _queue_head=_queue_tail=0; |
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435 | _curr_dist=1; |
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436 | for ( NodeIt u(*G) ; u!=INVALID ; ++u ) { |
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437 | _pred->set(u,INVALID); |
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438 | _reached->set(u,false); |
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439 | _processed->set(u,false); |
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440 | } |
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441 | } |
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442 | |
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443 | ///Adds a new source node. |
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444 | |
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445 | ///Adds a new source node to the set of nodes to be processed. |
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446 | /// |
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447 | void addSource(Node s) |
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448 | { |
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449 | if(!(*_reached)[s]) |
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450 | { |
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451 | _reached->set(s,true); |
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452 | _pred->set(s,INVALID); |
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453 | _dist->set(s,0); |
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454 | _queue[_queue_head++]=s; |
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455 | _queue_next_dist=_queue_head; |
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456 | } |
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457 | } |
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458 | |
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459 | ///Processes the next node. |
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460 | |
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461 | ///Processes the next node. |
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462 | /// |
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463 | ///\return The processed node. |
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464 | /// |
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465 | ///\warning The queue must not be empty! |
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466 | Node processNextNode() |
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467 | { |
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468 | if(_queue_tail==_queue_next_dist) { |
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469 | _curr_dist++; |
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470 | _queue_next_dist=_queue_head; |
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471 | } |
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472 | Node n=_queue[_queue_tail++]; |
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473 | _processed->set(n,true); |
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474 | Node m; |
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475 | for(OutArcIt e(*G,n);e!=INVALID;++e) |
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476 | if(!(*_reached)[m=G->target(e)]) { |
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477 | _queue[_queue_head++]=m; |
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478 | _reached->set(m,true); |
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479 | _pred->set(m,e); |
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480 | _dist->set(m,_curr_dist); |
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481 | } |
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482 | return n; |
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483 | } |
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484 | |
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485 | ///Processes the next node. |
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486 | |
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487 | ///Processes the next node. And checks that the given target node |
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488 | ///is reached. If the target node is reachable from the processed |
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489 | ///node then the reached parameter will be set true. The reached |
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490 | ///parameter should be initially false. |
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491 | /// |
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492 | ///\param target The target node. |
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493 | ///\retval reach Indicates that the target node is reached. |
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494 | ///\return The processed node. |
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495 | /// |
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496 | ///\warning The queue must not be empty! |
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497 | Node processNextNode(Node target, bool& reach) |
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498 | { |
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499 | if(_queue_tail==_queue_next_dist) { |
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500 | _curr_dist++; |
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501 | _queue_next_dist=_queue_head; |
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502 | } |
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503 | Node n=_queue[_queue_tail++]; |
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504 | _processed->set(n,true); |
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505 | Node m; |
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506 | for(OutArcIt e(*G,n);e!=INVALID;++e) |
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507 | if(!(*_reached)[m=G->target(e)]) { |
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508 | _queue[_queue_head++]=m; |
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509 | _reached->set(m,true); |
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510 | _pred->set(m,e); |
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511 | _dist->set(m,_curr_dist); |
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512 | reach = reach || (target == m); |
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513 | } |
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514 | return n; |
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515 | } |
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516 | |
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517 | ///Processes the next node. |
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518 | |
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519 | ///Processes the next node. And checks that at least one of |
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520 | ///reached node has true value in the \c nm node map. If one node |
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521 | ///with true value is reachable from the processed node then the |
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522 | ///rnode parameter will be set to the first of such nodes. |
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523 | /// |
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524 | ///\param nm The node map of possible targets. |
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525 | ///\retval rnode The reached target node. |
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526 | ///\return The processed node. |
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527 | /// |
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528 | ///\warning The queue must not be empty! |
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529 | template<class NM> |
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530 | Node processNextNode(const NM& nm, Node& rnode) |
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531 | { |
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532 | if(_queue_tail==_queue_next_dist) { |
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533 | _curr_dist++; |
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534 | _queue_next_dist=_queue_head; |
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535 | } |
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536 | Node n=_queue[_queue_tail++]; |
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537 | _processed->set(n,true); |
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538 | Node m; |
---|
539 | for(OutArcIt e(*G,n);e!=INVALID;++e) |
---|
540 | if(!(*_reached)[m=G->target(e)]) { |
---|
541 | _queue[_queue_head++]=m; |
---|
542 | _reached->set(m,true); |
---|
543 | _pred->set(m,e); |
---|
544 | _dist->set(m,_curr_dist); |
---|
545 | if (nm[m] && rnode == INVALID) rnode = m; |
---|
546 | } |
---|
547 | return n; |
---|
548 | } |
---|
549 | |
---|
550 | ///Next node to be processed. |
---|
551 | |
---|
552 | ///Next node to be processed. |
---|
553 | /// |
---|
554 | ///\return The next node to be processed or INVALID if the queue is |
---|
555 | /// empty. |
---|
556 | Node nextNode() |
---|
557 | { |
---|
558 | return _queue_tail<_queue_head?_queue[_queue_tail]:INVALID; |
---|
559 | } |
---|
560 | |
---|
561 | ///\brief Returns \c false if there are nodes |
---|
562 | ///to be processed in the queue |
---|
563 | /// |
---|
564 | ///Returns \c false if there are nodes |
---|
565 | ///to be processed in the queue |
---|
566 | bool emptyQueue() { return _queue_tail==_queue_head; } |
---|
567 | ///Returns the number of the nodes to be processed. |
---|
568 | |
---|
569 | ///Returns the number of the nodes to be processed in the queue. |
---|
570 | int queueSize() { return _queue_head-_queue_tail; } |
---|
571 | |
---|
572 | ///Executes the algorithm. |
---|
573 | |
---|
574 | ///Executes the algorithm. |
---|
575 | /// |
---|
576 | ///\pre init() must be called and at least one node should be added |
---|
577 | ///with addSource() before using this function. |
---|
578 | /// |
---|
579 | ///This method runs the %BFS algorithm from the root node(s) |
---|
580 | ///in order to |
---|
581 | ///compute the |
---|
582 | ///shortest path to each node. The algorithm computes |
---|
583 | ///- The shortest path tree. |
---|
584 | ///- The distance of each node from the root(s). |
---|
585 | void start() |
---|
586 | { |
---|
587 | while ( !emptyQueue() ) processNextNode(); |
---|
588 | } |
---|
589 | |
---|
590 | ///Executes the algorithm until \c dest is reached. |
---|
591 | |
---|
592 | ///Executes the algorithm until \c dest is reached. |
---|
593 | /// |
---|
594 | ///\pre init() must be called and at least one node should be added |
---|
595 | ///with addSource() before using this function. |
---|
596 | /// |
---|
597 | ///This method runs the %BFS algorithm from the root node(s) |
---|
598 | ///in order to compute the shortest path to \c dest. |
---|
599 | ///The algorithm computes |
---|
600 | ///- The shortest path to \c dest. |
---|
601 | ///- The distance of \c dest from the root(s). |
---|
602 | void start(Node dest) |
---|
603 | { |
---|
604 | bool reach = false; |
---|
605 | while ( !emptyQueue() && !reach ) processNextNode(dest, reach); |
---|
606 | } |
---|
607 | |
---|
608 | ///Executes the algorithm until a condition is met. |
---|
609 | |
---|
610 | ///Executes the algorithm until a condition is met. |
---|
611 | /// |
---|
612 | ///\pre init() must be called and at least one node should be added |
---|
613 | ///with addSource() before using this function. |
---|
614 | /// |
---|
615 | ///\param nm must be a bool (or convertible) node map. The |
---|
616 | ///algorithm will stop when it reaches a node \c v with |
---|
617 | /// <tt>nm[v]</tt> true. |
---|
618 | /// |
---|
619 | ///\return The reached node \c v with <tt>nm[v]</tt> true or |
---|
620 | ///\c INVALID if no such node was found. |
---|
621 | template<class NM> |
---|
622 | Node start(const NM &nm) |
---|
623 | { |
---|
624 | Node rnode = INVALID; |
---|
625 | while ( !emptyQueue() && rnode == INVALID ) { |
---|
626 | processNextNode(nm, rnode); |
---|
627 | } |
---|
628 | return rnode; |
---|
629 | } |
---|
630 | |
---|
631 | ///Runs %BFS algorithm from node \c s. |
---|
632 | |
---|
633 | ///This method runs the %BFS algorithm from a root node \c s |
---|
634 | ///in order to |
---|
635 | ///compute the |
---|
636 | ///shortest path to each node. The algorithm computes |
---|
637 | ///- The shortest path tree. |
---|
638 | ///- The distance of each node from the root. |
---|
639 | /// |
---|
640 | ///\note b.run(s) is just a shortcut of the following code. |
---|
641 | ///\code |
---|
642 | /// b.init(); |
---|
643 | /// b.addSource(s); |
---|
644 | /// b.start(); |
---|
645 | ///\endcode |
---|
646 | void run(Node s) { |
---|
647 | init(); |
---|
648 | addSource(s); |
---|
649 | start(); |
---|
650 | } |
---|
651 | |
---|
652 | ///Finds the shortest path between \c s and \c t. |
---|
653 | |
---|
654 | ///Finds the shortest path between \c s and \c t. |
---|
655 | /// |
---|
656 | ///\return The length of the shortest s---t path if there exists one, |
---|
657 | ///0 otherwise. |
---|
658 | ///\note Apart from the return value, b.run(s) is |
---|
659 | ///just a shortcut of the following code. |
---|
660 | ///\code |
---|
661 | /// b.init(); |
---|
662 | /// b.addSource(s); |
---|
663 | /// b.start(t); |
---|
664 | ///\endcode |
---|
665 | int run(Node s,Node t) { |
---|
666 | init(); |
---|
667 | addSource(s); |
---|
668 | start(t); |
---|
669 | return reached(t) ? _curr_dist : 0; |
---|
670 | } |
---|
671 | |
---|
672 | ///@} |
---|
673 | |
---|
674 | ///\name Query Functions |
---|
675 | ///The result of the %BFS algorithm can be obtained using these |
---|
676 | ///functions.\n |
---|
677 | ///Before the use of these functions, |
---|
678 | ///either run() or start() must be calleb. |
---|
679 | |
---|
680 | ///@{ |
---|
681 | |
---|
682 | typedef PredMapPath<Digraph, PredMap> Path; |
---|
683 | |
---|
684 | ///Gives back the shortest path. |
---|
685 | |
---|
686 | ///Gives back the shortest path. |
---|
687 | ///\pre The \c t should be reachable from the source. |
---|
688 | Path path(Node t) |
---|
689 | { |
---|
690 | return Path(*G, *_pred, t); |
---|
691 | } |
---|
692 | |
---|
693 | ///The distance of a node from the root(s). |
---|
694 | |
---|
695 | ///Returns the distance of a node from the root(s). |
---|
696 | ///\pre \ref run() must be called before using this function. |
---|
697 | ///\warning If node \c v in unreachable from the root(s) the return value |
---|
698 | ///of this function is undefined. |
---|
699 | int dist(Node v) const { return (*_dist)[v]; } |
---|
700 | |
---|
701 | ///Returns the 'previous arc' of the shortest path tree. |
---|
702 | |
---|
703 | ///For a node \c v it returns the 'previous arc' |
---|
704 | ///of the shortest path tree, |
---|
705 | ///i.e. it returns the last arc of a shortest path from the root(s) to \c |
---|
706 | ///v. It is \ref INVALID |
---|
707 | ///if \c v is unreachable from the root(s) or \c v is a root. The |
---|
708 | ///shortest path tree used here is equal to the shortest path tree used in |
---|
709 | ///\ref predNode(). |
---|
710 | ///\pre Either \ref run() or \ref start() must be called before using |
---|
711 | ///this function. |
---|
712 | Arc predArc(Node v) const { return (*_pred)[v];} |
---|
713 | |
---|
714 | ///Returns the 'previous node' of the shortest path tree. |
---|
715 | |
---|
716 | ///For a node \c v it returns the 'previous node' |
---|
717 | ///of the shortest path tree, |
---|
718 | ///i.e. it returns the last but one node from a shortest path from the |
---|
719 | ///root(a) to \c /v. |
---|
720 | ///It is INVALID if \c v is unreachable from the root(s) or |
---|
721 | ///if \c v itself a root. |
---|
722 | ///The shortest path tree used here is equal to the shortest path |
---|
723 | ///tree used in \ref predArc(). |
---|
724 | ///\pre Either \ref run() or \ref start() must be called before |
---|
725 | ///using this function. |
---|
726 | Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID: |
---|
727 | G->source((*_pred)[v]); } |
---|
728 | |
---|
729 | ///Returns a reference to the NodeMap of distances. |
---|
730 | |
---|
731 | ///Returns a reference to the NodeMap of distances. |
---|
732 | ///\pre Either \ref run() or \ref init() must |
---|
733 | ///be called before using this function. |
---|
734 | const DistMap &distMap() const { return *_dist;} |
---|
735 | |
---|
736 | ///Returns a reference to the shortest path tree map. |
---|
737 | |
---|
738 | ///Returns a reference to the NodeMap of the arcs of the |
---|
739 | ///shortest path tree. |
---|
740 | ///\pre Either \ref run() or \ref init() |
---|
741 | ///must be called before using this function. |
---|
742 | const PredMap &predMap() const { return *_pred;} |
---|
743 | |
---|
744 | ///Checks if a node is reachable from the root. |
---|
745 | |
---|
746 | ///Returns \c true if \c v is reachable from the root. |
---|
747 | ///\warning The source nodes are indicated as unreached. |
---|
748 | ///\pre Either \ref run() or \ref start() |
---|
749 | ///must be called before using this function. |
---|
750 | /// |
---|
751 | bool reached(Node v) { return (*_reached)[v]; } |
---|
752 | |
---|
753 | ///@} |
---|
754 | }; |
---|
755 | |
---|
756 | ///Default traits class of Bfs function. |
---|
757 | |
---|
758 | ///Default traits class of Bfs function. |
---|
759 | ///\param GR Digraph type. |
---|
760 | template<class GR> |
---|
761 | struct BfsWizardDefaultTraits |
---|
762 | { |
---|
763 | ///The digraph type the algorithm runs on. |
---|
764 | typedef GR Digraph; |
---|
765 | ///\brief The type of the map that stores the last |
---|
766 | ///arcs of the shortest paths. |
---|
767 | /// |
---|
768 | ///The type of the map that stores the last |
---|
769 | ///arcs of the shortest paths. |
---|
770 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
771 | /// |
---|
772 | typedef NullMap<typename Digraph::Node,typename GR::Arc> PredMap; |
---|
773 | ///Instantiates a PredMap. |
---|
774 | |
---|
775 | ///This function instantiates a \ref PredMap. |
---|
776 | ///\param g is the digraph, to which we would like to define the PredMap. |
---|
777 | ///\todo The digraph alone may be insufficient to initialize |
---|
778 | #ifdef DOXYGEN |
---|
779 | static PredMap *createPredMap(const GR &g) |
---|
780 | #else |
---|
781 | static PredMap *createPredMap(const GR &) |
---|
782 | #endif |
---|
783 | { |
---|
784 | return new PredMap(); |
---|
785 | } |
---|
786 | |
---|
787 | ///The type of the map that indicates which nodes are processed. |
---|
788 | |
---|
789 | ///The type of the map that indicates which nodes are processed. |
---|
790 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
791 | ///\todo named parameter to set this type, function to read and write. |
---|
792 | typedef NullMap<typename Digraph::Node,bool> ProcessedMap; |
---|
793 | ///Instantiates a ProcessedMap. |
---|
794 | |
---|
795 | ///This function instantiates a \ref ProcessedMap. |
---|
796 | ///\param g is the digraph, to which |
---|
797 | ///we would like to define the \ref ProcessedMap |
---|
798 | #ifdef DOXYGEN |
---|
799 | static ProcessedMap *createProcessedMap(const GR &g) |
---|
800 | #else |
---|
801 | static ProcessedMap *createProcessedMap(const GR &) |
---|
802 | #endif |
---|
803 | { |
---|
804 | return new ProcessedMap(); |
---|
805 | } |
---|
806 | ///The type of the map that indicates which nodes are reached. |
---|
807 | |
---|
808 | ///The type of the map that indicates which nodes are reached. |
---|
809 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
810 | ///\todo named parameter to set this type, function to read and write. |
---|
811 | typedef typename Digraph::template NodeMap<bool> ReachedMap; |
---|
812 | ///Instantiates a ReachedMap. |
---|
813 | |
---|
814 | ///This function instantiates a \ref ReachedMap. |
---|
815 | ///\param G is the digraph, to which |
---|
816 | ///we would like to define the \ref ReachedMap. |
---|
817 | static ReachedMap *createReachedMap(const GR &G) |
---|
818 | { |
---|
819 | return new ReachedMap(G); |
---|
820 | } |
---|
821 | ///The type of the map that stores the dists of the nodes. |
---|
822 | |
---|
823 | ///The type of the map that stores the dists of the nodes. |
---|
824 | ///It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
825 | /// |
---|
826 | typedef NullMap<typename Digraph::Node,int> DistMap; |
---|
827 | ///Instantiates a DistMap. |
---|
828 | |
---|
829 | ///This function instantiates a \ref DistMap. |
---|
830 | ///\param g is the digraph, to which we would like to define the \ref DistMap |
---|
831 | #ifdef DOXYGEN |
---|
832 | static DistMap *createDistMap(const GR &g) |
---|
833 | #else |
---|
834 | static DistMap *createDistMap(const GR &) |
---|
835 | #endif |
---|
836 | { |
---|
837 | return new DistMap(); |
---|
838 | } |
---|
839 | }; |
---|
840 | |
---|
841 | /// Default traits used by \ref BfsWizard |
---|
842 | |
---|
843 | /// To make it easier to use Bfs algorithm |
---|
844 | ///we have created a wizard class. |
---|
845 | /// This \ref BfsWizard class needs default traits, |
---|
846 | ///as well as the \ref Bfs class. |
---|
847 | /// The \ref BfsWizardBase is a class to be the default traits of the |
---|
848 | /// \ref BfsWizard class. |
---|
849 | template<class GR> |
---|
850 | class BfsWizardBase : public BfsWizardDefaultTraits<GR> |
---|
851 | { |
---|
852 | |
---|
853 | typedef BfsWizardDefaultTraits<GR> Base; |
---|
854 | protected: |
---|
855 | /// Type of the nodes in the digraph. |
---|
856 | typedef typename Base::Digraph::Node Node; |
---|
857 | |
---|
858 | /// Pointer to the underlying digraph. |
---|
859 | void *_g; |
---|
860 | ///Pointer to the map of reached nodes. |
---|
861 | void *_reached; |
---|
862 | ///Pointer to the map of processed nodes. |
---|
863 | void *_processed; |
---|
864 | ///Pointer to the map of predecessors arcs. |
---|
865 | void *_pred; |
---|
866 | ///Pointer to the map of distances. |
---|
867 | void *_dist; |
---|
868 | ///Pointer to the source node. |
---|
869 | Node _source; |
---|
870 | |
---|
871 | public: |
---|
872 | /// Constructor. |
---|
873 | |
---|
874 | /// This constructor does not require parameters, therefore it initiates |
---|
875 | /// all of the attributes to default values (0, INVALID). |
---|
876 | BfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0), |
---|
877 | _dist(0), _source(INVALID) {} |
---|
878 | |
---|
879 | /// Constructor. |
---|
880 | |
---|
881 | /// This constructor requires some parameters, |
---|
882 | /// listed in the parameters list. |
---|
883 | /// Others are initiated to 0. |
---|
884 | /// \param g is the initial value of \ref _g |
---|
885 | /// \param s is the initial value of \ref _source |
---|
886 | BfsWizardBase(const GR &g, Node s=INVALID) : |
---|
887 | _g(reinterpret_cast<void*>(const_cast<GR*>(&g))), |
---|
888 | _reached(0), _processed(0), _pred(0), _dist(0), _source(s) {} |
---|
889 | |
---|
890 | }; |
---|
891 | |
---|
892 | /// A class to make the usage of Bfs algorithm easier |
---|
893 | |
---|
894 | /// This class is created to make it easier to use Bfs algorithm. |
---|
895 | /// It uses the functions and features of the plain \ref Bfs, |
---|
896 | /// but it is much simpler to use it. |
---|
897 | /// |
---|
898 | /// Simplicity means that the way to change the types defined |
---|
899 | /// in the traits class is based on functions that returns the new class |
---|
900 | /// and not on templatable built-in classes. |
---|
901 | /// When using the plain \ref Bfs |
---|
902 | /// the new class with the modified type comes from |
---|
903 | /// the original class by using the :: |
---|
904 | /// operator. In the case of \ref BfsWizard only |
---|
905 | /// a function have to be called and it will |
---|
906 | /// return the needed class. |
---|
907 | /// |
---|
908 | /// It does not have own \ref run method. When its \ref run method is called |
---|
909 | /// it initiates a plain \ref Bfs class, and calls the \ref Bfs::run |
---|
910 | /// method of it. |
---|
911 | template<class TR> |
---|
912 | class BfsWizard : public TR |
---|
913 | { |
---|
914 | typedef TR Base; |
---|
915 | |
---|
916 | ///The type of the underlying digraph. |
---|
917 | typedef typename TR::Digraph Digraph; |
---|
918 | //\e |
---|
919 | typedef typename Digraph::Node Node; |
---|
920 | //\e |
---|
921 | typedef typename Digraph::NodeIt NodeIt; |
---|
922 | //\e |
---|
923 | typedef typename Digraph::Arc Arc; |
---|
924 | //\e |
---|
925 | typedef typename Digraph::OutArcIt OutArcIt; |
---|
926 | |
---|
927 | ///\brief The type of the map that stores |
---|
928 | ///the reached nodes |
---|
929 | typedef typename TR::ReachedMap ReachedMap; |
---|
930 | ///\brief The type of the map that stores |
---|
931 | ///the processed nodes |
---|
932 | typedef typename TR::ProcessedMap ProcessedMap; |
---|
933 | ///\brief The type of the map that stores the last |
---|
934 | ///arcs of the shortest paths. |
---|
935 | typedef typename TR::PredMap PredMap; |
---|
936 | ///The type of the map that stores the dists of the nodes. |
---|
937 | typedef typename TR::DistMap DistMap; |
---|
938 | |
---|
939 | public: |
---|
940 | /// Constructor. |
---|
941 | BfsWizard() : TR() {} |
---|
942 | |
---|
943 | /// Constructor that requires parameters. |
---|
944 | |
---|
945 | /// Constructor that requires parameters. |
---|
946 | /// These parameters will be the default values for the traits class. |
---|
947 | BfsWizard(const Digraph &g, Node s=INVALID) : |
---|
948 | TR(g,s) {} |
---|
949 | |
---|
950 | ///Copy constructor |
---|
951 | BfsWizard(const TR &b) : TR(b) {} |
---|
952 | |
---|
953 | ~BfsWizard() {} |
---|
954 | |
---|
955 | ///Runs Bfs algorithm from a given node. |
---|
956 | |
---|
957 | ///Runs Bfs algorithm from a given node. |
---|
958 | ///The node can be given by the \ref source function. |
---|
959 | void run() |
---|
960 | { |
---|
961 | if(Base::_source==INVALID) throw UninitializedParameter(); |
---|
962 | Bfs<Digraph,TR> alg(*reinterpret_cast<const Digraph*>(Base::_g)); |
---|
963 | if(Base::_reached) |
---|
964 | alg.reachedMap(*reinterpret_cast<ReachedMap*>(Base::_reached)); |
---|
965 | if(Base::_processed) |
---|
966 | alg.processedMap(*reinterpret_cast<ProcessedMap*>(Base::_processed)); |
---|
967 | if(Base::_pred) |
---|
968 | alg.predMap(*reinterpret_cast<PredMap*>(Base::_pred)); |
---|
969 | if(Base::_dist) |
---|
970 | alg.distMap(*reinterpret_cast<DistMap*>(Base::_dist)); |
---|
971 | alg.run(Base::_source); |
---|
972 | } |
---|
973 | |
---|
974 | ///Runs Bfs algorithm from the given node. |
---|
975 | |
---|
976 | ///Runs Bfs algorithm from the given node. |
---|
977 | ///\param s is the given source. |
---|
978 | void run(Node s) |
---|
979 | { |
---|
980 | Base::_source=s; |
---|
981 | run(); |
---|
982 | } |
---|
983 | |
---|
984 | template<class T> |
---|
985 | struct DefPredMapBase : public Base { |
---|
986 | typedef T PredMap; |
---|
987 | static PredMap *createPredMap(const Digraph &) { return 0; }; |
---|
988 | DefPredMapBase(const TR &b) : TR(b) {} |
---|
989 | }; |
---|
990 | |
---|
991 | ///\brief \ref named-templ-param "Named parameter" |
---|
992 | ///function for setting PredMap |
---|
993 | /// |
---|
994 | /// \ref named-templ-param "Named parameter" |
---|
995 | ///function for setting PredMap |
---|
996 | /// |
---|
997 | template<class T> |
---|
998 | BfsWizard<DefPredMapBase<T> > predMap(const T &t) |
---|
999 | { |
---|
1000 | Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
1001 | return BfsWizard<DefPredMapBase<T> >(*this); |
---|
1002 | } |
---|
1003 | |
---|
1004 | |
---|
1005 | template<class T> |
---|
1006 | struct DefReachedMapBase : public Base { |
---|
1007 | typedef T ReachedMap; |
---|
1008 | static ReachedMap *createReachedMap(const Digraph &) { return 0; }; |
---|
1009 | DefReachedMapBase(const TR &b) : TR(b) {} |
---|
1010 | }; |
---|
1011 | |
---|
1012 | ///\brief \ref named-templ-param "Named parameter" |
---|
1013 | ///function for setting ReachedMap |
---|
1014 | /// |
---|
1015 | /// \ref named-templ-param "Named parameter" |
---|
1016 | ///function for setting ReachedMap |
---|
1017 | /// |
---|
1018 | template<class T> |
---|
1019 | BfsWizard<DefReachedMapBase<T> > reachedMap(const T &t) |
---|
1020 | { |
---|
1021 | Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
1022 | return BfsWizard<DefReachedMapBase<T> >(*this); |
---|
1023 | } |
---|
1024 | |
---|
1025 | |
---|
1026 | template<class T> |
---|
1027 | struct DefProcessedMapBase : public Base { |
---|
1028 | typedef T ProcessedMap; |
---|
1029 | static ProcessedMap *createProcessedMap(const Digraph &) { return 0; }; |
---|
1030 | DefProcessedMapBase(const TR &b) : TR(b) {} |
---|
1031 | }; |
---|
1032 | |
---|
1033 | ///\brief \ref named-templ-param "Named parameter" |
---|
1034 | ///function for setting ProcessedMap |
---|
1035 | /// |
---|
1036 | /// \ref named-templ-param "Named parameter" |
---|
1037 | ///function for setting ProcessedMap |
---|
1038 | /// |
---|
1039 | template<class T> |
---|
1040 | BfsWizard<DefProcessedMapBase<T> > processedMap(const T &t) |
---|
1041 | { |
---|
1042 | Base::_pred=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
1043 | return BfsWizard<DefProcessedMapBase<T> >(*this); |
---|
1044 | } |
---|
1045 | |
---|
1046 | |
---|
1047 | template<class T> |
---|
1048 | struct DefDistMapBase : public Base { |
---|
1049 | typedef T DistMap; |
---|
1050 | static DistMap *createDistMap(const Digraph &) { return 0; }; |
---|
1051 | DefDistMapBase(const TR &b) : TR(b) {} |
---|
1052 | }; |
---|
1053 | |
---|
1054 | ///\brief \ref named-templ-param "Named parameter" |
---|
1055 | ///function for setting DistMap type |
---|
1056 | /// |
---|
1057 | /// \ref named-templ-param "Named parameter" |
---|
1058 | ///function for setting DistMap type |
---|
1059 | /// |
---|
1060 | template<class T> |
---|
1061 | BfsWizard<DefDistMapBase<T> > distMap(const T &t) |
---|
1062 | { |
---|
1063 | Base::_dist=reinterpret_cast<void*>(const_cast<T*>(&t)); |
---|
1064 | return BfsWizard<DefDistMapBase<T> >(*this); |
---|
1065 | } |
---|
1066 | |
---|
1067 | /// Sets the source node, from which the Bfs algorithm runs. |
---|
1068 | |
---|
1069 | /// Sets the source node, from which the Bfs algorithm runs. |
---|
1070 | /// \param s is the source node. |
---|
1071 | BfsWizard<TR> &source(Node s) |
---|
1072 | { |
---|
1073 | Base::_source=s; |
---|
1074 | return *this; |
---|
1075 | } |
---|
1076 | |
---|
1077 | }; |
---|
1078 | |
---|
1079 | ///Function type interface for Bfs algorithm. |
---|
1080 | |
---|
1081 | /// \ingroup search |
---|
1082 | ///Function type interface for Bfs algorithm. |
---|
1083 | /// |
---|
1084 | ///This function also has several |
---|
1085 | ///\ref named-templ-func-param "named parameters", |
---|
1086 | ///they are declared as the members of class \ref BfsWizard. |
---|
1087 | ///The following |
---|
1088 | ///example shows how to use these parameters. |
---|
1089 | ///\code |
---|
1090 | /// bfs(g,source).predMap(preds).run(); |
---|
1091 | ///\endcode |
---|
1092 | ///\warning Don't forget to put the \ref BfsWizard::run() "run()" |
---|
1093 | ///to the end of the parameter list. |
---|
1094 | ///\sa BfsWizard |
---|
1095 | ///\sa Bfs |
---|
1096 | template<class GR> |
---|
1097 | BfsWizard<BfsWizardBase<GR> > |
---|
1098 | bfs(const GR &g,typename GR::Node s=INVALID) |
---|
1099 | { |
---|
1100 | return BfsWizard<BfsWizardBase<GR> >(g,s); |
---|
1101 | } |
---|
1102 | |
---|
1103 | #ifdef DOXYGEN |
---|
1104 | /// \brief Visitor class for bfs. |
---|
1105 | /// |
---|
1106 | /// This class defines the interface of the BfsVisit events, and |
---|
1107 | /// it could be the base of a real Visitor class. |
---|
1108 | template <typename _Digraph> |
---|
1109 | struct BfsVisitor { |
---|
1110 | typedef _Digraph Digraph; |
---|
1111 | typedef typename Digraph::Arc Arc; |
---|
1112 | typedef typename Digraph::Node Node; |
---|
1113 | /// \brief Called when the arc reach a node. |
---|
1114 | /// |
---|
1115 | /// It is called when the bfs find an arc which target is not |
---|
1116 | /// reached yet. |
---|
1117 | void discover(const Arc& arc) {} |
---|
1118 | /// \brief Called when the node reached first time. |
---|
1119 | /// |
---|
1120 | /// It is Called when the node reached first time. |
---|
1121 | void reach(const Node& node) {} |
---|
1122 | /// \brief Called when the arc examined but target of the arc |
---|
1123 | /// already discovered. |
---|
1124 | /// |
---|
1125 | /// It called when the arc examined but the target of the arc |
---|
1126 | /// already discovered. |
---|
1127 | void examine(const Arc& arc) {} |
---|
1128 | /// \brief Called for the source node of the bfs. |
---|
1129 | /// |
---|
1130 | /// It is called for the source node of the bfs. |
---|
1131 | void start(const Node& node) {} |
---|
1132 | /// \brief Called when the node processed. |
---|
1133 | /// |
---|
1134 | /// It is Called when the node processed. |
---|
1135 | void process(const Node& node) {} |
---|
1136 | }; |
---|
1137 | #else |
---|
1138 | template <typename _Digraph> |
---|
1139 | struct BfsVisitor { |
---|
1140 | typedef _Digraph Digraph; |
---|
1141 | typedef typename Digraph::Arc Arc; |
---|
1142 | typedef typename Digraph::Node Node; |
---|
1143 | void discover(const Arc&) {} |
---|
1144 | void reach(const Node&) {} |
---|
1145 | void examine(const Arc&) {} |
---|
1146 | void start(const Node&) {} |
---|
1147 | void process(const Node&) {} |
---|
1148 | |
---|
1149 | template <typename _Visitor> |
---|
1150 | struct Constraints { |
---|
1151 | void constraints() { |
---|
1152 | Arc arc; |
---|
1153 | Node node; |
---|
1154 | visitor.discover(arc); |
---|
1155 | visitor.reach(node); |
---|
1156 | visitor.examine(arc); |
---|
1157 | visitor.start(node); |
---|
1158 | visitor.process(node); |
---|
1159 | } |
---|
1160 | _Visitor& visitor; |
---|
1161 | }; |
---|
1162 | }; |
---|
1163 | #endif |
---|
1164 | |
---|
1165 | /// \brief Default traits class of BfsVisit class. |
---|
1166 | /// |
---|
1167 | /// Default traits class of BfsVisit class. |
---|
1168 | /// \param _Digraph Digraph type. |
---|
1169 | template<class _Digraph> |
---|
1170 | struct BfsVisitDefaultTraits { |
---|
1171 | |
---|
1172 | /// \brief The digraph type the algorithm runs on. |
---|
1173 | typedef _Digraph Digraph; |
---|
1174 | |
---|
1175 | /// \brief The type of the map that indicates which nodes are reached. |
---|
1176 | /// |
---|
1177 | /// The type of the map that indicates which nodes are reached. |
---|
1178 | /// It must meet the \ref concepts::WriteMap "WriteMap" concept. |
---|
1179 | /// \todo named parameter to set this type, function to read and write. |
---|
1180 | typedef typename Digraph::template NodeMap<bool> ReachedMap; |
---|
1181 | |
---|
1182 | /// \brief Instantiates a ReachedMap. |
---|
1183 | /// |
---|
1184 | /// This function instantiates a \ref ReachedMap. |
---|
1185 | /// \param digraph is the digraph, to which |
---|
1186 | /// we would like to define the \ref ReachedMap. |
---|
1187 | static ReachedMap *createReachedMap(const Digraph &digraph) { |
---|
1188 | return new ReachedMap(digraph); |
---|
1189 | } |
---|
1190 | |
---|
1191 | }; |
---|
1192 | |
---|
1193 | /// \ingroup search |
---|
1194 | /// |
---|
1195 | /// \brief %BFS Visit algorithm class. |
---|
1196 | /// |
---|
1197 | /// This class provides an efficient implementation of the %BFS algorithm |
---|
1198 | /// with visitor interface. |
---|
1199 | /// |
---|
1200 | /// The %BfsVisit class provides an alternative interface to the Bfs |
---|
1201 | /// class. It works with callback mechanism, the BfsVisit object calls |
---|
1202 | /// on every bfs event the \c Visitor class member functions. |
---|
1203 | /// |
---|
1204 | /// \param _Digraph The digraph type the algorithm runs on. The default value is |
---|
1205 | /// \ref ListDigraph. The value of _Digraph is not used directly by Bfs, it |
---|
1206 | /// is only passed to \ref BfsDefaultTraits. |
---|
1207 | /// \param _Visitor The Visitor object for the algorithm. The |
---|
1208 | /// \ref BfsVisitor "BfsVisitor<_Digraph>" is an empty Visitor which |
---|
1209 | /// does not observe the Bfs events. If you want to observe the bfs |
---|
1210 | /// events you should implement your own Visitor class. |
---|
1211 | /// \param _Traits Traits class to set various data types used by the |
---|
1212 | /// algorithm. The default traits class is |
---|
1213 | /// \ref BfsVisitDefaultTraits "BfsVisitDefaultTraits<_Digraph>". |
---|
1214 | /// See \ref BfsVisitDefaultTraits for the documentation of |
---|
1215 | /// a Bfs visit traits class. |
---|
1216 | /// |
---|
1217 | /// \author Jacint Szabo, Alpar Juttner and Balazs Dezso |
---|
1218 | #ifdef DOXYGEN |
---|
1219 | template <typename _Digraph, typename _Visitor, typename _Traits> |
---|
1220 | #else |
---|
1221 | template <typename _Digraph = ListDigraph, |
---|
1222 | typename _Visitor = BfsVisitor<_Digraph>, |
---|
1223 | typename _Traits = BfsDefaultTraits<_Digraph> > |
---|
1224 | #endif |
---|
1225 | class BfsVisit { |
---|
1226 | public: |
---|
1227 | |
---|
1228 | /// \brief \ref Exception for uninitialized parameters. |
---|
1229 | /// |
---|
1230 | /// This error represents problems in the initialization |
---|
1231 | /// of the parameters of the algorithms. |
---|
1232 | class UninitializedParameter : public lemon::UninitializedParameter { |
---|
1233 | public: |
---|
1234 | virtual const char* what() const throw() |
---|
1235 | { |
---|
1236 | return "lemon::BfsVisit::UninitializedParameter"; |
---|
1237 | } |
---|
1238 | }; |
---|
1239 | |
---|
1240 | typedef _Traits Traits; |
---|
1241 | |
---|
1242 | typedef typename Traits::Digraph Digraph; |
---|
1243 | |
---|
1244 | typedef _Visitor Visitor; |
---|
1245 | |
---|
1246 | ///The type of the map indicating which nodes are reached. |
---|
1247 | typedef typename Traits::ReachedMap ReachedMap; |
---|
1248 | |
---|
1249 | private: |
---|
1250 | |
---|
1251 | typedef typename Digraph::Node Node; |
---|
1252 | typedef typename Digraph::NodeIt NodeIt; |
---|
1253 | typedef typename Digraph::Arc Arc; |
---|
1254 | typedef typename Digraph::OutArcIt OutArcIt; |
---|
1255 | |
---|
1256 | /// Pointer to the underlying digraph. |
---|
1257 | const Digraph *_digraph; |
---|
1258 | /// Pointer to the visitor object. |
---|
1259 | Visitor *_visitor; |
---|
1260 | ///Pointer to the map of reached status of the nodes. |
---|
1261 | ReachedMap *_reached; |
---|
1262 | ///Indicates if \ref _reached is locally allocated (\c true) or not. |
---|
1263 | bool local_reached; |
---|
1264 | |
---|
1265 | std::vector<typename Digraph::Node> _list; |
---|
1266 | int _list_front, _list_back; |
---|
1267 | |
---|
1268 | /// \brief Creates the maps if necessary. |
---|
1269 | /// |
---|
1270 | /// Creates the maps if necessary. |
---|
1271 | void create_maps() { |
---|
1272 | if(!_reached) { |
---|
1273 | local_reached = true; |
---|
1274 | _reached = Traits::createReachedMap(*_digraph); |
---|
1275 | } |
---|
1276 | } |
---|
1277 | |
---|
1278 | protected: |
---|
1279 | |
---|
1280 | BfsVisit() {} |
---|
1281 | |
---|
1282 | public: |
---|
1283 | |
---|
1284 | typedef BfsVisit Create; |
---|
1285 | |
---|
1286 | /// \name Named template parameters |
---|
1287 | |
---|
1288 | ///@{ |
---|
1289 | template <class T> |
---|
1290 | struct DefReachedMapTraits : public Traits { |
---|
1291 | typedef T ReachedMap; |
---|
1292 | static ReachedMap *createReachedMap(const Digraph &digraph) { |
---|
1293 | throw UninitializedParameter(); |
---|
1294 | } |
---|
1295 | }; |
---|
1296 | /// \brief \ref named-templ-param "Named parameter" for setting |
---|
1297 | /// ReachedMap type |
---|
1298 | /// |
---|
1299 | /// \ref named-templ-param "Named parameter" for setting ReachedMap type |
---|
1300 | template <class T> |
---|
1301 | struct DefReachedMap : public BfsVisit< Digraph, Visitor, |
---|
1302 | DefReachedMapTraits<T> > { |
---|
1303 | typedef BfsVisit< Digraph, Visitor, DefReachedMapTraits<T> > Create; |
---|
1304 | }; |
---|
1305 | ///@} |
---|
1306 | |
---|
1307 | public: |
---|
1308 | |
---|
1309 | /// \brief Constructor. |
---|
1310 | /// |
---|
1311 | /// Constructor. |
---|
1312 | /// |
---|
1313 | /// \param digraph the digraph the algorithm will run on. |
---|
1314 | /// \param visitor The visitor of the algorithm. |
---|
1315 | /// |
---|
1316 | BfsVisit(const Digraph& digraph, Visitor& visitor) |
---|
1317 | : _digraph(&digraph), _visitor(&visitor), |
---|
1318 | _reached(0), local_reached(false) {} |
---|
1319 | |
---|
1320 | /// \brief Destructor. |
---|
1321 | /// |
---|
1322 | /// Destructor. |
---|
1323 | ~BfsVisit() { |
---|
1324 | if(local_reached) delete _reached; |
---|
1325 | } |
---|
1326 | |
---|
1327 | /// \brief Sets the map indicating if a node is reached. |
---|
1328 | /// |
---|
1329 | /// Sets the map indicating if a node is reached. |
---|
1330 | /// If you don't use this function before calling \ref run(), |
---|
1331 | /// it will allocate one. The destuctor deallocates this |
---|
1332 | /// automatically allocated map, of course. |
---|
1333 | /// \return <tt> (*this) </tt> |
---|
1334 | BfsVisit &reachedMap(ReachedMap &m) { |
---|
1335 | if(local_reached) { |
---|
1336 | delete _reached; |
---|
1337 | local_reached = false; |
---|
1338 | } |
---|
1339 | _reached = &m; |
---|
1340 | return *this; |
---|
1341 | } |
---|
1342 | |
---|
1343 | public: |
---|
1344 | /// \name Execution control |
---|
1345 | /// The simplest way to execute the algorithm is to use |
---|
1346 | /// one of the member functions called \c run(...). |
---|
1347 | /// \n |
---|
1348 | /// If you need more control on the execution, |
---|
1349 | /// first you must call \ref init(), then you can adda source node |
---|
1350 | /// with \ref addSource(). |
---|
1351 | /// Finally \ref start() will perform the actual path |
---|
1352 | /// computation. |
---|
1353 | |
---|
1354 | /// @{ |
---|
1355 | /// \brief Initializes the internal data structures. |
---|
1356 | /// |
---|
1357 | /// Initializes the internal data structures. |
---|
1358 | /// |
---|
1359 | void init() { |
---|
1360 | create_maps(); |
---|
1361 | _list.resize(countNodes(*_digraph)); |
---|
1362 | _list_front = _list_back = -1; |
---|
1363 | for (NodeIt u(*_digraph) ; u != INVALID ; ++u) { |
---|
1364 | _reached->set(u, false); |
---|
1365 | } |
---|
1366 | } |
---|
1367 | |
---|
1368 | /// \brief Adds a new source node. |
---|
1369 | /// |
---|
1370 | /// Adds a new source node to the set of nodes to be processed. |
---|
1371 | void addSource(Node s) { |
---|
1372 | if(!(*_reached)[s]) { |
---|
1373 | _reached->set(s,true); |
---|
1374 | _visitor->start(s); |
---|
1375 | _visitor->reach(s); |
---|
1376 | _list[++_list_back] = s; |
---|
1377 | } |
---|
1378 | } |
---|
1379 | |
---|
1380 | /// \brief Processes the next node. |
---|
1381 | /// |
---|
1382 | /// Processes the next node. |
---|
1383 | /// |
---|
1384 | /// \return The processed node. |
---|
1385 | /// |
---|
1386 | /// \pre The queue must not be empty! |
---|
1387 | Node processNextNode() { |
---|
1388 | Node n = _list[++_list_front]; |
---|
1389 | _visitor->process(n); |
---|
1390 | Arc e; |
---|
1391 | for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) { |
---|
1392 | Node m = _digraph->target(e); |
---|
1393 | if (!(*_reached)[m]) { |
---|
1394 | _visitor->discover(e); |
---|
1395 | _visitor->reach(m); |
---|
1396 | _reached->set(m, true); |
---|
1397 | _list[++_list_back] = m; |
---|
1398 | } else { |
---|
1399 | _visitor->examine(e); |
---|
1400 | } |
---|
1401 | } |
---|
1402 | return n; |
---|
1403 | } |
---|
1404 | |
---|
1405 | /// \brief Processes the next node. |
---|
1406 | /// |
---|
1407 | /// Processes the next node. And checks that the given target node |
---|
1408 | /// is reached. If the target node is reachable from the processed |
---|
1409 | /// node then the reached parameter will be set true. The reached |
---|
1410 | /// parameter should be initially false. |
---|
1411 | /// |
---|
1412 | /// \param target The target node. |
---|
1413 | /// \retval reach Indicates that the target node is reached. |
---|
1414 | /// \return The processed node. |
---|
1415 | /// |
---|
1416 | /// \warning The queue must not be empty! |
---|
1417 | Node processNextNode(Node target, bool& reach) { |
---|
1418 | Node n = _list[++_list_front]; |
---|
1419 | _visitor->process(n); |
---|
1420 | Arc e; |
---|
1421 | for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) { |
---|
1422 | Node m = _digraph->target(e); |
---|
1423 | if (!(*_reached)[m]) { |
---|
1424 | _visitor->discover(e); |
---|
1425 | _visitor->reach(m); |
---|
1426 | _reached->set(m, true); |
---|
1427 | _list[++_list_back] = m; |
---|
1428 | reach = reach || (target == m); |
---|
1429 | } else { |
---|
1430 | _visitor->examine(e); |
---|
1431 | } |
---|
1432 | } |
---|
1433 | return n; |
---|
1434 | } |
---|
1435 | |
---|
1436 | /// \brief Processes the next node. |
---|
1437 | /// |
---|
1438 | /// Processes the next node. And checks that at least one of |
---|
1439 | /// reached node has true value in the \c nm node map. If one node |
---|
1440 | /// with true value is reachable from the processed node then the |
---|
1441 | /// rnode parameter will be set to the first of such nodes. |
---|
1442 | /// |
---|
1443 | /// \param nm The node map of possible targets. |
---|
1444 | /// \retval rnode The reached target node. |
---|
1445 | /// \return The processed node. |
---|
1446 | /// |
---|
1447 | /// \warning The queue must not be empty! |
---|
1448 | template <typename NM> |
---|
1449 | Node processNextNode(const NM& nm, Node& rnode) { |
---|
1450 | Node n = _list[++_list_front]; |
---|
1451 | _visitor->process(n); |
---|
1452 | Arc e; |
---|
1453 | for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) { |
---|
1454 | Node m = _digraph->target(e); |
---|
1455 | if (!(*_reached)[m]) { |
---|
1456 | _visitor->discover(e); |
---|
1457 | _visitor->reach(m); |
---|
1458 | _reached->set(m, true); |
---|
1459 | _list[++_list_back] = m; |
---|
1460 | if (nm[m] && rnode == INVALID) rnode = m; |
---|
1461 | } else { |
---|
1462 | _visitor->examine(e); |
---|
1463 | } |
---|
1464 | } |
---|
1465 | return n; |
---|
1466 | } |
---|
1467 | |
---|
1468 | /// \brief Next node to be processed. |
---|
1469 | /// |
---|
1470 | /// Next node to be processed. |
---|
1471 | /// |
---|
1472 | /// \return The next node to be processed or INVALID if the stack is |
---|
1473 | /// empty. |
---|
1474 | Node nextNode() { |
---|
1475 | return _list_front != _list_back ? _list[_list_front + 1] : INVALID; |
---|
1476 | } |
---|
1477 | |
---|
1478 | /// \brief Returns \c false if there are nodes |
---|
1479 | /// to be processed in the queue |
---|
1480 | /// |
---|
1481 | /// Returns \c false if there are nodes |
---|
1482 | /// to be processed in the queue |
---|
1483 | bool emptyQueue() { return _list_front == _list_back; } |
---|
1484 | |
---|
1485 | /// \brief Returns the number of the nodes to be processed. |
---|
1486 | /// |
---|
1487 | /// Returns the number of the nodes to be processed in the queue. |
---|
1488 | int queueSize() { return _list_back - _list_front; } |
---|
1489 | |
---|
1490 | /// \brief Executes the algorithm. |
---|
1491 | /// |
---|
1492 | /// Executes the algorithm. |
---|
1493 | /// |
---|
1494 | /// \pre init() must be called and at least one node should be added |
---|
1495 | /// with addSource() before using this function. |
---|
1496 | void start() { |
---|
1497 | while ( !emptyQueue() ) processNextNode(); |
---|
1498 | } |
---|
1499 | |
---|
1500 | /// \brief Executes the algorithm until \c dest is reached. |
---|
1501 | /// |
---|
1502 | /// Executes the algorithm until \c dest is reached. |
---|
1503 | /// |
---|
1504 | /// \pre init() must be called and at least one node should be added |
---|
1505 | /// with addSource() before using this function. |
---|
1506 | void start(Node dest) { |
---|
1507 | bool reach = false; |
---|
1508 | while ( !emptyQueue() && !reach ) processNextNode(dest, reach); |
---|
1509 | } |
---|
1510 | |
---|
1511 | /// \brief Executes the algorithm until a condition is met. |
---|
1512 | /// |
---|
1513 | /// Executes the algorithm until a condition is met. |
---|
1514 | /// |
---|
1515 | /// \pre init() must be called and at least one node should be added |
---|
1516 | /// with addSource() before using this function. |
---|
1517 | /// |
---|
1518 | ///\param nm must be a bool (or convertible) node map. The |
---|
1519 | ///algorithm will stop when it reaches a node \c v with |
---|
1520 | /// <tt>nm[v]</tt> true. |
---|
1521 | /// |
---|
1522 | ///\return The reached node \c v with <tt>nm[v]</tt> true or |
---|
1523 | ///\c INVALID if no such node was found. |
---|
1524 | template <typename NM> |
---|
1525 | Node start(const NM &nm) { |
---|
1526 | Node rnode = INVALID; |
---|
1527 | while ( !emptyQueue() && rnode == INVALID ) { |
---|
1528 | processNextNode(nm, rnode); |
---|
1529 | } |
---|
1530 | return rnode; |
---|
1531 | } |
---|
1532 | |
---|
1533 | /// \brief Runs %BFSVisit algorithm from node \c s. |
---|
1534 | /// |
---|
1535 | /// This method runs the %BFS algorithm from a root node \c s. |
---|
1536 | /// \note b.run(s) is just a shortcut of the following code. |
---|
1537 | ///\code |
---|
1538 | /// b.init(); |
---|
1539 | /// b.addSource(s); |
---|
1540 | /// b.start(); |
---|
1541 | ///\endcode |
---|
1542 | void run(Node s) { |
---|
1543 | init(); |
---|
1544 | addSource(s); |
---|
1545 | start(); |
---|
1546 | } |
---|
1547 | |
---|
1548 | /// \brief Runs %BFSVisit algorithm to visit all nodes in the digraph. |
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1549 | /// |
---|
1550 | /// This method runs the %BFS algorithm in order to |
---|
1551 | /// compute the %BFS path to each node. The algorithm computes |
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1552 | /// - The %BFS tree. |
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1553 | /// - The distance of each node from the root in the %BFS tree. |
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1554 | /// |
---|
1555 | ///\note b.run() is just a shortcut of the following code. |
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1556 | ///\code |
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1557 | /// b.init(); |
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1558 | /// for (NodeIt it(digraph); it != INVALID; ++it) { |
---|
1559 | /// if (!b.reached(it)) { |
---|
1560 | /// b.addSource(it); |
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1561 | /// b.start(); |
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1562 | /// } |
---|
1563 | /// } |
---|
1564 | ///\endcode |
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1565 | void run() { |
---|
1566 | init(); |
---|
1567 | for (NodeIt it(*_digraph); it != INVALID; ++it) { |
---|
1568 | if (!reached(it)) { |
---|
1569 | addSource(it); |
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1570 | start(); |
---|
1571 | } |
---|
1572 | } |
---|
1573 | } |
---|
1574 | ///@} |
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1575 | |
---|
1576 | /// \name Query Functions |
---|
1577 | /// The result of the %BFS algorithm can be obtained using these |
---|
1578 | /// functions.\n |
---|
1579 | /// Before the use of these functions, |
---|
1580 | /// either run() or start() must be called. |
---|
1581 | ///@{ |
---|
1582 | |
---|
1583 | /// \brief Checks if a node is reachable from the root. |
---|
1584 | /// |
---|
1585 | /// Returns \c true if \c v is reachable from the root(s). |
---|
1586 | /// \warning The source nodes are inditated as unreachable. |
---|
1587 | /// \pre Either \ref run() or \ref start() |
---|
1588 | /// must be called before using this function. |
---|
1589 | /// |
---|
1590 | bool reached(Node v) { return (*_reached)[v]; } |
---|
1591 | ///@} |
---|
1592 | }; |
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1593 | |
---|
1594 | } //END OF NAMESPACE LEMON |
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1595 | |
---|
1596 | #endif |
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1597 | |
---|