1 | /* -*- C++ -*- |
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2 | * lemon/concept/path.h - Part of LEMON, a generic C++ optimization library |
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3 | * |
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4 | * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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5 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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6 | * |
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7 | * Permission to use, modify and distribute this software is granted |
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8 | * provided that this copyright notice appears in all copies. For |
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9 | * precise terms see the accompanying LICENSE file. |
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10 | * |
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11 | * This software is provided "AS IS" with no warranty of any kind, |
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12 | * express or implied, and with no claim as to its suitability for any |
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13 | * purpose. |
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14 | * |
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15 | */ |
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16 | |
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17 | ///\ingroup concept |
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18 | ///\file |
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19 | ///\brief Classes for representing paths in graphs. |
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20 | /// |
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21 | ///\todo Iterators have obsolete style |
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22 | |
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23 | #ifndef LEMON_CONCEPT_PATH_H |
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24 | #define LEMON_CONCEPT_PATH_H |
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25 | |
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26 | #include <lemon/invalid.h> |
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27 | |
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28 | namespace lemon { |
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29 | namespace concept { |
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30 | /// \addtogroup concept |
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31 | /// @{ |
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32 | |
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33 | |
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34 | //! \brief A skeleton structure for representing directed paths in a graph. |
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35 | //! |
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36 | //! A skeleton structure for representing directed paths in a graph. |
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37 | //! \param GR The graph type in which the path is. |
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38 | //! |
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39 | //! In a sense, the path can be treated as a graph, for it has \c NodeIt |
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40 | //! and \c EdgeIt with the same usage. These types converts to the \c Node |
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41 | //! and \c Edge of the original graph. |
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42 | template<typename GR> |
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43 | class Path { |
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44 | public: |
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45 | |
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46 | /// Type of the underlying graph. |
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47 | typedef /*typename*/ GR Graph; |
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48 | /// Edge type of the underlying graph. |
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49 | typedef typename Graph::Edge GraphEdge; |
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50 | /// Node type of the underlying graph. |
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51 | typedef typename Graph::Node GraphNode; |
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52 | class NodeIt; |
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53 | class EdgeIt; |
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54 | |
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55 | /// \param _g The graph in which the path is. |
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56 | /// |
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57 | Path(const Graph &_g) {} |
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58 | |
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59 | /// Length of the path. |
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60 | int length() const {return 0;} |
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61 | /// Returns whether the path is empty. |
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62 | bool empty() const { return true;} |
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63 | |
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64 | /// Resets the path to an empty path. |
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65 | void clear() {} |
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66 | |
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67 | /// \brief Starting point of the path. |
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68 | /// |
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69 | /// Starting point of the path. |
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70 | /// Returns INVALID if the path is empty. |
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71 | GraphNode/*It*/ target() const {return INVALID;} |
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72 | /// \brief End point of the path. |
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73 | /// |
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74 | /// End point of the path. |
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75 | /// Returns INVALID if the path is empty. |
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76 | GraphNode/*It*/ source() const {return INVALID;} |
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77 | |
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78 | /// \brief First NodeIt/EdgeIt. |
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79 | /// |
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80 | /// Initializes node or edge iterator to point to the first |
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81 | /// node or edge. |
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82 | template<typename It> |
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83 | It& first(It &i) const { return i=It(*this); } |
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84 | |
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85 | /// \brief The target of an edge. |
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86 | /// |
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87 | /// Returns node iterator pointing to the target node of the |
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88 | /// given edge iterator. |
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89 | NodeIt target(const EdgeIt&) const {return INVALID;} |
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90 | |
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91 | /// \brief The source of an edge. |
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92 | /// |
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93 | /// Returns node iterator pointing to the source node of the |
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94 | /// given edge iterator. |
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95 | NodeIt source(const EdgeIt&) const {return INVALID;} |
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96 | |
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97 | |
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98 | /* Iterator classes */ |
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99 | |
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100 | /** |
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101 | * \brief Iterator class to iterate on the edges of the paths |
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102 | * |
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103 | * This class is used to iterate on the edges of the paths |
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104 | * |
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105 | * Of course it converts to Graph::Edge |
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106 | * |
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107 | */ |
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108 | class EdgeIt { |
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109 | public: |
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110 | /// Default constructor |
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111 | EdgeIt() {} |
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112 | /// Invalid constructor |
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113 | EdgeIt(Invalid) {} |
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114 | /// Constructor with starting point |
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115 | EdgeIt(const Path &) {} |
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116 | |
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117 | operator GraphEdge () const {} |
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118 | |
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119 | /// Next edge |
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120 | EdgeIt& operator++() {return *this;} |
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121 | |
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122 | /// Comparison operator |
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123 | bool operator==(const EdgeIt&) const {return true;} |
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124 | /// Comparison operator |
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125 | bool operator!=(const EdgeIt&) const {return true;} |
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126 | // /// Comparison operator |
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127 | // /// \todo It is not clear what is the "natural" ordering. |
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128 | // bool operator<(const EdgeIt& e) const {} |
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129 | |
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130 | }; |
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131 | |
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132 | /** |
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133 | * \brief Iterator class to iterate on the nodes of the paths |
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134 | * |
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135 | * This class is used to iterate on the nodes of the paths |
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136 | * |
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137 | * Of course it converts to Graph::Node. |
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138 | * |
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139 | */ |
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140 | class NodeIt { |
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141 | public: |
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142 | /// Default constructor |
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143 | NodeIt() {} |
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144 | /// Invalid constructor |
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145 | NodeIt(Invalid) {} |
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146 | /// Constructor with starting point |
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147 | NodeIt(const Path &) {} |
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148 | |
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149 | ///Conversion to Graph::Node |
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150 | operator const GraphNode& () const {} |
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151 | /// Next node |
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152 | NodeIt& operator++() {return *this;} |
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153 | |
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154 | /// Comparison operator |
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155 | bool operator==(const NodeIt&) const {return true;} |
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156 | /// Comparison operator |
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157 | bool operator!=(const NodeIt&) const {return true;} |
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158 | // /// Comparison operator |
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159 | // /// \todo It is not clear what is the "natural" ordering. |
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160 | // bool operator<(const NodeIt& e) const {} |
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161 | |
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162 | }; |
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163 | |
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164 | friend class Builder; |
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165 | |
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166 | /** |
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167 | * \brief Class to build paths |
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168 | * |
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169 | * This class is used to fill a path with edges. |
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170 | * |
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171 | * You can push new edges to the front and to the back of the path in |
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172 | * arbitrary order then you should commit these changes to the graph. |
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173 | * |
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174 | * While the builder is active (after the first modifying |
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175 | * operation and until the call of \ref commit()) the |
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176 | * underlining Path is in a "transitional" state (operations on |
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177 | * it have undefined result). |
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178 | */ |
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179 | class Builder { |
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180 | public: |
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181 | |
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182 | Path &P; |
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183 | |
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184 | ///\param _p the path you want to fill in. |
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185 | /// |
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186 | |
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187 | Builder(Path &_p) : P(_p) {} |
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188 | |
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189 | /// Sets the starting node of the path. |
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190 | |
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191 | /// Sets the starting node of the path. Edge added to the path |
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192 | /// afterwards have to be incident to this node. |
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193 | /// You \em must start building an empty path with these functions. |
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194 | /// (And you \em must \em not use it later). |
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195 | /// \sa pushFront() |
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196 | /// \sa pushBack() |
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197 | void setStartNode(const GraphNode &) {} |
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198 | |
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199 | ///Push a new edge to the front of the path |
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200 | |
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201 | ///Push a new edge to the front of the path. |
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202 | ///If the path is empty, you \em must call \ref setStartNode() before |
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203 | ///the first use of \ref pushFront(). |
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204 | void pushFront(const GraphEdge&) {} |
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205 | |
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206 | ///Push a new edge to the back of the path |
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207 | |
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208 | ///Push a new edge to the back of the path. |
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209 | ///If the path is empty, you \em must call \ref setStartNode() before |
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210 | ///the first use of \ref pushBack(). |
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211 | void pushBack(const GraphEdge&) {} |
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212 | |
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213 | ///Commit the changes to the path. |
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214 | void commit() {} |
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215 | |
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216 | ///Reserve (front) storage for the builder in advance. |
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217 | |
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218 | ///If you know a reasonable upper bound on the number of the edges |
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219 | ///to add to the front of the path, |
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220 | ///using this function you may speed up the building. |
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221 | void reserveFront(size_t) {} |
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222 | ///Reserve (back) storage for the builder in advance. |
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223 | |
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224 | ///If you know a reasonable upper bound on the number of the edges |
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225 | ///to add to the back of the path, |
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226 | ///using this function you may speed up the building. |
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227 | void reserveBack(size_t) {} |
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228 | }; |
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229 | }; |
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230 | |
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231 | ///@} |
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232 | } |
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233 | |
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234 | } // namespace lemon |
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235 | |
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236 | #endif // LEMON_CONCEPT_PATH_H |
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