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) 2003-2006 |
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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 | |
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20 | ///\ingroup paths |
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21 | ///\file |
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22 | ///\brief Classes for representing paths in graphs. |
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23 | /// |
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24 | |
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25 | #ifndef LEMON_PATH_H |
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26 | #define LEMON_PATH_H |
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27 | |
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28 | #include <vector> |
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29 | #include <algorithm> |
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30 | |
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31 | #include <lemon/error.h> |
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32 | #include <lemon/bits/invalid.h> |
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33 | |
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34 | namespace lemon { |
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35 | |
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36 | /// \addtogroup paths |
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37 | /// @{ |
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38 | |
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39 | |
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40 | //! \brief A structure for representing directed paths in a graph. |
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41 | //! |
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42 | //! A structure for representing directed path in a graph. |
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43 | //! \param Graph The graph type in which the path is. |
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44 | //! |
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45 | //! In a sense, the path can be treated as a graph, for is has \c NodeIt |
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46 | //! and \c EdgeIt with the same usage. These types converts to the \c Node |
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47 | //! and \c Edge of the original graph. |
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48 | //! |
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49 | //! \todo Thoroughfully check all the range and consistency tests. |
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50 | template<typename Graph> |
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51 | class Path { |
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52 | public: |
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53 | /// Edge type of the underlying graph. |
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54 | typedef typename Graph::Edge Edge; |
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55 | /// Node type of the underlying graph. |
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56 | typedef typename Graph::Node Node; |
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57 | |
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58 | class NodeIt; |
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59 | class EdgeIt; |
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60 | |
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61 | struct PathError : public LogicError { |
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62 | virtual const char* what() const throw() { |
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63 | return "lemon::PathError"; |
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64 | } |
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65 | }; |
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66 | |
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67 | public: |
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68 | |
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69 | /// \brief Constructor |
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70 | /// |
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71 | /// Constructor |
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72 | /// \param _G The graph in which the path is. |
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73 | Path(const Graph &_graph) : graph(&_graph), start(INVALID) {} |
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74 | |
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75 | /// \brief Subpath constructor. |
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76 | /// |
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77 | /// Subpath defined by two nodes. |
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78 | /// \warning It is an error if the two edges are not in order! |
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79 | Path(const Path &other, const NodeIt &a, const NodeIt &b) { |
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80 | graph = other.graph; |
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81 | start = a; |
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82 | edges.insert(edges.end(), |
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83 | other.edges.begin() + a.id, other.edges.begin() + b.id); |
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84 | } |
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85 | |
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86 | /// \brief Subpath constructor. |
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87 | /// |
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88 | /// Subpath defined by two edges. Contains edges in [a,b) |
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89 | /// \warning It is an error if the two edges are not in order! |
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90 | Path(const Path &other, const EdgeIt &a, const EdgeIt &b) { |
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91 | graph = other.graph; |
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92 | start = graph->source(a); |
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93 | edges.insert(edges.end(), |
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94 | other.edges.begin() + a.id, other.edges.begin() + b.id); |
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95 | } |
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96 | |
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97 | /// \brief Length of the path. |
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98 | /// |
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99 | /// The number of the edges in the path. It can be zero if the |
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100 | /// path has only one node or it is empty. |
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101 | int length() const { return edges.size(); } |
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102 | |
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103 | /// \brief Returns whether the path is empty. |
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104 | /// |
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105 | /// Returns true when the path does not contain neither edge nor |
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106 | /// node. |
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107 | bool empty() const { return start == INVALID; } |
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108 | |
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109 | /// \brief Resets the path to an empty path. |
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110 | /// |
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111 | /// Resets the path to an empty path. |
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112 | void clear() { edges.clear(); start = INVALID; } |
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113 | |
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114 | /// \brief Starting point of the path. |
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115 | /// |
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116 | /// Starting point of the path. |
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117 | /// Returns INVALID if the path is empty. |
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118 | Node source() const { |
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119 | return start; |
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120 | } |
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121 | /// \brief End point of the path. |
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122 | /// |
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123 | /// End point of the path. |
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124 | /// Returns INVALID if the path is empty. |
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125 | Node target() const { |
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126 | return length() == 0 ? start : graph->target(edges[length()-1]); |
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127 | } |
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128 | |
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129 | /// \brief Gives back a node iterator to point to the node of a |
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130 | /// given index. |
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131 | /// |
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132 | /// Gives back a node iterator to point to the node of a given |
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133 | /// index. |
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134 | /// \pre n should less or equal to \c length() |
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135 | NodeIt nthNode(int n) const { |
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136 | return NodeIt(*this, n); |
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137 | } |
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138 | |
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139 | /// \brief Gives back an edge iterator to point to the edge of a |
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140 | /// given index. |
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141 | /// |
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142 | /// Gives back an edge iterator to point to the node of a given |
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143 | /// index. |
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144 | /// \pre n should less than \c length() |
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145 | EdgeIt nthEdge(int n) const { |
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146 | return EdgeIt(*this, n); |
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147 | } |
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148 | |
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149 | /// \brief Returns node iterator pointing to the source node of the |
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150 | /// given edge iterator. |
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151 | /// |
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152 | /// Returns node iterator pointing to the source node of the given |
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153 | /// edge iterator. |
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154 | NodeIt source(const EdgeIt& e) const { |
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155 | return NodeIt(*this, e.id); |
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156 | } |
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157 | |
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158 | /// \brief Returns node iterator pointing to the target node of the |
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159 | /// given edge iterator. |
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160 | /// |
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161 | /// Returns node iterator pointing to the target node of the given |
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162 | /// edge iterator. |
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163 | NodeIt target(const EdgeIt& e) const { |
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164 | return NodeIt(*this, e.id + 1); |
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165 | } |
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166 | |
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167 | |
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168 | /// \brief Iterator class to iterate on the nodes of the paths |
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169 | /// |
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170 | /// This class is used to iterate on the nodes of the paths |
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171 | /// |
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172 | /// Of course it converts to Graph::Node |
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173 | class NodeIt { |
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174 | friend class Path; |
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175 | public: |
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176 | |
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177 | /// \brief Default constructor |
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178 | /// |
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179 | /// Default constructor |
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180 | NodeIt() {} |
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181 | |
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182 | /// \brief Invalid constructor |
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183 | /// |
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184 | /// Invalid constructor |
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185 | NodeIt(Invalid) : id(-1), path(0) {} |
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186 | |
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187 | /// \brief Constructor with starting point |
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188 | /// |
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189 | /// Constructor with starting point |
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190 | NodeIt(const Path &_path, int _id = 0) : id(_id), path(&_path) { |
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191 | if (id > path->length()) id = -1; |
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192 | } |
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193 | |
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194 | /// \brief Conversion to Graph::Node |
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195 | /// |
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196 | /// Conversion to Graph::Node |
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197 | operator Node() const { |
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198 | if (id > 0) { |
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199 | return path->graph->target(path->edges[id - 1]); |
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200 | } else if (id == 0) { |
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201 | return path->start; |
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202 | } else { |
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203 | return INVALID; |
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204 | } |
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205 | } |
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206 | |
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207 | /// \brief Steps to the next node |
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208 | /// |
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209 | /// Steps to the next node |
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210 | NodeIt& operator++() { |
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211 | ++id; |
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212 | if (id > path->length()) id = -1; |
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213 | return *this; |
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214 | } |
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215 | |
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216 | /// \brief Comparison operator |
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217 | /// |
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218 | /// Comparison operator |
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219 | bool operator==(const NodeIt& n) const { return id == n.id; } |
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220 | |
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221 | /// \brief Comparison operator |
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222 | /// |
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223 | /// Comparison operator |
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224 | bool operator!=(const NodeIt& n) const { return id != n.id; } |
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225 | |
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226 | /// \brief Comparison operator |
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227 | /// |
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228 | /// Comparison operator |
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229 | bool operator<(const NodeIt& n) const { return id < n.id; } |
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230 | |
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231 | private: |
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232 | int id; |
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233 | const Path *path; |
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234 | }; |
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235 | |
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236 | /// \brief Iterator class to iterate on the edges of the paths |
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237 | /// |
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238 | /// This class is used to iterate on the edges of the paths |
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239 | /// Of course it converts to Graph::Edge |
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240 | class EdgeIt { |
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241 | friend class Path; |
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242 | public: |
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243 | |
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244 | /// \brief Default constructor |
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245 | /// |
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246 | /// Default constructor |
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247 | EdgeIt() {} |
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248 | |
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249 | /// \brief Invalid constructor |
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250 | /// |
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251 | /// Invalid constructor |
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252 | EdgeIt(Invalid) : id(-1), path(0) {} |
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253 | |
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254 | /// \brief Constructor with starting point |
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255 | /// |
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256 | /// Constructor with starting point |
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257 | EdgeIt(const Path &_path, int _id = 0) : id(_id), path(&_path) { |
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258 | if (id >= path->length()) id = -1; |
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259 | } |
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260 | |
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261 | /// \brief Conversion to Graph::Edge |
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262 | /// |
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263 | /// Conversion to Graph::Edge |
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264 | operator Edge() const { |
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265 | return id != -1 ? path->edges[id] : INVALID; |
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266 | } |
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267 | |
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268 | /// \brief Steps to the next edge |
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269 | /// |
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270 | /// Steps to the next edge |
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271 | EdgeIt& operator++() { |
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272 | ++id; |
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273 | if (id >= path->length()) id = -1; |
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274 | return *this; |
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275 | } |
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276 | |
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277 | /// \brief Comparison operator |
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278 | /// |
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279 | /// Comparison operator |
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280 | bool operator==(const EdgeIt& e) const { return id == e.id; } |
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281 | |
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282 | /// \brief Comparison operator |
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283 | /// |
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284 | /// Comparison operator |
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285 | bool operator!=(const EdgeIt& e) const { return id != e.id; } |
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286 | |
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287 | /// \brief Comparison operator |
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288 | /// |
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289 | /// Comparison operator |
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290 | bool operator<(const EdgeIt& e) const { return id < e.id; } |
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291 | |
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292 | private: |
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293 | |
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294 | int id; |
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295 | const Path *path; |
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296 | }; |
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297 | |
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298 | protected: |
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299 | |
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300 | const Graph *graph; |
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301 | |
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302 | typedef std::vector<Edge> Container; |
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303 | Container edges; |
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304 | Node start; |
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305 | |
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306 | public: |
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307 | |
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308 | friend class Builder; |
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309 | |
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310 | /// \brief Class to build paths |
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311 | /// |
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312 | /// This class is used to fill a path with edges. |
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313 | /// |
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314 | /// You can push new edges to the front and to the back of the |
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315 | /// path in arbitrary order then you should commit these changes |
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316 | /// to the graph. |
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317 | /// |
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318 | /// Fundamentally, for most "Paths" (classes fulfilling the |
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319 | /// PathConcept) while the builder is active (after the first |
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320 | /// modifying operation and until the commit()) the original Path |
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321 | /// is in a "transitional" state (operations on it have undefined |
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322 | /// result). But in the case of Path the original path remains |
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323 | /// unchanged until the commit. However we don't recomend that you |
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324 | /// use this feature. |
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325 | class Builder { |
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326 | public: |
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327 | /// \brief Constructor |
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328 | /// |
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329 | /// Constructor |
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330 | /// \param _path the path you want to fill in. |
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331 | Builder(Path &_path) : path(_path), start(INVALID) {} |
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332 | |
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333 | /// \brief Destructor |
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334 | /// |
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335 | /// Destructor |
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336 | ~Builder() { |
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337 | LEMON_ASSERT(front.empty() && back.empty() && start == INVALID, |
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338 | PathError()); |
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339 | } |
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340 | |
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341 | /// \brief Sets the starting node of the path. |
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342 | /// |
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343 | /// Sets the starting node of the path. Edge added to the path |
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344 | /// afterwards have to be incident to this node. It should be |
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345 | /// called if and only if the path is empty and before any call |
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346 | /// to \ref pushFront() or \ref pushBack() |
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347 | void setStartNode(const Node &_start) { |
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348 | LEMON_ASSERT(path.empty() && start == INVALID, PathError()); |
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349 | start = _start; |
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350 | } |
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351 | |
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352 | /// \brief Push a new edge to the front of the path |
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353 | /// |
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354 | /// Push a new edge to the front of the path. |
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355 | /// \sa setStartNode |
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356 | void pushFront(const Edge& e) { |
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357 | LEMON_ASSERT(front.empty() || |
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358 | (path.graph->source(front.back()) == |
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359 | path.graph->target(e)), PathError()); |
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360 | LEMON_ASSERT(path.empty() || |
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361 | (path.source() == path.graph->target(e)), PathError()); |
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362 | LEMON_ASSERT(!path.empty() || !front.empty() || |
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363 | (start == path.graph->target(e)), PathError()); |
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364 | front.push_back(e); |
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365 | } |
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366 | |
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367 | /// \brief Push a new edge to the back of the path |
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368 | /// |
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369 | /// Push a new edge to the back of the path. |
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370 | /// \sa setStartNode |
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371 | void pushBack(const Edge& e) { |
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372 | LEMON_ASSERT(back.empty() || |
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373 | (path.graph->target(back.back()) == |
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374 | path.graph->source(e)), PathError()); |
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375 | LEMON_ASSERT(path.empty() || |
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376 | (path.target() == path.graph->source(e)), PathError()); |
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377 | LEMON_ASSERT(!path.empty() || !back.empty() || |
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378 | (start == path.graph->source(e)), PathError()); |
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379 | back.push_back(e); |
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380 | } |
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381 | |
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382 | /// \brief Commit the changes to the path. |
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383 | /// |
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384 | /// Commit the changes to the path. |
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385 | void commit() { |
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386 | if( !front.empty() || !back.empty() || start != INVALID) { |
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387 | Container tmp; |
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388 | tmp.reserve(front.size() + back.size() + path.length()); |
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389 | tmp.insert(tmp.end(), front.rbegin(), front.rend()); |
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390 | tmp.insert(tmp.end(), path.edges.begin(), path.edges.end()); |
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391 | tmp.insert(tmp.end(), back.begin(), back.end()); |
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392 | path.edges.swap(tmp); |
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393 | if (!front.empty()) { |
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394 | path.start = path.graph->source(front.back()); |
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395 | } else { |
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396 | path.start = start; |
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397 | } |
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398 | start = INVALID; |
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399 | front.clear(); |
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400 | back.clear(); |
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401 | } |
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402 | } |
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403 | |
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404 | /// \brief Reserve storage for the builder in advance. |
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405 | /// |
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406 | /// If you know a reasonable upper bound of the number of the |
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407 | /// edges to add to the front, using this function you can speed |
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408 | /// up the building. |
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409 | void reserveFront(size_t r) {front.reserve(r);} |
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410 | |
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411 | /// \brief Reserve storage for the builder in advance. |
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412 | /// |
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413 | /// If you know a reasonable upper bound of the number of the |
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414 | /// edges to add to the back, using this function you can speed |
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415 | /// up the building. |
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416 | void reserveBack(size_t r) {back.reserve(r);} |
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417 | |
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418 | private: |
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419 | |
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420 | Path &path; |
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421 | Container front, back; |
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422 | Node start; |
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423 | |
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424 | }; |
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425 | |
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426 | }; |
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427 | |
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428 | ///@} |
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429 | |
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430 | } // namespace lemon |
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431 | |
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432 | #endif // LEMON_PATH_H |
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