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 | ///\ingroup paths |
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20 | ///\file |
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21 | ///\brief Classes for representing paths in digraphs. |
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22 | /// |
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23 | |
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24 | #ifndef LEMON_PATH_UTILS_H |
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25 | #define LEMON_PATH_UTILS_H |
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26 | |
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27 | #include <lemon/concepts/path.h> |
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28 | |
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29 | namespace lemon { |
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30 | |
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31 | namespace _path_bits { |
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32 | |
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33 | template <typename Path, typename Enable = void> |
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34 | struct RevTagIndicator { |
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35 | static const bool value = false; |
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36 | }; |
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37 | |
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38 | template <typename Digraph> |
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39 | struct RevTagIndicator< |
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40 | Digraph, |
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41 | typename enable_if<typename Digraph::RevTag, void>::type |
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42 | > { |
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43 | static const bool value = true; |
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44 | }; |
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45 | |
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46 | template <typename Target, typename Source, |
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47 | typename BuildEnable = void, typename RevEnable = void> |
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48 | struct PathCopySelector { |
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49 | static void copy(Target& target, const Source& source) { |
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50 | target.clear(); |
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51 | for (typename Source::ArcIt it(source); it != INVALID; ++it) { |
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52 | target.addBack(it); |
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53 | } |
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54 | } |
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55 | }; |
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56 | |
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57 | template <typename Target, typename Source, typename BuildEnable> |
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58 | struct PathCopySelector< |
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59 | Target, Source, BuildEnable, |
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60 | typename enable_if<typename Source::RevPathTag, void>::type> { |
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61 | static void copy(Target& target, const Source& source) { |
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62 | target.clear(); |
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63 | for (typename Source::RevArcIt it(source); it != INVALID; ++it) { |
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64 | target.addFront(it); |
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65 | } |
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66 | } |
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67 | }; |
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68 | |
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69 | template <typename Target, typename Source, typename RevEnable> |
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70 | struct PathCopySelector< |
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71 | Target, Source, |
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72 | typename enable_if<typename Target::BuildTag, void>::type, RevEnable> { |
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73 | static void copy(Target& target, const Source& source) { |
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74 | target.clear(); |
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75 | target.build(source); |
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76 | } |
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77 | }; |
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78 | |
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79 | template <typename Target, typename Source> |
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80 | struct PathCopySelector< |
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81 | Target, Source, |
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82 | typename enable_if<typename Target::BuildTag, void>::type, |
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83 | typename enable_if<typename Source::RevPathTag, void>::type> { |
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84 | static void copy(Target& target, const Source& source) { |
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85 | target.clear(); |
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86 | target.buildRev(source); |
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87 | } |
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88 | }; |
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89 | |
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90 | } |
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91 | |
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92 | |
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93 | /// \brief Make a copy of a path. |
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94 | /// |
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95 | /// This function makes a copy of a path. |
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96 | template <typename Target, typename Source> |
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97 | void copyPath(Target& target, const Source& source) { |
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98 | checkConcept<concepts::PathDumper<typename Source::Digraph>, Source>(); |
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99 | _path_bits::PathCopySelector<Target, Source>::copy(target, source); |
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100 | } |
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101 | |
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102 | /// \brief Check the consistency of a path. |
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103 | /// |
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104 | /// This function checks that the target of each arc is the same |
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105 | /// as the source of the next one. |
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106 | /// |
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107 | template <typename Digraph, typename Path> |
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108 | bool checkPath(const Digraph& digraph, const Path& path) { |
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109 | typename Path::ArcIt it(path); |
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110 | if (it == INVALID) return true; |
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111 | typename Digraph::Node node = digraph.target(it); |
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112 | ++it; |
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113 | while (it != INVALID) { |
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114 | if (digraph.source(it) != node) return false; |
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115 | node = digraph.target(it); |
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116 | ++it; |
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117 | } |
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118 | return true; |
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119 | } |
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120 | |
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121 | /// \brief The source of a path |
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122 | /// |
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123 | /// This function returns the source of the given path. |
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124 | template <typename Digraph, typename Path> |
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125 | typename Digraph::Node pathSource(const Digraph& digraph, const Path& path) { |
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126 | return digraph.source(path.front()); |
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127 | } |
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128 | |
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129 | /// \brief The target of a path |
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130 | /// |
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131 | /// This function returns the target of the given path. |
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132 | template <typename Digraph, typename Path> |
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133 | typename Digraph::Node pathTarget(const Digraph& digraph, const Path& path) { |
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134 | return digraph.target(path.back()); |
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135 | } |
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136 | |
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137 | /// \brief Class which helps to iterate through the nodes of a path |
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138 | /// |
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139 | /// In a sense, the path can be treated as a list of arcs. The |
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140 | /// lemon path type stores only this list. As a consequence, it |
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141 | /// cannot enumerate the nodes in the path and the zero length paths |
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142 | /// cannot have a source node. |
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143 | /// |
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144 | /// This class implements the node iterator of a path structure. To |
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145 | /// provide this feature, the underlying digraph should be passed to |
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146 | /// the constructor of the iterator. |
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147 | template <typename Path> |
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148 | class PathNodeIt { |
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149 | private: |
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150 | const typename Path::Digraph *_digraph; |
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151 | typename Path::ArcIt _it; |
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152 | typename Path::Digraph::Node _nd; |
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153 | |
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154 | public: |
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155 | |
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156 | typedef typename Path::Digraph Digraph; |
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157 | typedef typename Digraph::Node Node; |
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158 | |
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159 | /// Default constructor |
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160 | PathNodeIt() {} |
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161 | /// Invalid constructor |
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162 | PathNodeIt(Invalid) |
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163 | : _digraph(0), _it(INVALID), _nd(INVALID) {} |
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164 | /// Constructor |
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165 | PathNodeIt(const Digraph& digraph, const Path& path) |
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166 | : _digraph(&digraph), _it(path) { |
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167 | _nd = (_it != INVALID ? _digraph->source(_it) : INVALID); |
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168 | } |
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169 | /// Constructor |
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170 | PathNodeIt(const Digraph& digraph, const Path& path, const Node& src) |
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171 | : _digraph(&digraph), _it(path), _nd(src) {} |
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172 | |
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173 | ///Conversion to Digraph::Node |
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174 | operator Node() const { |
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175 | return _nd; |
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176 | } |
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177 | |
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178 | /// Next node |
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179 | PathNodeIt& operator++() { |
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180 | if (_it == INVALID) _nd = INVALID; |
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181 | else { |
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182 | _nd = _digraph->target(_it); |
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183 | ++_it; |
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184 | } |
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185 | return *this; |
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186 | } |
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187 | |
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188 | /// Comparison operator |
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189 | bool operator==(const PathNodeIt& n) const { |
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190 | return _it == n._it && _nd == n._nd; |
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191 | } |
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192 | /// Comparison operator |
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193 | bool operator!=(const PathNodeIt& n) const { |
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194 | return _it != n._it || _nd != n._nd; |
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195 | } |
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196 | /// Comparison operator |
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197 | bool operator<(const PathNodeIt& n) const { |
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198 | return (_it < n._it && _nd != INVALID); |
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199 | } |
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200 | |
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201 | }; |
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202 | |
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203 | } |
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204 | |
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205 | #endif |
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