1 | /* -*- mode: C++; indent-tabs-mode: nil; -*- |
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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) 2003-2009 |
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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 concept |
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20 | ///\file |
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21 | ///\brief The concept of paths |
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22 | /// |
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23 | |
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24 | #ifndef LEMON_CONCEPTS_PATH_H |
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25 | #define LEMON_CONCEPTS_PATH_H |
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26 | |
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27 | #include <lemon/core.h> |
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28 | #include <lemon/concept_check.h> |
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29 | |
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30 | namespace lemon { |
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31 | namespace concepts { |
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32 | |
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33 | /// \addtogroup concept |
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34 | /// @{ |
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35 | |
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36 | /// \brief A skeleton structure for representing directed paths in |
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37 | /// a digraph. |
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38 | /// |
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39 | /// A skeleton structure for representing directed paths in a |
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40 | /// digraph. |
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41 | /// In a sense, a path can be treated as a list of arcs. |
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42 | /// LEMON path types just store this list. As a consequence, they cannot |
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43 | /// enumerate the nodes on the path directly and a zero length path |
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44 | /// cannot store its source node. |
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45 | /// |
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46 | /// The arcs of a path should be stored in the order of their directions, |
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47 | /// i.e. the target node of each arc should be the same as the source |
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48 | /// node of the next arc. This consistency could be checked using |
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49 | /// \ref checkPath(). |
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50 | /// The source and target nodes of a (consistent) path can be obtained |
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51 | /// using \ref pathSource() and \ref pathTarget(). |
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52 | /// |
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53 | /// A path can be constructed from another path of any type using the |
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54 | /// copy constructor or the assignment operator. |
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55 | /// |
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56 | /// \tparam GR The digraph type in which the path is. |
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57 | template <typename GR> |
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58 | class Path { |
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59 | public: |
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60 | |
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61 | /// Type of the underlying digraph. |
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62 | typedef GR Digraph; |
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63 | /// Arc type of the underlying digraph. |
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64 | typedef typename Digraph::Arc Arc; |
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65 | |
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66 | class ArcIt; |
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67 | |
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68 | /// \brief Default constructor |
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69 | Path() {} |
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70 | |
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71 | /// \brief Template copy constructor |
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72 | template <typename CPath> |
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73 | Path(const CPath& cpath) {} |
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74 | |
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75 | /// \brief Template assigment operator |
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76 | template <typename CPath> |
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77 | Path& operator=(const CPath& cpath) { |
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78 | ignore_unused_variable_warning(cpath); |
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79 | return *this; |
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80 | } |
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81 | |
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82 | /// Length of the path, i.e. the number of arcs on the path. |
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83 | int length() const { return 0;} |
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84 | |
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85 | /// Returns whether the path is empty. |
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86 | bool empty() const { return true;} |
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87 | |
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88 | /// Resets the path to an empty path. |
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89 | void clear() {} |
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90 | |
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91 | /// \brief LEMON style iterator for enumerating the arcs of a path. |
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92 | /// |
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93 | /// LEMON style iterator class for enumerating the arcs of a path. |
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94 | class ArcIt { |
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95 | public: |
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96 | /// Default constructor |
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97 | ArcIt() {} |
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98 | /// Invalid constructor |
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99 | ArcIt(Invalid) {} |
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100 | /// Sets the iterator to the first arc of the given path |
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101 | ArcIt(const Path &) {} |
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102 | |
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103 | /// Conversion to \c Arc |
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104 | operator Arc() const { return INVALID; } |
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105 | |
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106 | /// Next arc |
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107 | ArcIt& operator++() {return *this;} |
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108 | |
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109 | /// Comparison operator |
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110 | bool operator==(const ArcIt&) const {return true;} |
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111 | /// Comparison operator |
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112 | bool operator!=(const ArcIt&) const {return true;} |
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113 | /// Comparison operator |
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114 | bool operator<(const ArcIt&) const {return false;} |
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115 | |
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116 | }; |
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117 | |
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118 | template <typename _Path> |
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119 | struct Constraints { |
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120 | void constraints() { |
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121 | Path<Digraph> pc; |
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122 | _Path p, pp(pc); |
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123 | int l = p.length(); |
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124 | int e = p.empty(); |
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125 | p.clear(); |
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126 | |
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127 | p = pc; |
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128 | |
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129 | typename _Path::ArcIt id, ii(INVALID), i(p); |
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130 | |
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131 | ++i; |
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132 | typename Digraph::Arc ed = i; |
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133 | |
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134 | e = (i == ii); |
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135 | e = (i != ii); |
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136 | e = (i < ii); |
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137 | |
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138 | ignore_unused_variable_warning(l); |
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139 | ignore_unused_variable_warning(pp); |
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140 | ignore_unused_variable_warning(e); |
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141 | ignore_unused_variable_warning(id); |
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142 | ignore_unused_variable_warning(ii); |
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143 | ignore_unused_variable_warning(ed); |
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144 | } |
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145 | }; |
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146 | |
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147 | }; |
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148 | |
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149 | namespace _path_bits { |
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150 | |
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151 | template <typename _Digraph, typename _Path, typename RevPathTag = void> |
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152 | struct PathDumperConstraints { |
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153 | void constraints() { |
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154 | int l = p.length(); |
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155 | int e = p.empty(); |
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156 | |
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157 | typename _Path::ArcIt id, i(p); |
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158 | |
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159 | ++i; |
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160 | typename _Digraph::Arc ed = i; |
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161 | |
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162 | e = (i == INVALID); |
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163 | e = (i != INVALID); |
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164 | |
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165 | ignore_unused_variable_warning(l); |
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166 | ignore_unused_variable_warning(e); |
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167 | ignore_unused_variable_warning(id); |
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168 | ignore_unused_variable_warning(ed); |
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169 | } |
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170 | _Path& p; |
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171 | PathDumperConstraints() {} |
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172 | }; |
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173 | |
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174 | template <typename _Digraph, typename _Path> |
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175 | struct PathDumperConstraints< |
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176 | _Digraph, _Path, |
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177 | typename enable_if<typename _Path::RevPathTag, void>::type |
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178 | > { |
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179 | void constraints() { |
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180 | int l = p.length(); |
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181 | int e = p.empty(); |
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182 | |
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183 | typename _Path::RevArcIt id, i(p); |
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184 | |
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185 | ++i; |
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186 | typename _Digraph::Arc ed = i; |
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187 | |
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188 | e = (i == INVALID); |
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189 | e = (i != INVALID); |
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190 | |
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191 | ignore_unused_variable_warning(l); |
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192 | ignore_unused_variable_warning(e); |
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193 | ignore_unused_variable_warning(id); |
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194 | ignore_unused_variable_warning(ed); |
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195 | } |
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196 | _Path& p; |
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197 | PathDumperConstraints() {} |
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198 | }; |
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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 | /// \brief A skeleton structure for path dumpers. |
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204 | /// |
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205 | /// A skeleton structure for path dumpers. The path dumpers are |
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206 | /// the generalization of the paths, they can enumerate the arcs |
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207 | /// of the path either in forward or in backward order. |
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208 | /// These classes are typically not used directly, they are rather |
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209 | /// used to be assigned to a real path type. |
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210 | /// |
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211 | /// The main purpose of this concept is that the shortest path |
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212 | /// algorithms can enumerate the arcs easily in reverse order. |
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213 | /// In LEMON, such algorithms give back a (reverse) path dumper that |
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214 | /// can be assigned to a real path. The dumpers can be implemented as |
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215 | /// an adaptor class to the predecessor map. |
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216 | /// |
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217 | /// \tparam GR The digraph type in which the path is. |
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218 | template <typename GR> |
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219 | class PathDumper { |
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220 | public: |
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221 | |
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222 | /// Type of the underlying digraph. |
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223 | typedef GR Digraph; |
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224 | /// Arc type of the underlying digraph. |
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225 | typedef typename Digraph::Arc Arc; |
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226 | |
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227 | /// Length of the path, i.e. the number of arcs on the path. |
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228 | int length() const { return 0;} |
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229 | |
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230 | /// Returns whether the path is empty. |
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231 | bool empty() const { return true;} |
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232 | |
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233 | /// \brief Forward or reverse dumping |
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234 | /// |
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235 | /// If this tag is defined to be \c True, then reverse dumping |
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236 | /// is provided in the path dumper. In this case, \c RevArcIt |
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237 | /// iterator should be implemented instead of \c ArcIt iterator. |
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238 | typedef False RevPathTag; |
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239 | |
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240 | /// \brief LEMON style iterator for enumerating the arcs of a path. |
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241 | /// |
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242 | /// LEMON style iterator class for enumerating the arcs of a path. |
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243 | class ArcIt { |
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244 | public: |
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245 | /// Default constructor |
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246 | ArcIt() {} |
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247 | /// Invalid constructor |
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248 | ArcIt(Invalid) {} |
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249 | /// Sets the iterator to the first arc of the given path |
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250 | ArcIt(const PathDumper&) {} |
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251 | |
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252 | /// Conversion to \c Arc |
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253 | operator Arc() const { return INVALID; } |
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254 | |
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255 | /// Next arc |
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256 | ArcIt& operator++() {return *this;} |
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257 | |
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258 | /// Comparison operator |
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259 | bool operator==(const ArcIt&) const {return true;} |
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260 | /// Comparison operator |
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261 | bool operator!=(const ArcIt&) const {return true;} |
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262 | /// Comparison operator |
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263 | bool operator<(const ArcIt&) const {return false;} |
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264 | |
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265 | }; |
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266 | |
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267 | /// \brief LEMON style iterator for enumerating the arcs of a path |
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268 | /// in reverse direction. |
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269 | /// |
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270 | /// LEMON style iterator class for enumerating the arcs of a path |
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271 | /// in reverse direction. |
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272 | class RevArcIt { |
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273 | public: |
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274 | /// Default constructor |
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275 | RevArcIt() {} |
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276 | /// Invalid constructor |
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277 | RevArcIt(Invalid) {} |
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278 | /// Sets the iterator to the last arc of the given path |
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279 | RevArcIt(const PathDumper &) {} |
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280 | |
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281 | /// Conversion to \c Arc |
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282 | operator Arc() const { return INVALID; } |
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283 | |
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284 | /// Next arc |
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285 | RevArcIt& operator++() {return *this;} |
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286 | |
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287 | /// Comparison operator |
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288 | bool operator==(const RevArcIt&) const {return true;} |
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289 | /// Comparison operator |
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290 | bool operator!=(const RevArcIt&) const {return true;} |
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291 | /// Comparison operator |
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292 | bool operator<(const RevArcIt&) const {return false;} |
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293 | |
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294 | }; |
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295 | |
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296 | template <typename _Path> |
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297 | struct Constraints { |
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298 | void constraints() { |
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299 | function_requires<_path_bits:: |
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300 | PathDumperConstraints<Digraph, _Path> >(); |
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301 | } |
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302 | }; |
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303 | |
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304 | }; |
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305 | |
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306 | |
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307 | ///@} |
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308 | } |
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309 | |
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310 | } // namespace lemon |
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311 | |
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312 | #endif |
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