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) 2003-2008 |
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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 concept |
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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_CONCEPT_PATH_H |
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25 | #define LEMON_CONCEPT_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 | /// \tparam _Digraph The digraph type in which the path is. |
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42 | /// |
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43 | /// In a sense, the path can be treated as a list of arcs. The |
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44 | /// lemon path type stores just this list. As a consequence it |
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45 | /// cannot enumerate the nodes in the path and the zero length |
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46 | /// paths cannot store the source. |
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47 | /// |
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48 | template <typename _Digraph> |
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49 | class Path { |
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50 | public: |
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51 | |
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52 | /// Type of the underlying digraph. |
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53 | typedef _Digraph Digraph; |
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54 | /// Arc type of the underlying digraph. |
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55 | typedef typename Digraph::Arc Arc; |
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56 | |
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57 | class ArcIt; |
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58 | |
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59 | /// \brief Default constructor |
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60 | Path() {} |
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61 | |
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62 | /// \brief Template constructor |
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63 | template <typename CPath> |
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64 | Path(const CPath& cpath) {} |
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65 | |
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66 | /// \brief Template assigment |
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67 | template <typename CPath> |
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68 | Path& operator=(const CPath& cpath) { |
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69 | ignore_unused_variable_warning(cpath); |
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70 | return *this; |
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71 | } |
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72 | |
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73 | /// Length of the path ie. the number of arcs in the path. |
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74 | int length() const { return 0;} |
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75 | |
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76 | /// Returns whether the path is empty. |
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77 | bool empty() const { return true;} |
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78 | |
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79 | /// Resets the path to an empty path. |
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80 | void clear() {} |
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81 | |
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82 | /// \brief LEMON style iterator for path arcs |
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83 | /// |
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84 | /// This class is used to iterate on the arcs of the paths. |
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85 | class ArcIt { |
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86 | public: |
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87 | /// Default constructor |
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88 | ArcIt() {} |
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89 | /// Invalid constructor |
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90 | ArcIt(Invalid) {} |
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91 | /// Constructor for first arc |
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92 | ArcIt(const Path &) {} |
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93 | |
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94 | /// Conversion to Arc |
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95 | operator Arc() const { return INVALID; } |
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96 | |
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97 | /// Next arc |
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98 | ArcIt& operator++() {return *this;} |
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99 | |
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100 | /// Comparison operator |
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101 | bool operator==(const ArcIt&) const {return true;} |
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102 | /// Comparison operator |
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103 | bool operator!=(const ArcIt&) const {return true;} |
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104 | /// Comparison operator |
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105 | bool operator<(const ArcIt&) const {return false;} |
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106 | |
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107 | }; |
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108 | |
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109 | template <typename _Path> |
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110 | struct Constraints { |
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111 | void constraints() { |
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112 | Path<Digraph> pc; |
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113 | _Path p, pp(pc); |
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114 | int l = p.length(); |
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115 | int e = p.empty(); |
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116 | p.clear(); |
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117 | |
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118 | p = pc; |
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119 | |
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120 | typename _Path::ArcIt id, ii(INVALID), i(p); |
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121 | |
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122 | ++i; |
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123 | typename Digraph::Arc ed = i; |
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124 | |
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125 | e = (i == ii); |
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126 | e = (i != ii); |
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127 | e = (i < ii); |
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128 | |
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129 | ignore_unused_variable_warning(l); |
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130 | ignore_unused_variable_warning(pp); |
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131 | ignore_unused_variable_warning(e); |
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132 | ignore_unused_variable_warning(id); |
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133 | ignore_unused_variable_warning(ii); |
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134 | ignore_unused_variable_warning(ed); |
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135 | } |
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136 | }; |
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137 | |
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138 | }; |
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139 | |
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140 | namespace _path_bits { |
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141 | |
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142 | template <typename _Digraph, typename _Path, typename RevPathTag = void> |
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143 | struct PathDumperConstraints { |
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144 | void constraints() { |
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145 | int l = p.length(); |
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146 | int e = p.empty(); |
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147 | |
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148 | typename _Path::ArcIt id, i(p); |
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149 | |
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150 | ++i; |
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151 | typename _Digraph::Arc ed = i; |
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152 | |
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153 | e = (i == INVALID); |
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154 | e = (i != INVALID); |
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155 | |
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156 | ignore_unused_variable_warning(l); |
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157 | ignore_unused_variable_warning(e); |
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158 | ignore_unused_variable_warning(id); |
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159 | ignore_unused_variable_warning(ed); |
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160 | } |
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161 | _Path& p; |
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162 | }; |
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163 | |
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164 | template <typename _Digraph, typename _Path> |
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165 | struct PathDumperConstraints< |
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166 | _Digraph, _Path, |
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167 | typename enable_if<typename _Path::RevPathTag, void>::type |
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168 | > { |
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169 | void constraints() { |
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170 | int l = p.length(); |
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171 | int e = p.empty(); |
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172 | |
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173 | typename _Path::RevArcIt id, i(p); |
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174 | |
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175 | ++i; |
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176 | typename _Digraph::Arc ed = i; |
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177 | |
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178 | e = (i == INVALID); |
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179 | e = (i != INVALID); |
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180 | |
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181 | ignore_unused_variable_warning(l); |
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182 | ignore_unused_variable_warning(e); |
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183 | ignore_unused_variable_warning(id); |
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184 | ignore_unused_variable_warning(ed); |
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185 | } |
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186 | _Path& p; |
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187 | }; |
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188 | |
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189 | } |
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190 | |
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191 | |
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192 | /// \brief A skeleton structure for path dumpers. |
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193 | /// |
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194 | /// A skeleton structure for path dumpers. The path dumpers are |
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195 | /// the generalization of the paths. The path dumpers can |
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196 | /// enumerate the arcs of the path wheter in forward or in |
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197 | /// backward order. In most time these classes are not used |
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198 | /// directly rather it used to assign a dumped class to a real |
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199 | /// path type. |
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200 | /// |
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201 | /// The main purpose of this concept is that the shortest path |
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202 | /// algorithms can enumerate easily the arcs in reverse order. |
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203 | /// If we would like to give back a real path from these |
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204 | /// algorithms then we should create a temporarly path object. In |
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205 | /// LEMON such algorithms gives back a path dumper what can |
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206 | /// assigned to a real path and the dumpers can be implemented as |
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207 | /// an adaptor class to the predecessor map. |
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208 | |
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209 | /// \tparam _Digraph The digraph type in which the path is. |
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210 | /// |
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211 | /// The paths can be constructed from any path type by a |
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212 | /// template constructor or a template assignment operator. |
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213 | /// |
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214 | template <typename _Digraph> |
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215 | class PathDumper { |
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216 | public: |
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217 | |
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218 | /// Type of the underlying digraph. |
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219 | typedef _Digraph Digraph; |
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220 | /// Arc type of the underlying digraph. |
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221 | typedef typename Digraph::Arc Arc; |
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222 | |
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223 | /// Length of the path ie. the number of arcs in the path. |
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224 | int length() const { return 0;} |
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225 | |
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226 | /// Returns whether the path is empty. |
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227 | bool empty() const { return true;} |
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228 | |
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229 | /// \brief Forward or reverse dumping |
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230 | /// |
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231 | /// If the RevPathTag is defined and true then reverse dumping |
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232 | /// is provided in the path dumper. In this case instead of the |
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233 | /// ArcIt the RevArcIt iterator should be implemented in the |
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234 | /// dumper. |
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235 | typedef False RevPathTag; |
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236 | |
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237 | /// \brief LEMON style iterator for path arcs |
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238 | /// |
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239 | /// This class is used to iterate on the arcs of the paths. |
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240 | class ArcIt { |
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241 | public: |
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242 | /// Default constructor |
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243 | ArcIt() {} |
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244 | /// Invalid constructor |
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245 | ArcIt(Invalid) {} |
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246 | /// Constructor for first arc |
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247 | ArcIt(const PathDumper&) {} |
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248 | |
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249 | /// Conversion to Arc |
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250 | operator Arc() const { return INVALID; } |
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251 | |
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252 | /// Next arc |
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253 | ArcIt& operator++() {return *this;} |
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254 | |
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255 | /// Comparison operator |
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256 | bool operator==(const ArcIt&) const {return true;} |
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257 | /// Comparison operator |
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258 | bool operator!=(const ArcIt&) const {return true;} |
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259 | /// Comparison operator |
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260 | bool operator<(const ArcIt&) const {return false;} |
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261 | |
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262 | }; |
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263 | |
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264 | /// \brief LEMON style iterator for path arcs |
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265 | /// |
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266 | /// This class is used to iterate on the arcs of the paths in |
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267 | /// reverse direction. |
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268 | class RevArcIt { |
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269 | public: |
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270 | /// Default constructor |
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271 | RevArcIt() {} |
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272 | /// Invalid constructor |
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273 | RevArcIt(Invalid) {} |
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274 | /// Constructor for first arc |
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275 | RevArcIt(const PathDumper &) {} |
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276 | |
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277 | /// Conversion to Arc |
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278 | operator Arc() const { return INVALID; } |
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279 | |
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280 | /// Next arc |
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281 | RevArcIt& operator++() {return *this;} |
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282 | |
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283 | /// Comparison operator |
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284 | bool operator==(const RevArcIt&) const {return true;} |
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285 | /// Comparison operator |
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286 | bool operator!=(const RevArcIt&) const {return true;} |
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287 | /// Comparison operator |
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288 | bool operator<(const RevArcIt&) const {return false;} |
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289 | |
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290 | }; |
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291 | |
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292 | template <typename _Path> |
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293 | struct Constraints { |
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294 | void constraints() { |
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295 | function_requires<_path_bits:: |
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296 | PathDumperConstraints<Digraph, _Path> >(); |
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297 | } |
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298 | }; |
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299 | |
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300 | }; |
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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 | } // namespace lemon |
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307 | |
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308 | #endif // LEMON_CONCEPT_PATH_H |
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