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 | #ifndef LEMON_BITS_VARIANT_H |
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20 | #define LEMON_BITS_VARIANT_H |
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21 | |
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22 | #include <lemon/error.h> |
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23 | |
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24 | /// \file |
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25 | /// \brief Variant types |
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26 | |
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27 | namespace lemon { |
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28 | |
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29 | namespace _variant_bits { |
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30 | |
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31 | template <int left, int right> |
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32 | struct CTMax { |
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33 | static const int value = left < right ? right : left; |
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34 | }; |
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35 | |
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36 | } |
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37 | |
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38 | |
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39 | /// \brief Simple Variant type for two types |
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40 | /// |
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41 | /// Simple Variant type for two types. The Variant type is a type |
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42 | /// safe union. The C++ has strong limitations for using unions, by |
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43 | /// example we can not store type with non default constructor or |
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44 | /// destructor in an union. This class always knowns the current |
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45 | /// state of the variant and it cares for the proper construction |
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46 | /// and destruction. |
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47 | template <typename _First, typename _Second> |
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48 | class BiVariant { |
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49 | public: |
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50 | |
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51 | /// \brief The \c First type. |
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52 | typedef _First First; |
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53 | /// \brief The \c Second type. |
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54 | typedef _Second Second; |
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55 | |
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56 | struct WrongStateError : public lemon::LogicError { |
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57 | public: |
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58 | virtual const char* what() const throw() { |
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59 | return "lemon::BiVariant::WrongStateError"; |
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60 | } |
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61 | }; |
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62 | |
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63 | /// \brief Constructor |
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64 | /// |
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65 | /// This constructor initalizes to the default value of the \c First |
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66 | /// type. |
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67 | BiVariant() { |
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68 | flag = true; |
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69 | new(reinterpret_cast<First*>(data)) First(); |
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70 | } |
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71 | |
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72 | /// \brief Constructor |
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73 | /// |
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74 | /// This constructor initalizes to the given value of the \c First |
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75 | /// type. |
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76 | BiVariant(const First& first) { |
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77 | flag = true; |
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78 | new(reinterpret_cast<First*>(data)) First(first); |
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79 | } |
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80 | |
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81 | /// \brief Constructor |
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82 | /// |
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83 | /// This constructor initalizes to the given value of the \c |
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84 | /// Second type. |
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85 | BiVariant(const Second& second) { |
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86 | flag = false; |
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87 | new(reinterpret_cast<Second*>(data)) Second(second); |
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88 | } |
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89 | |
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90 | /// \brief Copy constructor |
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91 | /// |
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92 | /// Copy constructor |
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93 | BiVariant(const BiVariant& bivariant) { |
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94 | flag = bivariant.flag; |
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95 | if (flag) { |
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96 | new(reinterpret_cast<First*>(data)) First(bivariant.first()); |
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97 | } else { |
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98 | new(reinterpret_cast<Second*>(data)) Second(bivariant.second()); |
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99 | } |
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100 | } |
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101 | |
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102 | /// \brief Destrcutor |
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103 | /// |
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104 | /// Destructor |
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105 | ~BiVariant() { |
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106 | destroy(); |
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107 | } |
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108 | |
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109 | /// \brief Set to the default value of the \c First type. |
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110 | /// |
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111 | /// This function sets the variant to the default value of the \c |
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112 | /// First type. |
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113 | BiVariant& setFirst() { |
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114 | destroy(); |
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115 | flag = true; |
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116 | new(reinterpret_cast<First*>(data)) First(); |
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117 | return *this; |
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118 | } |
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119 | |
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120 | /// \brief Set to the given value of the \c First type. |
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121 | /// |
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122 | /// This function sets the variant to the given value of the \c |
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123 | /// First type. |
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124 | BiVariant& setFirst(const First& first) { |
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125 | destroy(); |
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126 | flag = true; |
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127 | new(reinterpret_cast<First*>(data)) First(first); |
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128 | return *this; |
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129 | } |
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130 | |
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131 | /// \brief Set to the default value of the \c Second type. |
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132 | /// |
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133 | /// This function sets the variant to the default value of the \c |
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134 | /// Second type. |
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135 | BiVariant& setSecond() { |
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136 | destroy(); |
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137 | flag = false; |
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138 | new(reinterpret_cast<Second*>(data)) Second(); |
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139 | return *this; |
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140 | } |
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141 | |
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142 | /// \brief Set to the given value of the \c Second type. |
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143 | /// |
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144 | /// This function sets the variant to the given value of the \c |
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145 | /// Second type. |
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146 | BiVariant& setSecond(const Second& second) { |
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147 | destroy(); |
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148 | flag = false; |
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149 | new(reinterpret_cast<Second*>(data)) Second(second); |
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150 | return *this; |
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151 | } |
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152 | |
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153 | /// \brief Operator form of the \c setFirst() |
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154 | BiVariant& operator=(const First& first) { |
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155 | return setFirst(first); |
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156 | } |
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157 | |
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158 | /// \brief Operator form of the \c setSecond() |
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159 | BiVariant& operator=(const Second& second) { |
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160 | return setSecond(second); |
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161 | } |
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162 | |
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163 | /// \brief Assign operator |
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164 | BiVariant& operator=(const BiVariant& bivariant) { |
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165 | if (this == &bivariant) return *this; |
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166 | destroy(); |
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167 | flag = bivariant.flag; |
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168 | if (flag) { |
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169 | new(reinterpret_cast<First*>(data)) First(bivariant.first()); |
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170 | } else { |
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171 | new(reinterpret_cast<Second*>(data)) Second(bivariant.second()); |
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172 | } |
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173 | return *this; |
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174 | } |
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175 | |
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176 | /// \brief Reference to the value |
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177 | /// |
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178 | /// Reference to the value of the \c First type. |
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179 | /// \pre The BiVariant should store value of \c First type. |
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180 | First& first() { |
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181 | LEMON_ASSERT(flag, WrongStateError()); |
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182 | return *reinterpret_cast<First*>(data); |
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183 | } |
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184 | |
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185 | /// \brief Const reference to the value |
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186 | /// |
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187 | /// Const reference to the value of the \c First type. |
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188 | /// \pre The BiVariant should store value of \c First type. |
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189 | const First& first() const { |
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190 | LEMON_ASSERT(flag, WrongStateError()); |
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191 | return *reinterpret_cast<const First*>(data); |
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192 | } |
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193 | |
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194 | /// \brief Operator form of the \c first() |
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195 | operator First&() { return first(); } |
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196 | /// \brief Operator form of the const \c first() |
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197 | operator const First&() const { return first(); } |
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198 | |
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199 | /// \brief Reference to the value |
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200 | /// |
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201 | /// Reference to the value of the \c Second type. |
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202 | /// \pre The BiVariant should store value of \c Second type. |
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203 | Second& second() { |
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204 | LEMON_ASSERT(!flag, WrongStateError()); |
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205 | return *reinterpret_cast<Second*>(data); |
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206 | } |
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207 | |
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208 | /// \brief Const reference to the value |
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209 | /// |
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210 | /// Const reference to the value of the \c Second type. |
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211 | /// \pre The BiVariant should store value of \c Second type. |
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212 | const Second& second() const { |
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213 | LEMON_ASSERT(!flag, WrongStateError()); |
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214 | return *reinterpret_cast<const Second*>(data); |
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215 | } |
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216 | |
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217 | /// \brief Operator form of the \c second() |
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218 | operator Second&() { return second(); } |
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219 | /// \brief Operator form of the const \c second() |
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220 | operator const Second&() const { return second(); } |
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221 | |
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222 | /// \brief %True when the variant is in the first state |
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223 | /// |
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224 | /// %True when the variant stores value of the \c First type. |
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225 | bool firstState() const { return flag; } |
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226 | |
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227 | /// \brief %True when the variant is in the second state |
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228 | /// |
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229 | /// %True when the variant stores value of the \c Second type. |
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230 | bool secondState() const { return !flag; } |
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231 | |
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232 | private: |
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233 | |
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234 | void destroy() { |
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235 | if (flag) { |
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236 | reinterpret_cast<First*>(data)->~First(); |
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237 | } else { |
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238 | reinterpret_cast<Second*>(data)->~Second(); |
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239 | } |
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240 | } |
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241 | |
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242 | char data[_variant_bits::CTMax<sizeof(First), sizeof(Second)>::value]; |
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243 | bool flag; |
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244 | }; |
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245 | |
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246 | namespace _variant_bits { |
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247 | |
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248 | template <int _idx, typename _TypeMap> |
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249 | struct Memory { |
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250 | |
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251 | typedef typename _TypeMap::template Map<_idx>::Type Current; |
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252 | |
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253 | static void destroy(int index, char* place) { |
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254 | if (index == _idx) { |
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255 | reinterpret_cast<Current*>(place)->~Current(); |
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256 | } else { |
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257 | Memory<_idx - 1, _TypeMap>::destroy(index, place); |
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258 | } |
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259 | } |
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260 | |
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261 | static void copy(int index, char* to, const char* from) { |
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262 | if (index == _idx) { |
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263 | new (reinterpret_cast<Current*>(to)) |
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264 | Current(reinterpret_cast<const Current*>(from)); |
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265 | } else { |
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266 | Memory<_idx - 1, _TypeMap>::copy(index, to, from); |
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267 | } |
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268 | } |
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269 | |
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270 | }; |
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271 | |
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272 | template <typename _TypeMap> |
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273 | struct Memory<-1, _TypeMap> { |
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274 | |
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275 | static void destroy(int, char*) { |
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276 | LEMON_ASSERT(false, "Wrong Variant Index."); |
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277 | } |
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278 | |
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279 | static void copy(int, char*, const char*) { |
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280 | LEMON_ASSERT(false, "Wrong Variant Index."); |
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281 | } |
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282 | }; |
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283 | |
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284 | template <int _idx, typename _TypeMap> |
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285 | struct Size { |
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286 | static const int value = |
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287 | CTMax<sizeof(typename _TypeMap::template Map<_idx>::Type), |
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288 | Size<_idx - 1, _TypeMap>::value>::value; |
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289 | }; |
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290 | |
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291 | template <typename _TypeMap> |
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292 | struct Size<0, _TypeMap> { |
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293 | static const int value = |
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294 | sizeof(typename _TypeMap::template Map<0>::Type); |
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295 | }; |
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296 | |
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297 | } |
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298 | |
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299 | /// \brief Variant type |
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300 | /// |
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301 | /// Simple Variant type. The Variant type is a type safe union. The |
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302 | /// C++ has strong limitations for using unions, by example we |
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303 | /// cannot store type with non default constructor or destructor in |
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304 | /// a union. This class always knowns the current state of the |
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305 | /// variant and it cares for the proper construction and |
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306 | /// destruction. |
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307 | /// |
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308 | /// \param _num The number of the types which can be stored in the |
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309 | /// variant type. |
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310 | /// \param _TypeMap This class describes the types of the Variant. The |
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311 | /// _TypeMap::Map<index>::Type should be a valid type for each index |
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312 | /// in the range {0, 1, ..., _num - 1}. The \c VariantTypeMap is helper |
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313 | /// class to define such type mappings up to 10 types. |
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314 | /// |
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315 | /// And the usage of the class: |
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316 | ///\code |
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317 | /// typedef Variant<3, VariantTypeMap<int, std::string, double> > MyVariant; |
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318 | /// MyVariant var; |
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319 | /// var.set<0>(12); |
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320 | /// std::cout << var.get<0>() << std::endl; |
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321 | /// var.set<1>("alpha"); |
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322 | /// std::cout << var.get<1>() << std::endl; |
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323 | /// var.set<2>(0.75); |
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324 | /// std::cout << var.get<2>() << std::endl; |
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325 | ///\endcode |
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326 | /// |
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327 | /// The result of course: |
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328 | ///\code |
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329 | /// 12 |
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330 | /// alpha |
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331 | /// 0.75 |
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332 | ///\endcode |
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333 | template <int _num, typename _TypeMap> |
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334 | class Variant { |
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335 | public: |
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336 | |
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337 | static const int num = _num; |
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338 | |
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339 | typedef _TypeMap TypeMap; |
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340 | |
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341 | struct WrongStateError : public lemon::LogicError { |
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342 | public: |
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343 | virtual const char* what() const throw() { |
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344 | return "lemon::Variant::WrongStateError"; |
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345 | } |
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346 | }; |
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347 | |
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348 | /// \brief Constructor |
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349 | /// |
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350 | /// This constructor initalizes to the default value of the \c type |
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351 | /// with 0 index. |
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352 | Variant() { |
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353 | flag = 0; |
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354 | new(reinterpret_cast<typename TypeMap::template Map<0>::Type*>(data)) |
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355 | typename TypeMap::template Map<0>::Type(); |
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356 | } |
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357 | |
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358 | |
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359 | /// \brief Copy constructor |
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360 | /// |
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361 | /// Copy constructor |
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362 | Variant(const Variant& variant) { |
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363 | flag = variant.flag; |
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364 | _variant_bits::Memory<num - 1, TypeMap>::copy(flag, data, variant.data); |
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365 | } |
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366 | |
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367 | /// \brief Assign operator |
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368 | /// |
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369 | /// Assign operator |
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370 | Variant& operator=(const Variant& variant) { |
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371 | if (this == &variant) return *this; |
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372 | _variant_bits::Memory<num - 1, TypeMap>:: |
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373 | destroy(flag, data); |
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374 | flag = variant.flag; |
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375 | _variant_bits::Memory<num - 1, TypeMap>:: |
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376 | copy(flag, data, variant.data); |
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377 | return *this; |
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378 | } |
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379 | |
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380 | /// \brief Destrcutor |
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381 | /// |
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382 | /// Destructor |
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383 | ~Variant() { |
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384 | _variant_bits::Memory<num - 1, TypeMap>::destroy(flag, data); |
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385 | } |
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386 | |
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387 | /// \brief Set to the default value of the type with \c _idx index. |
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388 | /// |
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389 | /// This function sets the variant to the default value of the |
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390 | /// type with \c _idx index. |
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391 | template <int _idx> |
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392 | Variant& set() { |
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393 | _variant_bits::Memory<num - 1, TypeMap>::destroy(flag, data); |
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394 | flag = _idx; |
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395 | new(reinterpret_cast<typename TypeMap::template Map<_idx>::Type*>(data)) |
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396 | typename TypeMap::template Map<_idx>::Type(); |
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397 | return *this; |
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398 | } |
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399 | |
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400 | /// \brief Set to the given value of the type with \c _idx index. |
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401 | /// |
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402 | /// This function sets the variant to the given value of the type |
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403 | /// with \c _idx index. |
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404 | template <int _idx> |
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405 | Variant& set(const typename _TypeMap::template Map<_idx>::Type& init) { |
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406 | _variant_bits::Memory<num - 1, TypeMap>::destroy(flag, data); |
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407 | flag = _idx; |
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408 | new(reinterpret_cast<typename TypeMap::template Map<_idx>::Type*>(data)) |
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409 | typename TypeMap::template Map<_idx>::Type(init); |
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410 | return *this; |
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411 | } |
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412 | |
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413 | /// \brief Gets the current value of the type with \c _idx index. |
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414 | /// |
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415 | /// Gets the current value of the type with \c _idx index. |
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416 | template <int _idx> |
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417 | const typename TypeMap::template Map<_idx>::Type& get() const { |
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418 | LEMON_ASSERT(_idx == flag, "Wrong Variant Index."); |
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419 | return *reinterpret_cast<const typename TypeMap:: |
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420 | template Map<_idx>::Type*>(data); |
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421 | } |
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422 | |
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423 | /// \brief Gets the current value of the type with \c _idx index. |
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424 | /// |
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425 | /// Gets the current value of the type with \c _idx index. |
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426 | template <int _idx> |
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427 | typename _TypeMap::template Map<_idx>::Type& get() { |
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428 | LEMON_ASSERT(_idx == flag, "Wrong Variant Index."); |
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429 | return *reinterpret_cast<typename TypeMap::template Map<_idx>::Type*> |
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430 | (data); |
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431 | } |
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432 | |
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433 | /// \brief Returns the current state of the variant. |
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434 | /// |
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435 | /// Returns the current state of the variant. |
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436 | int state() const { |
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437 | return flag; |
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438 | } |
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439 | |
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440 | private: |
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441 | |
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442 | char data[_variant_bits::Size<num - 1, TypeMap>::value]; |
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443 | int flag; |
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444 | }; |
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445 | |
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446 | namespace _variant_bits { |
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447 | |
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448 | template <int _index, typename _List> |
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449 | struct Get { |
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450 | typedef typename Get<_index - 1, typename _List::Next>::Type Type; |
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451 | }; |
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452 | |
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453 | template <typename _List> |
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454 | struct Get<0, _List> { |
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455 | typedef typename _List::Type Type; |
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456 | }; |
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457 | |
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458 | struct List {}; |
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459 | |
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460 | template <typename _Type, typename _List> |
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461 | struct Insert { |
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462 | typedef _List Next; |
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463 | typedef _Type Type; |
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464 | }; |
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465 | |
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466 | template <int _idx, typename _T0, typename _T1, typename _T2, |
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467 | typename _T3, typename _T5, typename _T4, typename _T6, |
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468 | typename _T7, typename _T8, typename _T9> |
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469 | struct Mapper { |
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470 | typedef List L10; |
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471 | typedef Insert<_T9, L10> L9; |
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472 | typedef Insert<_T8, L9> L8; |
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473 | typedef Insert<_T7, L8> L7; |
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474 | typedef Insert<_T6, L7> L6; |
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475 | typedef Insert<_T5, L6> L5; |
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476 | typedef Insert<_T4, L5> L4; |
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477 | typedef Insert<_T3, L4> L3; |
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478 | typedef Insert<_T2, L3> L2; |
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479 | typedef Insert<_T1, L2> L1; |
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480 | typedef Insert<_T0, L1> L0; |
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481 | typedef typename Get<_idx, L0>::Type Type; |
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482 | }; |
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483 | |
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484 | } |
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485 | |
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486 | /// \brief Helper class for Variant |
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487 | /// |
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488 | /// Helper class to define type mappings for Variant. This class |
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489 | /// converts the template parameters to be mappable by integer. |
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490 | /// \see Variant |
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491 | template < |
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492 | typename _T0, |
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493 | typename _T1 = void, typename _T2 = void, typename _T3 = void, |
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494 | typename _T5 = void, typename _T4 = void, typename _T6 = void, |
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495 | typename _T7 = void, typename _T8 = void, typename _T9 = void> |
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496 | struct VariantTypeMap { |
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497 | template <int _idx> |
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498 | struct Map { |
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499 | typedef typename _variant_bits:: |
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500 | Mapper<_idx, _T0, _T1, _T2, _T3, _T4, _T5, _T6, _T7, _T8, _T9>::Type |
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501 | Type; |
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502 | }; |
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503 | }; |
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504 | |
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505 | } |
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506 | |
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507 | |
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508 | #endif |
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