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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) 2003-2007 |
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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 // This file contains a modified version of the enable_if library from BOOST. |
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20 // See the appropriate copyright notice below. |
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21 |
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22 // Boost enable_if library |
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23 |
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24 // Copyright 2003 © The Trustees of Indiana University. |
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25 |
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26 // Use, modification, and distribution is subject to the Boost Software |
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27 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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28 // http://www.boost.org/LICENSE_1_0.txt) |
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29 |
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30 // Authors: Jaakko Järvi (jajarvi at osl.iu.edu) |
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31 // Jeremiah Willcock (jewillco at osl.iu.edu) |
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32 // Andrew Lumsdaine (lums at osl.iu.edu) |
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33 |
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34 |
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35 #ifndef LEMON_BITS_UTILITY_H |
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36 #define LEMON_BITS_UTILITY_H |
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37 |
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38 ///\file |
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39 ///\brief Miscellaneous basic utilities |
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40 /// |
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41 ///\todo Please rethink the organisation of the basic files like this. |
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42 ///E.g. this file might be merged with invalid.h. |
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43 |
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44 |
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45 namespace lemon |
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46 { |
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47 |
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48 /// Basic type for defining "tags". A "YES" condition for \c enable_if. |
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49 |
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50 /// Basic type for defining "tags". A "YES" condition for \c enable_if. |
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51 /// |
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52 ///\sa False |
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53 /// |
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54 /// \todo This should go to a separate "basic_types.h" (or something) |
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55 /// file. |
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56 struct True { |
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57 ///\e |
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58 static const bool value = true; |
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59 }; |
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60 |
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61 /// Basic type for defining "tags". A "NO" condition for \c enable_if. |
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62 |
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63 /// Basic type for defining "tags". A "NO" condition for \c enable_if. |
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64 /// |
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65 ///\sa True |
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66 struct False { |
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67 ///\e |
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68 static const bool value = false; |
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69 }; |
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70 |
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71 |
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72 struct InvalidType { |
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73 }; |
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74 |
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75 template <typename T> |
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76 struct Wrap { |
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77 const T &value; |
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78 Wrap(const T &t) : value(t) {} |
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79 }; |
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80 |
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81 /**************** dummy class to avoid ambiguity ****************/ |
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82 |
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83 template<int T> struct dummy { dummy(int) {} }; |
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84 |
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85 /**************** enable_if from BOOST ****************/ |
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86 |
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87 template <typename Type, typename T = void> |
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88 struct exists { |
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89 typedef T type; |
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90 }; |
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91 |
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92 |
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93 template <bool B, class T = void> |
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94 struct enable_if_c { |
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95 typedef T type; |
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96 }; |
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97 |
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98 template <class T> |
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99 struct enable_if_c<false, T> {}; |
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100 |
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101 template <class Cond, class T = void> |
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102 struct enable_if : public enable_if_c<Cond::value, T> {}; |
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103 |
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104 template <bool B, class T> |
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105 struct lazy_enable_if_c { |
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106 typedef typename T::type type; |
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107 }; |
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108 |
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109 template <class T> |
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110 struct lazy_enable_if_c<false, T> {}; |
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111 |
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112 template <class Cond, class T> |
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113 struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {}; |
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114 |
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115 |
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116 template <bool B, class T = void> |
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117 struct disable_if_c { |
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118 typedef T type; |
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119 }; |
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120 |
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121 template <class T> |
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122 struct disable_if_c<true, T> {}; |
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123 |
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124 template <class Cond, class T = void> |
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125 struct disable_if : public disable_if_c<Cond::value, T> {}; |
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126 |
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127 template <bool B, class T> |
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128 struct lazy_disable_if_c { |
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129 typedef typename T::type type; |
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130 }; |
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131 |
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132 template <class T> |
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133 struct lazy_disable_if_c<true, T> {}; |
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134 |
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135 template <class Cond, class T> |
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136 struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {}; |
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137 |
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138 } // namespace lemon |
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139 |
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140 #endif |