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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 // 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 (c) 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 Jarvi (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_ENABLE_IF_H |
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36 #define LEMON_BITS_ENABLE_IF_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 namespace lemon |
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42 { |
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43 |
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44 /// Basic type for defining "tags". A "YES" condition for \c enable_if. |
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45 |
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46 /// Basic type for defining "tags". A "YES" condition for \c enable_if. |
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47 /// |
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48 ///\sa False |
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49 struct True { |
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50 ///\e |
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51 static const bool value = true; |
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52 }; |
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53 |
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54 /// Basic type for defining "tags". A "NO" condition for \c enable_if. |
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55 |
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56 /// Basic type for defining "tags". A "NO" condition for \c enable_if. |
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57 /// |
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58 ///\sa True |
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59 struct False { |
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60 ///\e |
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61 static const bool value = false; |
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62 }; |
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63 |
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64 |
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65 |
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66 template <typename T> |
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67 struct Wrap { |
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68 const T &value; |
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69 Wrap(const T &t) : value(t) {} |
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70 }; |
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71 |
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72 /**************** dummy class to avoid ambiguity ****************/ |
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73 |
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74 template<int T> struct dummy { dummy(int) {} }; |
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75 |
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76 /**************** enable_if from BOOST ****************/ |
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77 |
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78 template <typename Type, typename T = void> |
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79 struct exists { |
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80 typedef T type; |
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81 }; |
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82 |
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83 |
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84 template <bool B, class T = void> |
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85 struct enable_if_c { |
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86 typedef T type; |
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87 }; |
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88 |
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89 template <class T> |
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90 struct enable_if_c<false, T> {}; |
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91 |
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92 template <class Cond, class T = void> |
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93 struct enable_if : public enable_if_c<Cond::value, T> {}; |
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94 |
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95 template <bool B, class T> |
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96 struct lazy_enable_if_c { |
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97 typedef typename T::type type; |
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98 }; |
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99 |
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100 template <class T> |
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101 struct lazy_enable_if_c<false, T> {}; |
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102 |
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103 template <class Cond, class T> |
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104 struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {}; |
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105 |
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106 |
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107 template <bool B, class T = void> |
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108 struct disable_if_c { |
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109 typedef T type; |
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110 }; |
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111 |
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112 template <class T> |
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113 struct disable_if_c<true, T> {}; |
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114 |
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115 template <class Cond, class T = void> |
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116 struct disable_if : public disable_if_c<Cond::value, T> {}; |
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117 |
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118 template <bool B, class T> |
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119 struct lazy_disable_if_c { |
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120 typedef typename T::type type; |
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121 }; |
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122 |
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123 template <class T> |
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124 struct lazy_disable_if_c<true, T> {}; |
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125 |
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126 template <class Cond, class T> |
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127 struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {}; |
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128 |
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129 } // namespace lemon |
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130 |
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131 #endif |