[977] | 1 | /* -*- C++ -*- |
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[1435] | 2 | * lemon/utility.h - Part of LEMON, a generic C++ optimization library |
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[977] | 3 | * |
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[1164] | 4 | * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi |
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[1359] | 5 | * Kutatocsoport (Egervary Research Group on Combinatorial Optimization, |
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[977] | 6 | * EGRES). |
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| 7 | * |
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| 8 | * Permission to use, modify and distribute this software is granted |
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| 9 | * provided that this copyright notice appears in all copies. For |
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| 10 | * precise terms see the accompanying LICENSE file. |
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| 11 | * |
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| 12 | * This software is provided "AS IS" with no warranty of any kind, |
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| 13 | * express or implied, and with no claim as to its suitability for any |
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| 14 | * purpose. |
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| 15 | * |
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| 16 | * This file contains a modified version of the enable_if library from BOOST. |
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| 17 | * See the appropriate copyright notice below. |
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| 18 | */ |
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| 19 | |
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| 20 | // Boost enable_if library |
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| 21 | |
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| 22 | // Copyright 2003 © The Trustees of Indiana University. |
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| 23 | |
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| 24 | // Use, modification, and distribution is subject to the Boost Software |
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| 25 | // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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| 26 | // http://www.boost.org/LICENSE_1_0.txt) |
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| 27 | |
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| 28 | // Authors: Jaakko Järvi (jajarvi at osl.iu.edu) |
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| 29 | // Jeremiah Willcock (jewillco at osl.iu.edu) |
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| 30 | // Andrew Lumsdaine (lums at osl.iu.edu) |
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| 31 | |
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| 32 | |
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| 33 | #ifndef LEMON_UTILITY_H |
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| 34 | #define LEMON_UTILITY_H |
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| 35 | |
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[1447] | 36 | ///\file |
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| 37 | ///\brief Miscellaneous basic utilities |
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| 38 | /// |
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| 39 | ///\todo Please rethink the organisation of the basic files like this. |
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| 40 | ///E.g. this file might be merged with invalid.h. |
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| 41 | |
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| 42 | |
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[977] | 43 | namespace lemon |
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| 44 | { |
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| 45 | |
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[1630] | 46 | /// Basic type for defining "tags". A "YES" condition for \c enable_if. |
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[977] | 47 | |
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[1630] | 48 | /// Basic type for defining "tags". A "YES" condition for \c enable_if. |
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| 49 | /// |
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| 50 | ///\sa False |
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| 51 | /// |
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[977] | 52 | /// \todo This should go to a separate "basic_types.h" (or something) |
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| 53 | /// file. |
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| 54 | struct True { |
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[1630] | 55 | ///\e |
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[977] | 56 | static const bool value = true; |
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| 57 | }; |
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| 58 | |
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[1630] | 59 | /// Basic type for defining "tags". A "NO" condition for \c enable_if. |
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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 | ///\sa True |
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[977] | 64 | struct False { |
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[1630] | 65 | ///\e |
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[977] | 66 | static const bool value = false; |
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| 67 | }; |
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| 68 | |
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| 69 | template <typename T> |
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| 70 | struct Wrap { |
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| 71 | const T &value; |
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| 72 | Wrap(const T &t) : value(t) {} |
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| 73 | }; |
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| 74 | |
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[1256] | 75 | /**************** dummy class to avoid ambiguity ****************/ |
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[977] | 76 | |
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[1256] | 77 | template<int T> struct dummy { dummy(int) {} }; |
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[977] | 78 | |
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| 79 | /**************** enable_if from BOOST ****************/ |
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| 80 | |
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| 81 | template <bool B, class T = void> |
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| 82 | struct enable_if_c { |
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| 83 | typedef T type; |
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| 84 | }; |
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| 85 | |
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| 86 | template <class T> |
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| 87 | struct enable_if_c<false, T> {}; |
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| 88 | |
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| 89 | template <class Cond, class T = void> |
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| 90 | struct enable_if : public enable_if_c<Cond::value, T> {}; |
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| 91 | |
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| 92 | template <bool B, class T> |
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| 93 | struct lazy_enable_if_c { |
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| 94 | typedef typename T::type type; |
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| 95 | }; |
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| 96 | |
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| 97 | template <class T> |
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| 98 | struct lazy_enable_if_c<false, T> {}; |
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| 99 | |
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| 100 | template <class Cond, class T> |
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| 101 | struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {}; |
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| 102 | |
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| 103 | |
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| 104 | template <bool B, class T = void> |
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| 105 | struct disable_if_c { |
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| 106 | typedef T 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 disable_if_c<true, T> {}; |
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| 111 | |
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| 112 | template <class Cond, class T = void> |
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| 113 | struct disable_if : public disable_if_c<Cond::value, T> {}; |
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| 114 | |
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| 115 | template <bool B, class T> |
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| 116 | struct lazy_disable_if_c { |
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| 117 | typedef typename T::type type; |
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| 118 | }; |
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| 119 | |
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| 120 | template <class T> |
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| 121 | struct lazy_disable_if_c<true, T> {}; |
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| 122 | |
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| 123 | template <class Cond, class T> |
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| 124 | struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {}; |
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| 125 | |
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[1418] | 126 | // smart referencing |
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| 127 | |
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| 128 | template <typename _Type, typename Enable = void> |
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| 129 | struct SmartReference { |
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| 130 | typedef _Type& Type; |
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| 131 | }; |
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| 132 | |
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| 133 | template <typename _Type> |
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| 134 | struct SmartReference< |
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| 135 | _Type, |
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| 136 | typename enable_if<typename _Type::NeedCopy, void>::type |
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| 137 | > { |
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| 138 | typedef _Type Type; |
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| 139 | }; |
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| 140 | |
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| 141 | template <typename _Type, typename Enable = void> |
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| 142 | struct SmartConstReference { |
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| 143 | typedef const _Type& Type; |
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| 144 | }; |
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| 145 | |
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| 146 | template <typename _Type> |
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| 147 | struct SmartConstReference< |
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| 148 | _Type, |
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| 149 | typename enable_if<typename _Type::NeedCopy, void>::type |
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| 150 | > { |
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| 151 | typedef const _Type Type; |
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| 152 | }; |
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| 153 | |
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| 154 | template <typename _Type, typename Enable = void> |
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| 155 | struct SmartParameter { |
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| 156 | typedef _Type& Type; |
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| 157 | }; |
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| 158 | |
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| 159 | template <typename _Type> |
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| 160 | struct SmartParameter< |
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| 161 | _Type, |
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| 162 | typename enable_if<typename _Type::NeedCopy, void>::type |
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| 163 | > { |
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| 164 | typedef const _Type& Type; |
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| 165 | }; |
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| 166 | |
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[977] | 167 | } // namespace lemon |
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| 168 | |
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| 169 | #endif |
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