[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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| 36 | namespace lemon |
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| 37 | { |
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| 38 | |
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[1270] | 39 | /// Basic type for defining "tags". A "YES" condition for enable_if. |
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[977] | 40 | |
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| 41 | /// \todo This should go to a separate "basic_types.h" (or something) |
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| 42 | /// file. |
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| 43 | struct True { |
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| 44 | static const bool value = true; |
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| 45 | }; |
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| 46 | |
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[1270] | 47 | /// Basic type for defining "tags". A "NO" condition for enable_if. |
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[977] | 48 | struct False { |
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| 49 | static const bool value = false; |
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| 50 | }; |
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| 51 | |
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| 52 | template <typename T> |
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| 53 | struct Wrap { |
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| 54 | const T &value; |
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| 55 | Wrap(const T &t) : value(t) {} |
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| 56 | }; |
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| 57 | |
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[1256] | 58 | /**************** dummy class to avoid ambiguity ****************/ |
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[977] | 59 | |
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[1256] | 60 | template<int T> struct dummy { dummy(int) {} }; |
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[977] | 61 | |
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| 62 | /**************** enable_if from BOOST ****************/ |
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| 63 | |
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| 64 | template <bool B, class T = void> |
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| 65 | struct enable_if_c { |
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| 66 | typedef T type; |
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| 67 | }; |
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| 68 | |
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| 69 | template <class T> |
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| 70 | struct enable_if_c<false, T> {}; |
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| 71 | |
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| 72 | template <class Cond, class T = void> |
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| 73 | struct enable_if : public enable_if_c<Cond::value, T> {}; |
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| 74 | |
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| 75 | template <bool B, class T> |
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| 76 | struct lazy_enable_if_c { |
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| 77 | typedef typename T::type type; |
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| 78 | }; |
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| 79 | |
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| 80 | template <class T> |
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| 81 | struct lazy_enable_if_c<false, T> {}; |
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| 82 | |
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| 83 | template <class Cond, class T> |
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| 84 | struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {}; |
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| 85 | |
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| 86 | |
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| 87 | template <bool B, class T = void> |
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| 88 | struct disable_if_c { |
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| 89 | typedef T type; |
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| 90 | }; |
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| 91 | |
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| 92 | template <class T> |
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| 93 | struct disable_if_c<true, T> {}; |
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| 94 | |
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| 95 | template <class Cond, class T = void> |
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| 96 | struct disable_if : public disable_if_c<Cond::value, T> {}; |
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| 97 | |
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| 98 | template <bool B, class T> |
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| 99 | struct lazy_disable_if_c { |
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| 100 | typedef typename T::type type; |
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| 101 | }; |
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| 102 | |
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| 103 | template <class T> |
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| 104 | struct lazy_disable_if_c<true, T> {}; |
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| 105 | |
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| 106 | template <class Cond, class T> |
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| 107 | struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {}; |
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| 108 | |
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[1418] | 109 | // smart referencing |
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| 110 | |
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| 111 | template <typename _Type, typename Enable = void> |
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| 112 | struct SmartReference { |
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| 113 | typedef _Type& Type; |
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| 114 | }; |
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| 115 | |
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| 116 | template <typename _Type> |
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| 117 | struct SmartReference< |
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| 118 | _Type, |
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| 119 | typename enable_if<typename _Type::NeedCopy, void>::type |
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| 120 | > { |
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| 121 | typedef _Type Type; |
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| 122 | }; |
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| 123 | |
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| 124 | template <typename _Type, typename Enable = void> |
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| 125 | struct SmartConstReference { |
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| 126 | typedef const _Type& Type; |
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| 127 | }; |
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| 128 | |
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| 129 | template <typename _Type> |
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| 130 | struct SmartConstReference< |
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| 131 | _Type, |
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| 132 | typename enable_if<typename _Type::NeedCopy, void>::type |
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| 133 | > { |
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| 134 | typedef const _Type Type; |
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| 135 | }; |
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| 136 | |
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| 137 | template <typename _Type, typename Enable = void> |
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| 138 | struct SmartParameter { |
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| 139 | typedef _Type& Type; |
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| 140 | }; |
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| 141 | |
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| 142 | template <typename _Type> |
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| 143 | struct SmartParameter< |
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| 144 | _Type, |
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| 145 | typename enable_if<typename _Type::NeedCopy, void>::type |
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| 146 | > { |
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| 147 | typedef const _Type& Type; |
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| 148 | }; |
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| 149 | |
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[977] | 150 | } // namespace lemon |
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| 151 | |
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| 152 | #endif |
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