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1 /* -*- C++ -*- |
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2 * |
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3 * src/lemon/utility.h - Part of LEMON, a generic C++ optimization library |
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4 * |
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5 * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi |
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6 * Kutatocsoport (Egervary Combinatorial Optimization Research Group, |
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7 * 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 * This file contains a modified version of the enable_if library from BOOST. |
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18 * See the appropriate copyright notice below. |
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19 */ |
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20 |
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21 // Boost enable_if library |
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22 |
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23 // Copyright 2003 © The Trustees of Indiana University. |
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24 |
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25 // Use, modification, and distribution is subject to the Boost Software |
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26 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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27 // http://www.boost.org/LICENSE_1_0.txt) |
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28 |
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29 // Authors: Jaakko Järvi (jajarvi at osl.iu.edu) |
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30 // Jeremiah Willcock (jewillco at osl.iu.edu) |
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31 // Andrew Lumsdaine (lums at osl.iu.edu) |
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32 |
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33 |
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34 #ifndef LEMON_UTILITY_H |
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35 #define LEMON_UTILITY_H |
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36 |
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37 namespace lemon |
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38 { |
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39 |
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40 /// Basic type for defining "tags". A "YES" condidion for enable_if. |
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41 |
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42 /// \todo This should go to a separate "basic_types.h" (or something) |
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43 /// file. |
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44 struct True { |
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45 static const bool value = true; |
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46 }; |
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47 |
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48 /// Basic type for defining "tags". A "NO" condidion for enable_if. |
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49 struct False { |
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50 static const bool value = false; |
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51 }; |
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52 |
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53 template <typename T> |
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54 struct Wrap { |
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55 const T &value; |
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56 Wrap(const T &t) : value(t) {} |
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57 }; |
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58 |
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59 |
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60 |
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61 /**************** enable_if from BOOST ****************/ |
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62 |
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63 template <bool B, class T = void> |
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64 struct enable_if_c { |
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65 typedef T type; |
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66 }; |
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67 |
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68 template <class T> |
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69 struct enable_if_c<false, T> {}; |
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70 |
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71 template <class Cond, class T = void> |
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72 struct enable_if : public enable_if_c<Cond::value, T> {}; |
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73 |
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74 template <bool B, class T> |
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75 struct lazy_enable_if_c { |
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76 typedef typename T::type type; |
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77 }; |
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78 |
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79 template <class T> |
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80 struct lazy_enable_if_c<false, T> {}; |
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81 |
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82 template <class Cond, class T> |
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83 struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {}; |
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84 |
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85 |
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86 template <bool B, class T = void> |
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87 struct disable_if_c { |
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88 typedef T type; |
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89 }; |
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90 |
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91 template <class T> |
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92 struct disable_if_c<true, T> {}; |
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93 |
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94 template <class Cond, class T = void> |
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95 struct disable_if : public disable_if_c<Cond::value, T> {}; |
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96 |
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97 template <bool B, class T> |
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98 struct lazy_disable_if_c { |
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99 typedef typename T::type type; |
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100 }; |
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101 |
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102 template <class T> |
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103 struct lazy_disable_if_c<true, T> {}; |
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104 |
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105 template <class Cond, class T> |
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106 struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {}; |
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107 |
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108 } // namespace lemon |
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109 |
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110 #endif |