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1 #ifndef BOOST_TT_IS_ABSTRACT_CLASS_HPP |
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2 #define BOOST_TT_IS_ABSTRACT_CLASS_HPP |
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3 |
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4 #if defined(_MSC_VER) && (_MSC_VER >= 1020) |
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5 # pragma once |
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6 #endif |
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7 |
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8 /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8 |
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9 // is_abstract_class.hpp: |
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10 // |
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11 // (C) Copyright 2002 Rani Sharoni (rani_sharoni@hotmail.com) and Robert Ramey |
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12 // Use, modification and distribution is subject to the Boost Software |
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13 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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14 // http://www.boost.org/LICENSE_1_0.txt) |
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15 // |
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16 // See http://www.boost.org for updates, documentation, and revision history. |
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17 // |
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18 |
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19 // Compile type discovery whether given type is abstract class or not. |
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20 // |
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21 // Requires DR 337 to be supported by compiler |
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22 // (http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/cwg_active.html#337). |
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23 // |
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24 // |
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25 // Believed (Jan 2004) to work on: |
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26 // - GCC 3.4 |
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27 // - VC++ 7.1 |
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28 // - compilers with new EDG frontend (Intel C++ 7, Comeau 4.3.2) |
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29 // |
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30 // Doesn't work on: |
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31 // - VC++6, VC++7.0 and less |
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32 // - GCC 3.3.X and less |
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33 // - Borland C++ 6 and less |
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34 // |
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35 // |
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36 // History: |
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37 // - Originally written by Rani Sharoni, see |
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38 // http://groups.google.com/groups?selm=df893da6.0207110613.75b2fe90%40posting.google.com |
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39 // At this time supported by EDG (Intel C++ 7, Comeau 4.3.2) and VC7.1. |
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40 // - Adapted and added into Boost.Serialization library by Robert Ramey |
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41 // (starting with submission #10). |
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42 // - Jan 2004: GCC 3.4 fixed to suport DR337 (Giovanni Bajo). |
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43 // - Jan 2004: modified to be part of Boost.TypeTraits (Pavel Vozenilek). |
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44 // - Nov 2004: Christoph Ludwig found that the implementation did not work with |
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45 // template types and gcc-3.4 or VC7.1, fix due to Christoph Ludwig |
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46 // and John Maddock. |
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47 // - Dec 2004: Added new config macro BOOST_NO_IS_ABSTRACT which causes the template |
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48 // to degrade gracefully, rather than trash the compiler (John Maddock). |
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49 // |
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50 |
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51 #include <boost/static_assert.hpp> |
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52 #include <boost/type_traits/detail/yes_no_type.hpp> |
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53 #include <boost/type_traits/is_class.hpp> |
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54 #include <boost/type_traits/detail/ice_and.hpp> |
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55 #ifdef BOOST_NO_IS_ABSTRACT |
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56 #include <boost/type_traits/is_polymorphic.hpp> |
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57 #endif |
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58 // should be the last #include |
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59 #include <boost/type_traits/detail/bool_trait_def.hpp> |
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60 |
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61 |
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62 namespace boost { |
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63 namespace detail{ |
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64 |
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65 #ifndef BOOST_NO_IS_ABSTRACT |
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66 template<class T> |
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67 struct is_abstract_imp2 |
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68 { |
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69 // Deduction fails if T is void, function type, |
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70 // reference type (14.8.2/2)or an abstract class type |
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71 // according to review status issue #337 |
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72 // |
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73 template<class U> |
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74 static type_traits::no_type check_sig(U (*)[1]); |
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75 template<class U> |
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76 static type_traits::yes_type check_sig(...); |
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77 // |
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78 // T must be a complete type, further if T is a template then |
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79 // it must be instantiated in order for us to get the right answer: |
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80 // |
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81 BOOST_STATIC_ASSERT(sizeof(T) != 0); |
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82 |
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83 // GCC2 won't even parse this template if we embed the computation |
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84 // of s1 in the computation of value. |
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85 #ifdef __GNUC__ |
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86 BOOST_STATIC_CONSTANT(unsigned, s1 = sizeof(is_abstract_imp2<T>::template check_sig<T>(0))); |
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87 #else |
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88 BOOST_STATIC_CONSTANT(unsigned, s1 = sizeof(check_sig<T>(0))); |
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89 #endif |
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90 |
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91 BOOST_STATIC_CONSTANT(bool, value = |
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92 (s1 == sizeof(type_traits::yes_type))); |
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93 }; |
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94 |
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95 template <bool v> |
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96 struct is_abstract_select |
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97 { |
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98 template <class T> |
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99 struct rebind |
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100 { |
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101 typedef is_abstract_imp2<T> type; |
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102 }; |
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103 }; |
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104 template <> |
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105 struct is_abstract_select<false> |
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106 { |
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107 template <class T> |
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108 struct rebind |
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109 { |
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110 typedef false_type type; |
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111 }; |
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112 }; |
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113 |
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114 template <class T> |
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115 struct is_abstract_imp |
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116 { |
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117 typedef is_abstract_select< ::boost::is_class<T>::value> selector; |
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118 typedef typename selector::template rebind<T> binder; |
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119 typedef typename binder::type type; |
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120 |
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121 BOOST_STATIC_CONSTANT(bool, value = type::value); |
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122 }; |
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123 |
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124 #endif |
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125 } |
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126 |
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127 #ifndef BOOST_NO_IS_ABSTRACT |
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128 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_abstract,T,::boost::detail::is_abstract_imp<T>::value) |
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129 #else |
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130 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_abstract,T,::boost::detail::is_polymorphic_imp<T>::value) |
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131 #endif |
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132 |
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133 } // namespace boost |
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134 |
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135 #include <boost/type_traits/detail/bool_trait_undef.hpp> |
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136 |
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137 #endif //BOOST_TT_IS_ABSTRACT_CLASS_HPP |