2 #ifndef BOOST_MPL_HAS_XXX_HPP_INCLUDED
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3 #define BOOST_MPL_HAS_XXX_HPP_INCLUDED
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5 // Copyright Aleksey Gurtovoy 2002-2006
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6 // Copyright David Abrahams 2002-2003
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8 // Distributed under the Boost Software License, Version 1.0.
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9 // (See accompanying file LICENSE_1_0.txt or copy at
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10 // http://www.boost.org/LICENSE_1_0.txt)
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12 // See http://www.boost.org/libs/mpl for documentation.
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14 // $Id: has_xxx.hpp 49273 2008-10-11 06:54:06Z agurtovoy $
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15 // $Date: 2008-10-11 02:54:06 -0400 (Sat, 11 Oct 2008) $
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16 // $Revision: 49273 $
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18 #include <boost/mpl/bool.hpp>
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19 #include <boost/mpl/aux_/type_wrapper.hpp>
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20 #include <boost/mpl/aux_/yes_no.hpp>
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21 #include <boost/mpl/aux_/config/has_xxx.hpp>
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22 #include <boost/mpl/aux_/config/msvc_typename.hpp>
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23 #include <boost/mpl/aux_/config/msvc.hpp>
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24 #include <boost/mpl/aux_/config/static_constant.hpp>
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25 #include <boost/mpl/aux_/config/workaround.hpp>
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27 #include <boost/preprocessor/cat.hpp>
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29 #if BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x590) )
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30 # include <boost/type_traits/is_class.hpp>
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33 #if !defined(BOOST_MPL_CFG_NO_HAS_XXX)
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35 # if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
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37 // agurt, 11/sep/02: MSVC-specific version (< 7.1), based on a USENET
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38 // newsgroup's posting by John Madsen (comp.lang.c++.moderated,
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39 // 1999-11-12 19:17:06 GMT); the code is _not_ standard-conforming, but
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40 // it works way more reliably than the SFINAE-based implementation
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42 // Modified dwa 8/Oct/02 to handle reference types.
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44 # include <boost/mpl/if.hpp>
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45 # include <boost/mpl/bool.hpp>
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47 namespace boost { namespace mpl { namespace aux {
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51 #if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
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52 template< typename U > struct msvc_incomplete_array
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54 typedef char (&type)[sizeof(U) + 1];
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58 template< typename T >
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59 struct msvc_is_incomplete
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61 // MSVC is capable of some kinds of SFINAE. If U is an incomplete
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62 // type, it won't pick the second overload
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63 static char tester(...);
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65 #if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
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66 template< typename U >
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67 static typename msvc_incomplete_array<U>::type tester(type_wrapper<U>);
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69 template< typename U >
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70 static char (& tester(type_wrapper<U>) )[sizeof(U)+1];
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73 BOOST_STATIC_CONSTANT(bool, value =
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74 sizeof(tester(type_wrapper<T>())) == 1
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79 struct msvc_is_incomplete<int>
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81 BOOST_STATIC_CONSTANT(bool, value = false);
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86 # define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF_(trait, name, default_) \
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87 template< typename T, typename name = ::boost::mpl::aux::has_xxx_tag > \
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88 struct BOOST_PP_CAT(trait,_impl) : T \
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90 static boost::mpl::aux::no_tag \
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91 test(void(*)(::boost::mpl::aux::has_xxx_tag)); \
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93 static boost::mpl::aux::yes_tag test(...); \
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95 BOOST_STATIC_CONSTANT(bool, value = \
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96 sizeof(test(static_cast<void(*)(name)>(0))) \
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97 != sizeof(boost::mpl::aux::no_tag) \
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99 typedef boost::mpl::bool_<value> type; \
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102 template< typename T, typename fallback_ = boost::mpl::bool_<default_> > \
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104 : boost::mpl::if_c< \
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105 boost::mpl::aux::msvc_is_incomplete<T>::value \
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106 , boost::mpl::bool_<false> \
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107 , BOOST_PP_CAT(trait,_impl)<T> \
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112 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, void) \
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113 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, bool) \
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114 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, char) \
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115 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, signed char) \
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116 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, unsigned char) \
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117 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, signed short) \
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118 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, unsigned short) \
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119 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, signed int) \
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120 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, unsigned int) \
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121 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, signed long) \
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122 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, unsigned long) \
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123 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, float) \
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124 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, double) \
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125 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, long double) \
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128 # define BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, T) \
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129 template<> struct trait<T> \
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131 BOOST_STATIC_CONSTANT(bool, value = false); \
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132 typedef boost::mpl::bool_<false> type; \
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136 #if !defined(BOOST_NO_INTRINSIC_WCHAR_T)
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137 # define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, unused) \
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138 BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF_(trait, name, unused) \
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139 BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, wchar_t) \
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142 # define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, unused) \
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143 BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF_(trait, name, unused) \
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148 // SFINAE-based implementations below are derived from a USENET newsgroup's
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149 // posting by Rani Sharoni (comp.lang.c++.moderated, 2002-03-17 07:45:09 PST)
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151 # elif BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1400)) \
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152 || BOOST_WORKAROUND(__IBMCPP__, <= 700)
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154 // MSVC 7.1+ & VACPP
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156 // agurt, 15/jun/05: replace overload-based SFINAE implementation with SFINAE
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157 // applied to partial specialization to fix some apparently random failures
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158 // (thanks to Daniel Wallin for researching this!)
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160 # define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, default_) \
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161 template< typename T > \
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162 struct BOOST_PP_CAT(trait, _msvc_sfinae_helper) \
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164 typedef void type; \
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167 template< typename T, typename U = void > \
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168 struct BOOST_PP_CAT(trait,_impl_) \
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170 BOOST_STATIC_CONSTANT(bool, value = false); \
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171 typedef boost::mpl::bool_<value> type; \
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174 template< typename T > \
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175 struct BOOST_PP_CAT(trait,_impl_)< \
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177 , typename BOOST_PP_CAT(trait, _msvc_sfinae_helper)< typename T::name >::type \
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180 BOOST_STATIC_CONSTANT(bool, value = true); \
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181 typedef boost::mpl::bool_<value> type; \
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184 template< typename T, typename fallback_ = boost::mpl::bool_<default_> > \
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186 : BOOST_PP_CAT(trait,_impl_)<T> \
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191 # elif BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x590) )
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193 # define BOOST_MPL_HAS_XXX_TRAIT_NAMED_BCB_DEF(trait, trait_tester, name, default_) \
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194 template< typename T, bool IS_CLASS > \
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195 struct trait_tester \
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197 BOOST_STATIC_CONSTANT( bool, value = false ); \
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199 template< typename T > \
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200 struct trait_tester< T, true > \
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202 struct trait_tester_impl \
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204 template < class U > \
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205 static int resolve( boost::mpl::aux::type_wrapper<U> const volatile * \
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206 , boost::mpl::aux::type_wrapper<typename U::name >* = 0 ); \
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207 static char resolve( ... ); \
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209 typedef boost::mpl::aux::type_wrapper<T> t_; \
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210 BOOST_STATIC_CONSTANT( bool, value = ( sizeof( trait_tester_impl::resolve( static_cast< t_ * >(0) ) ) == sizeof(int) ) ); \
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212 template< typename T, typename fallback_ = boost::mpl::bool_<default_> > \
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215 BOOST_STATIC_CONSTANT( bool, value = (trait_tester< T, boost::is_class< T >::value >::value) ); \
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216 typedef boost::mpl::bool_< trait< T, fallback_ >::value > type; \
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219 # define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, default_) \
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220 BOOST_MPL_HAS_XXX_TRAIT_NAMED_BCB_DEF( trait \
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221 , BOOST_PP_CAT(trait,_tester) \
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226 # else // other SFINAE-capable compilers
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228 # define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, default_) \
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229 template< typename T, typename fallback_ = boost::mpl::bool_<default_> > \
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232 struct gcc_3_2_wknd \
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234 template< typename U > \
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235 static boost::mpl::aux::yes_tag test( \
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236 boost::mpl::aux::type_wrapper<U> const volatile* \
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237 , boost::mpl::aux::type_wrapper<BOOST_MSVC_TYPENAME U::name>* = 0 \
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240 static boost::mpl::aux::no_tag test(...); \
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243 typedef boost::mpl::aux::type_wrapper<T> t_; \
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244 BOOST_STATIC_CONSTANT(bool, value = \
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245 sizeof(gcc_3_2_wknd::test(static_cast<t_*>(0))) \
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246 == sizeof(boost::mpl::aux::yes_tag) \
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248 typedef boost::mpl::bool_<value> type; \
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252 # endif // BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
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255 #else // BOOST_MPL_CFG_NO_HAS_XXX
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257 // placeholder implementation
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259 # define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, default_) \
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260 template< typename T, typename fallback_ = boost::mpl::bool_<default_> > \
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263 BOOST_STATIC_CONSTANT(bool, value = fallback_::value); \
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264 typedef fallback_ type; \
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270 #define BOOST_MPL_HAS_XXX_TRAIT_DEF(name) \
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271 BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(BOOST_PP_CAT(has_,name), name, false) \
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274 #endif // BOOST_MPL_HAS_XXX_HPP_INCLUDED
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