williamr@2: 
williamr@2: #ifndef BOOST_MPL_HAS_XXX_HPP_INCLUDED
williamr@2: #define BOOST_MPL_HAS_XXX_HPP_INCLUDED
williamr@2: 
williamr@2: // Copyright Aleksey Gurtovoy 2002-2006
williamr@2: // Copyright David Abrahams 2002-2003
williamr@2: //
williamr@2: // Distributed under the Boost Software License, Version 1.0. 
williamr@2: // (See accompanying file LICENSE_1_0.txt or copy at 
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: //
williamr@2: // See http://www.boost.org/libs/mpl for documentation.
williamr@2: 
williamr@2: // $Source: /cvsroot/boost/boost/boost/mpl/has_xxx.hpp,v $
williamr@2: // $Date: 2006/11/09 01:05:31 $
williamr@2: // $Revision: 1.4.6.1 $
williamr@2: 
williamr@2: #include <boost/mpl/bool.hpp>
williamr@2: #include <boost/mpl/aux_/type_wrapper.hpp>
williamr@2: #include <boost/mpl/aux_/yes_no.hpp>
williamr@2: #include <boost/mpl/aux_/config/has_xxx.hpp>
williamr@2: #include <boost/mpl/aux_/config/msvc_typename.hpp>
williamr@2: #include <boost/mpl/aux_/config/msvc.hpp>
williamr@2: #include <boost/mpl/aux_/config/static_constant.hpp>
williamr@2: #include <boost/mpl/aux_/config/workaround.hpp>
williamr@2: 
williamr@2: #include <boost/preprocessor/cat.hpp>
williamr@2: 
williamr@2: #if !defined(BOOST_MPL_CFG_NO_HAS_XXX)
williamr@2: 
williamr@2: #   if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
williamr@2: 
williamr@2: // agurt, 11/sep/02: MSVC-specific version (< 7.1), based on a USENET 
williamr@2: // newsgroup's posting by John Madsen (comp.lang.c++.moderated, 
williamr@2: // 1999-11-12 19:17:06 GMT); the code is _not_ standard-conforming, but 
williamr@2: // it works way more reliably than the SFINAE-based implementation
williamr@2: 
williamr@2: // Modified dwa 8/Oct/02 to handle reference types.
williamr@2: 
williamr@2: #   include <boost/mpl/if.hpp>
williamr@2: #   include <boost/mpl/bool.hpp>
williamr@2: 
williamr@2: namespace boost { namespace mpl { namespace aux {
williamr@2: 
williamr@2: struct has_xxx_tag;
williamr@2: 
williamr@2: #if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
williamr@2: template< typename U > struct msvc_incomplete_array
williamr@2: {
williamr@2:     typedef char (&type)[sizeof(U) + 1];
williamr@2: };
williamr@2: #endif
williamr@2: 
williamr@2: template< typename T >
williamr@2: struct msvc_is_incomplete
williamr@2: {
williamr@2:     // MSVC is capable of some kinds of SFINAE.  If U is an incomplete
williamr@2:     // type, it won't pick the second overload
williamr@2:     static char tester(...);
williamr@2: 
williamr@2: #if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
williamr@2:     template< typename U >
williamr@2:     static typename msvc_incomplete_array<U>::type tester(type_wrapper<U>);
williamr@2: #else
williamr@2:     template< typename U >
williamr@2:     static char (& tester(type_wrapper<U>) )[sizeof(U)+1];
williamr@2: #endif 
williamr@2:     
williamr@2:     BOOST_STATIC_CONSTANT(bool, value = 
williamr@2:           sizeof(tester(type_wrapper<T>())) == 1
williamr@2:         );
williamr@2: };
williamr@2: 
williamr@2: template<>
williamr@2: struct msvc_is_incomplete<int>
williamr@2: {
williamr@2:     BOOST_STATIC_CONSTANT(bool, value = false);
williamr@2: };
williamr@2: 
williamr@2: }}}
williamr@2: 
williamr@2: #   define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF_(trait, name, default_) \
williamr@2: template< typename T, typename name = ::boost::mpl::aux::has_xxx_tag > \
williamr@2: struct BOOST_PP_CAT(trait,_impl) : T \
williamr@2: { \
williamr@2:     static boost::mpl::aux::no_tag \
williamr@2:     test(void(*)(::boost::mpl::aux::has_xxx_tag)); \
williamr@2:     \
williamr@2:     static boost::mpl::aux::yes_tag test(...); \
williamr@2:     \
williamr@2:     BOOST_STATIC_CONSTANT(bool, value = \
williamr@2:           sizeof(test(static_cast<void(*)(name)>(0))) \
williamr@2:             != sizeof(boost::mpl::aux::no_tag) \
williamr@2:         ); \
williamr@2:     typedef boost::mpl::bool_<value> type; \
williamr@2: }; \
williamr@2: \
williamr@2: template< typename T, typename fallback_ = boost::mpl::bool_<default_> > \
williamr@2: struct trait \
williamr@2:     : boost::mpl::if_c< \
williamr@2:           boost::mpl::aux::msvc_is_incomplete<T>::value \
williamr@2:         , boost::mpl::bool_<false> \
williamr@2:         , BOOST_PP_CAT(trait,_impl)<T> \
williamr@2:         >::type \
williamr@2: { \
williamr@2: }; \
williamr@2: \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, void) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, bool) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, char) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, signed char) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, unsigned char) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, signed short) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, unsigned short) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, signed int) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, unsigned int) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, signed long) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, unsigned long) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, float) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, double) \
williamr@2: BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, long double) \
williamr@2: /**/
williamr@2: 
williamr@2: #   define BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, T) \
williamr@2: template<> struct trait<T> \
williamr@2: { \
williamr@2:     BOOST_STATIC_CONSTANT(bool, value = false); \
williamr@2:     typedef boost::mpl::bool_<false> type; \
williamr@2: }; \
williamr@2: /**/
williamr@2: 
williamr@2: #if !defined(BOOST_NO_INTRINSIC_WCHAR_T)
williamr@2: #   define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, unused) \
williamr@2:     BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF_(trait, name, unused) \
williamr@2:     BOOST_MPL_AUX_HAS_XXX_TRAIT_SPEC(trait, wchar_t) \
williamr@2: /**/
williamr@2: #else
williamr@2: #   define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, unused) \
williamr@2:     BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF_(trait, name, unused) \
williamr@2: /**/
williamr@2: #endif
williamr@2: 
williamr@2: 
williamr@2: // SFINAE-based implementations below are derived from a USENET newsgroup's 
williamr@2: // posting by Rani Sharoni (comp.lang.c++.moderated, 2002-03-17 07:45:09 PST)
williamr@2: 
williamr@2: #   elif BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1400)) \
williamr@2:       || BOOST_WORKAROUND(__IBMCPP__, <= 700)
williamr@2: 
williamr@2: // MSVC 7.1+ & VACPP
williamr@2: 
williamr@2: // agurt, 15/jun/05: replace overload-based SFINAE implementation with SFINAE
williamr@2: // applied to partial specialization to fix some apparently random failures 
williamr@2: // (thanks to Daniel Wallin for researching this!)
williamr@2: 
williamr@2: namespace boost { namespace mpl { namespace aux {
williamr@2: template< typename T > struct msvc71_sfinae_helper { typedef void type; };
williamr@2: }}}
williamr@2: 
williamr@2: #   define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, default_) \
williamr@2: template< typename T, typename U = void > \
williamr@2: struct BOOST_PP_CAT(trait,_impl_) \
williamr@2: { \
williamr@2:     BOOST_STATIC_CONSTANT(bool, value = false); \
williamr@2:     typedef boost::mpl::bool_<value> type; \
williamr@2: }; \
williamr@2: \
williamr@2: template< typename T > \
williamr@2: struct BOOST_PP_CAT(trait,_impl_)< \
williamr@2:       T \
williamr@2:     , typename boost::mpl::aux::msvc71_sfinae_helper< typename T::name >::type \
williamr@2:     > \
williamr@2: { \
williamr@2:     BOOST_STATIC_CONSTANT(bool, value = true); \
williamr@2:     typedef boost::mpl::bool_<value> type; \
williamr@2: }; \
williamr@2: \
williamr@2: template< typename T, typename fallback_ = boost::mpl::bool_<default_> > \
williamr@2: struct trait \
williamr@2:     : BOOST_PP_CAT(trait,_impl_)<T> \
williamr@2: { \
williamr@2: }; \
williamr@2: /**/
williamr@2: 
williamr@2: #   else // other SFINAE-capable compilers
williamr@2: 
williamr@2: #   define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, default_) \
williamr@2: template< typename T, typename fallback_ = boost::mpl::bool_<default_> > \
williamr@2: struct trait \
williamr@2: { \
williamr@2:     struct gcc_3_2_wknd \
williamr@2:     { \
williamr@2:         template< typename U > \
williamr@2:         static boost::mpl::aux::yes_tag test( \
williamr@2:               boost::mpl::aux::type_wrapper<U> const volatile* \
williamr@2:             , boost::mpl::aux::type_wrapper<BOOST_MSVC_TYPENAME U::name>* = 0 \
williamr@2:             ); \
williamr@2:     \
williamr@2:         static boost::mpl::aux::no_tag test(...); \
williamr@2:     }; \
williamr@2:     \
williamr@2:     typedef boost::mpl::aux::type_wrapper<T> t_; \
williamr@2:     BOOST_STATIC_CONSTANT(bool, value = \
williamr@2:           sizeof(gcc_3_2_wknd::test(static_cast<t_*>(0))) \
williamr@2:             == sizeof(boost::mpl::aux::yes_tag) \
williamr@2:         ); \
williamr@2:     typedef boost::mpl::bool_<value> type; \
williamr@2: }; \
williamr@2: /**/
williamr@2: 
williamr@2: #   endif // BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
williamr@2: 
williamr@2: 
williamr@2: #else // BOOST_MPL_CFG_NO_HAS_XXX
williamr@2: 
williamr@2: // placeholder implementation
williamr@2: 
williamr@2: #   define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, default_) \
williamr@2: template< typename T, typename fallback_ = boost::mpl::bool_<default_> > \
williamr@2: struct trait \
williamr@2: { \
williamr@2:     BOOST_STATIC_CONSTANT(bool, value = fallback_::value); \
williamr@2:     typedef fallback_ type; \
williamr@2: }; \
williamr@2: /**/
williamr@2: 
williamr@2: #endif
williamr@2: 
williamr@2: #define BOOST_MPL_HAS_XXX_TRAIT_DEF(name) \
williamr@2:     BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(BOOST_PP_CAT(has_,name), name, false) \
williamr@2: /**/
williamr@2: 
williamr@2: #endif // BOOST_MPL_HAS_XXX_HPP_INCLUDED