sl@0: // Copyright David Abrahams 2004. Use, modification and distribution is
sl@0: // subject to the Boost Software License, Version 1.0. (See accompanying
sl@0: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
sl@0: #ifndef IS_INCREMENTABLE_DWA200415_HPP
sl@0: # define IS_INCREMENTABLE_DWA200415_HPP
sl@0: 
sl@0: # include <boost/type_traits/detail/template_arity_spec.hpp>
sl@0: # include <boost/type_traits/remove_cv.hpp>
sl@0: # include <boost/mpl/aux_/lambda_support.hpp>
sl@0: # include <boost/mpl/bool.hpp>
sl@0: # include <boost/detail/workaround.hpp>
sl@0: 
sl@0: // Must be the last include
sl@0: # include <boost/type_traits/detail/bool_trait_def.hpp>
sl@0: 
sl@0: namespace boost { namespace detail { 
sl@0: 
sl@0: // is_incrementable<T> metafunction
sl@0: //
sl@0: // Requires: Given x of type T&, if the expression ++x is well-formed
sl@0: // it must have complete type; otherwise, it must neither be ambiguous
sl@0: // nor violate access.
sl@0: 
sl@0: // This namespace ensures that ADL doesn't mess things up.
sl@0: namespace is_incrementable_
sl@0: {
sl@0:   // a type returned from operator++ when no increment is found in the
sl@0:   // type's own namespace
sl@0:   struct tag {};
sl@0:   
sl@0:   // any soaks up implicit conversions and makes the following
sl@0:   // operator++ less-preferred than any other such operator that
sl@0:   // might be found via ADL.
sl@0:   struct any { template <class T> any(T const&); };
sl@0: 
sl@0:   // This is a last-resort operator++ for when none other is found
sl@0: # if BOOST_WORKAROUND(__GNUC__, == 4) && __GNUC_MINOR__ == 0 && __GNUC_PATCHLEVEL__ == 2
sl@0:   
sl@0: }
sl@0: 
sl@0: namespace is_incrementable_2
sl@0: {
sl@0:   is_incrementable_::tag operator++(is_incrementable_::any const&);
sl@0:   is_incrementable_::tag operator++(is_incrementable_::any const&,int);
sl@0: }
sl@0: using namespace is_incrementable_2;
sl@0: 
sl@0: namespace is_incrementable_
sl@0: {
sl@0:   
sl@0: # else
sl@0:   
sl@0:   tag operator++(any const&);
sl@0:   tag operator++(any const&,int);
sl@0:   
sl@0: # endif 
sl@0: 
sl@0: # if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3202)) \
sl@0:     || BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
sl@0: #  define BOOST_comma(a,b) (a)
sl@0: # else 
sl@0:   // In case an operator++ is found that returns void, we'll use ++x,0
sl@0:   tag operator,(tag,int);  
sl@0: #  define BOOST_comma(a,b) (a,b)
sl@0: # endif 
sl@0:   
sl@0:   // two check overloads help us identify which operator++ was picked
sl@0:   char (& check(tag) )[2];
sl@0:   
sl@0:   template <class T>
sl@0:   char check(T const&);
sl@0:   
sl@0: 
sl@0:   template <class T>
sl@0:   struct impl
sl@0:   {
sl@0:       static typename boost::remove_cv<T>::type& x;
sl@0: 
sl@0:       BOOST_STATIC_CONSTANT(
sl@0:           bool
sl@0:         , value = sizeof(is_incrementable_::check(BOOST_comma(++x,0))) == 1
sl@0:       );
sl@0:   };
sl@0: 
sl@0:   template <class T>
sl@0:   struct postfix_impl
sl@0:   {
sl@0:       static typename boost::remove_cv<T>::type& x;
sl@0: 
sl@0:       BOOST_STATIC_CONSTANT(
sl@0:           bool
sl@0:         , value = sizeof(is_incrementable_::check(BOOST_comma(x++,0))) == 1
sl@0:       );
sl@0:   };
sl@0: }
sl@0: 
sl@0: # undef BOOST_comma
sl@0: 
sl@0: template<typename T> 
sl@0: struct is_incrementable 
sl@0: BOOST_TT_AUX_BOOL_C_BASE(::boost::detail::is_incrementable_::impl<T>::value)
sl@0: { 
sl@0:     BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(::boost::detail::is_incrementable_::impl<T>::value)
sl@0:     BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_incrementable,(T))
sl@0: };
sl@0: 
sl@0: template<typename T> 
sl@0: struct is_postfix_incrementable 
sl@0: BOOST_TT_AUX_BOOL_C_BASE(::boost::detail::is_incrementable_::impl<T>::value)
sl@0: { 
sl@0:     BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(::boost::detail::is_incrementable_::postfix_impl<T>::value)
sl@0:     BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_postfix_incrementable,(T))
sl@0: };
sl@0: 
sl@0: } // namespace detail
sl@0: 
sl@0: BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(1, ::boost::detail::is_incrementable)
sl@0: BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(1, ::boost::detail::is_postfix_incrementable)
sl@0: 
sl@0: } // namespace boost
sl@0: 
sl@0: # include <boost/type_traits/detail/bool_trait_undef.hpp>
sl@0: 
sl@0: #endif // IS_INCREMENTABLE_DWA200415_HPP