Chris@16: // Copyright David Abrahams 2004. Use, modification and distribution is
Chris@16: // subject to the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: #ifndef IS_INCREMENTABLE_DWA200415_HPP
Chris@16: # define IS_INCREMENTABLE_DWA200415_HPP
Chris@16: 
Chris@16: # include <boost/type_traits/detail/template_arity_spec.hpp>
Chris@16: # include <boost/type_traits/remove_cv.hpp>
Chris@16: # include <boost/mpl/aux_/lambda_support.hpp>
Chris@16: # include <boost/mpl/bool.hpp>
Chris@16: # include <boost/detail/workaround.hpp>
Chris@16: 
Chris@16: // Must be the last include
Chris@16: # include <boost/type_traits/detail/bool_trait_def.hpp>
Chris@16: 
Chris@16: namespace boost { namespace detail { 
Chris@16: 
Chris@16: // is_incrementable<T> metafunction
Chris@16: //
Chris@16: // Requires: Given x of type T&, if the expression ++x is well-formed
Chris@16: // it must have complete type; otherwise, it must neither be ambiguous
Chris@16: // nor violate access.
Chris@16: 
Chris@16: // This namespace ensures that ADL doesn't mess things up.
Chris@16: namespace is_incrementable_
Chris@16: {
Chris@16:   // a type returned from operator++ when no increment is found in the
Chris@16:   // type's own namespace
Chris@16:   struct tag {};
Chris@16:   
Chris@16:   // any soaks up implicit conversions and makes the following
Chris@16:   // operator++ less-preferred than any other such operator that
Chris@16:   // might be found via ADL.
Chris@16:   struct any { template <class T> any(T const&); };
Chris@16: 
Chris@16:   // This is a last-resort operator++ for when none other is found
Chris@16: # if BOOST_WORKAROUND(__GNUC__, == 4) && __GNUC_MINOR__ == 0 && __GNUC_PATCHLEVEL__ == 2
Chris@16:   
Chris@16: }
Chris@16: 
Chris@16: namespace is_incrementable_2
Chris@16: {
Chris@16:   is_incrementable_::tag operator++(is_incrementable_::any const&);
Chris@16:   is_incrementable_::tag operator++(is_incrementable_::any const&,int);
Chris@16: }
Chris@16: using namespace is_incrementable_2;
Chris@16: 
Chris@16: namespace is_incrementable_
Chris@16: {
Chris@16:   
Chris@16: # else
Chris@16:   
Chris@16:   tag operator++(any const&);
Chris@16:   tag operator++(any const&,int);
Chris@16:   
Chris@16: # endif 
Chris@16: 
Chris@101: # if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3202)) 
Chris@16: #  define BOOST_comma(a,b) (a)
Chris@16: # else 
Chris@16:   // In case an operator++ is found that returns void, we'll use ++x,0
Chris@16:   tag operator,(tag,int);  
Chris@16: #  define BOOST_comma(a,b) (a,b)
Chris@16: # endif 
Chris@16: 
Chris@16: # if defined(BOOST_MSVC)
Chris@16: #  pragma warning(push)
Chris@16: #  pragma warning(disable:4913) // Warning about operator,
Chris@16: # endif 
Chris@16: 
Chris@16:   // two check overloads help us identify which operator++ was picked
Chris@16:   char (& check_(tag) )[2];
Chris@16:   
Chris@16:   template <class T>
Chris@16:   char check_(T const&);
Chris@16:   
Chris@16: 
Chris@16:   template <class T>
Chris@16:   struct impl
Chris@16:   {
Chris@16:       static typename boost::remove_cv<T>::type& x;
Chris@16: 
Chris@16:       BOOST_STATIC_CONSTANT(
Chris@16:           bool
Chris@16:         , value = sizeof(is_incrementable_::check_(BOOST_comma(++x,0))) == 1
Chris@16:       );
Chris@16:   };
Chris@16: 
Chris@16:   template <class T>
Chris@16:   struct postfix_impl
Chris@16:   {
Chris@16:       static typename boost::remove_cv<T>::type& x;
Chris@16: 
Chris@16:       BOOST_STATIC_CONSTANT(
Chris@16:           bool
Chris@16:         , value = sizeof(is_incrementable_::check_(BOOST_comma(x++,0))) == 1
Chris@16:       );
Chris@16:   };
Chris@16: 
Chris@16: # if defined(BOOST_MSVC)
Chris@16: #  pragma warning(pop)
Chris@16: # endif 
Chris@16: 
Chris@16: }
Chris@16: 
Chris@16: # undef BOOST_comma
Chris@16: 
Chris@16: template<typename T> 
Chris@16: struct is_incrementable 
Chris@16: BOOST_TT_AUX_BOOL_C_BASE(::boost::detail::is_incrementable_::impl<T>::value)
Chris@16: { 
Chris@16:     BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(::boost::detail::is_incrementable_::impl<T>::value)
Chris@16:     BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_incrementable,(T))
Chris@16: };
Chris@16: 
Chris@16: template<typename T> 
Chris@16: struct is_postfix_incrementable 
Chris@101: BOOST_TT_AUX_BOOL_C_BASE(::boost::detail::is_incrementable_::postfix_impl<T>::value)
Chris@16: { 
Chris@16:     BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(::boost::detail::is_incrementable_::postfix_impl<T>::value)
Chris@16:     BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_postfix_incrementable,(T))
Chris@16: };
Chris@16: 
Chris@16: } // namespace detail
Chris@16: 
Chris@16: BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(1, ::boost::detail::is_incrementable)
Chris@16: BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(1, ::boost::detail::is_postfix_incrementable)
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: # include <boost/type_traits/detail/bool_trait_undef.hpp>
Chris@16: 
Chris@16: #endif // IS_INCREMENTABLE_DWA200415_HPP