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