// Copyright David Abrahams 2004. Use, modification and distribution is | |
// subject to the Boost Software License, Version 1.0. (See accompanying | |
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
#ifndef IS_INCREMENTABLE_DWA200415_HPP | |
# define IS_INCREMENTABLE_DWA200415_HPP | |
# include <boost/type_traits/detail/template_arity_spec.hpp> | |
# include <boost/type_traits/remove_cv.hpp> | |
# include <boost/mpl/aux_/lambda_support.hpp> | |
# include <boost/mpl/bool.hpp> | |
# include <boost/detail/workaround.hpp> | |
// Must be the last include | |
# include <boost/type_traits/detail/bool_trait_def.hpp> | |
namespace boost { namespace detail { | |
// is_incrementable<T> metafunction | |
// | |
// Requires: Given x of type T&, if the expression ++x is well-formed | |
// it must have complete type; otherwise, it must neither be ambiguous | |
// nor violate access. | |
// This namespace ensures that ADL doesn't mess things up. | |
namespace is_incrementable_ | |
{ | |
// a type returned from operator++ when no increment is found in the | |
// type's own namespace | |
struct tag {}; | |
// any soaks up implicit conversions and makes the following | |
// operator++ less-preferred than any other such operator that | |
// might be found via ADL. | |
struct any { template <class T> any(T const&); }; | |
// This is a last-resort operator++ for when none other is found | |
# if BOOST_WORKAROUND(__GNUC__, == 4) && __GNUC_MINOR__ == 0 && __GNUC_PATCHLEVEL__ == 2 | |
} | |
namespace is_incrementable_2 | |
{ | |
is_incrementable_::tag operator++(is_incrementable_::any const&); | |
is_incrementable_::tag operator++(is_incrementable_::any const&,int); | |
} | |
using namespace is_incrementable_2; | |
namespace is_incrementable_ | |
{ | |
# else | |
tag operator++(any const&); | |
tag operator++(any const&,int); | |
# endif | |
# if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3202)) \ | |
|| BOOST_WORKAROUND(BOOST_MSVC, <= 1300) | |
# define BOOST_comma(a,b) (a) | |
# else | |
// In case an operator++ is found that returns void, we'll use ++x,0 | |
tag operator,(tag,int); | |
# define BOOST_comma(a,b) (a,b) | |
# endif | |
# if defined(BOOST_MSVC) | |
# pragma warning(push) | |
# pragma warning(disable:4913) // Warning about operator, | |
# endif | |
// two check overloads help us identify which operator++ was picked | |
char (& check_(tag) )[2]; | |
template <class T> | |
char check_(T const&); | |
template <class T> | |
struct impl | |
{ | |
static typename boost::remove_cv<T>::type& x; | |
BOOST_STATIC_CONSTANT( | |
bool | |
, value = sizeof(is_incrementable_::check_(BOOST_comma(++x,0))) == 1 | |
); | |
}; | |
template <class T> | |
struct postfix_impl | |
{ | |
static typename boost::remove_cv<T>::type& x; | |
BOOST_STATIC_CONSTANT( | |
bool | |
, value = sizeof(is_incrementable_::check_(BOOST_comma(x++,0))) == 1 | |
); | |
}; | |
# if defined(BOOST_MSVC) | |
# pragma warning(pop) | |
# endif | |
} | |
# undef BOOST_comma | |
template<typename T> | |
struct is_incrementable | |
BOOST_TT_AUX_BOOL_C_BASE(::boost::detail::is_incrementable_::impl<T>::value) | |
{ | |
BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(::boost::detail::is_incrementable_::impl<T>::value) | |
BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_incrementable,(T)) | |
}; | |
template<typename T> | |
struct is_postfix_incrementable | |
BOOST_TT_AUX_BOOL_C_BASE(::boost::detail::is_incrementable_::impl<T>::value) | |
{ | |
BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(::boost::detail::is_incrementable_::postfix_impl<T>::value) | |
BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_postfix_incrementable,(T)) | |
}; | |
} // namespace detail | |
BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(1, ::boost::detail::is_incrementable) | |
BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(1, ::boost::detail::is_postfix_incrementable) | |
} // namespace boost | |
# include <boost/type_traits/detail/bool_trait_undef.hpp> | |
#endif // IS_INCREMENTABLE_DWA200415_HPP |