135 lines
3.8 KiB
C++
135 lines
3.8 KiB
C++
// 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
|