boost/type_traits/is_const.hpp
// (C) Copyright Dave Abrahams, Steve Cleary, Beman Dawes,
// Howard Hinnant and John Maddock 2000.
// (C) Copyright Mat Marcus, Jesse Jones and Adobe Systems Inc 2001
// Use, modification and distribution are 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).
//
// See http://www.boost.org/libs/type_traits for most recent version including documentation.
// Fixed is_pointer, is_reference, is_const, is_volatile, is_same,
// is_member_pointer based on the Simulated Partial Specialization work
// of Mat Marcus and Jesse Jones. See http://opensource.adobe.com or
// http://groups.yahoo.com/group/boost/message/5441
// Some workarounds in here use ideas suggested from "Generic<Programming>:
// Mappings between Types and Values"
// by Andrei Alexandrescu (see http://www.cuj.com/experts/1810/alexandr.html).
#ifndef BOOST_TT_IS_CONST_HPP_INCLUDED
#define BOOST_TT_IS_CONST_HPP_INCLUDED
#include <boost/config.hpp>
#include <boost/detail/workaround.hpp>
#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
# include <boost/type_traits/detail/cv_traits_impl.hpp>
# ifdef __GNUC__
# include <boost/type_traits/is_reference.hpp>
# endif
# if BOOST_WORKAROUND(BOOST_MSVC, < 1400)
# include <boost/type_traits/remove_bounds.hpp>
# endif
#else
# include <boost/type_traits/is_reference.hpp>
# include <boost/type_traits/is_array.hpp>
# include <boost/type_traits/detail/yes_no_type.hpp>
# include <boost/type_traits/detail/false_result.hpp>
#endif
// should be the last #include
#include <boost/type_traits/detail/bool_trait_def.hpp>
namespace boost {
#if defined( __CODEGEARC__ )
BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_const,T,__is_const(T))
#elif !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
namespace detail{
//
// We can't filter out rvalue_references at the same level as
// references or we get ambiguities from msvc:
//
template <class T>
struct is_const_rvalue_filter
{
#if BOOST_WORKAROUND(BOOST_MSVC, < 1400)
BOOST_STATIC_CONSTANT(bool, value = ::boost::detail::cv_traits_imp<typename boost::remove_bounds<T>::type*>::is_const);
#else
BOOST_STATIC_CONSTANT(bool, value = ::boost::detail::cv_traits_imp<T*>::is_const);
#endif
};
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <class T>
struct is_const_rvalue_filter<T&&>
{
BOOST_STATIC_CONSTANT(bool, value = false);
};
#endif
}
//* is a type T declared const - is_const<T>
BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_const,T,::boost::detail::is_const_rvalue_filter<T>::value)
BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_const,T&,false)
#if defined(BOOST_ILLEGAL_CV_REFERENCES)
// these are illegal specialisations; cv-qualifies applied to
// references have no effect according to [8.3.2p1],
// C++ Builder requires them though as it treats cv-qualified
// references as distinct types...
BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_const,T& const,false)
BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_const,T& volatile,false)
BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_const,T& const volatile,false)
#endif
#if defined(__GNUC__) && (__GNUC__ < 3)
// special case for gcc where illegally cv-qualified reference types can be
// generated in some corner cases:
BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_const,T const,!(::boost::is_reference<T>::value))
BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_const,T volatile const,!(::boost::is_reference<T>::value))
#endif
#else
namespace detail {
using ::boost::type_traits::yes_type;
using ::boost::type_traits::no_type;
yes_type is_const_tester(const volatile void*);
no_type is_const_tester(volatile void *);
template <bool is_ref, bool array>
struct is_const_helper
: public ::boost::type_traits::false_result
{
};
template <>
struct is_const_helper<false,false>
{
template <typename T> struct result_
{
static T* t;
BOOST_STATIC_CONSTANT(bool, value = (
sizeof(boost::detail::yes_type) == sizeof(boost::detail::is_const_tester(t))
));
};
};
template <>
struct is_const_helper<false,true>
{
template <typename T> struct result_
{
static T t;
BOOST_STATIC_CONSTANT(bool, value = (
sizeof(boost::detail::yes_type) == sizeof(boost::detail::is_const_tester(&t))
));
};
};
template <typename T>
struct is_const_impl
: public is_const_helper<
is_reference<T>::value
, is_array<T>::value
>::template result_<T>
{
};
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_const,void,false)
#ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_const,void const,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_const,void volatile,false)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_const,void const volatile,true)
#endif
} // namespace detail
//* is a type T declared const - is_const<T>
BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_const,T,::boost::detail::is_const_impl<T>::value)
#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
} // namespace boost
#include <boost/type_traits/detail/bool_trait_undef.hpp>
#endif // BOOST_TT_IS_CONST_HPP_INCLUDED