is_const_member.hpp

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/*
 
@Copyright Barrett Adair 2015-2017
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
 
*/
 
#ifndef BOOST_CLBL_TRTS_IS_CONST_MEMBER_HPP
#define BOOST_CLBL_TRTS_IS_CONST_MEMBER_HPP
 
#include <boost/callable_traits/detail/core.hpp>
 
namespace boost { namespace callable_traits {
 
//[ is_const_member_hpp
/*`[section:ref_is_const_member is_const_member]
[heading Header]
``#include <boost/callable_traits/is_const_member.hpp>``
[heading Definition]
*/
 
// inherits from either std::true_type or std::false_type
template<typename T>
struct is_const_member;
 
//<-
template<typename T>
struct is_const_member
    : detail::traits<detail::shallow_decay<T>>::is_const_member {
    using type = typename detail::traits<
        detail::shallow_decay<T>>::is_const_member;
};
 
#ifdef BOOST_CLBL_TRTS_DISABLE_VARIABLE_TEMPLATES
 
template<typename T>
struct is_const_member_v {
    static_assert(std::is_same<T, detail::dummy>::value,
        "Variable templates not supported on this compiler.");
};
 
#else
//->
// only available when variable templates are supported
template<typename T>
//<-
BOOST_CLBL_TRAITS_INLINE_VAR
//->
constexpr bool is_const_member_v = //see below
//<-
    detail::traits<detail::shallow_decay<T>>::is_const_member::value;
 
#endif
 
}} // namespace boost::callable_traits
//->
 
/*`
[heading Constraints]
* none
 
[heading Behavior]
* `is_const_member<T>::value` is `true` when either:
  * `T` is a function type with a `const` member qualifier
  * `T` is a pointer to a member function with a `const` member qualifier
  * `T` is a function object with a non-overloaded `operator()`, where the `operator()` has a `const` member qualifier
* On compilers that support variable templates, `is_const_member_v<T>` is equivalent to `is_const_member<T>::value`.
 
[heading Input/Output Examples]
[table
    [[`T`]                              [`is_const_member_v<T>`]]
    [[`int() const`]                    [`true`]]
    [[`int() const volatile`]           [`true`]]
    [[`int() const & transaction_safe`] [`true`]]
    [[`int() const &&`]                 [`true`]]
    [[`int(foo::*&)() const`]           [`true`]]
    [[`int(foo::*)() const volatile`]   [`true`]]
    [[`int(foo::*)() const volatile &&`][`true`]]
    [[`int(foo::* const)() const`]      [`true`]]
    [[`int()`]                          [`false`]]
    [[`int() volatile`]                 [`false`]]
    [[`int() &&`]                       [`false`]]
    [[`int(*)()`]                       [`false`]]
    [[`int`]                            [`false`]]
    [[`int foo::*`]                     [`false`]]
    [[`const int foo::*`]               [`false`]]
]
 
[heading Example Program]
[import ../example/is_const_member.cpp]
[is_const_member]
[endsect]
*/
//]
 
#endif // #ifndef BOOST_CLBL_TRTS_IS_CONST_MEMBER_HPP