1/*
2 * Copyright Andrey Semashev 2007 - 2015.
3 * Distributed under the Boost Software License, Version 1.0.
4 * (See accompanying file LICENSE_1_0.txt or copy at
5 * http://www.boost.org/LICENSE_1_0.txt)
6 */
7/*!
8 * \file is_keyword_descriptor.hpp
9 * \author Andrey Semashev
10 * \date 14.07.2012
11 *
12 * The header contains attribute keyword descriptor detection trait.
13 */
14
15#ifndef BOOST_LOG_EXPRESSIONS_IS_KEYWORD_DESCRIPTOR_HPP_INCLUDED_
16#define BOOST_LOG_EXPRESSIONS_IS_KEYWORD_DESCRIPTOR_HPP_INCLUDED_
17
18#include <boost/mpl/bool.hpp>
19#include <boost/log/detail/config.hpp>
20#include <boost/log/detail/header.hpp>
21
22#ifdef BOOST_HAS_PRAGMA_ONCE
23#pragma once
24#endif
25
26namespace boost {
27
28BOOST_LOG_OPEN_NAMESPACE
29
30namespace expressions {
31
32/*!
33 * Base class for keyword descriptors. All keyword descriptors must derive from this class to support the \c is_keyword_descriptor trait.
34 */
35struct keyword_descriptor
36{
37#ifndef BOOST_LOG_DOXYGEN_PASS
38 typedef void _is_boost_log_keyword_descriptor;
39#endif // BOOST_LOG_DOXYGEN_PASS
40};
41
42/*!
43 * The metafunction detects if the type \c T is a keyword descriptor
44 */
45template< typename T, typename VoidT = void >
46struct is_keyword_descriptor :
47 public mpl::false_
48{
49};
50
51#ifndef BOOST_LOG_DOXYGEN_PASS
52template< typename T >
53struct is_keyword_descriptor< T, typename T::_is_boost_log_keyword_descriptor > :
54 public mpl::true_
55{
56};
57#endif
58
59} // namespace expressions
60
61BOOST_LOG_CLOSE_NAMESPACE // namespace log
62
63} // namespace boost
64
65#include <boost/log/detail/footer.hpp>
66
67#endif // BOOST_LOG_EXPRESSIONS_IS_KEYWORD_DESCRIPTOR_HPP_INCLUDED_
68

source code of boost/libs/log/include/boost/log/expressions/is_keyword_descriptor.hpp