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 attribute_cast.hpp
9 * \author Andrey Semashev
10 * \date 06.08.2010
11 *
12 * The header contains utilities for casting between attribute factories.
13 */
14
15#ifndef BOOST_LOG_ATTRIBUTES_ATTRIBUTE_CAST_HPP_INCLUDED_
16#define BOOST_LOG_ATTRIBUTES_ATTRIBUTE_CAST_HPP_INCLUDED_
17
18#include <boost/log/detail/config.hpp>
19#include <boost/log/attributes/attribute.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 attributes {
31
32/*!
33 * The class holds a reference to the attribute factory implementation being casted
34 */
35class cast_source
36{
37private:
38 attribute::impl* m_pImpl;
39
40public:
41 /*!
42 * Initializing constructor. Creates a source that refers to the specified factory implementation.
43 */
44 explicit cast_source(attribute::impl* p) : m_pImpl(p)
45 {
46 }
47
48 /*!
49 * The function attempts to cast the aggregated pointer to the implementation to the specified type.
50 *
51 * \return The converted pointer or \c NULL, if the conversion fails.
52 */
53 template< typename T >
54 T* as() const { return dynamic_cast< T* >(m_pImpl); }
55};
56
57} // namespace attributes
58
59/*!
60 * The function casts one attribute factory to another
61 */
62template< typename T >
63inline T attribute_cast(attribute const& attr)
64{
65 return T(attributes::cast_source(attr.get_impl()));
66}
67
68BOOST_LOG_CLOSE_NAMESPACE // namespace log
69
70} // namespace boost
71
72#include <boost/log/detail/footer.hpp>
73
74#endif // BOOST_LOG_ATTRIBUTES_ATTRIBUTE_CAST_HPP_INCLUDED_
75

source code of boost/libs/log/include/boost/log/attributes/attribute_cast.hpp