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 26 namespace boost { 27 28 BOOST_LOG_OPEN_NAMESPACE 29 30 namespace attributes { 31 32 /*! 33 * The class holds a reference to the attribute factory implementation being casted 34 */ 35 class cast_source 36 { 37 private: 38 attribute::impl* m_pImpl; 39 40 public: 41 /*! 42 * Initializing constructor. Creates a source that refers to the specified factory implementation. 43 */ cast_source(attribute::impl * p)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 > as() const54 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 */ 62 template< typename T > attribute_cast(attribute const & attr)63inline T attribute_cast(attribute const& attr) 64 { 65 return T(attributes::cast_source(attr.get_impl())); 66 } 67 68 BOOST_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