Chris@16: /*
Chris@101:  *          Copyright Andrey Semashev 2007 - 2015.
Chris@16:  * Distributed under the Boost Software License, Version 1.0.
Chris@16:  *    (See accompanying file LICENSE_1_0.txt or copy at
Chris@16:  *          http://www.boost.org/LICENSE_1_0.txt)
Chris@16:  */
Chris@16: /*!
Chris@16:  * \file   fallback_policy_fwd.hpp
Chris@16:  * \author Andrey Semashev
Chris@16:  * \date   18.08.2012
Chris@16:  *
Chris@16:  * The header contains forward declaration of fallback policies when attribute value visitation or extraction fails.
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_LOG_ATTRIBUTES_FALLBACK_POLICY_FWD_HPP_INCLUDED_
Chris@16: #define BOOST_LOG_ATTRIBUTES_FALLBACK_POLICY_FWD_HPP_INCLUDED_
Chris@16: 
Chris@16: #include <boost/log/detail/config.hpp>
Chris@16: 
Chris@16: #ifdef BOOST_HAS_PRAGMA_ONCE
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: BOOST_LOG_OPEN_NAMESPACE
Chris@16: 
Chris@16: /*!
Chris@16:  * The \c fallback_to_none policy results in returning an empty value reference if the attribute value cannot be extracted.
Chris@16:  */
Chris@16: struct fallback_to_none;
Chris@16: 
Chris@16: /*!
Chris@16:  * The \c fallback_to_throw policy results in throwing an exception if the attribute value cannot be extracted.
Chris@16:  */
Chris@16: struct fallback_to_throw;
Chris@16: 
Chris@16: /*!
Chris@16:  * The \c fallback_to_default policy results in a default value if the attribute value cannot be extracted.
Chris@16:  */
Chris@16: template< typename DefaultT >
Chris@16: struct fallback_to_default;
Chris@16: 
Chris@16: BOOST_LOG_CLOSE_NAMESPACE // namespace log
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // BOOST_LOG_ATTRIBUTES_FALLBACK_POLICY_FWD_HPP_INCLUDED_