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   add_value.hpp
Chris@16:  * \author Andrey Semashev
Chris@16:  * \date   26.11.2012
Chris@16:  *
Chris@16:  * This header contains the \c add_value manipulator.
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_LOG_UTILITY_MANIPULATORS_ADD_VALUE_HPP_INCLUDED_
Chris@16: #define BOOST_LOG_UTILITY_MANIPULATORS_ADD_VALUE_HPP_INCLUDED_
Chris@16: 
Chris@101: #include <boost/mpl/if.hpp>
Chris@101: #include <boost/type_traits/is_scalar.hpp>
Chris@16: #include <boost/type_traits/remove_cv.hpp>
Chris@16: #include <boost/type_traits/remove_reference.hpp>
Chris@16: #include <boost/log/detail/config.hpp>
Chris@16: #include <boost/log/detail/embedded_string_type.hpp>
Chris@16: #include <boost/log/attributes/attribute_name.hpp>
Chris@16: #include <boost/log/attributes/attribute_value_impl.hpp>
Chris@16: #include <boost/log/expressions/keyword_fwd.hpp>
Chris@16: #include <boost/log/sources/record_ostream.hpp>
Chris@16: #include <boost/log/detail/header.hpp>
Chris@16: 
Chris@16: #ifdef BOOST_HAS_PRAGMA_ONCE
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #ifdef _MSC_VER
Chris@16: #pragma warning(push)
Chris@16: // 'boost::log::v2s_mt_nt6::add_value_manip<RefT>::m_value' : reference member is initialized to a temporary that doesn't persist after the constructor exits
Chris@16: // This is intentional since the manipulator can be used with a temporary, which will be used before the streaming expression ends and it is destroyed.
Chris@16: #pragma warning(disable: 4413)
Chris@16: // returning address of local variable or temporary
Chris@16: // This warning refers to add_value_manip<RefT>::get_value() when RefT is an rvalue reference. We store the reference in the manipulator and we intend to return it as is.
Chris@16: #pragma warning(disable: 4172)
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: BOOST_LOG_OPEN_NAMESPACE
Chris@16: 
Chris@16: //! Attribute value manipulator
Chris@16: template< typename RefT >
Chris@16: class add_value_manip
Chris@16: {
Chris@16: public:
Chris@16:     //! Stored reference type
Chris@16:     typedef RefT reference_type;
Chris@16:     //! Attribute value type
Chris@16:     typedef typename remove_cv< typename remove_reference< reference_type >::type >::type value_type;
Chris@16: 
Chris@16: private:
Chris@101:     //  The stored reference type is an lvalue reference since apparently different compilers (GCC and MSVC) have different quirks when rvalue references are stored as members.
Chris@101:     //  Additionally, MSVC (at least 11.0) has a bug which causes a dangling reference to be stored in the manipulator, if a scalar rvalue is passed to the add_value generator.
Chris@101:     //  To work around this problem we save the value inside the manipulator in this case.
Chris@101:     typedef typename remove_reference< reference_type >::type& lvalue_reference_type;
Chris@101: 
Chris@101:     typedef typename mpl::if_<
Chris@101:         is_scalar< value_type >,
Chris@101:         value_type,
Chris@101:         lvalue_reference_type
Chris@101:     >::type stored_type;
Chris@101: 
Chris@101:     typedef typename mpl::if_<
Chris@101:         is_scalar< value_type >,
Chris@101:         value_type,
Chris@101:         reference_type
Chris@101:     >::type get_value_result_type;
Chris@16: 
Chris@16: private:
Chris@16:     //! Attribute value
Chris@101:     stored_type m_value;
Chris@16:     //! Attribute name
Chris@16:     attribute_name m_name;
Chris@16: 
Chris@16: public:
Chris@16:     //! Initializing constructor
Chris@101:     add_value_manip(attribute_name const& name, reference_type value) : m_value(static_cast< lvalue_reference_type >(value)), m_name(name)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     //! Returns attribute name
Chris@16:     attribute_name get_name() const { return m_name; }
Chris@16:     //! Returns attribute value
Chris@101:     get_value_result_type get_value() const { return static_cast< get_value_result_type >(m_value); }
Chris@16: };
Chris@16: 
Chris@16: //! The operator attaches an attribute value to the log record
Chris@16: template< typename CharT, typename RefT >
Chris@16: inline basic_record_ostream< CharT >& operator<< (basic_record_ostream< CharT >& strm, add_value_manip< RefT > const& manip)
Chris@16: {
Chris@16:     typedef typename aux::make_embedded_string_type< typename add_value_manip< RefT >::value_type >::type value_type;
Chris@16:     attribute_value value(new attributes::attribute_value_impl< value_type >(manip.get_value()));
Chris@16:     strm.get_record().attribute_values().insert(manip.get_name(), value);
Chris@16:     return strm;
Chris@16: }
Chris@16: 
Chris@16: //! The function creates a manipulator that attaches an attribute value to a log record
Chris@101: #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
Chris@16: 
Chris@16: template< typename T >
Chris@16: inline add_value_manip< T&& > add_value(attribute_name const& name, T&& value)
Chris@16: {
Chris@16:     return add_value_manip< T&& >(name, static_cast< T&& >(value));
Chris@16: }
Chris@16: 
Chris@16: //! \overload
Chris@16: template< typename DescriptorT, template< typename > class ActorT >
Chris@16: inline add_value_manip< typename DescriptorT::value_type&& >
Chris@16: add_value(expressions::attribute_keyword< DescriptorT, ActorT > const&, typename DescriptorT::value_type&& value)
Chris@16: {
Chris@16:     typedef typename DescriptorT::value_type value_type;
Chris@16:     return add_value_manip< value_type&& >(DescriptorT::get_name(), static_cast< value_type&& >(value));
Chris@16: }
Chris@16: 
Chris@16: //! \overload
Chris@16: template< typename DescriptorT, template< typename > class ActorT >
Chris@16: inline add_value_manip< typename DescriptorT::value_type& >
Chris@16: add_value(expressions::attribute_keyword< DescriptorT, ActorT > const&, typename DescriptorT::value_type& value)
Chris@16: {
Chris@16:     return add_value_manip< typename DescriptorT::value_type& >(DescriptorT::get_name(), value);
Chris@16: }
Chris@16: 
Chris@101: //! \overload
Chris@101: template< typename DescriptorT, template< typename > class ActorT >
Chris@101: inline add_value_manip< typename DescriptorT::value_type const& >
Chris@101: add_value(expressions::attribute_keyword< DescriptorT, ActorT > const&, typename DescriptorT::value_type const& value)
Chris@101: {
Chris@101:     return add_value_manip< typename DescriptorT::value_type const& >(DescriptorT::get_name(), value);
Chris@101: }
Chris@101: 
Chris@101: #else // !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
Chris@16: 
Chris@16: template< typename T >
Chris@16: inline add_value_manip< T const& > add_value(attribute_name const& name, T const& value)
Chris@16: {
Chris@16:     return add_value_manip< T const& >(name, value);
Chris@16: }
Chris@16: 
Chris@16: template< typename DescriptorT, template< typename > class ActorT >
Chris@16: inline add_value_manip< typename DescriptorT::value_type const& >
Chris@16: add_value(expressions::attribute_keyword< DescriptorT, ActorT > const&, typename DescriptorT::value_type const& value)
Chris@16: {
Chris@16:     return add_value_manip< typename DescriptorT::value_type const& >(DescriptorT::get_name(), value);
Chris@16: }
Chris@16: 
Chris@101: #endif // !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
Chris@16: 
Chris@16: BOOST_LOG_CLOSE_NAMESPACE // namespace log
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #ifdef _MSC_VER
Chris@16: #pragma warning(pop)
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/log/detail/footer.hpp>
Chris@16: 
Chris@16: #endif // BOOST_LOG_UTILITY_MANIPULATORS_ADD_VALUE_HPP_INCLUDED_