ceph/src/boost/libs/log/include/boost/log/utility/manipulators/add_value.hpp

   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   add_value.hpp
   9  * \author Andrey Semashev
  10  * \date   26.11.2012
  11  *
  12  * This header contains the \c add_value manipulator.
  13  */
  14
  15 #ifndef BOOST_LOG_UTILITY_MANIPULATORS_ADD_VALUE_HPP_INCLUDED_
  16 #define BOOST_LOG_UTILITY_MANIPULATORS_ADD_VALUE_HPP_INCLUDED_
  17
  18 #include <boost/mpl/if.hpp>
  19 #include <boost/type_traits/is_scalar.hpp>
  20 #include <boost/type_traits/remove_cv.hpp>
  21 #include <boost/type_traits/remove_reference.hpp>
  22 #include <boost/log/detail/config.hpp>
  23 #include <boost/log/detail/embedded_string_type.hpp>
  24 #include <boost/log/attributes/attribute_name.hpp>
  25 #include <boost/log/attributes/attribute_value_impl.hpp>
  26 #include <boost/log/expressions/keyword_fwd.hpp>
  27 #include <boost/log/sources/record_ostream.hpp>
  28 #include <boost/log/detail/header.hpp>
  29
  30 #ifdef BOOST_HAS_PRAGMA_ONCE
  31 #pragma once
  32 #endif
  33
  34 #ifdef _MSC_VER
  35 #pragma warning(push)
  36 // '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
  37 // 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.
  38 #pragma warning(disable: 4413)
  39 // returning address of local variable or temporary
  40 // 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.
  41 #pragma warning(disable: 4172)
  42 #endif
  43
  44 namespace boost {
  45
  46 BOOST_LOG_OPEN_NAMESPACE
  47
  48 //! Attribute value manipulator
  49 template< typename RefT >
  50 class add_value_manip
  51 {
  52 public:
  53     //! Stored reference type
  54     typedef RefT reference_type;
  55     //! Attribute value type
  56     typedef typename remove_cv< typename remove_reference< reference_type >::type >::type value_type;
  57
  58 private:
  59     //  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.
  60     //  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.
  61     //  To work around this problem we save the value inside the manipulator in this case.
  62     typedef typename remove_reference< reference_type >::type& lvalue_reference_type;
  63
  64     typedef typename mpl::if_<
  65         is_scalar< value_type >,
  66         value_type,
  67         lvalue_reference_type
  68     >::type stored_type;
  69
  70     typedef typename mpl::if_<
  71         is_scalar< value_type >,
  72         value_type,
  73         reference_type
  74     >::type get_value_result_type;
  75
  76 private:
  77     //! Attribute value
  78     stored_type m_value;
  79     //! Attribute name
  80     attribute_name m_name;
  81
  82 public:
  83     //! Initializing constructor
  84     add_value_manip(attribute_name const& name, reference_type value) : m_value(static_cast< lvalue_reference_type >(value)), m_name(name)
  85     {
  86     }
  87
  88     //! Returns attribute name
  89     attribute_name get_name() const { return m_name; }
  90     //! Returns attribute value
  91     get_value_result_type get_value() const { return static_cast< get_value_result_type >(m_value); }
  92 };
  93
  94 //! The operator attaches an attribute value to the log record
  95 template< typename CharT, typename RefT >
  96 inline basic_record_ostream< CharT >& operator<< (basic_record_ostream< CharT >& strm, add_value_manip< RefT > const& manip)
  97 {
  98     typedef typename aux::make_embedded_string_type< typename add_value_manip< RefT >::value_type >::type value_type;
  99     attribute_value value(new attributes::attribute_value_impl< value_type >(manip.get_value()));
 100     strm.get_record().attribute_values().insert(manip.get_name(), value);
 101     return strm;
 102 }
 103
 104 //! The function creates a manipulator that attaches an attribute value to a log record
 105 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
 106
 107 template< typename T >
 108 inline add_value_manip< T&& > add_value(attribute_name const& name, T&& value)
 109 {
 110     return add_value_manip< T&& >(name, static_cast< T&& >(value));
 111 }
 112
 113 //! \overload
 114 template< typename DescriptorT, template< typename > class ActorT >
 115 inline add_value_manip< typename DescriptorT::value_type&& >
 116 add_value(expressions::attribute_keyword< DescriptorT, ActorT > const&, typename DescriptorT::value_type&& value)
 117 {
 118     typedef typename DescriptorT::value_type value_type;
 119     return add_value_manip< value_type&& >(DescriptorT::get_name(), static_cast< value_type&& >(value));
 120 }
 121
 122 //! \overload
 123 template< typename DescriptorT, template< typename > class ActorT >
 124 inline add_value_manip< typename DescriptorT::value_type& >
 125 add_value(expressions::attribute_keyword< DescriptorT, ActorT > const&, typename DescriptorT::value_type& value)
 126 {
 127     return add_value_manip< typename DescriptorT::value_type& >(DescriptorT::get_name(), value);
 128 }
 129
 130 //! \overload
 131 template< typename DescriptorT, template< typename > class ActorT >
 132 inline add_value_manip< typename DescriptorT::value_type const& >
 133 add_value(expressions::attribute_keyword< DescriptorT, ActorT > const&, typename DescriptorT::value_type const& value)
 134 {
 135     return add_value_manip< typename DescriptorT::value_type const& >(DescriptorT::get_name(), value);
 136 }
 137
 138 #else // !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
 139
 140 template< typename T >
 141 inline add_value_manip< T const& > add_value(attribute_name const& name, T const& value)
 142 {
 143     return add_value_manip< T const& >(name, value);
 144 }
 145
 146 template< typename DescriptorT, template< typename > class ActorT >
 147 inline add_value_manip< typename DescriptorT::value_type const& >
 148 add_value(expressions::attribute_keyword< DescriptorT, ActorT > const&, typename DescriptorT::value_type const& value)
 149 {
 150     return add_value_manip< typename DescriptorT::value_type const& >(DescriptorT::get_name(), value);
 151 }
 152
 153 #endif // !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
 154
 155 BOOST_LOG_CLOSE_NAMESPACE // namespace log
 156
 157 } // namespace boost
 158
 159 #ifdef _MSC_VER
 160 #pragma warning(pop)
 161 #endif
 162
 163 #include <boost/log/detail/footer.hpp>
 164
 165 #endif // BOOST_LOG_UTILITY_MANIPULATORS_ADD_VALUE_HPP_INCLUDED_