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   attribute.hpp
Chris@16:  * \author Andrey Semashev
Chris@16:  * \date   15.04.2007
Chris@16:  *
Chris@16:  * The header contains attribute interface definition.
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_LOG_ATTRIBUTES_ATTRIBUTE_HPP_INCLUDED_
Chris@16: #define BOOST_LOG_ATTRIBUTES_ATTRIBUTE_HPP_INCLUDED_
Chris@16: 
Chris@16: #include <new>
Chris@16: #include <boost/move/core.hpp>
Chris@16: #include <boost/smart_ptr/intrusive_ptr.hpp>
Chris@16: #include <boost/smart_ptr/intrusive_ref_counter.hpp>
Chris@16: #include <boost/log/detail/config.hpp>
Chris@16: #include <boost/utility/explicit_operator_bool.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: namespace boost {
Chris@16: 
Chris@16: BOOST_LOG_OPEN_NAMESPACE
Chris@16: 
Chris@16: #ifndef BOOST_LOG_DOXYGEN_PASS
Chris@16: 
Chris@16: class attribute_value;
Chris@16: 
Chris@16: namespace aux {
Chris@16: 
Chris@16: //! Reference proxy object to implement \c operator[]
Chris@16: class attribute_set_reference_proxy;
Chris@16: 
Chris@16: } // namespace aux
Chris@16: 
Chris@16: #endif // BOOST_LOG_DOXYGEN_PASS
Chris@16: 
Chris@16: /*!
Chris@16:  * \brief A base class for an attribute value factory
Chris@16:  *
Chris@16:  * Every attribute is represented with a factory that is basically an attribute value generator.
Chris@16:  * The sole purpose of an attribute is to return an actual value when requested. A simplest attribute
Chris@16:  * can always return the same value that it stores internally, but more complex ones can
Chris@16:  * perform a considerable amount of work to return a value, and the returned values may differ
Chris@16:  * each time requested.
Chris@16:  *
Chris@16:  * A word about thread safety. An attribute should be prepared to be requested a value from
Chris@16:  * multiple threads concurrently.
Chris@16:  */
Chris@16: class attribute
Chris@16: {
Chris@16:     BOOST_COPYABLE_AND_MOVABLE(attribute)
Chris@16: 
Chris@16: public:
Chris@16:     /*!
Chris@16:      * \brief A base class for an attribute value factory
Chris@16:      *
Chris@16:      * All attributes must derive their implementation from this class.
Chris@16:      */
Chris@16:     struct BOOST_LOG_NO_VTABLE BOOST_SYMBOL_VISIBLE impl :
Chris@16:         public boost::intrusive_ref_counter< impl >
Chris@16:     {
Chris@16:         /*!
Chris@16:          * \brief Virtual destructor
Chris@16:          */
Chris@16:         virtual ~impl() {}
Chris@16: 
Chris@16:         /*!
Chris@16:          * \return The actual attribute value. It shall not return empty values (exceptions
Chris@16:          *         shall be used to indicate errors).
Chris@16:          */
Chris@16:         virtual attribute_value get_value() = 0;
Chris@16: 
Chris@16:         BOOST_LOG_API static void* operator new (std::size_t size);
Chris@16:         BOOST_LOG_API static void operator delete (void* p, std::size_t size) BOOST_NOEXCEPT;
Chris@16:     };
Chris@16: 
Chris@16: private:
Chris@16:     //! Pointer to the attribute factory implementation
Chris@16:     intrusive_ptr< impl > m_pImpl;
Chris@16: 
Chris@16: public:
Chris@16:     /*!
Chris@16:      * Default constructor. Creates an empty attribute value factory, which is not usable until
Chris@16:      * \c set_impl is called.
Chris@16:      */
Chris@16:     BOOST_DEFAULTED_FUNCTION(attribute(), {})
Chris@16: 
Chris@16:     /*!
Chris@16:      * Copy constructor
Chris@16:      */
Chris@16:     attribute(attribute const& that) BOOST_NOEXCEPT : m_pImpl(that.m_pImpl) {}
Chris@16: 
Chris@16:     /*!
Chris@16:      * Move constructor
Chris@16:      */
Chris@16:     attribute(BOOST_RV_REF(attribute) that) BOOST_NOEXCEPT { m_pImpl.swap(that.m_pImpl); }
Chris@16: 
Chris@16:     /*!
Chris@16:      * Initializing constructor
Chris@16:      *
Chris@16:      * \param p Pointer to the implementation. Must not be \c NULL.
Chris@16:      */
Chris@16:     explicit attribute(intrusive_ptr< impl > p) BOOST_NOEXCEPT { m_pImpl.swap(p); }
Chris@16: 
Chris@16:     /*!
Chris@16:      * Copy assignment
Chris@16:      */
Chris@16:     attribute& operator= (BOOST_COPY_ASSIGN_REF(attribute) that) BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         m_pImpl = that.m_pImpl;
Chris@16:         return *this;
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * Move assignment
Chris@16:      */
Chris@16:     attribute& operator= (BOOST_RV_REF(attribute) that) BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         m_pImpl.swap(that.m_pImpl);
Chris@16:         return *this;
Chris@16:     }
Chris@16: 
Chris@16: #ifndef BOOST_LOG_DOXYGEN_PASS
Chris@16:     attribute& operator= (aux::attribute_set_reference_proxy const& that) BOOST_NOEXCEPT;
Chris@16: #endif
Chris@16: 
Chris@16:     /*!
Chris@16:      * Verifies that the factory is not in empty state
Chris@16:      */
Chris@101:     BOOST_EXPLICIT_OPERATOR_BOOL_NOEXCEPT()
Chris@16: 
Chris@16:     /*!
Chris@16:      * Verifies that the factory is in empty state
Chris@16:      */
Chris@16:     bool operator! () const BOOST_NOEXCEPT { return !m_pImpl; }
Chris@16: 
Chris@16:     /*!
Chris@16:      * \return The actual attribute value. It shall not return empty values (exceptions
Chris@16:      *         shall be used to indicate errors).
Chris@16:      */
Chris@16:     attribute_value get_value() const;
Chris@16: 
Chris@16:     /*!
Chris@16:      * The method swaps two factories (i.e. their implementations).
Chris@16:      */
Chris@16:     void swap(attribute& that) BOOST_NOEXCEPT { m_pImpl.swap(that.m_pImpl); }
Chris@16: 
Chris@16: protected:
Chris@16:     /*!
Chris@16:      * \returns The pointer to the implementation
Chris@16:      */
Chris@16:     impl* get_impl() const BOOST_NOEXCEPT { return m_pImpl.get(); }
Chris@16:     /*!
Chris@16:      * Sets the pointer to the factory implementation.
Chris@16:      *
Chris@16:      * \param p Pointer to the implementation. Must not be \c NULL.
Chris@16:      */
Chris@16:     void set_impl(intrusive_ptr< impl > p) BOOST_NOEXCEPT { m_pImpl.swap(p); }
Chris@16: 
Chris@16:     template< typename T >
Chris@16:     friend T attribute_cast(attribute const&);
Chris@16: };
Chris@16: 
Chris@16: /*!
Chris@16:  * The function swaps two attribute value factories
Chris@16:  */
Chris@16: inline void swap(attribute& left, attribute& right) BOOST_NOEXCEPT
Chris@16: {
Chris@16:     left.swap(right);
Chris@16: }
Chris@16: 
Chris@16: BOOST_LOG_CLOSE_NAMESPACE // namespace log
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/log/detail/footer.hpp>
Chris@16: #if defined(BOOST_LOG_ATTRIBUTES_ATTRIBUTE_VALUE_HPP_INCLUDED_)
Chris@16: #include <boost/log/detail/attribute_get_value_impl.hpp>
Chris@16: #endif
Chris@16: 
Chris@16: #endif // BOOST_LOG_ATTRIBUTES_ATTRIBUTE_HPP_INCLUDED_