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   attr.hpp
Chris@16:  * \author Andrey Semashev
Chris@16:  * \date   21.07.2012
Chris@16:  *
Chris@16:  * The header contains implementation of a generic attribute placeholder in template expressions.
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_LOG_EXPRESSIONS_ATTR_HPP_INCLUDED_
Chris@16: #define BOOST_LOG_EXPRESSIONS_ATTR_HPP_INCLUDED_
Chris@16: 
Chris@16: #include <boost/mpl/bool.hpp>
Chris@16: #include <boost/utility/result_of.hpp>
Chris@16: #include <boost/phoenix/core/actor.hpp>
Chris@16: #include <boost/phoenix/core/terminal_fwd.hpp>
Chris@16: #include <boost/phoenix/core/is_nullary.hpp>
Chris@16: #include <boost/phoenix/core/environment.hpp>
Chris@16: #include <boost/fusion/sequence/intrinsic/at_c.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@101: #include <boost/log/detail/copy_cv.hpp>
Chris@16: #include <boost/log/detail/custom_terminal_spec.hpp>
Chris@16: #include <boost/log/attributes/attribute_name.hpp>
Chris@16: #include <boost/log/attributes/value_extraction.hpp>
Chris@16: #include <boost/log/attributes/fallback_policy.hpp>
Chris@16: #include <boost/log/expressions/attr_fwd.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: namespace expressions {
Chris@16: 
Chris@16: /*!
Chris@16:  * An attribute value extraction terminal
Chris@16:  */
Chris@16: template< typename T, typename FallbackPolicyT, typename TagT >
Chris@16: class attribute_terminal
Chris@16: {
Chris@16: private:
Chris@16:     //! Value extractor type
Chris@16:     typedef value_extractor< T, FallbackPolicyT, TagT > value_extractor_type;
Chris@16:     //! Self type
Chris@16:     typedef attribute_terminal< T, FallbackPolicyT, TagT > this_type;
Chris@16: 
Chris@16: public:
Chris@16:     //! Internal typedef for type categorization
Chris@16:     typedef void _is_boost_log_terminal;
Chris@16: 
Chris@16:     //! Attribute tag type
Chris@16:     typedef TagT tag_type;
Chris@16:     //! Attribute value type
Chris@16:     typedef typename value_extractor_type::value_type value_type;
Chris@16:     //! Fallback policy type
Chris@16:     typedef typename value_extractor_type::fallback_policy fallback_policy;
Chris@16: 
Chris@16:     //! Function result type
Chris@16:     template< typename >
Chris@16:     struct result;
Chris@16: 
Chris@101:     template< typename ThisT, typename ContextT >
Chris@101:     struct result< ThisT(ContextT) >
Chris@16:     {
Chris@16:         typedef typename remove_cv<
Chris@16:             typename remove_reference< typename phoenix::result_of::env< ContextT >::type >::type
Chris@16:         >::type env_type;
Chris@16:         typedef typename env_type::args_type args_type;
Chris@101:         typedef typename boost::log::aux::copy_cv< ThisT, value_extractor_type >::type cv_value_extractor_type;
Chris@16: 
Chris@101:         typedef typename boost::result_of< cv_value_extractor_type(attribute_name const&, typename fusion::result_of::at_c< args_type, 0 >::type) >::type type;
Chris@16:     };
Chris@16: 
Chris@16: private:
Chris@16:     //! Attribute value name
Chris@16:     const attribute_name m_name;
Chris@16:     //! Attribute value extractor
Chris@16:     value_extractor_type m_value_extractor;
Chris@16: 
Chris@16: public:
Chris@16:     /*!
Chris@16:      * Initializing constructor
Chris@16:      */
Chris@16:     explicit attribute_terminal(attribute_name const& name) : m_name(name)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * Initializing constructor
Chris@16:      */
Chris@16:     template< typename U >
Chris@16:     attribute_terminal(attribute_name const& name, U const& arg) : m_name(name), m_value_extractor(arg)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * \returns Attribute value name
Chris@16:      */
Chris@16:     attribute_name get_name() const
Chris@16:     {
Chris@16:         return m_name;
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * \returns Fallback policy
Chris@16:      */
Chris@16:     fallback_policy const& get_fallback_policy() const
Chris@16:     {
Chris@16:         return m_value_extractor.get_fallback_policy();
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * The operator extracts attribute value
Chris@16:      */
Chris@16:     template< typename ContextT >
Chris@16:     typename result< this_type(ContextT const&) >::type
Chris@16:     operator() (ContextT const& ctx)
Chris@16:     {
Chris@16:         return m_value_extractor(m_name, fusion::at_c< 0 >(phoenix::env(ctx).args()));
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * The operator extracts attribute value
Chris@16:      */
Chris@16:     template< typename ContextT >
Chris@16:     typename result< const this_type(ContextT const&) >::type
Chris@16:     operator() (ContextT const& ctx) const
Chris@16:     {
Chris@16:         return m_value_extractor(m_name, fusion::at_c< 0 >(phoenix::env(ctx).args()));
Chris@16:     }
Chris@16: 
Chris@16:     BOOST_DELETED_FUNCTION(attribute_terminal())
Chris@16: };
Chris@16: 
Chris@16: /*!
Chris@16:  * An attribute value extraction terminal actor
Chris@16:  */
Chris@16: template< typename T, typename FallbackPolicyT, typename TagT, template< typename > class ActorT >
Chris@16: class attribute_actor :
Chris@16:     public ActorT< attribute_terminal< T, FallbackPolicyT, TagT > >
Chris@16: {
Chris@16: public:
Chris@16:     //! Attribute tag type
Chris@16:     typedef TagT tag_type;
Chris@16:     //! Fallback policy
Chris@16:     typedef FallbackPolicyT fallback_policy;
Chris@16:     //! Base terminal type
Chris@16:     typedef attribute_terminal< T, fallback_policy, tag_type > terminal_type;
Chris@16:     //! Attribute value type
Chris@16:     typedef typename terminal_type::value_type value_type;
Chris@16: 
Chris@16:     //! Base actor type
Chris@16:     typedef ActorT< terminal_type > base_type;
Chris@16: 
Chris@16: public:
Chris@16:     //! Initializing constructor
Chris@16:     explicit attribute_actor(base_type const& act) : base_type(act)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * \returns The attribute name
Chris@16:      */
Chris@16:     attribute_name get_name() const
Chris@16:     {
Chris@16:         return this->proto_expr_.child0.get_name();
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * \returns Fallback policy
Chris@16:      */
Chris@16:     fallback_policy const& get_fallback_policy() const
Chris@16:     {
Chris@16:         return this->proto_expr_.child0.get_fallback_policy();
Chris@16:     }
Chris@16: 
Chris@16:     //! Expression with cached attribute name
Chris@16:     typedef attribute_actor< value_type, fallback_to_none, tag_type, ActorT > or_none_result_type;
Chris@16: 
Chris@16:     //! Generates an expression that extracts the attribute value or a default value
Chris@16:     or_none_result_type or_none() const
Chris@16:     {
Chris@16:         typedef typename or_none_result_type::terminal_type result_terminal;
Chris@16:         typename or_none_result_type::base_type act = {{ result_terminal(get_name()) }};
Chris@16:         return or_none_result_type(act);
Chris@16:     }
Chris@16: 
Chris@16:     //! Expression with cached attribute name
Chris@16:     typedef attribute_actor< value_type, fallback_to_throw, tag_type, ActorT > or_throw_result_type;
Chris@16: 
Chris@16:     //! Generates an expression that extracts the attribute value or throws an exception
Chris@16:     or_throw_result_type or_throw() const
Chris@16:     {
Chris@16:         typedef typename or_throw_result_type::terminal_type result_terminal;
Chris@16:         typename or_throw_result_type::base_type act = {{ result_terminal(get_name()) }};
Chris@16:         return or_throw_result_type(act);
Chris@16:     }
Chris@16: 
Chris@16:     //! Generates an expression that extracts the attribute value or a default value
Chris@16:     template< typename DefaultT >
Chris@16:     attribute_actor< value_type, fallback_to_default< DefaultT >, tag_type, ActorT > or_default(DefaultT const& def_val) const
Chris@16:     {
Chris@16:         typedef attribute_actor< value_type, fallback_to_default< DefaultT >, tag_type, ActorT > or_default_result_type;
Chris@16:         typedef typename or_default_result_type::terminal_type result_terminal;
Chris@16:         typename or_default_result_type::base_type act = {{ result_terminal(get_name(), def_val) }};
Chris@16:         return or_default_result_type(act);
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: /*!
Chris@16:  * The function generates a terminal node in a template expression. The node will extract the value of the attribute
Chris@16:  * with the specified name and type.
Chris@16:  */
Chris@16: template< typename AttributeValueT >
Chris@16: BOOST_FORCEINLINE attribute_actor< AttributeValueT > attr(attribute_name const& name)
Chris@16: {
Chris@16:     typedef attribute_actor< AttributeValueT > result_type;
Chris@16:     typedef typename result_type::terminal_type result_terminal;
Chris@16:     typename result_type::base_type act = {{ result_terminal(name) }};
Chris@16:     return result_type(act);
Chris@16: }
Chris@16: 
Chris@16: /*!
Chris@16:  * The function generates a terminal node in a template expression. The node will extract the value of the attribute
Chris@16:  * with the specified name and type.
Chris@16:  */
Chris@16: template< typename AttributeValueT, typename TagT >
Chris@16: BOOST_FORCEINLINE attribute_actor< AttributeValueT, fallback_to_none, TagT > attr(attribute_name const& name)
Chris@16: {
Chris@16:     typedef attribute_actor< AttributeValueT, fallback_to_none, TagT > result_type;
Chris@16:     typedef typename result_type::terminal_type result_terminal;
Chris@16:     typename result_type::base_type act = {{ result_terminal(name) }};
Chris@16:     return result_type(act);
Chris@16: }
Chris@16: 
Chris@16: } // namespace expressions
Chris@16: 
Chris@16: BOOST_LOG_CLOSE_NAMESPACE // namespace log
Chris@16: 
Chris@16: #ifndef BOOST_LOG_DOXYGEN_PASS
Chris@16: 
Chris@16: namespace phoenix {
Chris@16: 
Chris@16: namespace result_of {
Chris@16: 
Chris@16: template< typename T, typename FallbackPolicyT, typename TagT >
Chris@16: struct is_nullary< custom_terminal< boost::log::expressions::attribute_terminal< T, FallbackPolicyT, TagT > > > :
Chris@16:     public mpl::false_
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: } // namespace result_of
Chris@16: 
Chris@16: } // namespace phoenix
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/log/detail/footer.hpp>
Chris@16: #if defined(BOOST_LOG_EXPRESSIONS_FORMATTERS_STREAM_HPP_INCLUDED_)
Chris@16: #include <boost/log/detail/attr_output_impl.hpp>
Chris@16: #endif
Chris@16: 
Chris@16: #endif // BOOST_LOG_EXPRESSIONS_ATTR_HPP_INCLUDED_