| /* |
| * Copyright Andrey Semashev 2007 - 2015. |
| * Distributed under the Boost Software License, Version 1.0. |
| * (See accompanying file LICENSE_1_0.txt or copy at |
| * http://www.boost.org/LICENSE_1_0.txt) |
| */ |
| /*! |
| * \file attr.hpp |
| * \author Andrey Semashev |
| * \date 21.07.2012 |
| * |
| * The header contains implementation of a generic attribute placeholder in template expressions. |
| */ |
| |
| #ifndef BOOST_LOG_EXPRESSIONS_ATTR_HPP_INCLUDED_ |
| #define BOOST_LOG_EXPRESSIONS_ATTR_HPP_INCLUDED_ |
| |
| #include <boost/mpl/bool.hpp> |
| #include <boost/utility/result_of.hpp> |
| #include <boost/phoenix/core/actor.hpp> |
| #include <boost/phoenix/core/terminal_fwd.hpp> |
| #include <boost/phoenix/core/is_nullary.hpp> |
| #include <boost/phoenix/core/environment.hpp> |
| #include <boost/fusion/sequence/intrinsic/at_c.hpp> |
| #include <boost/type_traits/remove_cv.hpp> |
| #include <boost/type_traits/remove_reference.hpp> |
| #include <boost/log/detail/config.hpp> |
| #include <boost/log/detail/copy_cv.hpp> |
| #include <boost/log/detail/custom_terminal_spec.hpp> |
| #include <boost/log/attributes/attribute_name.hpp> |
| #include <boost/log/attributes/value_extraction.hpp> |
| #include <boost/log/attributes/fallback_policy.hpp> |
| #include <boost/log/expressions/attr_fwd.hpp> |
| #include <boost/log/detail/header.hpp> |
| |
| #ifdef BOOST_HAS_PRAGMA_ONCE |
| #pragma once |
| #endif |
| |
| namespace boost { |
| |
| BOOST_LOG_OPEN_NAMESPACE |
| |
| namespace expressions { |
| |
| /*! |
| * An attribute value extraction terminal |
| */ |
| template< typename T, typename FallbackPolicyT, typename TagT > |
| class attribute_terminal |
| { |
| private: |
| //! Value extractor type |
| typedef value_extractor< T, FallbackPolicyT, TagT > value_extractor_type; |
| //! Self type |
| typedef attribute_terminal< T, FallbackPolicyT, TagT > this_type; |
| |
| public: |
| //! Internal typedef for type categorization |
| typedef void _is_boost_log_terminal; |
| |
| //! Attribute tag type |
| typedef TagT tag_type; |
| //! Attribute value type |
| typedef typename value_extractor_type::value_type value_type; |
| //! Fallback policy type |
| typedef typename value_extractor_type::fallback_policy fallback_policy; |
| |
| //! Function result type |
| template< typename > |
| struct result; |
| |
| template< typename ThisT, typename ContextT > |
| struct result< ThisT(ContextT) > |
| { |
| typedef typename remove_cv< |
| typename remove_reference< typename phoenix::result_of::env< ContextT >::type >::type |
| >::type env_type; |
| typedef typename env_type::args_type args_type; |
| typedef typename boost::log::aux::copy_cv< ThisT, value_extractor_type >::type cv_value_extractor_type; |
| |
| typedef typename boost::result_of< cv_value_extractor_type(attribute_name const&, typename fusion::result_of::at_c< args_type, 0 >::type) >::type type; |
| }; |
| |
| private: |
| //! Attribute value name |
| const attribute_name m_name; |
| //! Attribute value extractor |
| value_extractor_type m_value_extractor; |
| |
| public: |
| /*! |
| * Initializing constructor |
| */ |
| explicit attribute_terminal(attribute_name const& name) : m_name(name) |
| { |
| } |
| |
| /*! |
| * Initializing constructor |
| */ |
| template< typename U > |
| attribute_terminal(attribute_name const& name, U const& arg) : m_name(name), m_value_extractor(arg) |
| { |
| } |
| |
| /*! |
| * \returns Attribute value name |
| */ |
| attribute_name get_name() const |
| { |
| return m_name; |
| } |
| |
| /*! |
| * \returns Fallback policy |
| */ |
| fallback_policy const& get_fallback_policy() const |
| { |
| return m_value_extractor.get_fallback_policy(); |
| } |
| |
| /*! |
| * The operator extracts attribute value |
| */ |
| template< typename ContextT > |
| typename result< this_type(ContextT const&) >::type |
| operator() (ContextT const& ctx) |
| { |
| return m_value_extractor(m_name, fusion::at_c< 0 >(phoenix::env(ctx).args())); |
| } |
| |
| /*! |
| * The operator extracts attribute value |
| */ |
| template< typename ContextT > |
| typename result< const this_type(ContextT const&) >::type |
| operator() (ContextT const& ctx) const |
| { |
| return m_value_extractor(m_name, fusion::at_c< 0 >(phoenix::env(ctx).args())); |
| } |
| |
| BOOST_DELETED_FUNCTION(attribute_terminal()) |
| }; |
| |
| /*! |
| * An attribute value extraction terminal actor |
| */ |
| template< typename T, typename FallbackPolicyT, typename TagT, template< typename > class ActorT > |
| class attribute_actor : |
| public ActorT< attribute_terminal< T, FallbackPolicyT, TagT > > |
| { |
| public: |
| //! Attribute tag type |
| typedef TagT tag_type; |
| //! Fallback policy |
| typedef FallbackPolicyT fallback_policy; |
| //! Base terminal type |
| typedef attribute_terminal< T, fallback_policy, tag_type > terminal_type; |
| //! Attribute value type |
| typedef typename terminal_type::value_type value_type; |
| |
| //! Base actor type |
| typedef ActorT< terminal_type > base_type; |
| |
| public: |
| //! Initializing constructor |
| explicit attribute_actor(base_type const& act) : base_type(act) |
| { |
| } |
| |
| /*! |
| * \returns The attribute name |
| */ |
| attribute_name get_name() const |
| { |
| return this->proto_expr_.child0.get_name(); |
| } |
| |
| /*! |
| * \returns Fallback policy |
| */ |
| fallback_policy const& get_fallback_policy() const |
| { |
| return this->proto_expr_.child0.get_fallback_policy(); |
| } |
| |
| //! Expression with cached attribute name |
| typedef attribute_actor< value_type, fallback_to_none, tag_type, ActorT > or_none_result_type; |
| |
| //! Generates an expression that extracts the attribute value or a default value |
| or_none_result_type or_none() const |
| { |
| typedef typename or_none_result_type::terminal_type result_terminal; |
| typename or_none_result_type::base_type act = {{ result_terminal(get_name()) }}; |
| return or_none_result_type(act); |
| } |
| |
| //! Expression with cached attribute name |
| typedef attribute_actor< value_type, fallback_to_throw, tag_type, ActorT > or_throw_result_type; |
| |
| //! Generates an expression that extracts the attribute value or throws an exception |
| or_throw_result_type or_throw() const |
| { |
| typedef typename or_throw_result_type::terminal_type result_terminal; |
| typename or_throw_result_type::base_type act = {{ result_terminal(get_name()) }}; |
| return or_throw_result_type(act); |
| } |
| |
| //! Generates an expression that extracts the attribute value or a default value |
| template< typename DefaultT > |
| attribute_actor< value_type, fallback_to_default< DefaultT >, tag_type, ActorT > or_default(DefaultT const& def_val) const |
| { |
| typedef attribute_actor< value_type, fallback_to_default< DefaultT >, tag_type, ActorT > or_default_result_type; |
| typedef typename or_default_result_type::terminal_type result_terminal; |
| typename or_default_result_type::base_type act = {{ result_terminal(get_name(), def_val) }}; |
| return or_default_result_type(act); |
| } |
| }; |
| |
| /*! |
| * The function generates a terminal node in a template expression. The node will extract the value of the attribute |
| * with the specified name and type. |
| */ |
| template< typename AttributeValueT > |
| BOOST_FORCEINLINE attribute_actor< AttributeValueT > attr(attribute_name const& name) |
| { |
| typedef attribute_actor< AttributeValueT > result_type; |
| typedef typename result_type::terminal_type result_terminal; |
| typename result_type::base_type act = {{ result_terminal(name) }}; |
| return result_type(act); |
| } |
| |
| /*! |
| * The function generates a terminal node in a template expression. The node will extract the value of the attribute |
| * with the specified name and type. |
| */ |
| template< typename AttributeValueT, typename TagT > |
| BOOST_FORCEINLINE attribute_actor< AttributeValueT, fallback_to_none, TagT > attr(attribute_name const& name) |
| { |
| typedef attribute_actor< AttributeValueT, fallback_to_none, TagT > result_type; |
| typedef typename result_type::terminal_type result_terminal; |
| typename result_type::base_type act = {{ result_terminal(name) }}; |
| return result_type(act); |
| } |
| |
| } // namespace expressions |
| |
| BOOST_LOG_CLOSE_NAMESPACE // namespace log |
| |
| #ifndef BOOST_LOG_DOXYGEN_PASS |
| |
| namespace phoenix { |
| |
| namespace result_of { |
| |
| template< typename T, typename FallbackPolicyT, typename TagT > |
| struct is_nullary< custom_terminal< boost::log::expressions::attribute_terminal< T, FallbackPolicyT, TagT > > > : |
| public mpl::false_ |
| { |
| }; |
| |
| } // namespace result_of |
| |
| } // namespace phoenix |
| |
| #endif |
| |
| } // namespace boost |
| |
| #include <boost/log/detail/footer.hpp> |
| #if defined(BOOST_LOG_EXPRESSIONS_FORMATTERS_STREAM_HPP_INCLUDED_) |
| #include <boost/log/detail/attr_output_impl.hpp> |
| #endif |
| |
| #endif // BOOST_LOG_EXPRESSIONS_ATTR_HPP_INCLUDED_ |