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   exception_handler.hpp
Chris@16:  * \author Andrey Semashev
Chris@16:  * \date   12.07.2009
Chris@16:  *
Chris@16:  * This header contains tools for exception handlers support in different parts of the library.
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_LOG_UTILITY_EXCEPTION_HANDLER_HPP_INCLUDED_
Chris@16: #define BOOST_LOG_UTILITY_EXCEPTION_HANDLER_HPP_INCLUDED_
Chris@16: 
Chris@101: #include <new> // std::nothrow_t
Chris@16: #include <boost/mpl/bind.hpp>
Chris@16: #include <boost/mpl/quote.hpp>
Chris@16: #include <boost/mpl/fold.hpp>
Chris@16: #include <boost/mpl/placeholders.hpp>
Chris@16: #include <boost/mpl/has_xxx.hpp>
Chris@16: #include <boost/mpl/vector.hpp>
Chris@16: #include <boost/preprocessor/cat.hpp>
Chris@16: #include <boost/preprocessor/repetition/enum_params.hpp>
Chris@16: #include <boost/preprocessor/repetition/repeat_from_to.hpp>
Chris@16: #include <boost/utility/enable_if.hpp>
Chris@16: #include <boost/log/detail/config.hpp>
Chris@16: #include <boost/log/utility/functional/nop.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: #ifndef BOOST_LOG_MAX_EXCEPTION_TYPES
Chris@16: //! Maximum number of exception types that can be specified for exception handlers
Chris@16: #define BOOST_LOG_MAX_EXCEPTION_TYPES 10
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: BOOST_LOG_OPEN_NAMESPACE
Chris@16: 
Chris@16: namespace aux {
Chris@16: 
Chris@16: BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_exception_types, exception_types, false)
Chris@16: 
Chris@16: //! Root class for the exception handler class hierarchy
Chris@16: template< typename HandlerT >
Chris@16: class eh_root
Chris@16: {
Chris@16: public:
Chris@16:     //! The exception handler type
Chris@16:     typedef HandlerT handler_type;
Chris@16:     //! The handler result type
Chris@16:     typedef void result_type;
Chris@16: 
Chris@16: protected:
Chris@16:     //! Exception handler
Chris@16:     handler_type m_Handler;
Chris@16: 
Chris@16: public:
Chris@16:     //! Initializing constructor
Chris@16:     explicit eh_root(handler_type const& handler) : m_Handler(handler)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     //! Exception launcher
Chris@16:     void operator()() const
Chris@16:     {
Chris@16:         throw;
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: //! A cons-list element of the exception handler class hierarchy
Chris@16: template< typename ExceptionT, typename BaseT >
Chris@16: class eh_cons :
Chris@16:     public BaseT
Chris@16: {
Chris@16:     //! Base type
Chris@16:     typedef BaseT base_type;
Chris@16: 
Chris@16: public:
Chris@16:     //! The exception handler type
Chris@16:     typedef typename base_type::handler_type handler_type;
Chris@16: 
Chris@16: public:
Chris@16:     //! Initializing constructor
Chris@16:     explicit eh_cons(handler_type const& handler) : base_type(handler)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     //! Exception launcher
Chris@16:     void operator()() const
Chris@16:     {
Chris@16:         try
Chris@16:         {
Chris@16:             base_type::operator()();
Chris@16:         }
Chris@16:         catch (ExceptionT& e)
Chris@16:         {
Chris@16:             this->m_Handler(e);
Chris@16:         }
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: template< template< typename, typename > class EHT, typename HandlerT >
Chris@16: struct make_self_contained_exception_handler
Chris@16: {
Chris@16:     typedef EHT< typename HandlerT::exception_types, HandlerT > type;
Chris@16: };
Chris@16: 
Chris@16: } // namespace aux
Chris@16: 
Chris@16: /*!
Chris@16:  * An exception handler functional object. The handler aggregates a user-defined
Chris@16:  * functional object that will be called when one of the specified exception types
Chris@16:  * is caught.
Chris@16:  */
Chris@16: template< typename SequenceT, typename HandlerT >
Chris@16: class exception_handler :
Chris@16:     public mpl::fold<
Chris@16:         SequenceT,
Chris@16:         aux::eh_root< HandlerT >,
Chris@16:         mpl::bind< mpl::quote2< aux::eh_cons >, mpl::_2, mpl::_1 >
Chris@16:     >::type
Chris@16: {
Chris@16:     //! Base type
Chris@16:     typedef typename mpl::fold<
Chris@16:         SequenceT,
Chris@16:         aux::eh_root< HandlerT >,
Chris@16:         mpl::bind< mpl::quote2< aux::eh_cons >, mpl::_2, mpl::_1 >
Chris@16:     >::type base_type;
Chris@16: 
Chris@16: public:
Chris@16: #ifndef BOOST_LOG_DOXYGEN_PASS
Chris@16:     typedef typename base_type::handler_type handler_type;
Chris@16: #else
Chris@16:     //! The exception handler type
Chris@16:     typedef HandlerT handler_type;
Chris@16:     //! The handler result type
Chris@16:     typedef void result_type;
Chris@16: #endif
Chris@16: 
Chris@16: public:
Chris@16:     /*!
Chris@16:      * Initializing constructor. Creates an exception handler with the specified
Chris@16:      * function object that will receive the exception.
Chris@16:      */
Chris@16:     explicit exception_handler(handler_type const& handler) : base_type(handler)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * Exception launcher. Rethrows the current exception in order to detect its type
Chris@16:      * and pass it to the aggregated function object.
Chris@16:      *
Chris@16:      * \note Must be called from within a \c catch statement.
Chris@16:      */
Chris@16:     void operator()() const
Chris@16:     {
Chris@16:         base_type::operator()();
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: /*!
Chris@16:  * A no-throw exception handler functional object. Acts similar to \c exception_handler,
Chris@16:  * but in case if the exception cannot be handled the exception is not propagated
Chris@16:  * from the handler. Instead the user-defined functional object is called with
Chris@16:  * no parameters.
Chris@16:  */
Chris@16: template< typename SequenceT, typename HandlerT >
Chris@16: class nothrow_exception_handler :
Chris@16:     public exception_handler< SequenceT, HandlerT >
Chris@16: {
Chris@16:     //! Base type
Chris@16:     typedef exception_handler< SequenceT, HandlerT > base_type;
Chris@16: 
Chris@16: public:
Chris@16: #ifndef BOOST_LOG_DOXYGEN_PASS
Chris@16:     typedef typename base_type::handler_type handler_type;
Chris@16: #else
Chris@16:     //! The exception handler type
Chris@16:     typedef HandlerT handler_type;
Chris@16:     //! The handler result type
Chris@16:     typedef void result_type;
Chris@16: #endif
Chris@16: 
Chris@16: public:
Chris@16:     /*!
Chris@16:      * Initializing constructor. Creates an exception handler with the specified
Chris@16:      * function object that will receive the exception.
Chris@16:      */
Chris@16:     explicit nothrow_exception_handler(handler_type const& handler) : base_type(handler)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * Exception launcher. Rethrows the current exception in order to detect its type
Chris@16:      * and pass it to the aggregated function object. If the type of the exception
Chris@16:      * could not be detected, the user-defined handler is called with no arguments.
Chris@16:      *
Chris@16:      * \note Must be called from within a \c catch statement.
Chris@16:      */
Chris@16:     void operator()() const
Chris@16:     {
Chris@16:         try
Chris@16:         {
Chris@16:             base_type::operator()();
Chris@16:         }
Chris@16:         catch (...)
Chris@16:         {
Chris@16:             this->m_Handler();
Chris@16:         }
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: /*!
Chris@16:  * The function creates an empty exception handler that effectively suppresses any exception
Chris@16:  */
Chris@16: inline nop make_exception_suppressor()
Chris@16: {
Chris@16:     return nop();
Chris@16: }
Chris@16: 
Chris@16: #ifndef BOOST_LOG_DOXYGEN_PASS
Chris@16: 
Chris@16: template< typename HandlerT >
Chris@16: inline typename lazy_enable_if<
Chris@16:     aux::has_exception_types< HandlerT >,
Chris@16:     aux::make_self_contained_exception_handler< exception_handler, HandlerT >
Chris@16: >::type make_exception_handler(HandlerT const& handler)
Chris@16: {
Chris@16:     typedef typename aux::make_self_contained_exception_handler< exception_handler, HandlerT >::type eh_t;
Chris@16:     return eh_t(handler);
Chris@16: }
Chris@16: 
Chris@16: template< typename HandlerT >
Chris@16: inline typename lazy_enable_if<
Chris@16:     aux::has_exception_types< HandlerT >,
Chris@16:     aux::make_self_contained_exception_handler< nothrow_exception_handler, HandlerT >
Chris@16: >::type make_exception_handler(HandlerT const& handler, std::nothrow_t const&)
Chris@16: {
Chris@16:     typedef typename aux::make_self_contained_exception_handler< nothrow_exception_handler, HandlerT >::type eh_t;
Chris@16:     return eh_t(handler);
Chris@16: }
Chris@16: 
Chris@16: #define BOOST_LOG_MAKE_EXCEPTION_HANDLER_INTERNAL(z, n, data)\
Chris@16:     template< BOOST_PP_ENUM_PARAMS(n, typename T), typename HandlerT >\
Chris@16:     inline exception_handler<\
Chris@16:         BOOST_PP_CAT(mpl::vector, n)< BOOST_PP_ENUM_PARAMS(n, T) >,\
Chris@16:         HandlerT\
Chris@16:     > make_exception_handler(HandlerT const& handler)\
Chris@16:     {\
Chris@16:         typedef exception_handler<\
Chris@16:             BOOST_PP_CAT(mpl::vector, n)< BOOST_PP_ENUM_PARAMS(n, T) >,\
Chris@16:             HandlerT\
Chris@16:         > eh_t;\
Chris@16:         return eh_t(handler);\
Chris@16:     }\
Chris@16:     template< BOOST_PP_ENUM_PARAMS(n, typename T), typename HandlerT >\
Chris@16:     inline nothrow_exception_handler<\
Chris@16:         BOOST_PP_CAT(mpl::vector, n)< BOOST_PP_ENUM_PARAMS(n, T) >,\
Chris@16:         HandlerT\
Chris@16:     > make_exception_handler(HandlerT const& handler, std::nothrow_t const&)\
Chris@16:     {\
Chris@16:         typedef nothrow_exception_handler<\
Chris@16:             BOOST_PP_CAT(mpl::vector, n)< BOOST_PP_ENUM_PARAMS(n, T) >,\
Chris@16:             HandlerT\
Chris@16:         > eh_t;\
Chris@16:         return eh_t(handler);\
Chris@16:     }
Chris@16: 
Chris@16: BOOST_PP_REPEAT_FROM_TO(1, BOOST_LOG_MAX_EXCEPTION_TYPES, BOOST_LOG_MAKE_EXCEPTION_HANDLER_INTERNAL, ~)
Chris@16: 
Chris@16: #undef BOOST_LOG_MAKE_EXCEPTION_HANDLER_INTERNAL
Chris@16: 
Chris@16: #else // BOOST_LOG_DOXYGEN_PASS
Chris@16: 
Chris@16: /*!
Chris@16:  * The function creates an exception handler functional object. The handler will call to the
Chris@16:  * user-specified functional object with an exception as its argument.
Chris@16:  *
Chris@16:  * \param handler User-defined functional object that will receive exceptions.
Chris@16:  * \return A nullary functional object that should be called from within a \c catch statement.
Chris@16:  *
Chris@16:  * \note This form requires the user-defined functional object to have an \c exception_types
Chris@16:  *       nested type. This type should be an MPL sequence of all expected exception types.
Chris@16:  */
Chris@16: template< typename HandlerT >
Chris@16: exception_handler< typename HandlerT::exception_types, HandlerT >
Chris@16: make_exception_handler(HandlerT const& handler);
Chris@16: 
Chris@16: /*!
Chris@16:  * The function creates an exception handler functional object. The handler will call to the
Chris@16:  * user-specified functional object with an exception as its argument. If the exception type
Chris@16:  * cannot be identified, the handler will call the user-defined functor with no arguments,
Chris@16:  * instead of propagating exception to the caller.
Chris@16:  *
Chris@16:  * \overload
Chris@16:  *
Chris@16:  * \param handler User-defined functional object that will receive exceptions.
Chris@16:  * \return A nullary functional object that should be called from within a \c catch statement.
Chris@16:  *
Chris@16:  * \note This form requires the user-defined functional object to have an \c exception_types
Chris@16:  *       nested type. This type should be an MPL sequence of all expected exception types.
Chris@16:  */
Chris@16: template< typename HandlerT >
Chris@16: nothrow_exception_handler< typename HandlerT::exception_types, HandlerT >
Chris@16: make_exception_handler(HandlerT const& handler, std::nothrow_t const&);
Chris@16: 
Chris@16: /*!
Chris@16:  * The function creates an exception handler functional object. The handler will call to the
Chris@16:  * user-specified functional object with an exception as its argument. All expected exception
Chris@16:  * types should be specified as first template parameters explicitly, in the order they would
Chris@16:  * be specified in a corresponding <tt>try/catch</tt> statement.
Chris@16:  *
Chris@16:  * \overload
Chris@16:  *
Chris@16:  * \param handler User-defined functional object that will receive exceptions.
Chris@16:  * \return A nullary functional object that should be called from within a \c catch statement.
Chris@16:  */
Chris@16: template< typename... ExceptionsT, typename HandlerT >
Chris@16: exception_handler< MPL_sequence_of_ExceptionsT, HandlerT >
Chris@16: make_exception_handler(HandlerT const& handler);
Chris@16: 
Chris@16: /*!
Chris@16:  * The function creates an exception handler functional object. The handler will call to the
Chris@16:  * user-specified functional object with an exception as its argument. If the exception type
Chris@16:  * cannot be identified, the handler will call the user-defined functor with no arguments,
Chris@16:  * instead of propagating exception to the caller. All expected exception types should be
Chris@16:  * specified as first template parameters explicitly, in the order they would be specified in
Chris@16:  * a corresponding <tt>try/catch</tt> statement.
Chris@16:  *
Chris@16:  * \overload
Chris@16:  *
Chris@16:  * \param handler User-defined functional object that will receive exceptions.
Chris@16:  * \return A nullary functional object that should be called from within a \c catch statement.
Chris@16:  */
Chris@16: template< typename... ExceptionsT, typename HandlerT >
Chris@16: nothrow_exception_handler< MPL_sequence_of_ExceptionsT, HandlerT >
Chris@16: make_exception_handler(HandlerT const& handler, std::nothrow_t const&);
Chris@16: 
Chris@16: #endif // BOOST_LOG_DOXYGEN_PASS
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: 
Chris@16: #endif // BOOST_LOG_UTILITY_EXCEPTION_HANDLER_HPP_INCLUDED_