161 lines
4.7 KiB
C++
161 lines
4.7 KiB
C++
/*
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* Copyright Andrey Semashev 2022.
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* https://www.boost.org/LICENSE_1_0.txt)
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*/
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/*!
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* \file utility/manipulators/invoke.hpp
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* \author Andrey Semashev
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* \date 27.02.2022
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*
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* The header contains implementation of a stream manipulator for invoking a user-defined function.
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*/
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#ifndef BOOST_LOG_UTILITY_MANIPULATORS_INVOKE_HPP_INCLUDED_
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#define BOOST_LOG_UTILITY_MANIPULATORS_INVOKE_HPP_INCLUDED_
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#include <cstddef>
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#include <boost/core/enable_if.hpp>
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#include <boost/log/detail/config.hpp>
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#include <boost/type_traits/remove_cv.hpp>
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#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
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#include <boost/type_traits/remove_reference.hpp>
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#endif
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#include <boost/log/detail/is_ostream.hpp>
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#include <boost/log/detail/header.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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#pragma once
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#endif
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namespace boost {
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BOOST_LOG_OPEN_NAMESPACE
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/*!
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* Stream manipulator for invoking a user-defined function as part of stream output.
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*/
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template< typename FunctionT >
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class invoke_manipulator
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{
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private:
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mutable FunctionT m_function;
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public:
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//! Initializing constructor
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explicit invoke_manipulator(FunctionT const& func) :
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m_function(func)
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{
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}
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#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
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//! Initializing constructor
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explicit invoke_manipulator(FunctionT&& func) :
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m_function(static_cast< FunctionT&& >(func))
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{
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}
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#endif
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//! The method invokes the saved function with the output stream
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template< typename StreamT >
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void output(StreamT& stream) const
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{
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m_function(stream);
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}
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};
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/*!
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* Stream output operator for \c invoke_manipulator. Invokes the function saved in the manipulator.
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*/
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template< typename StreamT, typename FunctionT >
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inline typename boost::enable_if_c< log::aux::is_ostream< StreamT >::value, StreamT& >::type operator<< (StreamT& stream, invoke_manipulator< FunctionT > const& manip)
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{
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manip.output(stream);
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return stream;
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}
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#if !defined(BOOST_LOG_DOXYGEN_PASS)
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#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
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//! Invoke manipulator generator function
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template< typename FunctionT >
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inline invoke_manipulator<
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typename boost::remove_cv<
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typename boost::remove_reference< FunctionT >::type
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>::type
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>
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invoke_manip(FunctionT&& func)
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{
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return invoke_manipulator<
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typename boost::remove_cv<
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typename boost::remove_reference< FunctionT >::type
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>::type
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>(static_cast< FunctionT&& >(func));
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}
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#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && \
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!defined(BOOST_NO_CXX14_GENERIC_LAMBDAS) && \
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!defined(BOOST_NO_CXX14_RETURN_TYPE_DEDUCTION)
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//! Invoke manipulator generator function
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template< typename FunctionT, typename Arg0, typename... Args >
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inline auto invoke_manip(FunctionT&& func, Arg0&& arg0, Args&&... args)
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{
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return boost::log::invoke_manip
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(
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#if !defined(BOOST_LOG_NO_CXX20_PACK_EXPANSION_IN_LAMBDA_INIT_CAPTURE)
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[func = static_cast< FunctionT&& >(func), arg0 = static_cast< Arg0&& >(arg0), ...args = static_cast< Args&& >(args)](auto& stream) mutable
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#else
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[func, arg0, args...](auto& stream) mutable
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#endif
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{
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#if !defined(BOOST_MSVC) || BOOST_MSVC >= 1910
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static_cast< FunctionT&& >(func)(stream, static_cast< Arg0&& >(arg0), static_cast< Args&& >(args)...);
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#else
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// MSVC 19.0 (VS 14.0) ICEs if we use perfect forwarding here
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func(stream, arg0, args...);
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#endif
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}
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);
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}
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#endif // !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) ...
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#else // !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
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//! Invoke manipulator generator function
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template< typename FunctionT >
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inline invoke_manipulator< typename boost::remove_cv< FunctionT >::type >
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invoke_manip(FunctionT const& func)
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{
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return invoke_manipulator< typename boost::remove_cv< FunctionT >::type >(func);
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}
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#endif // !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
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#else // !defined(BOOST_LOG_DOXYGEN_PASS)
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/*!
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* Invoke manipulator generator function.
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*
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* \param func User-defined function to invoke on output. The function must be callable with a reference to the output stream as the first argument, followed by \a args.
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* \param args Additional arguments to pass to \a func.
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* \returns Manipulator to be inserted into the stream.
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*
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* \note \a args are only supported since C++14.
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*/
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template< typename FunctionT, typename... Args >
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invoke_manipulator< unspecified > invoke_manip(FunctionT&& func, Args&&... args);
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#endif // !defined(BOOST_LOG_DOXYGEN_PASS)
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BOOST_LOG_CLOSE_NAMESPACE // namespace log
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} // namespace boost
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#include <boost/log/detail/footer.hpp>
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#endif // BOOST_LOG_UTILITY_MANIPULATORS_INVOKE_HPP_INCLUDED_
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