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319 lines
11 KiB
319 lines
11 KiB
//////////////////////////////////////////////////////////////////////////////
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//
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// (C) Copyright Ion Gaztanaga 2012-2012.
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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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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// See http://www.boost.org/libs/move for documentation.
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//
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//////////////////////////////////////////////////////////////////////////////
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//! \file
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//! This header defines core utilities to ease the development
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//! of move-aware functions. This header minimizes dependencies
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//! from other libraries.
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#ifndef BOOST_MOVE_MOVE_UTILITY_CORE_HPP
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#define BOOST_MOVE_MOVE_UTILITY_CORE_HPP
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#ifndef BOOST_CONFIG_HPP
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# include <boost/config.hpp>
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#endif
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#
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#if defined(BOOST_HAS_PRAGMA_ONCE)
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# pragma once
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#endif
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#include <boost/move/detail/config_begin.hpp>
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#include <boost/move/detail/workaround.hpp> //forceinline
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#include <boost/move/core.hpp>
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#include <boost/move/detail/meta_utils.hpp>
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#include <boost/static_assert.hpp>
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#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && !defined(BOOST_MOVE_DOXYGEN_INVOKED)
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namespace boost {
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template<class T>
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struct enable_move_utility_emulation
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{
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static const bool value = true;
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};
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//////////////////////////////////////////////////////////////////////////////
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//
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// move()
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//
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//////////////////////////////////////////////////////////////////////////////
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template <class T>
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BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
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< T &
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, enable_move_utility_emulation<T>
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, has_move_emulation_disabled<T>
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>::type
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move(T& x) BOOST_NOEXCEPT
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{
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return x;
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}
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template <class T>
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BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
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< rv<T>&
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, enable_move_utility_emulation<T>
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, has_move_emulation_enabled<T>
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>::type
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move(T& x) BOOST_NOEXCEPT
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{
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return *BOOST_MOVE_TO_RV_CAST(::boost::rv<T>*, ::boost::move_detail::addressof(x) );
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}
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template <class T>
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BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
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< rv<T>&
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, enable_move_utility_emulation<T>
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, has_move_emulation_enabled<T>
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>::type
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move(rv<T>& x) BOOST_NOEXCEPT
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{
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return x;
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}
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//////////////////////////////////////////////////////////////////////////////
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//
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// forward()
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//
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//////////////////////////////////////////////////////////////////////////////
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template <class T>
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BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
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< T &
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, enable_move_utility_emulation<T>
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, ::boost::move_detail::is_rv<T>
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>::type
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forward(const typename ::boost::move_detail::identity<T>::type &x) BOOST_NOEXCEPT
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{
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return const_cast<T&>(x);
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}
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template <class T>
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BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
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< const T &
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, enable_move_utility_emulation<T>
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, ::boost::move_detail::is_not_rv<T>
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>::type
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forward(const typename ::boost::move_detail::identity<T>::type &x) BOOST_NOEXCEPT
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{
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return x;
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}
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//////////////////////////////////////////////////////////////////////////////
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//
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// move_if_not_lvalue_reference()
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//
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//////////////////////////////////////////////////////////////////////////////
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template <class T>
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BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
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< T &
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, enable_move_utility_emulation<T>
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, ::boost::move_detail::is_rv<T>
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>::type
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move_if_not_lvalue_reference(const typename ::boost::move_detail::identity<T>::type &x) BOOST_NOEXCEPT
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{
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return const_cast<T&>(x);
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}
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template <class T>
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BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
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< typename ::boost::move_detail::add_lvalue_reference<T>::type
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, enable_move_utility_emulation<T>
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, ::boost::move_detail::is_not_rv<T>
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, ::boost::move_detail::or_
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< ::boost::move_detail::is_lvalue_reference<T>
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, has_move_emulation_disabled<T>
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>
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>::type
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move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type &x) BOOST_NOEXCEPT
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{
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return x;
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}
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template <class T>
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BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
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< rv<T>&
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, enable_move_utility_emulation<T>
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, ::boost::move_detail::is_not_rv<T>
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, ::boost::move_detail::and_
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< ::boost::move_detail::not_< ::boost::move_detail::is_lvalue_reference<T> >
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, has_move_emulation_enabled<T>
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>
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>::type
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move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type &x) BOOST_NOEXCEPT
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{
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return move(x);
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}
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} //namespace boost
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#else //#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && !defined(BOOST_MOVE_DOXYGEN_INVOKED)
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#if defined(BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE)
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#include <utility>
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namespace boost{
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using ::std::move;
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using ::std::forward;
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} //namespace boost
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#else //!BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE
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namespace boost {
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//! This trait's internal boolean `value` is false in compilers with rvalue references
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//! and true in compilers without rvalue references.
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//!
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//! A user can specialize this trait for a type T to false to SFINAE out `move` and `forward`
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//! so that the user can define a different move emulation for that type in namespace boost
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//! (e.g. another Boost library for its types) and avoid any overload ambiguity.
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template<class T>
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struct enable_move_utility_emulation
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{
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static const bool value = false;
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};
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//////////////////////////////////////////////////////////////////////////////
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//
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// move
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//
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//////////////////////////////////////////////////////////////////////////////
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#if defined(BOOST_MOVE_DOXYGEN_INVOKED)
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//! This function provides a way to convert a reference into a rvalue reference
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//! in compilers with rvalue references. For other compilers if `T` is Boost.Move
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//! enabled type then it converts `T&` into <tt>::boost::rv<T> &</tt> so that
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//! move emulation is activated, else it returns `T &`.
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template <class T>
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rvalue_reference move(input_reference) noexcept;
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#elif defined(BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES)
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//Old move approach, lvalues could bind to rvalue references
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template <class T>
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BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::remove_reference<T>::type && move(T&& t) BOOST_NOEXCEPT
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{ return t; }
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#else //BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES
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template <class T>
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BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::remove_reference<T>::type && move(T&& t) BOOST_NOEXCEPT
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{ return static_cast<typename ::boost::move_detail::remove_reference<T>::type &&>(t); }
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#endif //BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES
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//////////////////////////////////////////////////////////////////////////////
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//
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// forward
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//
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//////////////////////////////////////////////////////////////////////////////
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#if defined(BOOST_MOVE_DOXYGEN_INVOKED)
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//! This function provides limited form of forwarding that is usually enough for
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//! in-place construction and avoids the exponential overloading for
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//! achieve the limited forwarding in C++03.
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//!
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//! For compilers with rvalue references this function provides perfect forwarding.
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//!
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//! Otherwise:
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//! * If input_reference binds to const ::boost::rv<T> & then it output_reference is
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//! ::boost::rv<T> &
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//!
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//! * Else, output_reference is equal to input_reference.
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template <class T> output_reference forward(input_reference) noexcept;
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#elif defined(BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES)
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//Old move approach, lvalues could bind to rvalue references
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template <class T>
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BOOST_MOVE_FORCEINLINE T&& forward(typename ::boost::move_detail::identity<T>::type&& t) BOOST_NOEXCEPT
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{ return t; }
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#else //Old move
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template <class T>
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BOOST_MOVE_FORCEINLINE T&& forward(typename ::boost::move_detail::remove_reference<T>::type& t) BOOST_NOEXCEPT
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{ return static_cast<T&&>(t); }
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template <class T>
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BOOST_MOVE_FORCEINLINE T&& forward(typename ::boost::move_detail::remove_reference<T>::type&& t) BOOST_NOEXCEPT
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{
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//"boost::forward<T> error: 'T' is a lvalue reference, can't forward as rvalue.";
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BOOST_STATIC_ASSERT(!boost::move_detail::is_lvalue_reference<T>::value);
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return static_cast<T&&>(t);
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}
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#endif //BOOST_MOVE_DOXYGEN_INVOKED
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//////////////////////////////////////////////////////////////////////////////
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//
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// move_if_not_lvalue_reference
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//
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//////////////////////////////////////////////////////////////////////////////
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#if defined(BOOST_MOVE_DOXYGEN_INVOKED)
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//! <b>Effects</b>: Calls `boost::move` if `input_reference` is not a lvalue reference.
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//! Otherwise returns the reference
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template <class T> output_reference move_if_not_lvalue_reference(input_reference) noexcept;
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#elif defined(BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES)
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//Old move approach, lvalues could bind to rvalue references
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template <class T>
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BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::identity<T>::type&& t) BOOST_NOEXCEPT
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{ return t; }
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#else //Old move
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template <class T>
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BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type& t) BOOST_NOEXCEPT
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{ return static_cast<T&&>(t); }
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template <class T>
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BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type&& t) BOOST_NOEXCEPT
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{
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//"boost::forward<T> error: 'T' is a lvalue reference, can't forward as rvalue.";
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BOOST_STATIC_ASSERT(!boost::move_detail::is_lvalue_reference<T>::value);
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return static_cast<T&&>(t);
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}
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#endif //BOOST_MOVE_DOXYGEN_INVOKED
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} //namespace boost {
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#endif //#if defined(BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE)
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#endif //BOOST_NO_CXX11_RVALUE_REFERENCES
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#if !defined(BOOST_MOVE_DOXYGEN_INVOKED)
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namespace boost{
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namespace move_detail{
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template <typename T>
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typename boost::move_detail::add_rvalue_reference<T>::type declval();
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} //namespace move_detail{
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} //namespace boost{
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#endif //#if !defined(BOOST_MOVE_DOXYGEN_INVOKED)
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#include <boost/move/detail/config_end.hpp>
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#endif //#ifndef BOOST_MOVE_MOVE_UTILITY_CORE_HPP
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