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