143 lines
5.6 KiB
C++
143 lines
5.6 KiB
C++
//////////////////////////////////////////////////////////////////////////////
|
|
//
|
|
// (C) Copyright Ion Gaztanaga 2009-2012.
|
|
// 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
|
|
|
|
#ifndef BOOST_MOVE_MOVE_TRAITS_HPP
|
|
#define BOOST_MOVE_MOVE_TRAITS_HPP
|
|
|
|
#include <boost/move/detail/config_begin.hpp>
|
|
#include <boost/type_traits/has_trivial_destructor.hpp>
|
|
#include <boost/move/detail/meta_utils.hpp>
|
|
|
|
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
#include <boost/move/core.hpp>
|
|
#endif
|
|
|
|
namespace boost {
|
|
|
|
//! If this trait yields to true
|
|
//! (<i>has_trivial_destructor_after_move <T>::value == true</i>)
|
|
//! means that if T is used as argument of a move construction/assignment,
|
|
//! there is no need to call T's destructor.
|
|
//! This optimization tipically is used to improve containers' performance.
|
|
//!
|
|
//! By default this trait is true if the type has trivial destructor,
|
|
//! every class should specialize this trait if it wants to improve performance
|
|
//! when inserted in containers.
|
|
template <class T>
|
|
struct has_trivial_destructor_after_move
|
|
: ::boost::has_trivial_destructor<T>
|
|
{};
|
|
|
|
//! By default this traits returns false. Classes with non-throwing move constructor
|
|
//! and assignment can specialize this trait to obtain some performance improvements.
|
|
template <class T>
|
|
struct has_nothrow_move
|
|
: public ::boost::move_detail::integral_constant<bool, false>
|
|
{};
|
|
|
|
namespace move_detail {
|
|
|
|
// Code from Jeffrey Lee Hellrung, many thanks
|
|
|
|
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
template< class T> struct forward_type { typedef T type; };
|
|
#else // #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
template< class T>
|
|
struct forward_type
|
|
{ typedef const T &type; };
|
|
|
|
template< class T>
|
|
struct forward_type< boost::rv<T> >
|
|
{ typedef T type; };
|
|
#endif // #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
|
|
template< class T > struct is_rvalue_reference : ::boost::move_detail::integral_constant<bool, false> { };
|
|
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
template< class T > struct is_rvalue_reference< T&& > : ::boost::move_detail::integral_constant<bool, true> { };
|
|
#else // #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
template< class T > struct is_rvalue_reference< boost::rv<T>& >
|
|
: ::boost::move_detail::integral_constant<bool, true>
|
|
{};
|
|
|
|
template< class T > struct is_rvalue_reference< const boost::rv<T>& >
|
|
: ::boost::move_detail::integral_constant<bool, true>
|
|
{};
|
|
#endif // #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
|
|
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
template< class T > struct add_rvalue_reference { typedef T&& type; };
|
|
#else // #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
namespace detail_add_rvalue_reference
|
|
{
|
|
template< class T
|
|
, bool emulation = ::boost::has_move_emulation_enabled<T>::value
|
|
, bool rv = ::boost::move_detail::is_rv<T>::value >
|
|
struct add_rvalue_reference_impl { typedef T type; };
|
|
|
|
template< class T, bool emulation>
|
|
struct add_rvalue_reference_impl< T, emulation, true > { typedef T & type; };
|
|
|
|
template< class T, bool rv >
|
|
struct add_rvalue_reference_impl< T, true, rv > { typedef ::boost::rv<T>& type; };
|
|
} // namespace detail_add_rvalue_reference
|
|
|
|
template< class T >
|
|
struct add_rvalue_reference
|
|
: detail_add_rvalue_reference::add_rvalue_reference_impl<T>
|
|
{ };
|
|
|
|
template< class T >
|
|
struct add_rvalue_reference<T &>
|
|
{ typedef T & type; };
|
|
|
|
#endif // #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
|
|
template< class T > struct remove_rvalue_reference { typedef T type; };
|
|
|
|
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
template< class T > struct remove_rvalue_reference< T&& > { typedef T type; };
|
|
#else // #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
template< class T > struct remove_rvalue_reference< rv<T> > { typedef T type; };
|
|
template< class T > struct remove_rvalue_reference< const rv<T> > { typedef T type; };
|
|
template< class T > struct remove_rvalue_reference< volatile rv<T> > { typedef T type; };
|
|
template< class T > struct remove_rvalue_reference< const volatile rv<T> > { typedef T type; };
|
|
template< class T > struct remove_rvalue_reference< rv<T>& > { typedef T type; };
|
|
template< class T > struct remove_rvalue_reference< const rv<T>& > { typedef T type; };
|
|
template< class T > struct remove_rvalue_reference< volatile rv<T>& > { typedef T type; };
|
|
template< class T > struct remove_rvalue_reference< const volatile rv<T>& >{ typedef T type; };
|
|
#endif // #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
|
|
|
|
template <typename T>
|
|
typename boost::move_detail::add_rvalue_reference<T>::type declval();
|
|
|
|
} //move_detail {
|
|
|
|
// Ideas from Boost.Move review, Jeffrey Lee Hellrung:
|
|
//
|
|
//- TypeTraits metafunctions is_lvalue_reference, add_lvalue_reference, and remove_lvalue_reference ?
|
|
// Perhaps add_reference and remove_reference can be modified so that they behave wrt emulated rvalue
|
|
// references the same as wrt real rvalue references, i.e., add_reference< rv<T>& > -> T& rather than
|
|
// rv<T>& (since T&& & -> T&).
|
|
//
|
|
//- Add'l TypeTraits has_[trivial_]move_{constructor,assign}...?
|
|
//
|
|
//- An as_lvalue(T& x) function, which amounts to an identity operation in C++0x, but strips emulated
|
|
// rvalue references in C++03. This may be necessary to prevent "accidental moves".
|
|
|
|
|
|
} //namespace boost {
|
|
|
|
#include <boost/move/detail/config_end.hpp>
|
|
|
|
#endif //#ifndef BOOST_MOVE_MOVE_TRAITS_HPP
|