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//////////////////////////////////////////////////////////////////////////////
//
// (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
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