//////////////////////////////////////////////////////////////////////////////
//
// (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/detail/workaround.hpp>  //forceinline
#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>
BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
< T &
, enable_move_utility_emulation<T>
, has_move_emulation_disabled<T>
>::type
move(T& x) BOOST_NOEXCEPT
{
    return x;
}

template <class T>
BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
< rv<T>&
, enable_move_utility_emulation<T>
, has_move_emulation_enabled<T>
>::type
move(T& x) BOOST_NOEXCEPT
{
    return *BOOST_MOVE_TO_RV_CAST(::boost::rv<T>*, ::boost::move_detail::addressof(x) );
}

template <class T>
BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
< rv<T>&
, enable_move_utility_emulation<T>
, has_move_emulation_enabled<T>
>::type
move(rv<T>& x) BOOST_NOEXCEPT
{
    return x;
}

//////////////////////////////////////////////////////////////////////////////
//
//                            forward()
//
//////////////////////////////////////////////////////////////////////////////

template <class T>
BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
< T &
, enable_move_utility_emulation<T>
, ::boost::move_detail::is_rv<T>
>::type
forward(const typename ::boost::move_detail::identity<T>::type &x) BOOST_NOEXCEPT
{
    return const_cast<T&>(x);
}

template <class T>
BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
< const T &
, enable_move_utility_emulation<T>
, ::boost::move_detail::is_not_rv<T>
>::type
forward(const typename ::boost::move_detail::identity<T>::type &x) BOOST_NOEXCEPT
{
    return x;
}

//////////////////////////////////////////////////////////////////////////////
//
//                        move_if_not_lvalue_reference()
//
//////////////////////////////////////////////////////////////////////////////

template <class T>
BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
< T &
, enable_move_utility_emulation<T>
, ::boost::move_detail::is_rv<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>
BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
< typename ::boost::move_detail::add_lvalue_reference<T>::type
, enable_move_utility_emulation<T>
, ::boost::move_detail::is_not_rv<T>
, ::boost::move_detail::or_
< ::boost::move_detail::is_lvalue_reference<T>
, has_move_emulation_disabled<T>
>
>::type
move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type &x) BOOST_NOEXCEPT
{
    return x;
}

template <class T>
BOOST_MOVE_FORCEINLINE typename ::boost::move_detail::enable_if_and
< rv<T>&
, enable_move_utility_emulation<T>
, ::boost::move_detail::is_not_rv<T>
, ::boost::move_detail::and_
< ::boost::move_detail::not_< ::boost::move_detail::is_lvalue_reference<T> >
, has_move_emulation_enabled<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>
BOOST_MOVE_FORCEINLINE 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>
BOOST_MOVE_FORCEINLINE 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>
BOOST_MOVE_FORCEINLINE T&&
forward(typename ::boost::move_detail::identity<T>::type&& t) BOOST_NOEXCEPT
{  return t;   }

#else //Old move

template <class T>
BOOST_MOVE_FORCEINLINE T&&
forward(typename ::boost::move_detail::remove_reference<T>::type& t) BOOST_NOEXCEPT
{  return static_cast<T&&>(t);   }

template <class T>
BOOST_MOVE_FORCEINLINE 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

}  //namespace boost {

#endif   //BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE

//////////////////////////////////////////////////////////////////////////////
//
//                         move_if_not_lvalue_reference
//
//////////////////////////////////////////////////////////////////////////////

namespace boost {

#if defined(BOOST_MOVE_DOXYGEN_INVOKED)
//! <b>Effects</b>: Calls `boost::move` if `input_reference` is not a lvalue reference.
//!   Otherwise returns the reference
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>
BOOST_MOVE_FORCEINLINE T&&
move_if_not_lvalue_reference(typename ::boost::move_detail::identity<T>::type&& t) BOOST_NOEXCEPT
{  return t;   }

#else //Old move

template <class T>
BOOST_MOVE_FORCEINLINE 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>
BOOST_MOVE_FORCEINLINE 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   //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
