// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___TUPLE
#define _LIBCPP___TUPLE

#include <__config>
#include <cstddef>
#include <type_traits>

#pragma GCC system_header

#ifdef _LIBCPP_HAS_NO_VARIADICS

#include <__tuple_03>

#else

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Tp> class tuple_size;
template <size_t _Ip, class _Tp> class tuple_element;

template <class ..._Tp> class tuple;
template <class _T1, class _T2> class pair;
template <class _Tp, size_t _Size> struct array;

template <class _Tp> struct __tuple_like : false_type {};

template <class... _Tp> struct __tuple_like<tuple<_Tp...>> : true_type {};
template <class... _Tp> struct __tuple_like<const tuple<_Tp...>> : true_type {};
template <class _T1, class _T2> struct __tuple_like<pair<_T1, _T2> > : true_type {};
template <class _T1, class _T2> struct __tuple_like<const pair<_T1, _T2> > : true_type {};
template <class _Tp, size_t _Size> struct __tuple_like<array<_Tp, _Size> > : true_type {};
template <class _Tp, size_t _Size> struct __tuple_like<const array<_Tp, _Size> > : true_type {};


template <size_t _Ip, class ..._Tp>
typename tuple_element<_Ip, tuple<_Tp...>>::type&
get(tuple<_Tp...>&);

template <size_t _Ip, class ..._Tp>
const typename tuple_element<_Ip, tuple<_Tp...>>::type&
get(const tuple<_Tp...>&);

template <size_t _Ip, class _T1, class _T2>
typename tuple_element<_Ip, pair<_T1, _T2> >::type&
get(pair<_T1, _T2>&);

template <size_t _Ip, class _T1, class _T2>
const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
get(const pair<_T1, _T2>&);

template <size_t _Ip, class _Tp, size_t _Size>
_Tp&
get(array<_Tp, _Size>&);

template <size_t _Ip, class _Tp, size_t _Size>
const _Tp&
get(const array<_Tp, _Size>&);

// __make_tuple_indices

template <size_t...> struct __tuple_indices {};

template <size_t _Sp, class _IntTuple, size_t _Ep>
struct __make_indices_imp;

template <size_t _Sp, size_t ..._Indices, size_t _Ep>
struct __make_indices_imp<_Sp, __tuple_indices<_Indices...>, _Ep>
{
    typedef typename __make_indices_imp<_Sp+1, __tuple_indices<_Indices..., _Sp>, _Ep>::type type;
};

template <size_t _Ep, size_t ..._Indices>
struct __make_indices_imp<_Ep, __tuple_indices<_Indices...>, _Ep>
{
    typedef __tuple_indices<_Indices...> type;
};

template <size_t _Ep, size_t _Sp = 0>
struct __make_tuple_indices
{
    static_assert(_Sp <= _Ep, "__make_tuple_indices input error");
    typedef typename __make_indices_imp<_Sp, __tuple_indices<>, _Ep>::type type;
};

// __tuple_types

template <class ..._Tp> struct __tuple_types {};

template <size_t _Ip>
class tuple_element<_Ip, __tuple_types<>>
{
public:
    static_assert(_Ip == 0, "tuple_element index out of range");
    static_assert(_Ip != 0, "tuple_element index out of range");
};

template <class _Hp, class ..._Tp>
class tuple_element<0, __tuple_types<_Hp, _Tp...>>
{
public:
    typedef _Hp type;
};

template <size_t _Ip, class _Hp, class ..._Tp>
class tuple_element<_Ip, __tuple_types<_Hp, _Tp...>>
{
public:
    typedef typename tuple_element<_Ip-1, __tuple_types<_Tp...>>::type type;
};

template <class ..._Tp>
class tuple_size<__tuple_types<_Tp...>>
    : public integral_constant<size_t, sizeof...(_Tp)>
{
};

template <class... _Tp> struct __tuple_like<__tuple_types<_Tp...>> : true_type {};

// __make_tuple_types

template <class _TupleTypes, class _Tp, size_t _Sp, size_t _Ep>
struct __make_tuple_types_imp;

template <class ..._Types, class _Tp, size_t _Sp, size_t _Ep>
struct __make_tuple_types_imp<__tuple_types<_Types...>, _Tp, _Sp, _Ep>
{
    typedef typename remove_reference<_Tp>::type _Tpr;
    typedef typename __make_tuple_types_imp<__tuple_types<_Types...,
                                            typename conditional<is_reference<_Tp>::value,
                                                typename tuple_element<_Sp, _Tpr>::type&,
                                                typename tuple_element<_Sp, _Tpr>::type>::type>,
                                            _Tp, _Sp+1, _Ep>::type type;
};

template <class ..._Types, class _Tp, size_t _Ep>
struct __make_tuple_types_imp<__tuple_types<_Types...>, _Tp, _Ep, _Ep>
{
    typedef __tuple_types<_Types...> type;
};

template <class _Tp, size_t _Ep = tuple_size<typename remove_reference<_Tp>::type>::value, size_t _Sp = 0>
struct __make_tuple_types
{
    static_assert(_Sp <= _Ep, "__make_tuple_types input error");
    typedef typename __make_tuple_types_imp<__tuple_types<>, _Tp, _Sp, _Ep>::type type;
};

// __make_assignable_types

template <class _Tuple, class _Tp, size_t _Sp, size_t _Ep>
struct __make_assignable_types_imp;

template <class ..._Types, class _Tp, size_t _Sp, size_t _Ep>
struct __make_assignable_types_imp<__tuple_types<_Types...>, _Tp, _Sp, _Ep>
{
    typedef typename __make_assignable_types_imp<__tuple_types<_Types...,
                                      typename remove_reference<typename tuple_element<_Sp, _Tp>::type>::type>,
                                      _Tp, _Sp+1, _Ep>::type type;
};

template <class ..._Types, class _Tp, size_t _Ep>
struct __make_assignable_types_imp<__tuple_types<_Types...>, _Tp, _Ep, _Ep>
{
    typedef __tuple_types<_Types...> type;
};

template <class _Tp, size_t _Ep = tuple_size<typename remove_reference<_Tp>::type>::value, size_t _Sp = 0>
struct __make_assignable_types
{
    static_assert(_Sp <= _Ep, "__make_assignable_types input error");
    typedef typename __make_assignable_types_imp<__tuple_types<>, typename remove_reference<_Tp>::type, _Sp, _Ep>::type type;
};

// __tuple_convertible

template <bool, class _Tp, class _Up>
struct __tuple_convertible_imp : public false_type {};

template <class _Tp0, class ..._Tp, class _Up0, class ..._Up>
struct __tuple_convertible_imp<true, __tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...>>
    : public integral_constant<bool,
                               is_convertible<_Tp0, _Up0>::value &&
                               __tuple_convertible_imp<true, __tuple_types<_Tp...>, __tuple_types<_Up...>>::value> {};

template <>
struct __tuple_convertible_imp<true, __tuple_types<>, __tuple_types<>>
    : public true_type {};

template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
                                bool = __tuple_like<_Up>::value>
struct __tuple_convertible
    : public false_type {};

template <class _Tp, class _Up>
struct __tuple_convertible<_Tp, _Up, true, true>
    : public __tuple_convertible_imp<tuple_size<typename remove_reference<_Tp>::type>::value ==
                                     tuple_size<_Up>::value,
             typename __make_tuple_types<_Tp>::type, typename __make_tuple_types<_Up>::type>
{};

// __tuple_assignable

template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
                                bool = __tuple_like<_Up>::value>
struct __tuple_assignable
    : public false_type {};

template <class _Tp, class _Up>
struct __tuple_assignable<_Tp, _Up, true, true>
    : public __tuple_convertible_imp<tuple_size<typename remove_reference<_Tp>::type>::value ==
                                     tuple_size<_Up>::value,
             typename __make_tuple_types<_Tp>::type, typename __make_assignable_types<_Up>::type>
{};

_LIBCPP_END_NAMESPACE_STD

#endif  // _LIBCPP_HAS_NO_VARIADICS

#endif  // _LIBCPP___TUPLE