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Implement n3584 - Addressing Tuples by Type

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git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@186237 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Marshall Clow
2013-07-13 02:54:05 +00:00
parent ef7a7b730c
commit e8029e54f1
11 changed files with 387 additions and 0 deletions
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65
include/tuple
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@@ -94,6 +94,13 @@ template <intsize_t I, class... T>
typename tuple_element<I, tuple<T...>>::type&&
get(tuple<T...>&&) noexcept;
template <class T1, class... T>
constexpr T1& get(tuple<T...>&) noexcept; // C++14
template <class T1, class... T>
constexpr T1 const& get(const tuple<T...>&) noexcept; // C++14
template <class T1, class... T>
constexpr T1&& get(tuple<T...>&&) noexcept; // C++14
// 20.4.1.6, relational operators:
template<class... T, class... U> bool operator==(const tuple<T...>&, const tuple<U...>&);
template<class... T, class... U> bool operator<(const tuple<T...>&, const tuple<U...>&);
@@ -783,6 +790,64 @@ get(tuple<_Tp...>&& __t) _NOEXCEPT
static_cast<__tuple_leaf<_Ip, type>&&>(__t.base_).get());
}
#if _LIBCPP_STD_VER > 11
// get by type
template <typename _T1, size_t _Idx, typename... _Args>
struct __find_exactly_one_t_helper;
// -- find exactly one
template <typename _T1, size_t _Idx, typename... _Args>
struct __find_exactly_one_t_checker {
static constexpr size_t value = _Idx;
// Check the rest of the list to make sure there's only one
static_assert ( __find_exactly_one_t_helper<_T1, 0, _Args...>::value == -1, "type can only occur once in type list" );
};
template <typename _T1, size_t _Idx>
struct __find_exactly_one_t_helper <_T1, _Idx> {
static constexpr size_t value = -1;
};
template <typename _T1, size_t _Idx, typename _Head, typename... _Args>
struct __find_exactly_one_t_helper <_T1, _Idx, _Head, _Args...> {
static constexpr size_t value =
std::conditional<
std::is_same<_T1, _Head>::value,
__find_exactly_one_t_checker<_T1, _Idx,   _Args...>,
__find_exactly_one_t_helper <_T1, _Idx+1, _Args...>
>::type::value;
};
template <typename _T1, typename... _Args>
struct __find_exactly_one_t {
static constexpr size_t value = __find_exactly_one_t_helper<_T1, 0, _Args...>::value;
static_assert ( value != -1, "type not found in type list" );
};
template <class _T1, class... _Args>
inline _LIBCPP_INLINE_VISIBILITY
constexpr _T1& get(tuple<_Args...>& __tup) noexcept
{
return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
}
template <class _T1, class... _Args>
inline _LIBCPP_INLINE_VISIBILITY
constexpr _T1 const& get(tuple<_Args...> const& __tup) noexcept
{
return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
}
template <class _T1, class... _Args>
inline _LIBCPP_INLINE_VISIBILITY
constexpr _T1&& get(tuple<_Args...>&& __tup) noexcept
{
return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move<tuple<_Args...>>(__tup));
}
#endif
// tie
template <class ..._Tp>