Implement n3584 - Addressing Tuples by Type
llvm-svn: 186237
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: e99520c72e2906fea3c9ff39d4a46384cdf205f1
diff --git a/include/tuple b/include/tuple
index 0df315e..d8a36e6 100644
--- a/include/tuple
+++ b/include/tuple
@@ -94,6 +94,13 @@
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 @@
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>