Implement the in_place tags from p0032r3.
That paper also has changes to any/optional but those will
be implemented later.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@276537 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/utility b/include/utility
index 7b978ad..fd8a7f2 100644
--- a/include/utility
+++ b/include/utility
@@ -171,6 +171,20 @@
template<class T, class U=T>
T exchange(T& obj, U&& new_value);
+
+// 20.2.7, in-place construction // C++17
+struct in_place_tag { in_place_tag() = delete; }; // C++17
+using in_place_t = in_place_tag(&)(unspecified );
+template <class T>
+ using in_place_type_t = in_place_tag(&)(unspecified <T>);
+template <size_t I>
+ using in_place_index_t = in_place_tag(&)(unspecified <I>);
+in_place_tag in_place(unspecified );
+template <class T>
+ in_place_tag in_place(unspecified <T>);
+template <size_t I>
+ in_place_tag in_place(unspecified <I>);
+
} // std
*/
@@ -179,6 +193,7 @@
#include <__tuple>
#include <type_traits>
#include <initializer_list>
+#include <__debug>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
@@ -782,6 +797,49 @@
}
#endif // _LIBCPP_STD_VER > 11
+#if _LIBCPP_STD_VER > 14
+
+struct _LIBCPP_TYPE_VIS_ONLY __in_place_tag {};
+template <class> struct _LIBCPP_TYPE_VIS_ONLY __in_place_type_tag {};
+template <size_t> struct _LIBCPP_TYPE_VIS_ONLY __in_place_index_tag {};
+
+struct _LIBCPP_TYPE_VIS_ONLY in_place_tag;
+
+using in_place_t = in_place_tag(&)(__in_place_tag);
+template <class _Tp>
+using in_place_type_t = in_place_tag(&)(__in_place_type_tag<_Tp>);
+template <size_t _Nx>
+using in_place_index_t = in_place_tag(&)(__in_place_index_tag<_Nx>);
+
+struct in_place_tag {
+ in_place_tag() = delete;
+private:
+ explicit in_place_tag(__in_place_tag) {}
+
+ friend inline in_place_tag in_place(__in_place_tag __t);
+ template <class _Tp>
+ friend inline in_place_tag in_place(__in_place_type_tag<_Tp>);
+ template <size_t _Nx>
+ friend inline in_place_tag in_place(__in_place_index_tag<_Nx>);
+};
+
+inline in_place_tag in_place(__in_place_tag __t) {
+ _LIBCPP_ASSERT(false, "The in_place function cannot be invoked");
+ return in_place_tag(__t);
+}
+template <class _Tp>
+inline in_place_tag in_place(__in_place_type_tag<_Tp>) {
+ _LIBCPP_ASSERT(false, "The in_place function cannot be invoked");
+ return in_place_tag(__in_place_tag{});
+}
+template <size_t _Nx>
+inline in_place_tag in_place(__in_place_index_tag<_Nx>) {
+ _LIBCPP_ASSERT(false, "The in_place function cannot be invoked");
+ return in_place_tag(__in_place_tag{});
+}
+
+#endif // _LIBCPP_STD_VER > 14
+
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_UTILITY