| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef _LIBCPP___TYPE_TRAITS_OPERATION_TRAITS_H |
| #define _LIBCPP___TYPE_TRAITS_OPERATION_TRAITS_H |
| |
| #include <__config> |
| #include <__type_traits/integral_constant.h> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| # pragma GCC system_header |
| #endif |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| // Tags to represent the canonical operations |
| struct __equal_tag {}; |
| struct __plus_tag {}; |
| |
| // This class template is used to determine whether an operation "desugars" |
| // (or boils down) to a given canonical operation. |
| // |
| // For example, `std::equal_to<>`, our internal `std::__equal_to` helper and |
| // `ranges::equal_to` are all just fancy ways of representing a transparent |
| // equality operation, so they all desugar to `__equal_tag`. |
| // |
| // This is useful to optimize some functions in cases where we know e.g. the |
| // predicate being passed is actually going to call a builtin operator, or has |
| // some specific semantics. |
| template <class _CanonicalTag, class _Operation, class... _Args> |
| struct __desugars_to : false_type {}; |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| #endif // _LIBCPP___TYPE_TRAITS_OPERATION_TRAITS_H |
