| // -*- C++ -*- |
| //===----------------------------------------------------------------------===// |
| // |
| // 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___ITERATOR_FUNCTION_LIKE_H |
| #define _LIBCPP___ITERATOR_FUNCTION_LIKE_H |
| |
| #include <__config> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| #pragma GCC system_header |
| #endif |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| #if !defined(_LIBCPP_HAS_NO_RANGES) |
| |
| namespace ranges { |
| // Per [range.iter.ops.general] and [algorithms.requirements], functions in namespace std::ranges |
| // can't be found by ADL and inhibit ADL when found by unqualified lookup. The easiest way to |
| // facilitate this is to use function objects. |
| // |
| // Since these are still standard library functions, we use `__function_like` to eliminate most of |
| // the properties that function objects get by default (e.g. semiregularity, addressability), to |
| // limit the surface area of the unintended public interface, so as to curb the effect of Hyrum's |
| // law. |
| struct __function_like { |
| __function_like() = delete; |
| __function_like(__function_like const&) = delete; |
| __function_like& operator=(__function_like const&) = delete; |
| |
| void operator&() const = delete; |
| |
| struct __tag { }; |
| |
| protected: |
| constexpr explicit __function_like(__tag) noexcept {} |
| ~__function_like() = default; |
| }; |
| } // namespace ranges |
| |
| #endif // !defined(_LIBCPP_HAS_NO_RANGES) |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| #endif // _LIBCPP___ITERATOR_FUNCTION_LIKE_H |