libcxx/include/__algorithm/ranges_clamp.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___ALGORITHM_RANGES_CLAMP_H
  10 #define _LIBCPP___ALGORITHM_RANGES_CLAMP_H
  11
  12 #include <__assert>
  13 #include <__config>
  14 #include <__functional/identity.h>
  15 #include <__functional/invoke.h>
  16 #include <__functional/ranges_operations.h>
  17 #include <__iterator/concepts.h>
  18 #include <__iterator/projected.h>
  19 #include <__utility/forward.h>
  20
  21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  22 #  pragma GCC system_header
  23 #endif
  24
  25 #if _LIBCPP_STD_VER >= 20
  26
  27 _LIBCPP_BEGIN_NAMESPACE_STD
  28
  29 namespace ranges {
  30 namespace __clamp {
  31 struct __fn {
  32   template <class _Type,
  33             class _Proj                                                      = identity,
  34             indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less>
  35   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr const _Type& operator()(
  36       const _Type& __value, const _Type& __low, const _Type& __high, _Comp __comp = {}, _Proj __proj = {}) const {
  37     _LIBCPP_ASSERT_UNCATEGORIZED(!bool(std::invoke(__comp, std::invoke(__proj, __high), std::invoke(__proj, __low))),
  38                                  "Bad bounds passed to std::ranges::clamp");
  39
  40     auto&& __projected = std::invoke(__proj, __value);
  41     if (std::invoke(__comp, std::forward<decltype(__projected)>(__projected), std::invoke(__proj, __low)))
  42       return __low;
  43     else if (std::invoke(__comp, std::invoke(__proj, __high), std::forward<decltype(__projected)>(__projected)))
  44       return __high;
  45     else
  46       return __value;
  47   }
  48 };
  49 } // namespace __clamp
  50
  51 inline namespace __cpo {
  52 inline constexpr auto clamp = __clamp::__fn{};
  53 } // namespace __cpo
  54 } // namespace ranges
  55
  56 _LIBCPP_END_NAMESPACE_STD
  57
  58 #endif // _LIBCPP_STD_VER >= 20
  59
  60 #endif // _LIBCPP___ALGORITHM_RANGES_CLAMP_H