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 _LIBCPP_PUSH_MACROS
  26 #include <__undef_macros>
  27
  28 #if _LIBCPP_STD_VER >= 20
  29
  30 _LIBCPP_BEGIN_NAMESPACE_STD
  31
  32 namespace ranges {
  33 struct __clamp {
  34   template <class _Type,
  35             class _Proj                                                      = identity,
  36             indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less>
  37   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Type& operator()(
  38       const _Type& __value, const _Type& __low, const _Type& __high, _Comp __comp = {}, _Proj __proj = {}) const {
  39     _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
  40         !bool(std::invoke(__comp, std::invoke(__proj, __high), std::invoke(__proj, __low))),
  41         "Bad bounds passed to std::ranges::clamp");
  42
  43     auto&& __projected = std::invoke(__proj, __value);
  44     if (std::invoke(__comp, std::forward<decltype(__projected)>(__projected), std::invoke(__proj, __low)))
  45       return __low;
  46     else if (std::invoke(__comp, std::invoke(__proj, __high), std::forward<decltype(__projected)>(__projected)))
  47       return __high;
  48     else
  49       return __value;
  50   }
  51 };
  52
  53 inline namespace __cpo {
  54 inline constexpr auto clamp = __clamp{};
  55 } // namespace __cpo
  56 } // namespace ranges
  57
  58 _LIBCPP_END_NAMESPACE_STD
  59
  60 #endif // _LIBCPP_STD_VER >= 20
  61
  62 _LIBCPP_POP_MACROS
  63
  64 #endif // _LIBCPP___ALGORITHM_RANGES_CLAMP_H