//===----------------------------------------------------------------------===//
//
// 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___ALGORITHM_RANGES_MINMAX_H
#define _LIBCPP___ALGORITHM_RANGES_MINMAX_H
#include <__algorithm/min_max_result.h>
#include <__algorithm/minmax_element.h>
#include <__assert>
#include <__concepts/copyable.h>
#include <__concepts/same_as.h>
#include <__config>
#include <__functional/identity.h>
#include <__functional/invoke.h>
#include <__functional/ranges_operations.h>
#include <__iterator/concepts.h>
#include <__iterator/next.h>
#include <__iterator/projected.h>
#include <__ranges/access.h>
#include <__ranges/concepts.h>
#include <__type_traits/desugars_to.h>
#include <__type_traits/is_integral.h>
#include <__type_traits/is_reference.h>
#include <__type_traits/is_trivially_copyable.h>
#include <__type_traits/remove_cvref.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <__utility/pair.h>
#include <initializer_list>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
#if _LIBCPP_STD_VER >= 20
_LIBCPP_PUSH_MACROS
# include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
namespace ranges {
template <class _T1>
using minmax_result = min_max_result<_T1>;
struct __minmax {
template <class _Type,
class _Proj = identity,
indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr ranges::minmax_result<const _Type&>
operator()(_LIBCPP_LIFETIMEBOUND const _Type& __a,
_LIBCPP_LIFETIMEBOUND const _Type& __b,
_Comp __comp = {},
_Proj __proj = {}) const {
if (std::invoke(__comp, std::invoke(__proj, __b), std::invoke(__proj, __a)))
return {__b, __a};
return {__a, __b};
}
template <copyable _Type,
class _Proj = identity,
indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr ranges::minmax_result<_Type>
operator()(initializer_list<_Type> __il, _Comp __comp = {}, _Proj __proj = {}) const {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
__il.begin() != __il.end(), "initializer_list has to contain at least one element");
auto __iters = std::__minmax_element_impl(__il.begin(), __il.end(), __comp, __proj);
return ranges::minmax_result<_Type>{*__iters.first, *__iters.second};
}
template <input_range _Range,
class _Proj = identity,
indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>> _Comp = ranges::less>
requires indirectly_copyable_storable<iterator_t<_Range>, range_value_t<_Range>*>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr ranges::minmax_result<range_value_t<_Range>>
operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
auto __first = ranges::begin(__r);
auto __last = ranges::end(__r);
using _ValueT = range_value_t<_Range>;
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__first != __last, "range has to contain at least one element");
// This optimiation is not in minmax_element because clang doesn't see through the pointers and as a result doesn't
// vectorize the code.
if constexpr (contiguous_range<_Range> && is_integral_v<_ValueT> &&
__is_cheap_to_copy<_ValueT> & __is_identity<_Proj>::value &&
__desugars_to_v<__totally_ordered_less_tag, _Comp, _ValueT, _ValueT>) {
minmax_result<_ValueT> __result = {__r[0], __r[0]};
for (auto __e : __r) {
if (__e < __result.min)
__result.min = __e;
if (__result.max < __e)
__result.max = __e;
}
return __result;
} else if constexpr (forward_range<_Range>) {
// Special-case the one element case. Avoid repeatedly initializing objects from the result of an iterator
// dereference when doing so might not be idempotent. The `if constexpr` avoids the extra branch in cases where
// it's not needed.
if constexpr (!same_as<remove_cvref_t<range_reference_t<_Range>>, _ValueT> ||
is_rvalue_reference_v<range_reference_t<_Range>>) {
if (ranges::next(__first) == __last) {
// During initialization, members are allowed to refer to already initialized members
// (see http://eel.is/c++draft/dcl.init.aggr#6)
minmax_result<_ValueT> __result = {*__first, __result.min};
return __result;
}
}
auto __result = std::__minmax_element_impl(__first, __last, __comp, __proj);
return {*__result.first, *__result.second};
} else {
// input_iterators can't be copied, so the implementation for input_iterators has to store
// the values instead of a pointer to the correct values
auto __less = [&](auto&& __a, auto&& __b) -> bool {
return std::invoke(__comp,
std::invoke(__proj, std::forward<decltype(__a)>(__a)),
std::invoke(__proj, std::forward<decltype(__b)>(__b)));
};
// During initialization, members are allowed to refer to already initialized members
// (see http://eel.is/c++draft/dcl.init.aggr#6)
ranges::minmax_result<_ValueT> __result = {*__first, __result.min};
if (__first == __last || ++__first == __last)
return __result;
if (__less(*__first, __result.min))
__result.min = *__first;
else
__result.max = *__first;
while (++__first != __last) {
_ValueT __i = *__first;
if (++__first == __last) {
if (__less(__i, __result.min))
__result.min = __i;
else if (!__less(__i, __result.max))
__result.max = __i;
return __result;
}
if (__less(*__first, __i)) {
if (__less(*__first, __result.min))
__result.min = *__first;
if (!__less(__i, __result.max))
__result.max = std::move(__i);
} else {
if (__less(__i, __result.min))
__result.min = std::move(__i);
if (!__less(*__first, __result.max))
__result.max = *__first;
}
}
return __result;
}
}
};
inline namespace __cpo {
inline constexpr auto minmax = __minmax{};
} // namespace __cpo
} // namespace ranges
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP_STD_VER >= 20
#endif // _LIBCPP___ALGORITHM_RANGES_MINMAX_H
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