chromium/third_party/libc++/src/include/__algorithm/lexicographical_compare_three_way.h

//===----------------------------------------------------------------------===//
//
// 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_LEXICOGRAPHICAL_COMPARE_THREE_WAY_H
#define _LIBCPP___ALGORITHM_LEXICOGRAPHICAL_COMPARE_THREE_WAY_H

#include <__algorithm/min.h>
#include <__algorithm/three_way_comp_ref_type.h>
#include <__compare/compare_three_way.h>
#include <__compare/ordering.h>
#include <__concepts/arithmetic.h>
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__type_traits/common_type.h>
#include <__type_traits/is_constructible.h>
#include <__utility/move.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER >= 20

// Fast path for random access iterators which computes the number of loop iterations up-front and
// then skips the iterator comparisons inside the loop.
template <class _InputIterator1, class _InputIterator2, class _Cmp>
_LIBCPP_HIDE_FROM_ABI constexpr auto __lexicographical_compare_three_way_fast_path(
    _InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2, _Cmp& __comp)
    -> decltype(__comp(*__first1, *__first2)) { … }

// Unoptimized implementation which compares the iterators against the end in every loop iteration
template <class _InputIterator1, class _InputIterator2, class _Cmp>
_LIBCPP_HIDE_FROM_ABI constexpr auto __lexicographical_compare_three_way_slow_path(
    _InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2, _Cmp& __comp)
    -> decltype(__comp(*__first1, *__first2)) { … }

template <class _InputIterator1, class _InputIterator2, class _Cmp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto lexicographical_compare_three_way(
    _InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2, _Cmp __comp)
    -> decltype(__comp(*__first1, *__first2)) { … }

template <class _InputIterator1, class _InputIterator2>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto lexicographical_compare_three_way(
    _InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2) { … }

#endif // _LIBCPP_STD_VER >= 20

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP___ALGORITHM_LEXICOGRAPHICAL_COMPARE_THREE_WAY_H