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_EQUAL_RANGE_H
10#define _LIBCPP___ALGORITHM_EQUAL_RANGE_H
11
12#include <__algorithm/comp.h>
13#include <__algorithm/comp_ref_type.h>
14#include <__algorithm/half_positive.h>
15#include <__algorithm/iterator_operations.h>
16#include <__algorithm/lower_bound.h>
17#include <__algorithm/upper_bound.h>
18#include <__config>
19#include <__functional/identity.h>
20#include <__functional/invoke.h>
21#include <__iterator/advance.h>
22#include <__iterator/distance.h>
23#include <__iterator/iterator_traits.h>
24#include <__iterator/next.h>
25#include <__type_traits/is_callable.h>
26#include <__type_traits/is_copy_constructible.h>
27#include <__utility/move.h>
28#include <__utility/pair.h>
29
30#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
31#  pragma GCC system_header
32#endif
33
34_LIBCPP_BEGIN_NAMESPACE_STD
35
36template <class _AlgPolicy, class _Compare, class _Iter, class _Sent, class _Tp, class _Proj>
37_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Iter, _Iter>
38__equal_range(_Iter __first, _Sent __last, const _Tp& __value, _Compare&& __comp, _Proj&& __proj) {
39  auto __len  = _IterOps<_AlgPolicy>::distance(__first, __last);
40  _Iter __end = _IterOps<_AlgPolicy>::next(__first, __last);
41  while (__len != 0) {
42    auto __half_len = std::__half_positive(__len);
43    _Iter __mid     = _IterOps<_AlgPolicy>::next(__first, __half_len);
44    if (std::__invoke(__comp, std::__invoke(__proj, *__mid), __value)) {
45      __first = ++__mid;
46      __len -= __half_len + 1;
47    } else if (std::__invoke(__comp, __value, std::__invoke(__proj, *__mid))) {
48      __end = __mid;
49      __len = __half_len;
50    } else {
51      _Iter __mp1 = __mid;
52      return pair<_Iter, _Iter>(
53          std::__lower_bound_impl<_AlgPolicy>(__first, __mid, __value, __comp, __proj),
54          std::__upper_bound<_AlgPolicy>(++__mp1, __end, __value, __comp, __proj));
55    }
56  }
57  return pair<_Iter, _Iter>(__first, __first);
58}
59
60template <class _ForwardIterator, class _Tp, class _Compare>
61_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
62equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value, _Compare __comp) {
63  static_assert(__is_callable<_Compare, decltype(*__first), const _Tp&>::value,
64                "The comparator has to be callable");
65  static_assert(is_copy_constructible<_ForwardIterator>::value,
66                "Iterator has to be copy constructible");
67  return std::__equal_range<_ClassicAlgPolicy>(
68      std::move(__first),
69      std::move(__last),
70      __value,
71      static_cast<__comp_ref_type<_Compare> >(__comp),
72      std::__identity());
73}
74
75template <class _ForwardIterator, class _Tp>
76_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
77equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
78  return std::equal_range(
79      std::move(__first),
80      std::move(__last),
81      __value,
82      __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
83}
84
85_LIBCPP_END_NAMESPACE_STD
86
87#endif // _LIBCPP___ALGORITHM_EQUAL_RANGE_H
88