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_PUSH_MACROS
35 #include <__undef_macros>
36 
37 _LIBCPP_BEGIN_NAMESPACE_STD
38 
39 template <class _AlgPolicy, class _Compare, class _Iter, class _Sent, class _Tp, class _Proj>
40 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Iter, _Iter>
41 __equal_range(_Iter __first, _Sent __last, const _Tp& __value, _Compare&& __comp, _Proj&& __proj) {
42   auto __len  = _IterOps<_AlgPolicy>::distance(__first, __last);
43   _Iter __end = _IterOps<_AlgPolicy>::next(__first, __last);
44   while (__len != 0) {
45     auto __half_len = std::__half_positive(__len);
46     _Iter __mid     = _IterOps<_AlgPolicy>::next(__first, __half_len);
47     if (std::__invoke(__comp, std::__invoke(__proj, *__mid), __value)) {
48       __first = ++__mid;
49       __len -= __half_len + 1;
50     } else if (std::__invoke(__comp, __value, std::__invoke(__proj, *__mid))) {
51       __end = __mid;
52       __len = __half_len;
53     } else {
54       _Iter __mp1 = __mid;
55       return pair<_Iter, _Iter>(std::__lower_bound<_AlgPolicy>(__first, __mid, __value, __comp, __proj),
56                                 std::__upper_bound<_AlgPolicy>(++__mp1, __end, __value, __comp, __proj));
57     }
58   }
59   return pair<_Iter, _Iter>(__first, __first);
60 }
61 
62 template <class _ForwardIterator, class _Tp, class _Compare>
63 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
64 equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value, _Compare __comp) {
65   static_assert(__is_callable<_Compare, decltype(*__first), const _Tp&>::value, "The comparator has to be callable");
66   static_assert(is_copy_constructible<_ForwardIterator>::value, "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 
75 template <class _ForwardIterator, class _Tp>
76 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
77 equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
78   return std::equal_range(std::move(__first), std::move(__last), __value, __less<>());
79 }
80 
81 _LIBCPP_END_NAMESPACE_STD
82 
83 _LIBCPP_POP_MACROS
84 
85 #endif // _LIBCPP___ALGORITHM_EQUAL_RANGE_H
86