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/lower_bound.h>
16 #include <__algorithm/upper_bound.h>
17 #include <__config>
18 #include <iterator>
19 
20 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
21 #  pragma GCC system_header
22 #  pragma clang include_instead(<algorithm>)
23 #endif
24 
25 _LIBCPP_BEGIN_NAMESPACE_STD
26 
27 template <class _Compare, class _ForwardIterator, class _Tp>
28 _LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_ForwardIterator, _ForwardIterator>
29 __equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
30 {
31     typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
32     difference_type __len = _VSTD::distance(__first, __last);
33     while (__len != 0)
34     {
35         difference_type __l2 = _VSTD::__half_positive(__len);
36         _ForwardIterator __m = __first;
37         _VSTD::advance(__m, __l2);
38         if (__comp(*__m, __value_))
39         {
40             __first = ++__m;
41             __len -= __l2 + 1;
42         }
43         else if (__comp(__value_, *__m))
44         {
45             __last = __m;
46             __len = __l2;
47         }
48         else
49         {
50             _ForwardIterator __mp1 = __m;
51             return pair<_ForwardIterator, _ForwardIterator>
52                    (
53                       _VSTD::__lower_bound<_Compare>(__first, __m, __value_, __comp),
54                       _VSTD::__upper_bound<_Compare>(++__mp1, __last, __value_, __comp)
55                    );
56         }
57     }
58     return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
59 }
60 
61 template <class _ForwardIterator, class _Tp, class _Compare>
62 _LIBCPP_NODISCARD_EXT inline
63 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
64 pair<_ForwardIterator, _ForwardIterator>
65 equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
66 {
67     typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
68     return _VSTD::__equal_range<_Comp_ref>(__first, __last, __value_, __comp);
69 }
70 
71 template <class _ForwardIterator, class _Tp>
72 _LIBCPP_NODISCARD_EXT inline
73 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
74 pair<_ForwardIterator, _ForwardIterator>
75 equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
76 {
77     return _VSTD::equal_range(__first, __last, __value_,
78                              __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
79 }
80 
81 _LIBCPP_END_NAMESPACE_STD
82 
83 #endif // _LIBCPP___ALGORITHM_EQUAL_RANGE_H
84