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 <__config>
13 #include <__algorithm/comp.h>
14 #include <__algorithm/comp_ref_type.h>
15 #include <__algorithm/half_positive.h>
16 #include <__algorithm/lower_bound.h>
17 #include <__algorithm/upper_bound.h>
18 #include <iterator>
19 
20 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
21 #pragma GCC system_header
22 #endif
23 
24 _LIBCPP_PUSH_MACROS
25 #include <__undef_macros>
26 
27 _LIBCPP_BEGIN_NAMESPACE_STD
28 
29 template <class _Compare, class _ForwardIterator, class _Tp>
30 _LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_ForwardIterator, _ForwardIterator>
31 __equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
32 {
33     typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
34     difference_type __len = _VSTD::distance(__first, __last);
35     while (__len != 0)
36     {
37         difference_type __l2 = _VSTD::__half_positive(__len);
38         _ForwardIterator __m = __first;
39         _VSTD::advance(__m, __l2);
40         if (__comp(*__m, __value_))
41         {
42             __first = ++__m;
43             __len -= __l2 + 1;
44         }
45         else if (__comp(__value_, *__m))
46         {
47             __last = __m;
48             __len = __l2;
49         }
50         else
51         {
52             _ForwardIterator __mp1 = __m;
53             return pair<_ForwardIterator, _ForwardIterator>
54                    (
55                       _VSTD::__lower_bound<_Compare>(__first, __m, __value_, __comp),
56                       _VSTD::__upper_bound<_Compare>(++__mp1, __last, __value_, __comp)
57                    );
58         }
59     }
60     return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
61 }
62 
63 template <class _ForwardIterator, class _Tp, class _Compare>
64 _LIBCPP_NODISCARD_EXT inline
65 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
66 pair<_ForwardIterator, _ForwardIterator>
67 equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
68 {
69     typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
70     return _VSTD::__equal_range<_Comp_ref>(__first, __last, __value_, __comp);
71 }
72 
73 template <class _ForwardIterator, class _Tp>
74 _LIBCPP_NODISCARD_EXT inline
75 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
76 pair<_ForwardIterator, _ForwardIterator>
77 equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
78 {
79     return _VSTD::equal_range(__first, __last, __value_,
80                              __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
81 }
82 
83 _LIBCPP_END_NAMESPACE_STD
84 
85 _LIBCPP_POP_MACROS
86 
87 #endif // _LIBCPP___ALGORITHM_EQUAL_RANGE_H
88