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