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_LOWER_BOUND_H
10 #define _LIBCPP___ALGORITHM_LOWER_BOUND_H
11 
12 #include <__config>
13 #include <__algorithm/comp.h>
14 #include <__algorithm/half_positive.h>
15 #include <iterator>
16 
17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
18 #pragma GCC system_header
19 #endif
20 
21 _LIBCPP_PUSH_MACROS
22 #include <__undef_macros>
23 
24 _LIBCPP_BEGIN_NAMESPACE_STD
25 
26 template <class _Compare, class _ForwardIterator, class _Tp>
27 _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
28 __lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
29 {
30     typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
31     difference_type __len = _VSTD::distance(__first, __last);
32     while (__len != 0)
33     {
34         difference_type __l2 = _VSTD::__half_positive(__len);
35         _ForwardIterator __m = __first;
36         _VSTD::advance(__m, __l2);
37         if (__comp(*__m, __value_))
38         {
39             __first = ++__m;
40             __len -= __l2 + 1;
41         }
42         else
43             __len = __l2;
44     }
45     return __first;
46 }
47 
48 template <class _ForwardIterator, class _Tp, class _Compare>
49 _LIBCPP_NODISCARD_EXT inline
50 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
51 _ForwardIterator
52 lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
53 {
54     typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
55     return _VSTD::__lower_bound<_Comp_ref>(__first, __last, __value_, __comp);
56 }
57 
58 template <class _ForwardIterator, class _Tp>
59 _LIBCPP_NODISCARD_EXT inline
60 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
61 _ForwardIterator
62 lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
63 {
64     return _VSTD::lower_bound(__first, __last, __value_,
65                              __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
66 }
67 
68 _LIBCPP_END_NAMESPACE_STD
69 
70 _LIBCPP_POP_MACROS
71 
72 #endif // _LIBCPP___ALGORITHM_LOWER_BOUND_H
73