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