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