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 <__functional/identity.h> 16 #include <__functional/invoke.h> 17 #include <__iterator/advance.h> 18 #include <__iterator/distance.h> 19 #include <__iterator/iterator_traits.h> 20 #include <__type_traits/is_callable.h> 21 #include <type_traits> 22 23 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 24 # pragma GCC system_header 25 #endif 26 27 _LIBCPP_BEGIN_NAMESPACE_STD 28 29 template <class _Iter, class _Sent, class _Type, class _Proj, class _Comp> 30 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 31 _Iter __lower_bound_impl(_Iter __first, _Sent __last, const _Type& __value, _Comp& __comp, _Proj& __proj) { 32 auto __len = std::__ranges_distance(__first, __last); 33 34 while (__len != 0) { 35 auto __l2 = std::__half_positive(__len); 36 _Iter __m = __first; 37 std::__ranges_advance(__m, __l2); 38 if (std::__invoke(__comp, std::__invoke(__proj, *__m), __value)) { 39 __first = ++__m; 40 __len -= __l2 + 1; 41 } else { 42 __len = __l2; 43 } 44 } 45 return __first; 46 } 47 48 template <class _ForwardIterator, class _Tp, class _Compare> 49 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 50 _ForwardIterator lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp) { 51 static_assert(__is_callable<_Compare, decltype(*__first), const _Tp&>::value, 52 "The comparator has to be callable"); 53 auto __proj = std::__identity(); 54 return std::__lower_bound_impl(__first, __last, __value_, __comp, __proj); 55 } 56 57 template <class _ForwardIterator, class _Tp> 58 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 59 _ForwardIterator lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_) { 60 return std::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