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 <__algorithm/iterator_operations.h> 15 #include <__config> 16 #include <__functional/identity.h> 17 #include <__functional/invoke.h> 18 #include <__iterator/advance.h> 19 #include <__iterator/distance.h> 20 #include <__iterator/iterator_traits.h> 21 #include <__type_traits/is_callable.h> 22 #include <type_traits> 23 24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 25 # pragma GCC system_header 26 #endif 27 28 _LIBCPP_BEGIN_NAMESPACE_STD 29 30 template <class _IterOps, class _Iter, class _Sent, class _Type, class _Proj, class _Comp> 31 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 32 _Iter __lower_bound_impl(_Iter __first, _Sent __last, const _Type& __value, _Comp& __comp, _Proj& __proj) { 33 auto __len = _IterOps::distance(__first, __last); 34 35 while (__len != 0) { 36 auto __l2 = std::__half_positive(__len); 37 _Iter __m = __first; 38 _IterOps::advance(__m, __l2); 39 if (std::__invoke(__comp, std::__invoke(__proj, *__m), __value)) { 40 __first = ++__m; 41 __len -= __l2 + 1; 42 } else { 43 __len = __l2; 44 } 45 } 46 return __first; 47 } 48 49 template <class _ForwardIterator, class _Tp, class _Compare> 50 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 51 _ForwardIterator lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp) { 52 static_assert(__is_callable<_Compare, decltype(*__first), const _Tp&>::value, 53 "The comparator has to be callable"); 54 auto __proj = std::__identity(); 55 return std::__lower_bound_impl<_StdIterOps>(__first, __last, __value_, __comp, __proj); 56 } 57 58 template <class _ForwardIterator, class _Tp> 59 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 60 _ForwardIterator lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_) { 61 return std::lower_bound(__first, __last, __value_, 62 __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>()); 63 } 64 65 _LIBCPP_END_NAMESPACE_STD 66 67 #endif // _LIBCPP___ALGORITHM_LOWER_BOUND_H 68