libcxx/include/__algorithm/equal_range.h

   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_EQUAL_RANGE_H
  10 #define _LIBCPP___ALGORITHM_EQUAL_RANGE_H
  11
  12 #include <__algorithm/comp.h>
  13 #include <__algorithm/comp_ref_type.h>
  14 #include <__algorithm/half_positive.h>
  15 #include <__algorithm/iterator_operations.h>
  16 #include <__algorithm/lower_bound.h>
  17 #include <__algorithm/upper_bound.h>
  18 #include <__config>
  19 #include <__functional/identity.h>
  20 #include <__functional/invoke.h>
  21 #include <__iterator/advance.h>
  22 #include <__iterator/distance.h>
  23 #include <__iterator/iterator_traits.h>
  24 #include <__iterator/next.h>
  25 #include <__type_traits/is_callable.h>
  26 #include <__type_traits/is_copy_constructible.h>
  27 #include <__utility/move.h>
  28 #include <__utility/pair.h>
  29
  30 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  31 #  pragma GCC system_header
  32 #endif
  33
  34 _LIBCPP_BEGIN_NAMESPACE_STD
  35
  36 template <class _AlgPolicy, class _Compare, class _Iter, class _Sent, class _Tp, class _Proj>
  37 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Iter, _Iter>
  38 __equal_range(_Iter __first, _Sent __last, const _Tp& __value, _Compare&& __comp, _Proj&& __proj) {
  39   auto __len  = _IterOps<_AlgPolicy>::distance(__first, __last);
  40   _Iter __end = _IterOps<_AlgPolicy>::next(__first, __last);
  41   while (__len != 0) {
  42     auto __half_len = std::__half_positive(__len);
  43     _Iter __mid     = _IterOps<_AlgPolicy>::next(__first, __half_len);
  44     if (std::__invoke(__comp, std::__invoke(__proj, *__mid), __value)) {
  45       __first = ++__mid;
  46       __len -= __half_len + 1;
  47     } else if (std::__invoke(__comp, __value, std::__invoke(__proj, *__mid))) {
  48       __end = __mid;
  49       __len = __half_len;
  50     } else {
  51       _Iter __mp1 = __mid;
  52       return pair<_Iter, _Iter>(
  53           std::__lower_bound<_AlgPolicy>(__first, __mid, __value, __comp, __proj),
  54           std::__upper_bound<_AlgPolicy>(++__mp1, __end, __value, __comp, __proj));
  55     }
  56   }
  57   return pair<_Iter, _Iter>(__first, __first);
  58 }
  59
  60 template <class _ForwardIterator, class _Tp, class _Compare>
  61 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
  62 equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value, _Compare __comp) {
  63   static_assert(__is_callable<_Compare, decltype(*__first), const _Tp&>::value,
  64                 "The comparator has to be callable");
  65   static_assert(is_copy_constructible<_ForwardIterator>::value,
  66                 "Iterator has to be copy constructible");
  67   return std::__equal_range<_ClassicAlgPolicy>(
  68       std::move(__first),
  69       std::move(__last),
  70       __value,
  71       static_cast<__comp_ref_type<_Compare> >(__comp),
  72       std::__identity());
  73 }
  74
  75 template <class _ForwardIterator, class _Tp>
  76 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
  77 equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
  78   return std::equal_range(std::move(__first), std::move(__last), __value, __less<>());
  79 }
  80
  81 _LIBCPP_END_NAMESPACE_STD
  82
  83 #endif // _LIBCPP___ALGORITHM_EQUAL_RANGE_H