libcxx/include/__algorithm/min_element.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_MIN_ELEMENT_H
  10 #define _LIBCPP___ALGORITHM_MIN_ELEMENT_H
  11
  12 #include <__algorithm/comp.h>
  13 #include <__algorithm/comp_ref_type.h>
  14 #include <__config>
  15 #include <__functional/identity.h>
  16 #include <__functional/invoke.h>
  17 #include <__iterator/iterator_traits.h>
  18 #include <__type_traits/is_callable.h>
  19 #include <__utility/move.h>
  20
  21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  22 #  pragma GCC system_header
  23 #endif
  24
  25 _LIBCPP_PUSH_MACROS
  26 #include <__undef_macros>
  27
  28 _LIBCPP_BEGIN_NAMESPACE_STD
  29
  30 template <class _Comp, class _Iter, class _Sent, class _Proj>
  31 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
  32 _Iter __min_element(_Iter __first, _Sent __last, _Comp __comp, _Proj& __proj) {
  33   if (__first == __last)
  34     return __first;
  35
  36   _Iter __i = __first;
  37   while (++__i != __last)
  38     if (std::__invoke(__comp, std::__invoke(__proj, *__i), std::__invoke(__proj, *__first)))
  39       __first = __i;
  40
  41   return __first;
  42 }
  43
  44 template <class _Comp, class _Iter, class _Sent>
  45 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
  46 _Iter __min_element(_Iter __first, _Sent __last, _Comp __comp) {
  47   auto __proj = __identity();
  48   return std::__min_element<_Comp>(std::move(__first), std::move(__last), __comp, __proj);
  49 }
  50
  51 template <class _ForwardIterator, class _Compare>
  52 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _ForwardIterator
  53 min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
  54 {
  55   static_assert(__has_forward_iterator_category<_ForwardIterator>::value,
  56       "std::min_element requires a ForwardIterator");
  57   static_assert(__is_callable<_Compare, decltype(*__first), decltype(*__first)>::value,
  58               "The comparator has to be callable");
  59
  60   return std::__min_element<__comp_ref_type<_Compare> >(std::move(__first), std::move(__last), __comp);
  61 }
  62
  63 template <class _ForwardIterator>
  64 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _ForwardIterator
  65 min_element(_ForwardIterator __first, _ForwardIterator __last)
  66 {
  67     return _VSTD::min_element(__first, __last, __less<>());
  68 }
  69
  70 _LIBCPP_END_NAMESPACE_STD
  71
  72 _LIBCPP_POP_MACROS
  73
  74 #endif // _LIBCPP___ALGORITHM_MIN_ELEMENT_H