libcxx/include/__algorithm/min_element.h

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___ALGORITHM_MIN_ELEMENT_H
#define _LIBCPP___ALGORITHM_MIN_ELEMENT_H

#include <__algorithm/comp.h>
#include <__algorithm/comp_ref_type.h>
#include <__config>
#include <__functional/identity.h>
#include <__iterator/iterator_traits.h>
#include <__type_traits/invoke.h>
#include <__type_traits/is_callable.h>
#include <__utility/move.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Comp, class _Iter, class _Sent, class _Proj>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter
__min_element(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
  if (__first == __last)
    return __first;

  _Iter __i = __first;
  while (++__i != __last)
    if (std::__invoke(__comp, std::__invoke(__proj, *__i), std::__invoke(__proj, *__first)))
      __first = __i;

  return __first;
}

template <class _Comp, class _Iter, class _Sent>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter __min_element(_Iter __first, _Sent __last, _Comp __comp) {
  auto __proj = __identity();
  return std::__min_element<_Comp>(std::move(__first), std::move(__last), __comp, __proj);
}

template <class _ForwardIterator, class _Compare>
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _ForwardIterator
min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp) {
  static_assert(
      __has_forward_iterator_category<_ForwardIterator>::value, "std::min_element requires a ForwardIterator");
  static_assert(
      __is_callable<_Compare&, decltype(*__first), decltype(*__first)>::value, "The comparator has to be callable");

  return std::__min_element<__comp_ref_type<_Compare> >(std::move(__first), std::move(__last), __comp);
}

template <class _ForwardIterator>
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _ForwardIterator
min_element(_ForwardIterator __first, _ForwardIterator __last) {
  return std::min_element(__first, __last, __less<>());
}

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP___ALGORITHM_MIN_ELEMENT_H