llvm-project/libcxx/include/__ranges/size.h

133 lines
3.8 KiB
C++

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// 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___RANGES_SIZE_H
#define _LIBCPP___RANGES_SIZE_H
#include <__config>
#include <__iterator/concepts.h>
#include <__iterator/iterator_traits.h>
#include <__ranges/access.h>
#include <__utility/__decay_copy.h>
#include <__utility/forward.h>
#include <concepts>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#if !defined(_LIBCPP_HAS_NO_RANGES)
// clang-format off
namespace ranges {
template<class>
inline constexpr bool disable_sized_range = false;
// [range.prim.size]
namespace __size {
void size(auto&) = delete;
void size(const auto&) = delete;
template <class _Tp>
concept __size_enabled = !disable_sized_range<remove_cvref_t<_Tp>>;
template <class _Tp>
concept __member_size = __size_enabled<_Tp> && requires(_Tp&& __t) {
{ _VSTD::__decay_copy(_VSTD::forward<_Tp>(__t).size()) } -> __integer_like;
};
template <class _Tp>
concept __unqualified_size =
__size_enabled<_Tp> &&
!__member_size<_Tp> &&
__class_or_enum<remove_cvref_t<_Tp>> &&
requires(_Tp&& __t) {
{ _VSTD::__decay_copy(size(_VSTD::forward<_Tp>(__t))) } -> __integer_like;
};
template <class _Tp>
concept __difference =
!__member_size<_Tp> &&
!__unqualified_size<_Tp> &&
__class_or_enum<remove_cvref_t<_Tp>> &&
requires(_Tp&& __t) {
{ ranges::begin(__t) } -> forward_iterator;
{ ranges::end(__t) } -> sized_sentinel_for<decltype(ranges::begin(declval<_Tp>()))>;
};
struct __fn {
template <class _Tp, size_t _Sz>
[[nodiscard]] constexpr size_t operator()(_Tp (&&)[_Sz]) const noexcept {
return _Sz;
}
template <class _Tp, size_t _Sz>
[[nodiscard]] constexpr size_t operator()(_Tp (&)[_Sz]) const noexcept {
return _Sz;
}
template <__member_size _Tp>
[[nodiscard]] constexpr __integer_like auto operator()(_Tp&& __t) const
noexcept(noexcept(_VSTD::forward<_Tp>(__t).size())) {
return _VSTD::forward<_Tp>(__t).size();
}
template <__unqualified_size _Tp>
[[nodiscard]] constexpr __integer_like auto operator()(_Tp&& __t) const
noexcept(noexcept(size(_VSTD::forward<_Tp>(__t)))) {
return size(_VSTD::forward<_Tp>(__t));
}
template<__difference _Tp>
[[nodiscard]] constexpr __integer_like auto operator()(_Tp&& __t) const
noexcept(noexcept(ranges::end(__t) - ranges::begin(__t))) {
return _VSTD::__to_unsigned_like(ranges::end(__t) - ranges::begin(__t));
}
};
} // end namespace __size
inline namespace __cpo {
inline constexpr auto size = __size::__fn{};
} // namespace __cpo
namespace __ssize {
struct __fn {
template<class _Tp>
requires requires (_Tp&& __t) { ranges::size(__t); }
[[nodiscard]] constexpr integral auto operator()(_Tp&& __t) const
noexcept(noexcept(ranges::size(__t))) {
using _Signed = make_signed_t<decltype(ranges::size(__t))>;
if constexpr (sizeof(ptrdiff_t) > sizeof(_Signed))
return static_cast<ptrdiff_t>(ranges::size(__t));
else
return static_cast<_Signed>(ranges::size(__t));
}
};
}
inline namespace __cpo {
inline constexpr const auto ssize = __ssize::__fn{};
} // namespace __cpo
} // namespace ranges
// clang-format off
#endif // !defined(_LIBCPP_HAS_NO_RANGES)
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANGES_SIZE_H