Upgrade to 2022-era LLVM LIBCXX

third_party/libcxx/__ranges/counted.h

@@ -0,0 +1,83 @@
+// -*- 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_COUNTED_H
+#define _LIBCPP___RANGES_COUNTED_H
+
+#include <__concepts/convertible_to.h>
+#include <__config>
+#include <__iterator/concepts.h>
+#include <__iterator/counted_iterator.h>
+#include <__iterator/default_sentinel.h>
+#include <__iterator/incrementable_traits.h>
+#include <__iterator/iterator_traits.h>
+#include <__memory/pointer_traits.h>
+#include <__ranges/subrange.h>
+#include <__type_traits/decay.h>
+#include <__utility/forward.h>
+#include <__utility/move.h>
+#include <cstddef>
+#include <span>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 20
+
+namespace ranges::views {
+
+namespace __counted {
+
+  struct __fn {
+    template<contiguous_iterator _It>
+    _LIBCPP_HIDE_FROM_ABI
+    static constexpr auto __go(_It __it, iter_difference_t<_It> __count)
+      noexcept(noexcept(span(std::to_address(__it), static_cast<size_t>(__count))))
+      // Deliberately omit return-type SFINAE, because to_address is not SFINAE-friendly
+      { return          span(std::to_address(__it), static_cast<size_t>(__count)); }
+
+    template<random_access_iterator _It>
+    _LIBCPP_HIDE_FROM_ABI
+    static constexpr auto __go(_It __it, iter_difference_t<_It> __count)
+      noexcept(noexcept(subrange(__it, __it + __count)))
+      -> decltype(      subrange(__it, __it + __count))
+      { return          subrange(__it, __it + __count); }
+
+    template<class _It>
+    _LIBCPP_HIDE_FROM_ABI
+    static constexpr auto __go(_It __it, iter_difference_t<_It> __count)
+      noexcept(noexcept(subrange(counted_iterator(std::move(__it), __count), default_sentinel)))
+      -> decltype(      subrange(counted_iterator(std::move(__it), __count), default_sentinel))
+      { return          subrange(counted_iterator(std::move(__it), __count), default_sentinel); }
+
+    template<class _It, convertible_to<iter_difference_t<_It>> _Diff>
+      requires input_or_output_iterator<decay_t<_It>>
+    [[nodiscard]] _LIBCPP_HIDE_FROM_ABI
+    constexpr auto operator()(_It&& __it, _Diff&& __count) const
+      noexcept(noexcept(__go(std::forward<_It>(__it), std::forward<_Diff>(__count))))
+      -> decltype(      __go(std::forward<_It>(__it), std::forward<_Diff>(__count)))
+      { return          __go(std::forward<_It>(__it), std::forward<_Diff>(__count)); }
+  };
+
+} // namespace __counted
+
+inline namespace __cpo {
+  inline constexpr auto counted = __counted::__fn{};
+} // namespace __cpo
+
+} // namespace ranges::views
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___RANGES_COUNTED_H