commit dd772db4655cc1f31995ace75a584b60bf761d6a
author zoecarver <z.zoelec2@gmail.com> Thu May 06 13:19:13 2021 -0700
committer Copybara-Service <copybara-worker@google.com> Fri Jun 11 11:05:26 2021 -0700
tree fe1801514d4f6b15d249f87a49bcd34faed52a57
parent 0b0690907e0ecf2ba037542832c80614f2f2517b

[libcxx][ranges] Add class ref_view.

Differential Revision: https://reviews.llvm.org/D102020

NOKEYCHECK=True
GitOrigin-RevId: 7eba4856c702b1d9d0bd1d3ef58661ba6c0e58de

include/CMakeLists.txt

diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
index d2f866a..1db968b 100644
--- a/include/CMakeLists.txt
+++ b/include/CMakeLists.txt
@@ -51,6 +51,7 @@
   __ranges/enable_borrowed_range.h
   __ranges/enable_view.h
   __ranges/view_interface.h
+  __ranges/ref_view.h
   __ranges/size.h
   __ranges/subrange.h
   __split_buffer

include/__ranges/ref_view.h

diff --git a/include/__ranges/ref_view.h b/include/__ranges/ref_view.h
new file mode 100644
index 0000000..de0aad7
--- /dev/null
+++ b/include/__ranges/ref_view.h
@@ -0,0 +1,78 @@
+// -*- 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_REF_VIEW_H
+#define _LIBCPP___RANGES_REF_VIEW_H
+
+#include <__config>
+#include <__iterator/concepts.h>
+#include <__iterator/iterator_traits.h>
+#include <__ranges/access.h>
+#include <__ranges/data.h>
+#include <__ranges/view_interface.h>
+#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)
+
+namespace ranges {
+  template<range _Range>
+    requires is_object_v<_Range>
+  class ref_view : public view_interface<ref_view<_Range>> {
+    _Range *__range_;
+
+    static void __fun(_Range&);
+    static void __fun(_Range&&) = delete;
+
+public:
+    template<class _Tp>
+      requires __different_from<_Tp, ref_view> &&
+        convertible_to<_Tp, _Range&> && requires { __fun(declval<_Tp>()); }
+    constexpr ref_view(_Tp&& __t)
+      : __range_(_VSTD::addressof(static_cast<_Range&>(_VSTD::forward<_Tp>(__t))))
+    {}
+
+    constexpr _Range& base() const { return *__range_; }
+
+    constexpr iterator_t<_Range> begin() const { return ranges::begin(*__range_); }
+    constexpr sentinel_t<_Range> end() const { return ranges::end(*__range_); }
+
+    constexpr bool empty() const
+      requires requires { ranges::empty(*__range_); }
+    { return ranges::empty(*__range_); }
+
+    constexpr auto size() const
+      requires sized_range<_Range>
+    { return ranges::size(*__range_); }
+
+    // TODO: This needs to use contiguous_range.
+    constexpr auto data() const
+      requires contiguous_iterator<iterator_t<_Range>>
+    { return ranges::data(*__range_); }
+  };
+
+  template<class _Range>
+  ref_view(_Range&) -> ref_view<_Range>;
+
+} // namespace ranges
+
+#endif // !defined(_LIBCPP_HAS_NO_RANGES)
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___RANGES_REF_VIEW_H

include/ranges

diff --git a/include/ranges b/include/ranges
index edf7474..75c9f20 100644
--- a/include/ranges
+++ b/include/ranges
@@ -100,6 +100,7 @@
 #include <__ranges/empty_view.h>
 #include <__ranges/enable_borrowed_range.h>
 #include <__ranges/enable_view.h>
+#include <__ranges/ref_view.h>
 #include <__ranges/size.h>
 #include <__ranges/subrange.h>
 #include <__ranges/view_interface.h>