From ac439331d6ccc3c4f0ac8dba17668e95a9a1ee90 Mon Sep 17 00:00:00 2001
From: Ole Erik Peistorpet <oleerikp@gmail.com>
Date: Fri, 25 Aug 2023 13:25:55 +0200
Subject: [PATCH] Made OwningView, using it in view::all

Also MoveView, TransformView::base() const & noexcept
---
 view/all.h           | 19 +++++--------
 view/detail/owning.h | 67 ++++++++++++++++++++++++++++++++++++++++++++
 view/move.h          |  4 +--
 view/transform.h     |  4 +--
 4 files changed, 78 insertions(+), 16 deletions(-)
 create mode 100644 view/detail/owning.h

diff --git a/view/all.h b/view/all.h
index da014274..7293215c 100644
--- a/view/all.h
+++ b/view/all.h
@@ -8,6 +8,7 @@
 
 #include "counted.h"
 #include "subrange.h"
+#include "detail/owning.h"
 
 /** @file
 */
@@ -26,25 +27,19 @@ namespace _detail
 		}
 	#endif
 
-		template< typename I >
-		constexpr auto operator()(view::counted<I> v) const { return v; }
-
-		template< typename I, typename S >
-		constexpr auto operator()(view::subrange<I, S> v) const { return v; }
-
 		template< typename SizedRange >
 		constexpr auto operator()(SizedRange & r) const
 		->	decltype( view::counted(begin(r), oel::ssize(r)) )
 		{	return    view::counted(begin(r), oel::ssize(r)); }
 
-		template< typename Range, typename... None >
-		constexpr auto operator()(Range & r, None...) const
+		template< typename Range >
+		constexpr auto operator()(Range && r) const
 		{
-			return view::subrange(begin(r), end(r));
+			if constexpr (std::is_lvalue_reference_v<Range>)
+				return view::subrange(begin(r), end(r));
+			else
+				return OwningView{static_cast<Range &&>(r)};
 		}
-
-		template< typename R >
-		void operator()(R &&) const = delete;
 	};
 }
 
diff --git a/view/detail/owning.h b/view/detail/owning.h
new file mode 100644
index 00000000..57728b7d
--- /dev/null
+++ b/view/detail/owning.h
@@ -0,0 +1,67 @@
+#pragma once
+
+// Copyright 2020 Ole Erik Peistorpet
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+
+#include "../../util.h"
+
+namespace oel::_detail
+{
+	template< typename Range >
+	class OwningView
+	{
+		using _iter = iterator_t<Range>;
+
+		Range _r;
+
+	public:
+		using difference_type = iter_difference_t<_iter>;
+
+		OwningView() = default;
+		OwningView(OwningView &&) = default;
+		OwningView(const OwningView &) = delete;
+		OwningView & operator =(OwningView &&) = default;
+		OwningView & operator =(const OwningView &) = delete;
+
+		constexpr explicit OwningView(Range && r) : _r{std::move(r)} {}
+
+		OEL_ALWAYS_INLINE constexpr _iter begin() { return adl_begin(_r); }
+
+		template< typename R = Range >
+		OEL_ALWAYS_INLINE constexpr auto  end()
+		->	decltype( adl_end(std::declval<R &>()) ) { return adl_end(_r); }
+
+		template< typename R = Range >
+		OEL_ALWAYS_INLINE constexpr auto size()
+		->	decltype(as_unsigned( _detail::Size(std::declval<R &>()) ))
+		{
+			return _detail::Size(_r);
+		}
+
+		// Might want to be more generic here, don't know if _r.empty exists
+		constexpr bool empty() { return _r.empty(); }
+
+		constexpr decltype(auto) operator[](difference_type index)
+			OEL_REQUIRES(iter_is_random_access<_iter>)
+		{
+			return adl_begin(_r)[index];
+		}
+
+		constexpr Range &&      base() && noexcept      { return std::move(_r); }
+		constexpr const Range & base() const & noexcept { return _r; }
+	};
+}
+
+#if OEL_STD_RANGES
+
+template< typename R >
+inline constexpr bool std::ranges::enable_borrowed_range< oel::_detail::OwningView<R> >
+	= std::ranges::enable_borrowed_range< std::remove_cv_t<R> >;
+
+template< typename R >
+inline constexpr bool std::ranges::enable_view< oel::_detail::OwningView<R> > = true;
+
+#endif
diff --git a/view/move.h b/view/move.h
index 9a34ba8c..746cd353 100644
--- a/view/move.h
+++ b/view/move.h
@@ -77,8 +77,8 @@ namespace _detail
 		OEL_ALWAYS_INLINE constexpr decltype(auto) operator[](difference_type index)
 			OEL_REQUIRES(iter_is_random_access< iterator_t<InputView> >)  { return begin()[index]; }
 
-		constexpr InputView         base() &&      { return std::move(_base); }
-		constexpr const InputView & base() const & { return _base; }
+		constexpr InputView         base() &&               { return std::move(_base); }
+		constexpr const InputView & base() const & noexcept { return _base; }
 	};
 }
 
diff --git a/view/transform.h b/view/transform.h
index a59b95ae..188aee3f 100644
--- a/view/transform.h
+++ b/view/transform.h
@@ -91,8 +91,8 @@ namespace _detail
 		OEL_ALWAYS_INLINE constexpr auto size()
 		->	decltype( std::declval<V_>().size() ) { return _m.first.size(); }
 
-		constexpr View         base() &&      { return std::move(_m.first); }
-		constexpr const View & base() const & { return _m.first; }
+		constexpr View         base() &&               { return std::move(_m.first); }
+		constexpr const View & base() const & noexcept { return _m.first; }
 	};
 
 	template< typename F >