Made _detail::rangeIsSized, used in several places

auxi/impl_algo.h

@@ -128,28 +128,25 @@ namespace oel::_detail
 
 
 
-	template< typename Range, typename... None >
-	auto UDist(Range & r, None...)
+	template< typename Range >
+	inline constexpr auto rangeIsForwardOrSized = iter_is_forward< iterator_t<Range> > or rangeIsSized<Range>;
+
+	// Used only if rangeIsForwardOrSized
+	template< typename Range >
+	auto UDist(Range & r)
 	{
-		using I = decltype(begin(r));
-		if constexpr (iter_is_forward<I>)
+		if constexpr (rangeIsSized<Range>)
 		{
-			auto    it = begin(r);
+			return as_unsigned(_detail::Size(r));
+		}
+		else
+		{	auto    it = begin(r);
 			auto const l = end(r);
-			std::make_unsigned_t< iter_difference_t<I> > n{};
+			using D = iter_difference_t<decltype(it)>;
+			std::make_unsigned_t<D> n{};
 			while (it != l) { ++it; ++n; }
 
 			return n;
 		}
 	}
-
-	template< typename Range >
-	auto UDist(Range & r)
-	->	decltype( as_unsigned(_detail::Size(r)) )
-	{	return    as_unsigned(_detail::Size(r)); }
-
-
-	template< typename Range >
-	inline constexpr auto rangeIsForwardOrSized =
-		!std::is_same_v< decltype( _detail::UDist(std::declval<Range &>()) ), void >;
 }

auxi/range_algo_detail.h

@@ -77,36 +77,35 @@ namespace oel::_detail
 	}
 
 
-	template< typename InputRange, typename OutputRange, typename... None >
-	bool CopyFit(InputRange & src, OutputRange & dest, None...)
+	template< typename InputRange, typename RandomAccessRange >
+	bool CopyFit(InputRange & src, RandomAccessRange & dest)
 	{
-		auto it = begin(src);  auto const last = end(src);
-		auto di = begin(dest);  auto const dl = end(dest);
-		while (it != last)
+		if constexpr (rangeIsSized<InputRange>)
 		{
-			if (di != dl)
+			auto       n        = as_unsigned(_detail::Size(src));
+			auto const destSize = as_unsigned(_detail::Size(dest));
+			bool const success{n <= destSize};
+			if (!success)
+				n = destSize;
+
+			_detail::CopyUnsf(begin(src), n, begin(dest));
+			return success;
+		}
+		else
+		{	auto it = begin(src);  auto const last = end(src);
+			auto di = begin(dest);  auto const dl = end(dest);
+			while (it != last)
 			{
-				*di = *it;
-				++di; ++it;
-			}
-			else
-			{	return false;
+				if (di != dl)
+				{
+					*di = *it;
+					++di; ++it;
+				}
+				else
+				{	return false;
+				}
 			}
+			return true;
 		}
-		return true;
-	}
-
-	template< typename SizedRange, typename RandomAccessRange >
-	auto CopyFit(SizedRange & src, RandomAccessRange & dest)
-	->	decltype( _detail::Size(src), bool() ) // better match if Size(src) is well-formed (SFINAE)
-	{
-		auto       n        = as_unsigned(_detail::Size(src));
-		auto const destSize = as_unsigned(_detail::Size(dest));
-		bool const success{n <= destSize};
-		if (!success)
-			n = destSize;
-
-		_detail::CopyUnsf(begin(src), n, begin(dest));
-		return success;
 	}
 }

auxi/range_traits.h

@@ -136,6 +136,15 @@ namespace _detail
 	constexpr auto Size(Range && r, None...)
 	->	decltype(end(r) - begin(r))
 	{	return   end(r) - begin(r); }
+
+
+	template< typename Range, typename = void >
+	inline constexpr bool rangeIsSized = false;
+
+	template< typename Range >
+	inline constexpr bool rangeIsSized< Range,
+		std::void_t< decltype( _detail::Size(std::declval<Range &>()) ) >
+	>	= true;
 }
 
 } // oel

unit_test/util_gtest.cpp

@@ -123,6 +123,8 @@ struct DummyRange
 
 TEST(utilTest, ssize)
 {
+	static_assert(oel::_detail::rangeIsSized< DummyRange<int> >);
+
 	using test  = decltype( oel::ssize(DummyRange<unsigned short>{0}) );
 	using test2 = decltype( oel::ssize(DummyRange<std::uintmax_t>{0}) );
 
@@ -247,6 +249,7 @@ int * end(EmptyRandomAccessRange)   { return {}; }
 TEST(utilTest, detailSize_rangeNoMember)
 {
 	EmptyRandomAccessRange r;
+	static_assert(oel::_detail::rangeIsSized<decltype(r)>);
 	EXPECT_EQ(0, oel::_detail::Size(r));
 }
 
@@ -299,6 +302,7 @@ TEST(utilTest, detailCountOrEnd_disabledSize)
 	A src{1};
 	auto v = oel::view::subrange(TooSimpleIter<A::iterator>{src.begin()}, src.end());
 
+	static_assert( !oel::_detail::rangeIsSized<decltype(v)> );
 	static_assert(oel::_detail::rangeIsForwardOrSized<decltype(v)>);
 
 	auto n = oel::_detail::UDist(v);

unit_test/view_gtest.cpp

@@ -270,6 +270,7 @@ TEST(viewTest, viewMoveEndDifferentType)
 	oel::transform_iterator it{nonEmpty, src + 0};
 	auto v = view::subrange(it, makeSentinel(src + 1)) | view::move;
 
+	static_assert(oel::_detail::rangeIsSized<decltype(v)>);
 	EXPECT_NE(v.begin(), v.end());
 	EXPECT_EQ(src + 1, v.end().base()._s);
 }

view/all.h

@@ -27,18 +27,19 @@ namespace _detail
 		}
 	#endif
 
-		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 >
 		constexpr auto operator()(Range && r) const
 		{
 			if constexpr (std::is_lvalue_reference_v<Range>)
-				return view::subrange(begin(r), end(r));
+			{
+				if constexpr (_detail::rangeIsSized<Range>)
+					return view::counted(begin(r), oel::ssize(r));
+				else
+					return view::subrange(begin(r), end(r));
+			}
 			else
-				return view::owning(static_cast<Range &&>(r));
+			{	return view::owning(static_cast<Range &&>(r));
+			}
 		}
 	};
 }