Copied getSubarrayView method from NDArrayView to NDArray

src/TNL/Containers/NDArray.h

@@ -173,6 +173,32 @@ public:
       return ConstViewType( array.getData(), sizes );
    }
 
+   template< std::size_t... Dimensions, typename... IndexTypes >
+   __cuda_callable__
+   auto getSubarrayView( IndexTypes&&... indices )
+   {
+      static_assert( sizeof...( indices ) == getDimension(), "got wrong number of indices" );
+      static_assert( 0 < sizeof...(Dimensions) && sizeof...(Dimensions) <= getDimension(), "got wrong number of dimensions" );
+      static_assert( __ndarray_impl::all_elements_in_range( 0, Permutation::size(), {Dimensions...} ),
+                     "invalid dimensions" );
+// FIXME: nvcc chokes on the variadic brace-initialization
+#ifndef __NVCC__
+      static_assert( __ndarray_impl::is_increasing_sequence( {Dimensions...} ),
+                     "specifying permuted dimensions is not supported" );
+#endif
+
+      using Getter = __ndarray_impl::SubarrayGetter< Base, Permutation, Dimensions... >;
+      using Subpermutation = typename Getter::Subpermutation;
+      auto& begin = operator()( std::forward< IndexTypes >( indices )... );
+      auto subarray_sizes = Getter::filterSizes( sizes, std::forward< IndexTypes >( indices )... );
+      auto strides = Getter::getStrides( sizes, std::forward< IndexTypes >( indices )... );
+      static_assert( Subpermutation::size() == sizeof...(Dimensions), "Bug - wrong subpermutation length." );
+      static_assert( decltype(subarray_sizes)::getDimension() == sizeof...(Dimensions), "Bug - wrong dimension of the new sizes." );
+      static_assert( decltype(strides)::getDimension() == sizeof...(Dimensions), "Bug - wrong dimension of the strides." );
+      using SubarrayView = NDArrayView< ValueType, Device, decltype(subarray_sizes), Subpermutation, Base, decltype(strides) >;
+      return SubarrayView{ &begin, subarray_sizes, strides };
+   }
+
    template< typename Device2 = DeviceType, typename Func >
    void forAll( Func f ) const
    {