sub() function in range base

src/include/ranges/multi_range.h

@@ -186,6 +186,8 @@ namespace MultiArrayTools
 	template <size_t N>
 	auto getPtr() const -> decltype( std::get<N>( mSpace ) )&;
 
+	virtual std::shared_ptr<RangeBase> sub(size_t num) const override;
+	
 	virtual size_t dim() const final;
 	virtual size_t size() const final;
 
@@ -535,6 +537,12 @@ namespace MultiArrayTools
 	return std::get<N>(mSpace);
     }
 
+    template <class... Indices>
+    std::shared_ptr<RangeBase> MultiRange<Indices...>::sub(size_t num) const
+    {
+	return RPackNum<sizeof...(Indices)-1>::getSub(mSpace, num);
+    }
+
     template <class... Ranges>
     size_t MultiRange<Ranges...>::dim() const
     {

src/include/ranges/range_base.h

@@ -85,6 +85,8 @@ namespace MultiArrayTools
 
 	virtual SpaceType spaceType() const = 0;
         virtual DataHeader dataHeader() const = 0;
+
+	virtual std::shared_ptr<RangeBase> sub(size_t num) const { return std::shared_ptr<RangeBase>(); }
 	//virtual bool regular() const = 0; // integer distance (e.g. 2,3,4,...)
 	//virtual bool linear() const = 0; // 1dim valuable (e.g. 2.45, 3.12, 3.56,...)
 	//virtual bool multi() const = 0; // mdim

src/include/ranges/rpack_num.h

@@ -160,6 +160,17 @@ namespace MultiArrayHelper
 	    RPackNum<N-1>::setMeta(target, source);
 	}
 
+	template <class SpaceClass>
+	inline static std::shared_ptr<RangeBase> getSub(const SpaceClass& space, size_t num)
+	{
+	    if(num == N){
+		return std::get<N>(space);
+	    }
+	    else {
+		return RPackNum<N-1>::getSub(space, num);
+	    }
+	}
+
 	template <class IndexPack>
 	static void setIndexPack(IndexPack& iPack, size_t pos)
 	{
@@ -414,6 +425,18 @@ namespace MultiArrayHelper
 	    std::get<0>(target)->at( std::get<0>( source ) );
 	}
 
+	template <class SpaceClass>
+	inline static std::shared_ptr<RangeBase> getSub(const SpaceClass& space, size_t num)
+	{
+	    if(num == 0){
+		return std::get<0>(space);
+	    }
+	    else {
+		assert(0);
+		return std::shared_ptr<RangeBase>();
+	    }
+	}
+
 	template <class IndexPack>
 	static void setIndexPack(IndexPack& iPack, size_t pos)
 	{