From fe22b1ad8090287325d1a678f5e4661e136a6331 Mon Sep 17 00:00:00 2001
From: Christian Zimmermann <christian.zimmermann@ur.de>
Date: Sun, 11 Apr 2021 16:34:01 +0200
Subject: [PATCH] im com + remove Getter class

---
 src/include/map_range.cc.h             |   4 +-
 src/include/multi_array_operation.cc.h |  23 ++-
 src/include/multi_array_operation.h    |  35 +++-
 src/include/pack_num.h                 |  21 +-
 src/include/statics/static_for.h       |  25 +--
 src/include/xfor/exttype.h             | 262 +++++++++++++++++++++----
 src/include/xfor/xfor.h                | 156 +--------------
 7 files changed, 279 insertions(+), 247 deletions(-)

diff --git a/src/include/map_range.cc.h b/src/include/map_range.cc.h
index 8f786dd..4495c58 100644
--- a/src/include/map_range.cc.h
+++ b/src/include/map_range.cc.h
@@ -49,7 +49,7 @@ namespace MultiArrayTools
         if(pos != mIndPtr->max()){
             const ExtType npos = last + mExt*pos;
             const size_t mnpos = PosForward<ForType::DEFAULT>::valuex(mlast, mStep, pos);
-            mExpr(mnpos, Getter<NEXT>::template getX<ExtType>( npos ) );
+            mExpr(mnpos, getX<NEXT>( npos ) );
         }
     }
 
@@ -63,7 +63,7 @@ namespace MultiArrayTools
         if(pos != mIndPtr->max()){
             const ExtType npos = last + mExt*pos;
             const size_t mnpos = PosForward<ForType::DEFAULT>::valuex(mlast, mStep, pos);
-            mExpr(mnpos, Getter<NEXT>::template getX<ExtType>( npos ));
+            mExpr(mnpos, getX<NEXT>( npos ));
         }
     }
     
diff --git a/src/include/multi_array_operation.cc.h b/src/include/multi_array_operation.cc.h
index e3f578a..6c0644f 100644
--- a/src/include/multi_array_operation.cc.h
+++ b/src/include/multi_array_operation.cc.h
@@ -226,29 +226,27 @@ namespace MultiArrayTools
     template <typename T, class... Ops>
     inline size_t MOp<T,Ops...>::get(ExtType last) const
     {
-	return RootSumN<sizeof...(Ops)-1>::get(last,mOps);
+	return RootSumN<sizeof...(Ops)-1>::get(last,mOps.mOps);
     }
 
     template <typename T, class... Ops>
     inline MOp<T,Ops...>& MOp<T,Ops...>::set(ExtType last)
     {
-	RootSumN<sizeof...(Ops)-1>::set(last,mOps);
+	RootSumN<sizeof...(Ops)-1>::set(last,mOps.mOps);
 	return *this;
     }
     
     template <typename T, class... Ops>
     template <class Expr>
     auto MOp<T,Ops...>::loop(Expr exp) const
-	-> decltype(PackNum<sizeof...(Ops)-1>::mkLoop( mOps, exp))
     {
-	return PackNum<sizeof...(Ops)-1>::mkLoop( mOps, exp);
+	return MA_SCRAFOR(i,sizeof...(Ops),0,i-1,std::get<i>(mOps.mOps),loop,exp);
     }
 
     template <typename T, class... Ops>
-    auto MOp<T,Ops...>::rootSteps(std::intptr_t iPtrNum) const
+    auto MOp<T,Ops...>::rootSteps(std::intptr_t iPtrNum) const -> ExtType
     {
-	return MA_SCFOR(i,0,sizeof...(Ops),i+1,std::get<i>(mOps).rootSteps(iPtrNum),extend);
-	//return RootSumN<sizeof...(Ops)-1>::rootSteps(mOps,iPtrNum);
+	return mOps.rootSteps(iPtrNum);
     }
 
     template <class OpClass, class NextExpr>
@@ -989,7 +987,7 @@ namespace MultiArrayTools
     {
 	typedef std::tuple<Ops...> OpTuple;
 	return PackNum<sizeof...(Ops)-1>::
-	    template mkOpExpr<SIZE,ET,OpTuple,OpFunction>(mF, pos, mOps);
+	    template mkOpExpr<SIZE,ET,OpTuple,OpFunction>(mF, pos, mOps.mOps);
     }
 
     template <typename T, class OpFunction, class... Ops>
@@ -998,7 +996,7 @@ namespace MultiArrayTools
     {
 	typedef std::tuple<Ops...> OpTuple;
 	return PackNum<sizeof...(Ops)-1>::
-	    template mkVOpExpr<SIZE,V,ET,OpTuple,VFunc<OpFunction>>(mkVFuncPtr(mF), pos, mOps); // implement!!!
+	    template mkVOpExpr<SIZE,V,ET,OpTuple,VFunc<OpFunction>>(mkVFuncPtr(mF), pos, mOps.mOps); // implement!!!
     }
 
     template <typename T, class OpFunction, class... Ops>
@@ -1006,21 +1004,22 @@ namespace MultiArrayTools
     inline Operation<T,OpFunction,Ops...>& Operation<T,OpFunction,Ops...>::set(ET pos)
     {
 	typedef std::tuple<Ops...> OpTuple;
-	PackNum<sizeof...(Ops)-1>::template setOpPos<SIZE,OpTuple,ET>(mOps,pos);
+	PackNum<sizeof...(Ops)-1>::template setOpPos<SIZE,OpTuple,ET>(mOps.mOps,pos);
 	return *this;
     }
 
     template <typename T, class OpFunction, class... Ops>
     auto Operation<T,OpFunction,Ops...>::rootSteps(std::intptr_t iPtrNum) const
+	-> ExtType
     {
-	return MA_SCFOR(i,0,sizeof...(Ops),i+1,std::get<i>(mOps).rootSteps(iPtrNum),extend);
+	return mOps.rootSteps(iPtrNum);
     }
 
     template <typename T, class OpFunction, class... Ops>
     template <class Expr>
     auto Operation<T,OpFunction,Ops...>::loop(Expr exp) const
     {
-	return MA_SCRAFOR(i,sizeof...(Ops),0,i-1,std::get<i>(mOps),loop,exp);
+	return MA_SCRAFOR(i,sizeof...(Ops),0,i-1,std::get<i>(mOps.mOps),loop,exp);
     }
 
     
diff --git a/src/include/multi_array_operation.h b/src/include/multi_array_operation.h
index e9ff90f..fedbec5 100644
--- a/src/include/multi_array_operation.h
+++ b/src/include/multi_array_operation.h
@@ -300,19 +300,33 @@ namespace MultiArrayTools
     template <typename T, class Target, class OpClass, OpIndexAff OIA=OpIndexAff::EXTERN>
     using AddExpr = AssignmentExpr<T,IPlus<T>,Target,OpClass,OIA>;
 
+    template <class... Ops>
+    struct OperationTuple
+    {
+	OperationTuple(const Ops&... ops) : mOps(ops...) {}
+	std::tuple<Ops...> mOps;
+	auto rootSteps(std::intptr_t iPtrNum) const;
+    };
+
+    template <class... Ops>
+    auto OperationTuple<Ops...>::rootSteps(std::intptr_t iPtrNum) const
+    {
+	return MA_SCFOR(i,0,sizeof...(Ops),i+1,std::get<i>(mOps).rootSteps(iPtrNum),extend);
+    }
+    
     template <typename T, class... Ops>
     class MOp
     {
     private:
 	MOp() = default;
-	std::tuple<Ops...> mOps;
-
+	OperationTuple<Ops...> mOps;
+	
     public:
         static constexpr size_t LAYER = 0;
 	static constexpr size_t NHLAYER = 0;
 	static constexpr size_t SIZE = (... + Ops::SIZE);
-        typedef decltype(RootSumN<sizeof...(Ops)-1>::rootSteps(mOps,0) ) ExtType;
-
+	typedef decltype(mOps.rootSteps(0)) ExtType;
+	
 	MOp(const Ops&... exprs);
 	
 	MOp(const MOp& in) = default;
@@ -326,11 +340,10 @@ namespace MultiArrayTools
 	inline size_t vget(ExtType last) const { return get(last); }
 	
 	inline MOp& set(ExtType last);
-        auto rootSteps(std::intptr_t iPtrNum = 0) const;
+        auto rootSteps(std::intptr_t iPtrNum = 0) const -> ExtType;
 
 	template <class Expr>
-	auto loop(Expr exp) const
-	    -> decltype(PackNum<sizeof...(Ops)-1>::mkLoop( mOps, exp));
+	auto loop(Expr exp) const;
 
 	T* data() const { assert(0); return nullptr; }
 
@@ -782,8 +795,9 @@ namespace MultiArrayTools
 	    (... and (Ops::VABLE and std::is_same<T,typename Ops::value_type>::value));
 
     private:
-	std::tuple<Ops...> mOps;
+	OperationTuple<Ops...> mOps;
 	std::shared_ptr<OpFunction> mF; // only if non-static
+	typedef decltype(mOps.rootSteps(0)) ExtType;
 	
     public:
 		
@@ -798,8 +812,9 @@ namespace MultiArrayTools
 
 	template <class ET>
 	inline Operation& set(ET pos);
-
-	auto rootSteps(std::intptr_t iPtrNum = 0) const; // nullptr for simple usage with decltype
+	
+	auto rootSteps(std::intptr_t iPtrNum = 0) const
+	    -> ExtType; // nullptr for simple usage with decltype
 
 	template <class Expr>
 	auto loop(Expr exp) const;
diff --git a/src/include/pack_num.h b/src/include/pack_num.h
index 234e6bf..4f8c3b1 100644
--- a/src/include/pack_num.h
+++ b/src/include/pack_num.h
@@ -76,9 +76,9 @@ namespace MultiArrayHelper
 	    typedef typename std::remove_reference<decltype(std::get<N>(ops))>::type NextOpType;
 	    static_assert(LAST >= NextOpType::SIZE, "inconsistent array positions");
 	    static constexpr size_t NEXT = LAST - NextOpType::SIZE;
-	    typedef decltype(std::get<N>(ops).get(Getter<NEXT>::template getX<ETuple>( pos ))) ArgT;
+	    typedef decltype(std::get<N>(ops).get(getX<NEXT>( pos ))) ArgT;
 	    return PackNum<N-1>::template mkOpExpr<NEXT,ETuple,OpTuple,OpFunction,ArgT,Args...>
-		( f, pos, ops, std::get<N>(ops).get(Getter<NEXT>::template getX<ETuple>( pos )), args...);
+		( f, pos, ops, std::get<N>(ops).get(getX<NEXT>( pos )), args...);
 	}
 
 	template <size_t LAST, typename V, class ETuple, class OpTuple, class OpFunction, typename... Args>
@@ -87,9 +87,9 @@ namespace MultiArrayHelper
 	    typedef typename std::remove_reference<decltype(std::get<N>(ops))>::type NextOpType;
 	    static_assert(LAST >= NextOpType::SIZE, "inconsistent array positions");
 	    static constexpr size_t NEXT = LAST - NextOpType::SIZE;
-	    typedef decltype(std::get<N>(ops).template vget<V>(Getter<NEXT>::template getX<ETuple>( pos ))) ArgT;
+	    typedef decltype(std::get<N>(ops).template vget<V>(getX<NEXT>( pos ))) ArgT;
 	    return PackNum<N-1>::template mkVOpExpr<NEXT,V,ETuple,OpTuple,OpFunction,ArgT,Args...>
-		( f, pos, ops, std::get<N>(ops).template vget<V>(Getter<NEXT>::template getX<ETuple>( pos )), args...);
+		( f, pos, ops, std::get<N>(ops).template vget<V>(getX<NEXT>( pos )), args...);
 	}
 
 	template <class OpTuple, class Expr>
@@ -132,7 +132,7 @@ namespace MultiArrayHelper
 	    typedef typename std::remove_reference<decltype(std::get<N>(ot))>::type NextOpType;
 	    static_assert(LAST >= NextOpType::SIZE, "inconsistent array positions");
 	    static constexpr size_t NEXT = LAST - NextOpType::SIZE;
-	    std::get<N>( ot ).set( Getter<NEXT>::template getX<ETuple>( et ) );
+	    std::get<N>( ot ).set( getX<NEXT>( et ) );
 	    PackNum<N-1>::template setOpPos<NEXT,OpTuple,ETuple>(ot, et);
 	}
     };
@@ -174,9 +174,8 @@ namespace MultiArrayHelper
 	    typedef typename std::remove_reference<decltype(std::get<0>(ops))>::type NextOpType;
 	    static constexpr size_t NEXT = LAST - NextOpType::SIZE;
 	    static_assert(NEXT == 0, "inconsistent array positions");
-	    typedef decltype(std::get<0>(ops).get(Getter<0>::template getX<ETuple>( pos ))) ArgT;
-	    return Application<OpFunction::FISSTATIC>::template apply<OpFunction,ArgT,Args...>(f, std::get<0>(ops).get(Getter<0>::template getX<ETuple>( pos )), args...);
-	    //return OpFunction::apply(std::get<0>(ops).get(Getter<0>::template getX<ETuple>( pos )), args...);
+	    typedef decltype(std::get<0>(ops).get(getX<0>( pos ))) ArgT;
+	    return Application<OpFunction::FISSTATIC>::template apply<OpFunction,ArgT,Args...>(f, std::get<0>(ops).get(getX<0>( pos )), args...);
 	}
 
 	template <size_t LAST, typename V, class ETuple, class OpTuple, class OpFunction, typename... Args>
@@ -185,8 +184,8 @@ namespace MultiArrayHelper
 	    typedef typename std::remove_reference<decltype(std::get<0>(ops))>::type NextOpType;
 	    static constexpr size_t NEXT = LAST - NextOpType::SIZE;
 	    static_assert(NEXT == 0, "inconsistent array positions");
-	    typedef decltype(std::get<0>(ops).template vget<V>(Getter<0>::template getX<ETuple>( pos ))) ArgT;
-	    return Application<OpFunction::FISSTATIC>::template apply<OpFunction,ArgT,Args...>(f, std::get<0>(ops).template vget<V>(Getter<0>::template getX<ETuple>( pos )), args...);
+	    typedef decltype(std::get<0>(ops).template vget<V>(getX<0>( pos ))) ArgT;
+	    return Application<OpFunction::FISSTATIC>::template apply<OpFunction,ArgT,Args...>(f, std::get<0>(ops).template vget<V>(getX<0>( pos )), args...);
 	}
 
 	template <class OpTuple, class Expr>
@@ -229,7 +228,7 @@ namespace MultiArrayHelper
 	    typedef typename std::remove_reference<decltype(std::get<0>(ot))>::type NextOpType;
 	    static constexpr size_t NEXT = LAST - NextOpType::SIZE;
 	    static_assert(NEXT == 0, "inconsistent array positions");
-	    std::get<0>( ot ).set( Getter<NEXT>::template getX<ETuple>( et ) );
+	    std::get<0>( ot ).set( getX<NEXT>( et ) );
 	}
 
     };
diff --git a/src/include/statics/static_for.h b/src/include/statics/static_for.h
index a8c21a1..8176f9f 100644
--- a/src/include/statics/static_for.h
+++ b/src/include/statics/static_for.h
@@ -50,23 +50,12 @@ namespace MultiArrayTools
 	    //static_assert(abs(idx.value - END) >= abs(incr(idx) - END),
 	    //		  "this turns out to be a static endless loop");
 	    auto tmp = f(idxm);
-	    return sfor<incr(idx),END,OFF>::unpack(incr, f, create, args..., tmp);
-	}
-    };
-
-    template <size_t END, int OFF>
-    struct sfor<END,END,OFF>
-    {
-	template <typename Incr, typename F, typename Conc>
-	static inline auto exec(Incr incr, F f, Conc conc)
-	{
-	    return 0;
-	}
-
-	template <typename Incr, typename F, typename Create, typename... Args>
-	static inline auto unpack(Incr incr, F f, Create create, const Args&... args)
-	{
-	    return create(args...);
+	    if constexpr(BEG == END){
+		return create(args...);
+	    }
+	    else {
+		return sfor<incr(idx),END,OFF>::unpack(incr, f, create, args..., tmp);
+	    }
 	}
     };
 }
@@ -78,4 +67,6 @@ namespace MultiArrayTools
 #define MA_SCRAFOR(i,beg,end,decr,expr,conc,arg) sfor<beg,end,-1>::exec([&](auto i) constexpr { return decr; }, [&](auto i){ return expr; }, [&](auto f, auto next) { return f.conc(next); }, arg)
 #define MA_CFOR(i,beg,end,incr,expr,cre) sfor<beg,end,0>::unpack([&](auto i) constexpr { return incr; }, [&](auto i){ expr }, [&](auto... args) { return cre(args...); })
 
+#define MA_SCFOR_X(i,beg,end,incr,expr,conc) sfor<beg,end,0>::exec([](auto i) constexpr { return incr; }, [](auto i){ return expr; }, [](auto f, auto next) { return f.conc(next); })
+
 #endif
diff --git a/src/include/xfor/exttype.h b/src/include/xfor/exttype.h
index b6202c4..50b2229 100644
--- a/src/include/xfor/exttype.h
+++ b/src/include/xfor/exttype.h
@@ -6,43 +6,91 @@
 
 namespace MultiArrayHelper
 {
-
-    template <size_t I>
-    struct Getter
-    {
-	template <class ExtType>
-	static inline size_t get(const ExtType& et)
-	{
-	    return Getter<I-1>::get(et.next());
-	}
-
-	template <class ExtType>
-	static inline auto getX(const ExtType& et)
-	    -> decltype(Getter<I-1>::getX(et.next()))
-	{
-	    return Getter<I-1>::getX(et.next());
-	}	
-    };
-
-    template <>
-    struct Getter<0>
-    {
-	template <class ExtType>
-	static inline size_t get(const ExtType& et)
-	{
-	    return et.get();
-	}
-
-	template <class ExtType>
-	static inline auto getX(const ExtType& et)
-	    -> ExtType
-	{
-	    return et;
-	}	
-    };
-
+    
     struct None;
     
+    class ExtBase
+    {
+    public:
+	ExtBase() = default;
+	ExtBase(const ExtBase& in) = default;
+	ExtBase(ExtBase&& in) = default;
+	ExtBase& operator=(const ExtBase& in) = default;
+	ExtBase& operator=(ExtBase&& in) = default;
+        
+	virtual size_t size() const = 0;
+	virtual const size_t& val() const = 0;
+	//virtual size_t rootSteps() const = 0;
+	virtual bool operator==(const ExtBase& in) const = 0;
+	virtual bool operator==(size_t in) const = 0;
+	    
+	virtual std::shared_ptr<ExtBase> operator+(const ExtBase& in) const = 0;
+	virtual std::shared_ptr<ExtBase> operator*(size_t in) const = 0;
+	virtual void zero() = 0;
+
+	virtual std::shared_ptr<ExtBase> deepCopy() const = 0;
+	
+	template <class ExtType>
+	const ExtType& expl() const;
+
+        virtual std::string stype() const = 0;
+    };
+
+    typedef std::shared_ptr<ExtBase> DExt;
+
+    template <class ExtType>
+    class ExtT : public ExtBase
+    {
+    private:
+	ExtType mExt;
+    public:
+	static constexpr size_t SIZE = ExtType::SIZE;
+	static constexpr size_t NUM = ExtType::NUM;
+	
+	ExtT() = default;
+	ExtT(const ExtT& in) = default;
+	ExtT(ExtT&& in) = default;
+	ExtT& operator=(const ExtT& in) = default;
+	ExtT& operator=(ExtT&& in) = default;
+
+	ExtT(const ExtType& in) : mExt(in) {}
+
+	virtual std::shared_ptr<ExtBase> deepCopy() const override final { return std::make_shared<ExtT<ExtType>>(mExt); }
+
+	virtual size_t size() const override final { return sizeof(ExtType)/sizeof(size_t); }
+	//virtual size_t size() const override final { return ExtType::MExtSize(); }
+	//virtual size_t rootSteps() const override final;
+	const ExtType& ext() const { return mExt; }
+	virtual const size_t& val() const override final { return mExt.val(); }
+	virtual void zero() override final { mExt.zero(); }
+
+	virtual bool operator==(const ExtBase& in) const override final
+	{ return mExt == dynamic_cast<const ExtT<ExtType>&>(in).mExt; }
+	
+	virtual bool operator==(size_t in) const override final
+	{ return mExt == in; }
+
+	virtual DExt operator+(const ExtBase& in) const override final
+	{ return std::make_shared<ExtT<ExtType>>( mExt + dynamic_cast<const ExtT<ExtType>&>(in).mExt ); }
+	virtual DExt operator*(size_t in) const override final
+	{ return std::make_shared<ExtT<ExtType>>( mExt * in ); }
+
+        virtual std::string stype() const override final { return std::string("T[") + mExt.stype() + "]"; }
+    };
+    //class DExtT;
+
+    template <class ExtType>
+    DExt mkDExt(const ExtT<ExtType>& in)
+    {
+        return std::make_shared<ExtT<ExtType>>(in);
+    }
+
+    template <class ExtType>
+    ExtT<ExtType> mkExtT(const ExtType& in)
+    {
+        return ExtT<ExtType>(in);
+    }
+    
     template <class X>
     class MExt
     {
@@ -82,9 +130,7 @@ namespace MultiArrayHelper
 	inline const X& next() const;
 
         template <size_t N>
-        inline auto nn() const
-            -> decltype(Getter<N>::getX(*this))
-        { return Getter<N>::getX(*this); }
+        inline auto nn() const;
 
 	inline bool operator==(const MExt& in) const
 	{
@@ -194,9 +240,7 @@ namespace MultiArrayHelper
 	inline void zero();
 	
         template <size_t N>
-        inline auto nn() const
-            -> decltype(Getter<N>::getX(*this))
-        { return Getter<N>::getX(*this); }
+        inline auto nn() const;
         
 	inline MExt operator+(const MExt& in) const;
 	inline MExt operator+(const None& in) const;
@@ -210,7 +254,124 @@ namespace MultiArrayHelper
 
     };    
 
+    template <class X>
+    class DExtTX
+    {
+    private:
+	mutable DExt mDExt = nullptr;
+	X mNext;
 
+        template <class Y>
+        friend class DExtTX;
+    public:
+	static constexpr size_t NUM = X::SIZE;
+	static constexpr size_t SIZE = NUM + 1;
+	
+        DExtTX() { mDExt = std::make_shared<ExtT<None>>(); }
+        DExtTX(const DExtTX& in) : mDExt(in.mDExt->deepCopy()), mNext(in.mNext) {}
+        DExtTX(DExtTX&& in) : mDExt(in.mDExt->deepCopy()), mNext(in.mNext) {}
+        DExtTX& operator=(const DExtTX& in) { mNext = in.mNext; mDExt = in.mDExt->deepCopy(); return *this; }
+        DExtTX& operator=(DExtTX&& in) { mNext = in.mNext; mDExt = in.mDExt->deepCopy(); return *this; }
+        explicit DExtTX(const DExt& in) : mDExt(in) {}
+        /*
+	template <class Y>
+	DExtTX& operator=(const Y& y) { mDExt = std::make_shared<ExtT<Y>>(y); return *this; }
+
+	template <class Y>
+	DExtTX(const Y& y) : mDExt(std::make_shared<ExtT<Y>>(y)) {}
+        */
+	bool operator==(const DExtTX& in) const
+	{ return *mDExt == *in.mDExt and mNext == in.mNext; }
+	
+	bool operator==(size_t in) const
+	{ return *mDExt == in and mNext == in; }
+
+        template <class Y>
+        DExtTX(const DExtTX<Y>& in) : mDExt(in.mDExt), mNext(in.mNext) {}
+        
+	DExtTX(const DExt& y, const X& x) : mDExt(y->deepCopy()),
+                                            mNext(x) {}
+
+        virtual size_t size() const { return mDExt->size(); }
+        inline const DExt& get() const { return mDExt; }
+
+        inline DExtTX<None> reduce() const { return DExtTX<None>(mDExt,None(0)); }
+        
+        inline DExtTX operator+(const DExtTX& in) const
+        { if (not mDExt) return in; else return DExtTX( (*mDExt) + (*in.mDExt), mNext + in.mNext ); }
+        inline DExtTX operator*(size_t in) const
+        { if (not mDExt) return *this; else return DExtTX((*mDExt) * in, mNext * in); }
+
+	template <class ExtType>
+	inline const ExtType& expl() const
+	{ if(mDExt == nullptr) mDExt = std::make_shared<ExtT<ExtType>>(); assert(mDExt != nullptr); return mDExt->expl<ExtType>(); }
+
+	template <class Y>
+	inline auto extend(const Y& y) const -> DExtTX<decltype(mNext.extend(y))>
+	{ return DExtTX<decltype(mNext.extend(y))>(mDExt, mNext.extend(y)); }
+
+	inline const size_t& val() const { return mDExt->val(); }
+	inline const X& next() const { return mNext; }
+
+	inline void zero() { mDExt->zero(); }
+	
+	template <size_t N>
+	inline auto nn() const;
+
+        std::string stype() const { return std::string("D[") + mDExt->stype() + "," + mNext.stype() + "]"; }
+    };
+
+    typedef DExtTX<None> DExtT;
+    
+    inline MExt<None> mkExt(size_t s) { return MExt<None>(s); }
+
+
+    template <size_t I, class X>
+    auto getX(const MExt<X>& et)
+    {
+	if constexpr(I == 0){
+	    return et;
+	}
+	else {
+	    return getX<I-1>(et.next());
+	}
+    }
+
+    template <size_t I, class X>
+    auto getX(const DExtTX<X>& et)
+    {
+	if constexpr(I == 0){
+	    return et;
+	}
+	else {
+	    return getX<I-1>(et.next());
+	}
+    }
+
+    template <size_t I>
+    auto getX(const None& et)
+    {
+	static_assert(I == 0);
+	return et;
+    }
+
+    template <size_t I, class X>
+    size_t get(const MExt<X>& et)
+    {
+	return getX<I>(et).get();
+    }
+
+    template <size_t I, class X>
+    size_t get(const DExtTX<X>& et)
+    {
+	return getX<I>(et).get();
+    }
+
+    template <size_t I>
+    size_t get(const None& et)
+    {
+	return getX<I>(et).get();
+    }
 
 } // end namespace MultiArrayHelper
 
@@ -263,6 +424,13 @@ namespace MultiArrayHelper
 	mNext.zero();
     }
 
+    template <class X>
+    template <size_t N>
+    inline auto MExt<X>::nn() const
+    {
+	return getX<N>(*this);
+    }
+
     template <class X>
     inline MExt<X> MExt<X>::operator+(const MExt<X>& in) const
     {
@@ -312,6 +480,12 @@ namespace MultiArrayHelper
 	mExt = 0u;
     }
 
+    template <size_t N>
+    inline auto MExt<None>::nn() const
+    {
+	return getX<N>(*this);
+    }
+
     inline const size_t& MExt<None>::val() const
     {
 	return mExt;
@@ -334,6 +508,12 @@ namespace MultiArrayHelper
 	return MExt<None>(mExt * in);
     }
 
+    template <class X>
+    template <size_t N>
+    inline auto DExtTX<X>::nn() const
+    {
+	return getX<N>(*this);
+    }
 
 } // end namespace MultiArrayHelper
 
diff --git a/src/include/xfor/xfor.h b/src/include/xfor/xfor.h
index 372c334..0b761b3 100644
--- a/src/include/xfor/xfor.h
+++ b/src/include/xfor/xfor.h
@@ -23,159 +23,7 @@ namespace MultiArrayHelper
 
     //typedef std::pair<size_t const*,size_t> DExt;
 
-    class ExtBase
-    {
-    public:
-	ExtBase() = default;
-	ExtBase(const ExtBase& in) = default;
-	ExtBase(ExtBase&& in) = default;
-	ExtBase& operator=(const ExtBase& in) = default;
-	ExtBase& operator=(ExtBase&& in) = default;
-        
-	virtual size_t size() const = 0;
-	virtual const size_t& val() const = 0;
-	//virtual size_t rootSteps() const = 0;
-	virtual bool operator==(const ExtBase& in) const = 0;
-	virtual bool operator==(size_t in) const = 0;
-	    
-	virtual std::shared_ptr<ExtBase> operator+(const ExtBase& in) const = 0;
-	virtual std::shared_ptr<ExtBase> operator*(size_t in) const = 0;
-	virtual void zero() = 0;
 
-	virtual std::shared_ptr<ExtBase> deepCopy() const = 0;
-	
-	template <class ExtType>
-	const ExtType& expl() const;
-
-        virtual std::string stype() const = 0;
-    };
-
-    typedef std::shared_ptr<ExtBase> DExt;
-
-    template <class ExtType>
-    class ExtT : public ExtBase
-    {
-    private:
-	ExtType mExt;
-    public:
-	static constexpr size_t SIZE = ExtType::SIZE;
-	static constexpr size_t NUM = ExtType::NUM;
-	
-	ExtT() = default;
-	ExtT(const ExtT& in) = default;
-	ExtT(ExtT&& in) = default;
-	ExtT& operator=(const ExtT& in) = default;
-	ExtT& operator=(ExtT&& in) = default;
-
-	ExtT(const ExtType& in) : mExt(in) {}
-
-	virtual std::shared_ptr<ExtBase> deepCopy() const override final { return std::make_shared<ExtT<ExtType>>(mExt); }
-
-	virtual size_t size() const override final { return sizeof(ExtType)/sizeof(size_t); }
-	//virtual size_t size() const override final { return ExtType::MExtSize(); }
-	//virtual size_t rootSteps() const override final;
-	const ExtType& ext() const { return mExt; }
-	virtual const size_t& val() const override final { return mExt.val(); }
-	virtual void zero() override final { mExt.zero(); }
-
-	virtual bool operator==(const ExtBase& in) const override final
-	{ return mExt == dynamic_cast<const ExtT<ExtType>&>(in).mExt; }
-	
-	virtual bool operator==(size_t in) const override final
-	{ return mExt == in; }
-
-	virtual DExt operator+(const ExtBase& in) const override final
-	{ return std::make_shared<ExtT<ExtType>>( mExt + dynamic_cast<const ExtT<ExtType>&>(in).mExt ); }
-	virtual DExt operator*(size_t in) const override final
-	{ return std::make_shared<ExtT<ExtType>>( mExt * in ); }
-
-        virtual std::string stype() const override final { return std::string("T[") + mExt.stype() + "]"; }
-    };
-    //class DExtT;
-
-    template <class ExtType>
-    DExt mkDExt(const ExtT<ExtType>& in)
-    {
-        return std::make_shared<ExtT<ExtType>>(in);
-    }
-
-    template <class ExtType>
-    ExtT<ExtType> mkExtT(const ExtType& in)
-    {
-        return ExtT<ExtType>(in);
-    }
-    
-    template <class X>
-    class DExtTX
-    {
-    private:
-	mutable DExt mDExt = nullptr;
-	X mNext;
-
-        template <class Y>
-        friend class DExtTX;
-    public:
-	static constexpr size_t NUM = X::SIZE;
-	static constexpr size_t SIZE = NUM + 1;
-	
-        DExtTX() { mDExt = std::make_shared<ExtT<None>>(); }
-        DExtTX(const DExtTX& in) : mDExt(in.mDExt->deepCopy()), mNext(in.mNext) {}
-        DExtTX(DExtTX&& in) : mDExt(in.mDExt->deepCopy()), mNext(in.mNext) {}
-        DExtTX& operator=(const DExtTX& in) { mNext = in.mNext; mDExt = in.mDExt->deepCopy(); return *this; }
-        DExtTX& operator=(DExtTX&& in) { mNext = in.mNext; mDExt = in.mDExt->deepCopy(); return *this; }
-        explicit DExtTX(const DExt& in) : mDExt(in) {}
-        /*
-	template <class Y>
-	DExtTX& operator=(const Y& y) { mDExt = std::make_shared<ExtT<Y>>(y); return *this; }
-
-	template <class Y>
-	DExtTX(const Y& y) : mDExt(std::make_shared<ExtT<Y>>(y)) {}
-        */
-	bool operator==(const DExtTX& in) const
-	{ return *mDExt == *in.mDExt and mNext == in.mNext; }
-	
-	bool operator==(size_t in) const
-	{ return *mDExt == in and mNext == in; }
-
-        template <class Y>
-        DExtTX(const DExtTX<Y>& in) : mDExt(in.mDExt), mNext(in.mNext) {}
-        
-	DExtTX(const DExt& y, const X& x) : mDExt(y->deepCopy()),
-                                            mNext(x) {}
-
-        virtual size_t size() const { return mDExt->size(); }
-        inline const DExt& get() const { return mDExt; }
-
-        inline DExtTX<None> reduce() const { return DExtTX<None>(mDExt,None(0)); }
-        
-        inline DExtTX operator+(const DExtTX& in) const
-        { if (not mDExt) return in; else return DExtTX( (*mDExt) + (*in.mDExt), mNext + in.mNext ); }
-        inline DExtTX operator*(size_t in) const
-        { if (not mDExt) return *this; else return DExtTX((*mDExt) * in, mNext * in); }
-
-	template <class ExtType>
-	inline const ExtType& expl() const
-	{ if(mDExt == nullptr) mDExt = std::make_shared<ExtT<ExtType>>(); assert(mDExt != nullptr); return mDExt->expl<ExtType>(); }
-
-	template <class Y>
-	inline auto extend(const Y& y) const -> DExtTX<decltype(mNext.extend(y))>
-	{ return DExtTX<decltype(mNext.extend(y))>(mDExt, mNext.extend(y)); }
-
-	inline const size_t& val() const { return mDExt->val(); }
-	inline const X& next() const { return mNext; }
-
-	inline void zero() { mDExt->zero(); }
-	
-	template <size_t N>
-	inline auto nn() const -> decltype(Getter<N>::getX(*this))
-	    { return Getter<N>::getX(*this); }
-
-        std::string stype() const { return std::string("D[") + mDExt->stype() + "," + mNext.stype() + "]"; }
-    };
-
-    typedef DExtTX<None> DExtT;
-    
-    inline MExt<None> mkExt(size_t s) { return MExt<None>(s); }
     
     class ExpressionBase
     {
@@ -1061,7 +909,7 @@ namespace MultiArrayHelper
         const size_t pos = (*mSubSet)[last.val()];
         const size_t mnpos = mlast;
         const ExtType npos = last + mExt*pos;
-        mExpr(mnpos, Getter<1>::template getX<ExtType>( npos ));
+        mExpr(mnpos, getX<1>( npos ));
     }
 
     template <class IndexClass, class Expr>
@@ -1072,7 +920,7 @@ namespace MultiArrayHelper
         const size_t pos = (*mSubSet)[last.val()];
         const size_t mnpos = mlast;
         const ExtType npos = last + mExt*pos;
-        mExpr(mnpos, Getter<1>::template getX<ExtType>( npos ));
+        mExpr(mnpos, getX<1>( npos ));
     }