Recursion Primer using C++: Part 3

// Compile time Structured Tail Recursion

#include <iostream>

// Termination of Link List 
struct End 
{ 
};

// Node of Static Link List 
template <int iData, typename Type> 
struct Node 
{ 
	enum { value = iData }; 
	typedef Type Next; 
};

// Structure to add the items in Static Link List 
template <typename T> 
struct Add; 

// Partial Template Specialization call recursively to add items 
template <int iData, typename Type> 
struct Add<Node<iData, Type> > 
{ 
	enum { value = iData + Add<Type>::value }; 
};

// Template Specialization to terminate recursion 
template <> 
struct Add<End> 
{ 
	enum { value = 0 }; 
};

// Structure to calculate the length of Static Link List 
template <typename T> 
struct Length; 

// Partial Template Specialization call recursiveely calculate the length 
template <int iData, typename Type> 
struct Length<Node<iData, Type> > 
{ 
	enum { value = 1 + Length<Type>::value }; 
}; 

// Template Specialization to terminate recursion 
template <> struct Length<End> 
{ 
	enum { value = 0 }; 
};

// Structure to multiply the items in Static Link List 
template <typename T> 
struct Multiply;

// Partial Template Specialization call recursively to multiply items 
template <int iData, typename Type> 
struct Multiply<Node<iData, Type> > 
{ 
	enum { value =  iData * Multiply<Type>::value }; 
}; 

// Template Specialization to terminate recursion 
template <> struct Multiply<End> 
{ 
	enum { value = 1 }; 
};

int main()
{
	typedef Node<15, Node<20, Node<35, End> > > staticList; 
	
	std::cout << Length<staticList>::value << std::endl; 
	std::cout << Add<staticList>::value << std::endl; 
	std::cout << Multiply<staticList>::value << std::endl;
}