class IPersistentDataStructure
{

	public:
		virtual ~IPersistentDataStructure();

		virtual IPersistentDataStructure &SetVersion(size_t) = 0;
		virtual size_t GetVersionCount() const = 0;
		virtual size_t GetCurrentVersion() const = 0;

};

class CAbstractPersistentDataStructure:
	public IPersistentDataStructure
{

	public:
		CAbstractPersistentDataStructure();
		CAbstractPersistentDataStructure(const CAbstractPersistentDataStructure &);

		CAbstractPersistentDataStructure &operator=(const CAbstractPersistentDataStructure &);

		// ...

};

template<typename T, typename Operation>
class ISegmentTree
{

	public:
		virtual ~ISegmentTree();

		virtual ISegmentTree<T, Operation> &Change(size_t, const T &) = 0;
		virtual T operator()(size_t, size_t) const = 0;

};

template<typename T, typename Operation, T DefaultValue>
class CSegmentTree:
	public ISegmentTree<T, Operation>
{

	public:
		template<typename InputIterator>
		CSegmentTree(InputIterator, InputIterator);
		CSegmentTree(const CSegmentTree<T, Operation, DefaultValue> &);

		// ...

};

template<typename T, typename Operation, T DefaultValue>
class CPersistentSegmentTree:
	public CAbstractPersistentDataStructure, public ISegmentTree<T, Operation>
{

	public:
		template<typename InputIterator>
		CPersistentSegmentTree(InputIterator, InputIterator);
		CPersistentSegmentTree(const CPersistentSegmentTree<T, Operation, DefaultValue> &);

		// ...

};