使用二叉树实现CMap类封装

#pragma once

template<typename KEY, typename VALUE, typename ARG_KEY = KEY&, typename ARG_VALUE = VALUE&>
class CMap
{
	struct SNode
	{
		KEY key;
		VALUE value;
		SNode *pLeft, *pRight;
	};
	SNode *m_pRoot;
	int m_nSize;
public:
	typedef SNode * POSTION;
	void SetAt(KEY key, ARG_VALUE value);
	bool Lookup(KEY key, ARG_VALUE rValue) const;
	ARG_VALUE operator[](KEY key);
	void RemoveAll();
	void RemoveKey(SNode * p);
	CMap();
	virtual ~CMap();
	int GetSize()const
	{
		return m_nSize;
	}
	void * GetRootPoint() const
	{
		return m_pRoot;
	}

};

template<typename KEY, typename VALUE, typename ARG_KEY, typename ARG_VALUE>
void CMap<KEY, VALUE, ARG_KEY, ARG_VALUE>::SetAt(KEY key, ARG_VALUE value)
{
	(*this)[key] = value;
}

template<typename KEY, typename VALUE, typename ARG_KEY, typename ARG_VALUE>
bool CMap<KEY, VALUE, ARG_KEY, ARG_VALUE>::Lookup(KEY key, ARG_VALUE rValue) const
{
	SNode *p = m_pRoot;
	while (p)
	{
		if (p->key == key)
		{
			rValue = p->value;
			return true;
		}
		else if (p->key > key)
			p = p->pLeft;
		else
			p = p->pRight;
	}
	return false;
}

template<typename KEY, typename VALUE, typename ARG_KEY, typename ARG_VALUE>
ARG_VALUE CMap<KEY, VALUE, ARG_KEY, ARG_VALUE>::operator[](KEY key)
{
	SNode **p = &m_pRoot;
	while (*p)
	{
		if ((*p)->key == key)
			break;
		else if ((*p)->key > key)
			p = &((*p)->pLeft);
		else
			p = &((*p)->pRight);
	}
	if (*p)
	{
		return (*p)->value;
	}
	SNode *pNew = new SNode();
	pNew->key = key;
	*p = pNew;
	++m_nSize;
	return (*p)->value;
}

template<typename KEY, typename VALUE, typename ARG_KEY, typename ARG_VALUE>
void CMap<KEY, VALUE, ARG_KEY, ARG_VALUE>::RemoveAll()
{
	if (m_pRoot)
		RemoveKey(m_pRoot);
	m_pRoot = nullptr;
	m_nSize = 0;
}

template<typename KEY, typename VALUE, typename ARG_KEY, typename ARG_VALUE>
void CMap<KEY, VALUE, ARG_KEY, ARG_VALUE>::RemoveKey(SNode * p)
{
	if (p->pLeft)
		RemoveKey(p->pLeft);
	if (p->pRight)
		RemoveKey(p->pRight);
	delete p;
}

template<typename KEY, typename VALUE, typename ARG_KEY, typename ARG_VALUE>
CMap<KEY, VALUE, ARG_KEY, ARG_VALUE>::CMap()
{
	m_pRoot = nullptr;
	m_nSize = 0;
}

template<typename KEY, typename VALUE, typename ARG_KEY, typename ARG_VALUE>
CMap<KEY, VALUE, ARG_KEY, ARG_VALUE>::~CMap()
{
	RemoveAll();
}