CMap源代码

template
class CMap : public CObject
{
protected:
	// Association
	struct CAssoc
	{
		CAssoc* pNext;
		UINT nHashValue;  // needed for efficient iteration
		KEY key;
		VALUE value;
	};
public:
	// Construction
	CMap(int nBlockSize = 10);

	// Attributes
	// number of elements
	int GetCount() const;
	BOOL IsEmpty() const;

	// Lookup
	BOOL Lookup(ARG_KEY key, VALUE& rValue) const;

	// Operations
	// Lookup and add if not there
	VALUE& operator[](ARG_KEY key);

	// add a new (key, value) pair
	void SetAt(ARG_KEY key, ARG_VALUE newValue);

	// removing existing (key, ?) pair
	BOOL RemoveKey(ARG_KEY key);
	void RemoveAll();

	// iterating all (key, value) pairs
	POSITION GetStartPosition() const;
	void GetNextAssoc(POSITION& rNextPosition, KEY& rKey, VALUE& rValue) const;

	// advanced features for derived classes
	UINT GetHashTableSize() const;
	void InitHashTable(UINT hashSize, BOOL bAllocNow = TRUE);

	// Implementation
protected:
	CAssoc** m_pHashTable;
	UINT m_nHashTableSize;
	int m_nCount;
	CAssoc* m_pFreeList;
	struct CPlex* m_pBlocks;
	int m_nBlockSize;

	CAssoc* NewAssoc();
	void FreeAssoc(CAssoc*);
	CAssoc* GetAssocAt(ARG_KEY, UINT&) const;

public:
	~CMap();
	void Serialize(CArchive&);
#ifdef _DEBUG
	void Dump(CDumpContext&) const;
	void AssertValid() const;
#endif
};



template
CMap::CAssoc*
	CMap::NewAssoc()
{
	if (m_pFreeList == NULL)
	{
		// add another block
		CPlex* newBlock = CPlex::Create(m_pBlocks, m_nBlockSize, sizeof(CMap::CAssoc));
		// chain them into free list
		CMap::CAssoc* pAssoc = (CMap::CAssoc*) newBlock->data();
		// free in reverse order to make it easier to debug
		pAssoc += m_nBlockSize - 1;
		for (int i = m_nBlockSize-1; i >= 0; i--, pAssoc--)
		{
			pAssoc->pNext = m_pFreeList;
			m_pFreeList = pAssoc;
		}
	}
	ASSERT(m_pFreeList != NULL);  // we must have something

	CMap::CAssoc* pAssoc = m_pFreeList;
	m_pFreeList = m_pFreeList->pNext;
	m_nCount++;
	ASSERT(m_nCount > 0);  // make sure we don't overflow
	ConstructElements(&pAssoc->key, 1);
	ConstructElements(&pAssoc->value, 1);   // special construct values
	return pAssoc;
}

template
void CMap::FreeAssoc(CMap::CAssoc* pAssoc)
{
	DestructElements(&pAssoc->value, 1);
	DestructElements(&pAssoc->key, 1);
	pAssoc->pNext = m_pFreeList;
	m_pFreeList = pAssoc;
	m_nCount--;
	ASSERT(m_nCount >= 0);  // make sure we don't underflow

	// if no more elements, cleanup completely
	if (m_nCount == 0)
		RemoveAll();
}



template
VALUE& CMap::operator[](ARG_KEY key)
{
	ASSERT_VALID(this);

	UINT nHash;
	CAssoc* pAssoc;
	if ((pAssoc = GetAssocAt(key, nHash)) == NULL)
	{
		if (m_pHashTable == NULL)
			InitHashTable(m_nHashTableSize);

		// it doesn't exist, add a new Association
		pAssoc = NewAssoc();
		pAssoc->nHashValue = nHash;
		pAssoc->key = key;
		// 'pAssoc->value' is a constructed object, nothing more

		// put into hash table
		pAssoc->pNext = m_pHashTable[nHash];
		m_pHashTable[nHash] = pAssoc;
	}
	return pAssoc->value;  // return new reference
}

if ((pAssoc = GetAssocAt(key, nHash)) == NULL)
{
	if (m_pHashTable == NULL)
		InitHashTable(m_nHashTableSize);

	// it doesn't exist, add a new Association
	pAssoc = NewAssoc();
	pAssoc->nHashValue = nHash;
	pAssoc->key = key;
	// 'pAssoc->value' is a constructed object, nothing more

	// put into hash table
	pAssoc->pNext = m_pHashTable[nHash];
	m_pHashTable[nHash] = pAssoc;
}
struct CPlex     // warning variable length structure
{
	CPlex* pNext;
#if (_AFX_PACKING >= 8)
	DWORD dwReserved[1];    // align on 8 byte boundary
#endif
	// BYTE data[maxNum*elementSize];

	void* data() { return this+1; }

	static CPlex* PASCAL Create(CPlex*& head, UINT nMax, UINT cbElement);
	// like 'calloc' but no zero fill
	// may throw memory exceptions

	void FreeDataChain();       // free this one and links
};

CPlex* PASCAL CPlex::Create(CPlex*& pHead, UINT nMax, UINT cbElement)
{
	ASSERT(nMax > 0 && cbElement > 0);
	CPlex* p = (CPlex*) new BYTE[sizeof(CPlex) + nMax * cbElement];
	// may throw exception
	p->pNext = pHead;
	pHead = p;  // change head (adds in reverse order for simplicity)
	return p;
}

void CPlex::FreeDataChain()     // free this one and links
{
	CPlex* p = this;
	while (p != NULL)
	{
		BYTE* bytes = (BYTE*) p;
		CPlex* pNext = p->pNext;
		delete[] bytes;
		p = pNext;
	}
}