string.cpp

用ATL写的操作数据库实例

///////////////////////////////////////////////////////////////////////////////
// OLE BSTR support
#include "stdafx.h"
#include "String.h"
#include "Limits.h"

#ifdef _X86_
	#define DOUBLE_ARG  _AFX_DOUBLE
#else
	#define DOUBLE_ARG  double
#endif

// afxChNil is left for backward compatibility
TCHAR afxChNil = '\0';


#ifndef AFX_STATIC
	#define AFX_STATIC extern
	#define AFX_STATIC_DATA extern __declspec(selectany)
#endif
// For an empty string, m_pchData will point here
// (note: avoids special case of checking for NULL m_pchData)
// empty string data (and locked)
AFX_STATIC_DATA int _afxInitData[] = { -1, 0, 0, 0 };
AFX_STATIC_DATA CStringData* _afxDataNil = (CStringData*)&_afxInitData;
AFX_COMDAT LPCTSTR _afxPchNil = (LPCTSTR)(((BYTE*)&_afxInitData)+sizeof(CStringData));

// AfxIsValidAddress() returns TRUE if the passed parameter points
// to at least nBytes of accessible memory. If bReadWrite is TRUE,
// the memory must be writeable; if bReadWrite is FALSE, the memory
// may be const.

BOOL AFXAPI AfxIsValidAddress(const void* lp, UINT nBytes,
	BOOL bReadWrite /* = TRUE */)
{
	// simple version using Win-32 APIs for pointer validation.
	return (lp != NULL && !IsBadReadPtr(lp, nBytes) &&
		(!bReadWrite || !IsBadWritePtr((LPVOID)lp, nBytes)));
}

// AfxIsValidString() returns TRUE if the passed pointer
// references a string of at least the given length in characters.
// A length of -1 (the default parameter) means that the string
// buffer's minimum length isn't known, and the function will
// return TRUE no matter how long the string is. The memory
// used by the string can be read-only.

BOOL AFXAPI AfxIsValidString(LPCWSTR lpsz, int nLength /* = -1 */)
{
	if (lpsz == NULL)
		return FALSE;
	return ::IsBadStringPtrW(lpsz, nLength) == 0;
}

// As above, but for ANSI strings.

BOOL AFXAPI AfxIsValidString(LPCSTR lpsz, int nLength /* = -1 */)
{
	if (lpsz == NULL)
		return FALSE;
	return ::IsBadStringPtrA(lpsz, nLength) == 0;
}

//------------------------------------------------------------------------------


BSTR CString::AllocSysString() const
{
#if defined(_UNICODE) || defined(OLE2ANSI)
	BSTR bstr = ::SysAllocStringLen(m_pchData, GetData()->nDataLength);
	if (bstr == NULL)
		return NULL;
#else
	int nLen = MultiByteToWideChar(CP_ACP, 0, m_pchData,
		GetData()->nDataLength, NULL, NULL);
	BSTR bstr = ::SysAllocStringLen(NULL, nLen);
	if (bstr == NULL)
		return NULL;
	MultiByteToWideChar(CP_ACP, 0, m_pchData, GetData()->nDataLength,
		bstr, nLen);
#endif

	return bstr;
}

BSTR CString::SetSysString(BSTR* pbstr) const
{
	ATLASSERT(AfxIsValidAddress(pbstr, sizeof(BSTR)));

#if defined(_UNICODE) || defined(OLE2ANSI)
	if (!::SysReAllocStringLen(pbstr, m_pchData, GetData()->nDataLength))
		return *pbstr;
#else
	int nLen = MultiByteToWideChar(CP_ACP, 0, m_pchData,
		GetData()->nDataLength, NULL, NULL);
	if (!::SysReAllocStringLen(pbstr, NULL, nLen))
		return *pbstr;
	MultiByteToWideChar(CP_ACP, 0, m_pchData, GetData()->nDataLength,
		*pbstr, nLen);
#endif

	ATLASSERT(*pbstr != NULL);
	return *pbstr;
}
//------------------------------------------------------------------------------
#ifdef _AFXDLL
CString::CString()
{
	Init();
}
#endif

CString::CString(const CString& stringSrc)
{
	ATLASSERT(stringSrc.GetData()->nRefs != 0);
	if (stringSrc.GetData()->nRefs >= 0)
	{
		ATLASSERT(stringSrc.GetData() != _afxDataNil);
		m_pchData = stringSrc.m_pchData;
		InterlockedIncrement(&GetData()->nRefs);
	}
	else
	{
		Init();
		*this = stringSrc.m_pchData;
	}
}

#ifndef _DEBUG

#pragma warning(disable: 4074)
#pragma init_seg(compiler)

#define ROUND(x,y) (((x)+(y-1))&~(y-1))
#define ROUND4(x) ROUND(x, 4)
AFX_STATIC CFixedAlloc _afxAlloc64(ROUND4(65*sizeof(TCHAR)+sizeof(CStringData)));
AFX_STATIC CFixedAlloc _afxAlloc128(ROUND4(129*sizeof(TCHAR)+sizeof(CStringData)));
AFX_STATIC CFixedAlloc _afxAlloc256(ROUND4(257*sizeof(TCHAR)+sizeof(CStringData)));
AFX_STATIC CFixedAlloc _afxAlloc512(ROUND4(513*sizeof(TCHAR)+sizeof(CStringData)));

#endif //!_DEBUG

void CString::AllocBuffer(int nLen)
// always allocate one extra character for '\0' termination
// assumes [optimistically] that data length will equal allocation length
{
	ATLASSERT(nLen >= 0);
	ATLASSERT(nLen <= INT_MAX-1);    // max size (enough room for 1 extra)

	if (nLen == 0)
		Init();
	else
	{
		CStringData* pData;
#ifndef _DEBUG
		if (nLen <= 64)
		{
			pData = (CStringData*)_afxAlloc64.Alloc();
			pData->nAllocLength = 64;
		}
		else if (nLen <= 128)
		{
			pData = (CStringData*)_afxAlloc128.Alloc();
			pData->nAllocLength = 128;
		}
		else if (nLen <= 256)
		{
			pData = (CStringData*)_afxAlloc256.Alloc();
			pData->nAllocLength = 256;
		}
		else if (nLen <= 512)
		{
			pData = (CStringData*)_afxAlloc512.Alloc();
			pData->nAllocLength = 512;
		}
		else
#endif
		{
			pData = (CStringData*)
				new BYTE[sizeof(CStringData) + (nLen+1)*sizeof(TCHAR)];
			pData->nAllocLength = nLen;
		}
		pData->nRefs = 1;
		pData->data()[nLen] = '\0';
		pData->nDataLength = nLen;
		m_pchData = pData->data();
	}
}

void FASTCALL CString::FreeData(CStringData* pData)
{
#ifndef _DEBUG
	int nLen = pData->nAllocLength;
	if (nLen == 64)
		_afxAlloc64.Free(pData);
	else if (nLen == 128)
		_afxAlloc128.Free(pData);
	else if (nLen == 256)
		_afxAlloc256.Free(pData);
	else  if (nLen == 512)
		_afxAlloc512.Free(pData);
	else
	{
		ATLASSERT(nLen > 512);
		delete[] (BYTE*)pData;
	}
#else
	delete[] (BYTE*)pData;
#endif
}

void CString::Release()
{
	if (GetData() != _afxDataNil)
	{
		ATLASSERT(GetData()->nRefs != 0);
		if (InterlockedDecrement(&GetData()->nRefs) <= 0)
			FreeData(GetData());
		Init();
	}
}

void PASCAL CString::Release(CStringData* pData)
{
	if (pData != _afxDataNil)
	{
		ATLASSERT(pData->nRefs != 0);
		if (InterlockedDecrement(&pData->nRefs) <= 0)
			FreeData(pData);
	}
}

void CString::Empty()
{
	if (GetData()->nDataLength == 0)
		return;
	if (GetData()->nRefs >= 0)
		Release();
	else
		*this = &afxChNil;
	ATLASSERT(GetData()->nDataLength == 0);
	ATLASSERT(GetData()->nRefs < 0 || GetData()->nAllocLength == 0);
}

void CString::CopyBeforeWrite()
{
	if (GetData()->nRefs > 1)
	{
		CStringData* pData = GetData();
		Release();
		AllocBuffer(pData->nDataLength);
		memcpy(m_pchData, pData->data(), (pData->nDataLength+1)*sizeof(TCHAR));
	}
	ATLASSERT(GetData()->nRefs <= 1);
}

void CString::AllocBeforeWrite(int nLen)
{
	if (GetData()->nRefs > 1 || nLen > GetData()->nAllocLength)
	{
		Release();
		AllocBuffer(nLen);
	}
	ATLASSERT(GetData()->nRefs <= 1);
}

CString::~CString()
//  free any attached data
{
	if (GetData() != _afxDataNil)
	{
		if (InterlockedDecrement(&GetData()->nRefs) <= 0)
			FreeData(GetData());
	}
}

//////////////////////////////////////////////////////////////////////////////
// Helpers for the rest of the implementation

void CString::AllocCopy(CString& dest, int nCopyLen, int nCopyIndex,
	 int nExtraLen) const
{
	// will clone the data attached to this string
	// allocating 'nExtraLen' characters
	// Places results in uninitialized string 'dest'
	// Will copy the part or all of original data to start of new string

	int nNewLen = nCopyLen + nExtraLen;
	if (nNewLen == 0)
	{
		dest.Init();
	}
	else
	{
		dest.AllocBuffer(nNewLen);
		memcpy(dest.m_pchData, m_pchData+nCopyIndex, nCopyLen*sizeof(TCHAR));
	}
}

//////////////////////////////////////////////////////////////////////////////
// More sophisticated construction

CString::CString(LPCTSTR lpsz)
{
	Init();
	if (lpsz != NULL && HIWORD(lpsz) == NULL)
	{
		UINT nID = LOWORD((DWORD)lpsz);
		if (!LoadString(nID))
			ATLTRACE("Warning: implicit LoadString(%u) failed\n", nID);
	}
	else
	{
		int nLen = SafeStrlen(lpsz);
		if (nLen != 0)
		{
			AllocBuffer(nLen);
			memcpy(m_pchData, lpsz, nLen*sizeof(TCHAR));
		}
	}
}

/////////////////////////////////////////////////////////////////////////////
// Special conversion constructors

#ifdef _UNICODE
CString::CString(LPCSTR lpsz)
{
	Init();
	int nSrcLen = lpsz != NULL ? lstrlenA(lpsz) : 0;
	if (nSrcLen != 0)
	{
		AllocBuffer(nSrcLen);
		_mbstowcsz(m_pchData, lpsz, nSrcLen+1);
		ReleaseBuffer();
	}
}
#else //_UNICODE
CString::CString(LPCWSTR lpsz)
{
	Init();
	int nSrcLen = lpsz != NULL ? wcslen(lpsz) : 0;
	if (nSrcLen != 0)
	{
		AllocBuffer(nSrcLen*2);
		_wcstombsz(m_pchData, lpsz, (nSrcLen*2)+1);
		ReleaseBuffer();
	}
}
#endif //!_UNICODE

//////////////////////////////////////////////////////////////////////////////
// Diagnostic support

//////////////////////////////////////////////////////////////////////////////
// Assignment operators
//  All assign a new value to the string
//      (a) first see if the buffer is big enough
//      (b) if enough room, copy on top of old buffer, set size and type
//      (c) otherwise free old string data, and create a new one
//
//  All routines return the new string (but as a 'const CString&' so that
//      assigning it again will cause a copy, eg: s1 = s2 = "hi there".
//

void CString::AssignCopy(int nSrcLen, LPCTSTR lpszSrcData)
{
	AllocBeforeWrite(nSrcLen);
	memcpy(m_pchData, lpszSrcData, nSrcLen*sizeof(TCHAR));
	GetData()->nDataLength = nSrcLen;
	m_pchData[nSrcLen] = '\0';
}

const CString& CString::operator=(const CString& stringSrc)
{
	if (m_pchData != stringSrc.m_pchData)
	{
		if ((GetData()->nRefs < 0 && GetData() != _afxDataNil) ||
			stringSrc.GetData()->nRefs < 0)
		{
			// actual copy necessary since one of the strings is locked
			AssignCopy(stringSrc.GetData()->nDataLength, stringSrc.m_pchData);
		}
		else
		{
			// can just copy references around
			Release();
			ATLASSERT(stringSrc.GetData() != _afxDataNil);
			m_pchData = stringSrc.m_pchData;
			InterlockedIncrement(&GetData()->nRefs);
		}
	}
	return *this;
}

const CString& CString::operator=(LPCTSTR lpsz)
{
	ATLASSERT(lpsz == NULL || AfxIsValidString(lpsz));
	AssignCopy(SafeStrlen(lpsz), lpsz);
	return *this;
}

/////////////////////////////////////////////////////////////////////////////
// Special conversion assignment

#ifdef _UNICODE
const CString& CString::operator=(LPCSTR lpsz)
{
	int nSrcLen = lpsz != NULL ? lstrlenA(lpsz) : 0;
	AllocBeforeWrite(nSrcLen);
	_mbstowcsz(m_pchData, lpsz, nSrcLen+1);
	ReleaseBuffer();
	return *this;
}
#else //!_UNICODE
const CString& CString::operator=(LPCWSTR lpsz)
{
	int nSrcLen = lpsz != NULL ? wcslen(lpsz) : 0;
	AllocBeforeWrite(nSrcLen*2);
	_wcstombsz(m_pchData, lpsz, (nSrcLen*2)+1);
	ReleaseBuffer();
	return *this;
}
#endif  //!_UNICODE

//////////////////////////////////////////////////////////////////////////////
// concatenation

// NOTE: "operator+" is done as friend functions for simplicity
//      There are three variants:
//          CString + CString
// and for ? = TCHAR, LPCTSTR
//          CString + ?
//          ? + CString

void CString::ConcatCopy(int nSrc1Len, LPCTSTR lpszSrc1Data,
	int nSrc2Len, LPCTSTR lpszSrc2Data)
{
  // -- master concatenation routine
  // Concatenate two sources
  // -- assume that 'this' is a new CString object

	int nNewLen = nSrc1Len + nSrc2Len;
	if (nNewLen != 0)
	{
		AllocBuffer(nNewLen);
		memcpy(m_pchData, lpszSrc1Data, nSrc1Len*sizeof(TCHAR));
		memcpy(m_pchData+nSrc1Len, lpszSrc2Data, nSrc2Len*sizeof(TCHAR));
	}
}

CString AFXAPI operator+(const CString& string1, const CString& string2)
{
	CString s;
	s.ConcatCopy(string1.GetData()->nDataLength, string1.m_pchData,
		string2.GetData()->nDataLength, string2.m_pchData);
	return s;
}

CString AFXAPI operator+(const CString& string, LPCTSTR lpsz)
{
	ATLASSERT(lpsz == NULL || AfxIsValidString(lpsz));
	CString s;
	s.ConcatCopy(string.GetData()->nDataLength, string.m_pchData,
		CString::SafeStrlen(lpsz), lpsz);
	return s;
}

CString AFXAPI operator+(LPCTSTR lpsz, const CString& string)
{
	ATLASSERT(lpsz == NULL || AfxIsValidString(lpsz));
	CString s;
	s.ConcatCopy(CString::SafeStrlen(lpsz), lpsz, string.GetData()->nDataLength,
		string.m_pchData);
	return s;
}

//////////////////////////////////////////////////////////////////////////////
// concatenate in place

void CString::ConcatInPlace(int nSrcLen, LPCTSTR lpszSrcData)
{
	//  -- the main routine for += operators

	// concatenating an empty string is a no-op!
	if (nSrcLen == 0)
		return;

	// if the buffer is too small, or we have a width mis-match, just
	//   allocate a new buffer (slow but sure)
	if (GetData()->nRefs > 1 || GetData()->nDataLength + nSrcLen > GetData()->nAllocLength)
	{
		// we have to grow the buffer, use the ConcatCopy routine
		CStringData* pOldData = GetData();
		ConcatCopy(GetData()->nDataLength, m_pchData, nSrcLen, lpszSrcData);
		ATLASSERT(pOldData != NULL);
		CString::Release(pOldData);
	}
	else
	{
		// fast concatenation when buffer big enough
		memcpy(m_pchData+GetData()->nDataLength, lpszSrcData, nSrcLen*sizeof(TCHAR));
		GetData()->nDataLength += nSrcLen;
		ATLASSERT(GetData()->nDataLength <= GetData()->nAllocLength);
		m_pchData[GetData()->nDataLength] = '\0';
	}
}

const CString& CString::operator+=(LPCTSTR lpsz)
{
	ATLASSERT(lpsz == NULL || AfxIsValidString(lpsz));
	ConcatInPlace(SafeStrlen(lpsz), lpsz);
	return *this;
}

const CString& CString::operator+=(TCHAR ch)
{
	ConcatInPlace(1, &ch);
	return *this;
}

const CString& CString::operator+=(const CString& string)
{
	ConcatInPlace(string.GetData()->nDataLength, string.m_pchData);
	return *this;
}

///////////////////////////////////////////////////////////////////////////////
// Advanced direct buffer access

LPTSTR CString::GetBuffer(int nMinBufLength)
{
	ATLASSERT(nMinBufLength >= 0);

	if (GetData()->nRefs > 1 || nMinBufLength > GetData()->nAllocLength)
	{
#ifdef _DEBUG
		// give a warning in case locked string becomes unlocked