C++字符串类

好久没有写过程序，最近想学习下界面库的开发，基于directui的界面个人觉得还不错，像金山的源代码和duilib都是不错的。本人想结合二者做一个轻量级的界面库，同时又不依赖于常用的MFC、WTL等。在程序开发中字符串的使用是必须的，C++语音没有原生字符串，STL等标准库又多是模板类，如果开发DLL导出时就出现问题了。今天从WTL库里摘出来一个简单的字符串类，实现了基本功能，可在此基础上进行扩展。

　　头文件

 struct CStringDataE
 {
     long nRefs;
     int nDataLength;
     int nAllocLength;
     TCHAR* data()    {        return (TCHAR*)(this + );    }
 };
 _declspec(selectany) int rgInitData[] = { -, , ,  };
 _declspec(selectany) CStringDataE* _atltmpDataNil = (CStringDataE*)&rgInitData;
 _declspec(selectany) LPCTSTR _atltmpPchNil = (LPCTSTR)(((BYTE*)&rgInitData) + sizeof(CStringDataE));
 class UI_API CUIString
 {
 public:
     CUIString(void);
     CUIString(const CUIString& stringSrc);
     ~CUIString(void);

     CUIString& operator =(const CUIString& stringSrc);
     CUIString& operator =(TCHAR ch);
     CUIString& operator =(LPCTSTR lpsz);
 protected:
     LPTSTR m_pchData;   // pointer to ref counted string data
     CStringDataE* GetData() const;
     void Init();
     BOOL AllocBuffer(int nLen);
     void AssignCopy(int nSrcLen, LPCTSTR lpszSrcData);
     BOOL AllocBeforeWrite(int nLen);
     void Release();
     static const CUIString& PASCAL _GetEmptyString();
 };

源文件

 #include "stdafx.h"
 #include "UIString.h"
 #include "tchar.h"
 #include "limits.h"
 #include "assert.h"
 CUIString::CUIString(void)
 {
     Init();
 }
 CUIString::CUIString(const CUIString& stringSrc)
 {
     assert(stringSrc.GetData()->nRefs != );
     if (stringSrc.GetData()->nRefs >= )
     {
         assert(stringSrc.GetData() != _atltmpDataNil);
         m_pchData = stringSrc.m_pchData;
         InterlockedIncrement(&GetData()->nRefs);
     }
     else
     {
         Init();
         *this = stringSrc.m_pchData;
     }
 }
 // overloaded assignment
 CUIString& CUIString::operator =(const CUIString& stringSrc)
 {
     if (m_pchData != stringSrc.m_pchData)
     {
         if ((GetData()->nRefs <  && GetData() != _atltmpDataNil) || stringSrc.GetData()->nRefs < )
         {
             // actual copy necessary since one of the strings is locked
             AssignCopy(stringSrc.GetData()->nDataLength, stringSrc.m_pchData);
         }
         else
         {
             // can just copy references around
             Release();
             assert(stringSrc.GetData() != _atltmpDataNil);
             m_pchData = stringSrc.m_pchData;
             InterlockedIncrement(&GetData()->nRefs);
         }
     }
     return *this;
 }
 CUIString& CUIString::operator =(TCHAR ch)
 {
     assert(!_istlead(ch));   // can't set single lead byte
     AssignCopy(, &ch);
     return *this;
 }
 CUIString& CUIString::operator =(LPCTSTR lpsz)
 {
     assert(lpsz!= NULL );
     AssignCopy(lstrlen(lpsz), lpsz);
     return *this;
 }
 CUIString::~CUIString(void)
 {
     if (GetData() != _atltmpDataNil)
     {
         if (InterlockedDecrement(&GetData()->nRefs) <= )
             delete[](BYTE*)GetData();
     }
 }

 void CUIString::Init()
 {
     m_pchData = _GetEmptyString().m_pchData;
 }

 BOOL CUIString::AllocBuffer(int nLen)
 {
     assert(nLen >= );
     assert(nLen <= INT_MAX - );   // max size (enough room for 1 extra)
     if (nLen == )
     {
         Init();
     }
     else
     {
         CStringDataE* pData = NULL;
         assert(pData = (CStringDataE*)new BYTE[sizeof(CStringDataE) + (nLen + ) * sizeof(TCHAR)]);
         if (pData == NULL)
             return FALSE;
         pData->nRefs = ;
         pData->data()[nLen] = TEXT('\0');
         pData->nDataLength = nLen;
         pData->nAllocLength = nLen;
         m_pchData = pData->data();
     }
     return TRUE;
 }
 CStringDataE* CUIString::GetData() const
 {
     assert(m_pchData != NULL);
     return ((CStringDataE*)m_pchData) - ;
 }
 void CUIString::AssignCopy(int nSrcLen, LPCTSTR lpszSrcData)
 {
     if (AllocBeforeWrite(nSrcLen))
     {
         memcpy(m_pchData, lpszSrcData, nSrcLen * sizeof(TCHAR));//需改动
         //SecureHelper::memcpy_x(m_pchData, (nSrcLen + 1) * sizeof(TCHAR), lpszSrcData, nSrcLen * sizeof(TCHAR));
         GetData()->nDataLength = nSrcLen;
         m_pchData[nSrcLen] = TEXT('\0');
     }
 }

 BOOL CUIString::AllocBeforeWrite(int nLen)
 {
     BOOL bRet = TRUE;
     if (GetData()->nRefs >  || nLen > GetData()->nAllocLength)
     {
         Release();
         bRet = AllocBuffer(nLen);
     }
     assert(GetData()->nRefs <= );
     return bRet;
 }
 void CUIString::Release()
 {
     if (GetData() != _atltmpDataNil)
     {
         assert(GetData()->nRefs != );
         if (InterlockedDecrement(&GetData()->nRefs) <= )
             delete[](BYTE*)GetData();
         Init();
     }
 }

 const CUIString&  CUIString::_GetEmptyString()
 {
     return *(CUIString*)&_atltmpPchNil;
 }

欢迎吐槽