helpers.h

//---------------------------------------------------------------------------
// Helpers.h
//---------------------------------------------------------------------------
// General OLE Automation helper functions.
//---------------------------------------------------------------------------
/*	Copyright (C) Microsoft Corporation, 1999.  All rights reserved.


	This source code is intended only as a supplement to Microsoft
	Development Tools and/or on-line documentation.  See these other
	materials for detailed information regarding Microsoft code samples.
*/

#pragma once

//---------------------------------------------------------------------------
// To make the OLE-related code easier to read
//---------------------------------------------------------------------------
#define CHECK(x)       { hr = (x);  if (hr) { FAIL("Bad hr"); goto CleanUp; } }
#define CHECKSZ(x,sz)  { hr = (x);  if (hr) { FAIL(sz);       goto CleanUp; } }
#define CHECKCL(x)     { hr = (x);  if (hr) { FAIL("Bad hr"); goto CheckLoop; } }
#define ARGSZ(f,sz)    {            if (f)  { FAIL(sz);       return E_INVALIDARG; } }
#define CHECKOS(x) { if (ERROR_SUCCESS!=(x)) { FAIL("Bad"); hr=E_FAIL; goto CleanUp; } }

#define RELEASEPTRTYPE(p,typ) \
  {                           \
    if (p)                    \
      {                       \
      typ *__punk = (p);      \
      (p) = NULL;             \
      __punk->Release();      \
      }                       \
  }

#define RELEASEPTR(p)     RELEASEPTRTYPE(p,IUnknown)


//---------------------------------------------------------------------------
// Allocates a temporary buffer that will disappear when it goes out of scope
// NOTE: Be careful of that-- make sure you use the string in the same or
// nested scope in which you created this buffer.  People should not use this
// class directly; use the macro(s) below.
//---------------------------------------------------------------------------
class TempBuffer
  {
  public:
    TempBuffer(const ULONG cb)
      {
      m_fAlloc = (cb > 256);
      if (m_fAlloc)
        m_pbBuf = new char[cb];
      else
        m_pbBuf = m_szBufT;
      }
    ~TempBuffer()
      { if (m_pbBuf && m_fAlloc) delete [] m_pbBuf; }
    void *GetBuffer() const
      { return m_pbBuf; }

  private:
    void *m_pbBuf;
    char  m_szBufT[256];  // We'll use this temp buffer for small cases.
    bool  m_fAlloc;
  };


//---------------------------------------------------------------------------
// String helpers.
//---------------------------------------------------------------------------
// Given and ANSI String, copy it into a wide buffer.
// NOTE: Be careful about scoping when using this macro!
//
// How to use the below two macros:
//
//  ...
//  LPSTR pszA;
//  pszA = MyGetpszAnsiingRoutine();
//  MAKE_WIDEPTR_FROMANSI(pwsz, pszA);
//  MyUseWideStringRoutine(pwsz);
//  ...
//
// Similarily for MAKE_ANSIPTR_FROMWIDE().  Note that the first param does
// not have to be declared, and no clean up must be done.
//---------------------------------------------------------------------------
#define UNICODE_FROM_ANSI(pwszUnicode, pszAnsi, cb) \
    MultiByteToWideChar(CP_ACP, 0, pszAnsi, -1, pwszUnicode, cb);

#define MAKE_WIDEPTR_FROMANSI(ptrname, pszAnsi) \
    char *__psz##ptrname = pszAnsi?pszAnsi:""; \
    long __l##ptrname = (lstrlen(__psz##ptrname) + 1) * sizeof(WCHAR); \
    TempBuffer __TempBuffer##ptrname(__l##ptrname); \
    MultiByteToWideChar(CP_ACP, 0, __psz##ptrname, -1, (LPWSTR)__TempBuffer##ptrname.GetBuffer(), __l##ptrname); \
    LPWSTR ptrname = (LPWSTR)__TempBuffer##ptrname.GetBuffer()

#define MAKE_ANSIPTR_FROMWIDE(ptrname, pwszUnicode) \
    WCHAR *__pwsz##ptrname = pwszUnicode?pwszUnicode:L""; \
    long __l##ptrname = (lstrlenW(__pwsz##ptrname) + 1) * sizeof(char); \
    TempBuffer __TempBuffer##ptrname(__l##ptrname); \
    WideCharToMultiByte(CP_ACP, 0, __pwsz##ptrname, -1, (LPSTR)__TempBuffer##ptrname.GetBuffer(), __l##ptrname, NULL, NULL); \
    LPSTR ptrname = (LPSTR)__TempBuffer##ptrname.GetBuffer()

//--- EOF -------------------------------------------------------------------