windows-nt/Source/XPSP1/NT/enduser/netmeeting/ui/conf/enumvar.cpp

/************************************************************************* 
** 
**  This is a part of the Microsoft Source Code Samples. 
** 
**  Copyright 1992 - 1998 Microsoft Corporation. All rights reserved. 
** 
**  This source code is only intended as a supplement to Microsoft Development 
**  Tools and/or WinHelp documentation.  See these sources for detailed 
**  information regarding the Microsoft samples programs. 
** 
**  OLE Automation TypeLibrary Browse Helper Sample 
** 
**  enumvar.cpp 
** 
**  CEnumVariant implementation 
** 
**  Written by Microsoft Product Support Services, Windows Developer Support 
** 
*************************************************************************/ 

#include <windows.h> 
#include "precomp.h"
#include "Enumvar.h"   
 
/* 
 * CEnumVariant::Create 
 * 
 * Purpose: 
 *  Creates an instance of the IEnumVARIANT enumerator object and initializes it. 
 * 
 * Parameters: 
 *  psa        Safe array containing items to be enumerated. 
 *  cElements  Number of items to be enumerated.  
 *  ppenumvariant    Returns enumerator object. 
 * 
 * Return Value: 
 *  HRESULT 
 * 
 */ 
//static 
HRESULT  
CEnumVariant::Create(SAFEARRAY FAR* psa, ULONG cElements, CEnumVariant** ppenumvariant)  
{    
    HRESULT hr; 
    CEnumVariant FAR* penumvariant = NULL; 
    long lLBound; 
                       
    *ppenumvariant = NULL; 
     
    penumvariant = new CEnumVariant(); 
    if (penumvariant == NULL) 
        goto error;  
         
    penumvariant->m_cRef = 0; 
     
    // Copy elements into safe array that is used in enumerator implemenatation and  
    // initialize state of enumerator. 
    hr = SafeArrayGetLBound(psa, 1, &lLBound); 
    if (FAILED(hr)) 
        goto error; 
    penumvariant->m_cElements = cElements;     
    penumvariant->m_lLBound = lLBound; 
    penumvariant->m_lCurrent = lLBound;                   
    hr = SafeArrayCopy(psa, &penumvariant->m_psa); 
    if (FAILED(hr)) 
       goto error; 
     
    *ppenumvariant = penumvariant; 
    return NOERROR; 
     
error:  
    if (penumvariant == NULL) 
        return E_OUTOFMEMORY;    
                               
    if (penumvariant->m_psa)  
        SafeArrayDestroy(penumvariant->m_psa);    
    penumvariant->m_psa = NULL;      
    delete penumvariant; 
    return hr; 
} 
 
/* 
 * CEnumVariant::CEnumVariant 
 * 
 * Purpose: 
 *  Constructor for CEnumVariant object. Initializes members to NULL. 
 * 
 */ 
CEnumVariant::CEnumVariant() 
{     
    m_psa = NULL; 
} 
 
/* 
 * CEnumVariant::~CEnumVariant 
 * 
 * Purpose: 
 *  Destructor for CEnumVariant object.  
 * 
 */ 
CEnumVariant::~CEnumVariant() 
{                    
    if (m_psa) SafeArrayDestroy(m_psa); 
} 
 
/* 
 * CEnumVariant::QueryInterface, AddRef, Release 
 * 
 * Purpose: 
 *  Implements IUnknown::QueryInterface, AddRef, Release 
 * 
 */ 
STDMETHODIMP 
CEnumVariant::QueryInterface(REFIID iid, void FAR* FAR* ppv)  
{    
    *ppv = NULL; 
         
    if (iid == IID_IUnknown || iid == IID_IEnumVARIANT)  
        *ppv = this;      
    else return E_NOINTERFACE;  
 
    AddRef(); 
    return NOERROR;     
} 
 
 
STDMETHODIMP_(ULONG) 
CEnumVariant::AddRef(void) 
{ 
 
#ifdef _DEBUG    
    TCHAR ach[50]; 
    wsprintf(ach, TEXT("Ref = %ld, Enum\r\n"), m_cRef+1);  
    TRACE_OUT((ach));
#endif   
     
    return ++m_cRef;  // AddRef Application Object if enumerator will outlive application object 
} 
 
 
STDMETHODIMP_(ULONG) 
CEnumVariant::Release(void) 
{ 
 
#ifdef _DEBUG    
    TCHAR ach[50]; 
    wsprintf(ach, TEXT("Ref = %ld, Enum\r\n"), m_cRef-1);  
    TRACE_OUT((ach));
#endif   
     
    if(--m_cRef == 0) 
    { 
        delete this; 
        return 0; 
    } 
    return m_cRef; 
} 
 
/* 
 * CEnumVariant::Next 
 * 
 * Purpose: 
 *  Retrieves the next cElements elements. Implements IEnumVARIANT::Next.  
 * 
 */ 
STDMETHODIMP 
CEnumVariant::Next(ULONG cElements, VARIANT FAR* pvar, ULONG FAR* pcElementFetched) 
{  
    HRESULT hr; 
    ULONG l; 
    long l1; 
    ULONG l2; 
     
    if (pcElementFetched != NULL) 
        *pcElementFetched = 0; 
         
    // Retrieve the next cElements elements. 
    for (l1=m_lCurrent, l2=0; l1<(long)(m_lLBound+m_cElements) && l2<cElements; l1++, l2++) 
    { 
       hr = SafeArrayGetElement(m_psa, &l1, &pvar[l2]);  
       if (FAILED(hr)) 
           goto error;  
    } 
    // Set count of elements retrieved 
    if (pcElementFetched != NULL) 
        *pcElementFetched = l2; 
    m_lCurrent = l1; 
     
    return  (l2 < cElements) ? S_FALSE : NOERROR; 
 
error: 
    for (l=0; l<cElements; l++) 
        VariantClear(&pvar[l]); 
    return hr;     
} 
 
/* 
 * CEnumVariant::Skip 
 * 
 * Purpose: 
 *  Skips the next cElements elements. Implements IEnumVARIANT::Skip.  
 * 
 */ 
STDMETHODIMP 
CEnumVariant::Skip(ULONG cElements) 
{    
    m_lCurrent += cElements;  
    if (m_lCurrent > (long)(m_lLBound+m_cElements)) 
    { 
        m_lCurrent =  m_lLBound+m_cElements; 
        return S_FALSE; 
    }  
    else return NOERROR; 
} 
 
/* 
 * CEnumVariant::Reset 
 * 
 * Purpose: 
 *  Resets the current element in the enumerator to the beginning. Implements IEnumVARIANT::Reset.  
 * 
 */ 
STDMETHODIMP 
CEnumVariant::Reset() 
{  
    m_lCurrent = m_lLBound; 
    return NOERROR; 
} 
 
/* 
 * CEnumVariant::Clone 
 * 
 * Purpose: 
 *  Creates a copy of the current enumeration state. Implements IEnumVARIANT::Clone.  
 * 
 */ 
STDMETHODIMP 
CEnumVariant::Clone(IEnumVARIANT FAR* FAR* ppenum) 
{ 
    CEnumVariant FAR* penum = NULL; 
    HRESULT hr; 
     
    *ppenum = NULL; 
     
    hr = CEnumVariant::Create(m_psa, m_cElements, &penum); 
    if (FAILED(hr)) 
        goto error;         
    penum->AddRef(); 
    penum->m_lCurrent = m_lCurrent;  
     
    *ppenum = penum;         
    return NOERROR; 
      
error: 
    if (penum) 
        penum->Release(); 
    return hr;   
}