IENUMUNK.CPP

/* 
 * IENUMUNK.CPP 
 * 
 * Standard implementation of am IUnknown enumerator with the 
 * IEnumUnknown interface that will generally not need 
 * modification. 
 * 
 * Copyright (c)1993-1996 Microsoft Corporation, All Rights Reserved 
 * 
 * Kraig Brockschmidt, Software Design Engineer 
 * Microsoft Systems Developer Relations 
 * 
 * Internet  :  kraigb@microsoft.com 
 * Compuserve:  >INTERNET:kraigb@microsoft.com 
 */ 
 
 
#include "ienumunk.h" 
 
 
/* 
 * CEnumUnknown::CEnumUnknown 
 * CEnumUnknown::~CEnumUnknown 
 * 
 * Parameters (Constructor): 
 *  pUnkRef         LPUNKNOWN to use for reference counting. 
 *  cUnk            ULONG number of LPUNKNOWNs in prgUnk 
 *  prgUnk          LPUNKNOWN to the array to enumerate. 
 */ 
 
CEnumUnknown::CEnumUnknown(LPUNKNOWN pUnkRef, ULONG cUnk 
    , LPUNKNOWN prgUnk) 
    { 
    UINT        i; 
 
    m_cRef=0; 
    m_pUnkRef=pUnkRef; 
 
    m_iCur=0; 
    m_cUnk=cUnk; 
    m_prgUnk=new LPUNKNOWN[(UINT)cUnk]; 
 
    if (NULL!=m_prgUnk) 
        { 
        for (i=0; i < cUnk; i++) 
            m_prgUnk[i]=prgUnk[i]; 
        } 
 
    return; 
    } 
 
 
CEnumUnknown::~CEnumUnknown(void) 
    { 
    if (NULL!=m_prgUnk) 
        delete [] m_prgUnk; 
 
    return; 
    } 
 
 
 
 
 
 
/* 
 * CEnumUnknown::QueryInterface 
 * CEnumUnknown::AddRef 
 * CEnumUnknown::Release 
 * 
 * Purpose: 
 *  IUnknown members for CEnumUnknown object. 
 */ 
 
STDMETHODIMP CEnumUnknown::QueryInterface(REFIID riid 
    , LPVOID *ppv) 
    { 
    *ppv=NULL; 
 
    /* 
     * Enumerators are separate objects, not the data object, so 
     * we only need to support out IUnknown and IEnumUnknown 
     * interfaces here with no concern for aggregation. 
     */ 
    if (IsEqualIID(riid, IID_IUnknown) 
        || IsEqualIID(riid, IID_IEnumUnknown)) 
        *ppv=(LPVOID)this; 
 
    //AddRef any interface we'll return. 
    if (NULL!=*ppv) 
        { 
        ((LPUNKNOWN)*ppv)->AddRef(); 
        return NOERROR; 
        } 
 
    return E_NOINTERFACE; 
    } 
 
 
STDMETHODIMP_(ULONG) CEnumUnknown::AddRef(void) 
    { 
    ++m_cRef; 
    m_pUnkRef->AddRef(); 
    return m_cRef; 
    } 
 
STDMETHODIMP_(ULONG) CEnumUnknown::Release(void) 
    { 
    ULONG       cRefT; 
 
    cRefT=--m_cRef; 
 
    m_pUnkRef->Release(); 
 
    if (0L==m_cRef) 
        delete this; 
 
    return cRefT; 
    } 
 
 
 
 
 
 
 
/* 
 * CEnumUnknown::Next 
 * 
 * Purpose: 
 *  Returns the next element in the enumeration. 
 * 
 * Parameters: 
 *  cUnk            ULONG number of LPUNKNOWNs to return. 
 *  pUnk            LPUNKNOWN in which to store the returned 
 *                  structures. 
 *  pulUnk          ULONG * in which to return how many we 
 *                  enumerated. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR if successful, S_FALSE otherwise, 
 */ 
 
STDMETHODIMP CEnumUnknown::Next(ULONG cUnk, LPUNKNOWN pUnk 
    , ULONG * pulUnk) 
    { 
    ULONG               cReturn=0L; 
 
    if (NULL==m_prgUnk) 
        return S_FALSE; 
 
    if (NULL==pulUnk) 
        { 
        if (1L!=cUnk) 
            return E_POINTER; 
        } 
    else 
        *pulUnk=0L; 
 
    if (NULL==pUnk || m_iCur >= m_cUnk) 
        return S_FALSE; 
 
    while (m_iCur < m_cUnk && cUnk > 0) 
        { 
        *pUnk++=m_prgUnk[m_iCur++]; 
        cReturn++; 
        cUnk--; 
        } 
 
    if (NULL!=pulUnk) 
        *pulUnk=cReturn; 
 
    return NOERROR; 
    } 
 
 
 
 
 
 
 
/* 
 * CEnumUnknown::Skip 
 * 
 * Purpose: 
 *  Skips the next n elements in the enumeration. 
 * 
 * Parameters: 
 *  cSkip           ULONG number of elements to skip. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR if successful, S_FALSE if we could not 
 *                  skip the requested number. 
 */ 
 
STDMETHODIMP CEnumUnknown::Skip(ULONG cSkip) 
    { 
    if (((m_iCur+cSkip) >= m_cUnk) || NULL==m_prgUnk) 
        return S_FALSE; 
 
    m_iCur+=cSkip; 
    return NOERROR; 
    } 
 
 
 
 
 
 
/* 
 * CEnumUnknown::Reset 
 * 
 * Purpose: 
 *  Resets the current element index in the enumeration to zero. 
 * 
 * Parameters: 
 *  None 
 * 
 * Return Value: 
 *  HRESULT         NOERROR 
 */ 
 
STDMETHODIMP CEnumUnknown::Reset(void) 
    { 
    m_iCur=0; 
    return NOERROR; 
    } 
 
 
 
 
 
 
/* 
 * CEnumUnknown::Clone 
 * 
 * Purpose: 
 *  Returns another IEnumUnknown with the same state as ourselves. 
 * 
 * Parameters: 
 *  ppEnum          LPENUMUNKNOWN * in which to return the 
 *                  new object. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR or a general error value. 
 */ 
 
STDMETHODIMP CEnumUnknown::Clone(LPENUMUNKNOWN *ppEnum) 
    { 
    PCEnumUnknown   pNew; 
 
    *ppEnum=NULL; 
 
    //Create the clone 
    pNew=new CEnumUnknown(m_pUnkRef, m_cUnk, m_prgUnk); 
 
    if (NULL==pNew) 
        return E_OUTOFMEMORY; 
 
    pNew->AddRef(); 
    pNew->m_iCur=m_iCur; 
 
    *ppEnum=pNew; 
    return NOERROR; 
    }