IENUMSTR.CPP

/* 
 * IENUMSTR.CPP 
 * 
 * Standard implementation of a string enumerator with the 
 * IEnumString 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 "ienumstr.h" 
 
 
/* 
 * CEnumString::CEnumString 
 * CEnumString::~CEnumString 
 * 
 * Parameters (Constructor): 
 *  pUnkRef         LPUNKNOWN to use for reference counting. 
 *  cstr            ULONG number of LPTSTRs in pstr 
 *  prgstr          LPTSTR to the array to enumerate. 
 */ 
 
CEnumString::CEnumString(LPUNKNOWN pUnkRef, ULONG cstr 
    , LPTSTR prgstr) 
    { 
    UINT        i; 
 
    m_cRef=0; 
    m_pUnkRef=pUnkRef; 
 
    m_iCur=0; 
    m_cstr=cFE; 
    m_prgstr=new LPTSTR[(UINT)cFE]; 
 
    if (NULL!=m_prgstr) 
        { 
        for (i=0; i < cFE; i++) 
            m_prgstr[i]=prgFE[i]; 
        } 
 
    return; 
    } 
 
 
CEnumString::~CEnumString(void) 
    { 
    if (NULL!=m_prgstr) 
        delete [] m_prgstr; 
 
    return; 
    } 
 
 
 
 
 
 
/* 
 * CEnumString::QueryInterface 
 * CEnumString::AddRef 
 * CEnumString::Release 
 * 
 * Purpose: 
 *  IUnknown members for CEnumString object. 
 */ 
 
STDMETHODIMP CEnumString::QueryInterface(REFIID riid 
    , LPVOID *ppv) 
    { 
    *ppv=NULL; 
 
    if (IsEqualIID(riid, IID_IUnknown) 
        || IsEqualIID(riid, IID_IEnumString)) 
        *ppv=(LPVOID)this; 
 
    //AddRef any interface we'll return. 
    if (NULL!=*ppv) 
        { 
        ((LPUNKNOWN)*ppv)->AddRef(); 
        return NOERROR; 
        } 
 
    return E_NOINTERFACE; 
    } 
 
 
STDMETHODIMP_(ULONG) CEnumString::AddRef(void) 
    { 
    ++m_cRef; 
    m_pUnkRef->AddRef(); 
    return m_cRef; 
    } 
 
STDMETHODIMP_(ULONG) CEnumString::Release(void) 
    { 
    ULONG       cRefT; 
 
    cRefT=--m_cRef; 
 
    m_pUnkRef->Release(); 
 
    if (0L==m_cRef) 
        delete this; 
 
    return cRefT; 
    } 
 
 
 
 
 
 
 
/* 
 * CEnumString::Next 
 * 
 * Purpose: 
 *  Returns the next element in the enumeration. 
 * 
 * Parameters: 
 *  cstr            ULONG number of LPTSTRs to return. 
 *  pstr            LPTSTR in which to store the returned 
 *                  structures. 
 *  pulstr          ULONG * in which to return how many we 
 *                  enumerated. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR if successful, S_FALSE otherwise, 
 */ 
 
STDMETHODIMP CEnumString::Next(ULONG cstr, LPTSTR pstr 
    , ULONG * pulstr) 
    { 
    ULONG               cReturn=0L; 
 
    if (NULL==m_prgstr) 
        return S_FALSE; 
 
    if (NULL==pulstr) 
        { 
        if (1L!=cstr) 
            return E_POINTER; 
        } 
    else 
        *pulstr=0L; 
 
    if (NULL==pstr || m_iCur >= m_cstr) 
        return S_FALSE; 
 
    while (m_iCur < m_cstr && cstr > 0) 
        { 
        *pstr++=m_prgstr[m_iCur++]; 
        cReturn++; 
        cstr--; 
        } 
 
    if (NULL!=pulstr) 
        *pulstr=cReturn; 
 
    return NOERROR; 
    } 
 
 
 
 
 
 
 
/* 
 * CEnumString::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 CEnumString::Skip(ULONG cSkip) 
    { 
    if (((m_iCur+cSkip) >= m_cstr) || NULL==m_prgstr) 
        return S_FALSE; 
 
    m_iCur+=cSkip; 
    return NOERROR; 
    } 
 
 
 
 
 
 
/* 
 * CEnumString::Reset 
 * 
 * Purpose: 
 *  Resets the current element index in the enumeration to zero. 
 * 
 * Parameters: 
 *  None 
 * 
 * Return Value: 
 *  HRESULT         NOERROR 
 */ 
 
STDMETHODIMP CEnumString::Reset(void) 
    { 
    m_iCur=0; 
    return NOERROR; 
    } 
 
 
 
 
 
 
/* 
 * CEnumString::Clone 
 * 
 * Purpose: 
 *  Returns another IEnumString with the same state as ourselves. 
 * 
 * Parameters: 
 *  ppEnum          LPENUMSTRING * in which to return the 
 *                  new object. 
 * 
 * Return Value: 
 *  HRESULT         NOERROR or a general error value. 
 */ 
 
STDMETHODIMP CEnumString::Clone(LPENUMSTRING *ppEnum) 
    { 
    PCEnumString    pNew; 
 
    *ppEnum=NULL; 
 
    //Create the clone 
    pNew=new CEnumString(m_pUnkRef, m_cstr, m_prgstr); 
 
    if (NULL==pNew) 
        return E_OUTOFMEMORY; 
 
    pNew->AddRef(); 
    pNew->m_iCur=m_iCur; 
 
    *ppEnum=pNew; 
    return NOERROR; 
    }