STDENUM.H

//=--------------------------------------------------------------------------= 
// StdEnum.H 
//=--------------------------------------------------------------------------= 
// Copyright 1995 - 1998 Microsoft Corporation.  All Rights Reserved. 
// 
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF  
// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO  
// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A  
// PARTICULAR PURPOSE. 
//=--------------------------------------------------------------------------= 
// 
// object definition for a generic enumerator object. 
// 
#ifndef _STDENUM_H_ 
 
#include "Unknown.H" 
 
// to support a generic Enumerator object, we'll just define this 
// interface.  it can be safely cast to any other enumerator, since all 
// they differ in is their pointer type in Next(). 
// 
class IEnumGeneric: public IUnknown { 
 
  public: 
    virtual HRESULT __stdcall Next(ULONG celt, LPVOID rgelt, ULONG *pceltFetched) = 0; 
    virtual HRESULT __stdcall Skip(ULONG celt) = 0; 
    virtual HRESULT __stdcall Reset(void) = 0; 
    virtual HRESULT __stdcall Clone(IEnumGeneric **ppenum) = 0; 
}; 
 
//=--------------------------------------------------------------------------= 
// StandardEnum 
//=--------------------------------------------------------------------------= 
// a generic enumerator object.  given a pointer to generic data, some 
// information about the elements, and a function to copy the elements, 
// we can implement a generic enumerator. 
// 
// NOTE: this class assumes that rgElements is HeapAlloc'd, and will free it 
//       in it's destructor [although it IS valid for this to be NULL if there 
//       are no elements to enumerate over.] 
// 
class CStandardEnum: public CUnknownObject, public IEnumGeneric { 
 
public: 
    // IUnknown methods 
    // 
    DECLARE_STANDARD_UNKNOWN(); 
 
    // IEnumVariant methods 
    // 
    STDMETHOD(Next)(unsigned long celt, void * rgvar, unsigned long * pceltFetched);  
    STDMETHOD(Skip)(unsigned long celt);  
    STDMETHOD(Reset)();  
    STDMETHOD(Clone)(IEnumGeneric **ppEnumOut);  
 
    CStandardEnum(REFIID riid, int cElement, int cbElement, void *rgElements, 
                 void (WINAPI * pfnCopyElement)(void *, const void *, DWORD)); 
    ~CStandardEnum(); 
 
private: 
    virtual HRESULT InternalQueryInterface(REFIID riid, void **ppvObjOut); 
 
    IID m_iid;                        // type of enumerator that we are 
    int m_cElements;                  // Total number of elements 
    int m_cbElementSize;              // Size of each element 
    int m_iCurrent;                   // Current position: 0 = front, m_cElt = end 
    VOID * m_rgElements;              // Array of elements   
    CStandardEnum *m_pEnumClonedFrom; // If we were cloned, from whom? 
    void  (WINAPI * m_pfnCopyElement)(void *, const void *, DWORD); 
}; 
 
 
 
#define _STDENUM_H_ 
#endif // _STDENUM_H_