IAutoComplete tutorial

[kingting]

Hi All,

I have been using this tutorial to implement Auto completion in one of my text boxes. However I don't understand what they mean by Implementing IEnumString...

I've looked at this link http://www.codeproject.com/Articles/...-implementatio and they skip the actual reasoning and explanation of the implementation. I guess it is just my unfamiliarity with Interfaces in general. You take a new object (say CCustomAutoComplete) and implement the following functions as (public/private?) functions:

Clone(), Next(), Reset(), Skip()

the question is... how do you know how they are implemented? is each CCustomAutoComplete just a string that links to another CCustomAutoComplete (like a linked list?) Can I use TCHARS?

Thanks for the help.. I'm quite clueless on COM and OOP

MSDN Tutorial:

http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx

UPDATE:

I've created a skeleton for the new class:

My questions are:

1) am I on the right track here? Am I even defining this class correctly, and do i need more auxiliary functions and members and what not?
2) Is it OK to create the object using a pointer to an array of TCHAR arrays (essentially a TCHAR **)?
3) How does memory allocation work in this case?
4) Do I even need the COM IUnknown implementation if this is just a simple enumString implementation (I don't think IenumString is derived from IUnknown).

I probably have more questions but I can't think of anymore right now. I would also like to stick with a simple TCHAR implementation of this...

// custom auto complete 


class CCustomAutoComplete : public IEnumString
{

private:

	// Private members
        TCHAR  m_CurrList[256][64];
	ULONG m_nCurrentElement;
	ULONG m_nRefCount;
	BOOL m_fBound;


public:


	// Constructors/destructors

	CCustomAutoComplete()
	{
		InternalInit();

	}

	CCustomAutoComplete(TCHAR ** p_ArrayList)
	{
		InternalInit();

		SetList(p_ArrayList);

	}
	
	
	~CCustomAutoComplete()
	{
			// free array...?
	}

public:

	// Implementation

	BOOL SetList(TCHAR ** p_ArrayList)
	{

		return TRUE;

	}


	BOOL AddItem(TCHAR * p_Item)
	{

		return TRUE;

	}


	
	BOOL RemoveItem(TCHAR * p_RemoveItem)
	{

		return TRUE;
	}


	BOOL Clear()
	{


		return TRUE;

	}


public:

	//
	//	IUnknown implementation
	//
	STDMETHODIMP_(ULONG) AddRef()
	{
		return ::InterlockedIncrement(reinterpret_cast<LONG*>(&m_nRefCount));
	}

	STDMETHODIMP_(ULONG) Release()
	{
		ULONG nCount = 0;
		nCount = (ULONG) ::InterlockedDecrement(reinterpret_cast<LONG*>(&m_nRefCount));

		if (nCount == 0)
			delete this;

		return nCount;

	}

	STDMETHODIMP QueryInterface(REFIID riid, void** ppvObject)
	{

		HRESULT hr = E_NOINTERFACE;
		
		if (ppvObject != NULL)
		{
			*ppvObject = NULL;

			if (IID_IUnknown == riid)
				*ppvObject = static_cast<IUnknown*>(this);

			if (IID_IEnumString == riid)
				*ppvObject = static_cast<IEnumString*>(this);

			if (*ppvObject != NULL)
			{
				hr = S_OK;
				((LPUNKNOWN)*ppvObject)->AddRef();
			}

		}
		else
		{
			hr = E_POINTER;
		}
		
		return hr;

	}

public:

	//
	//	IEnumString implementation
	//
	STDMETHODIMP Next(ULONG celt, LPOLESTR* rgelt, ULONG* pceltFetched)
	{

	

		return S_OK;
	}
 
	STDMETHODIMP Skip(ULONG celt)
	{
		

		return S_OK;
	}
 
	STDMETHODIMP Reset(void)
	{
		
		return S_OK;
	}
 
	STDMETHODIMP Clone(IEnumString** ppenum)
	{

		return S_OK;

	}

private:

	// Internal implementation

	void InternalInit()
	{

		m_nCurrentElement = 0;
		m_nRefCount = 0;
		m_fBound = FALSE;


	}

	

};

[kingting]

I think I have it implemented and everything creates properly. When I place a break point at the CCustomAutoComplete::Next() it returns a string, however I do not see anything appear.... any thoughts?

UPDATE:

// custom auto complete 


class CCustomAutoComplete : public IEnumString
{

private:

	TCHAR  **m_CurrList;


	// Private members
	ULONG m_nLastElement;
	ULONG m_nCurrentElement;
	ULONG m_nRefCount;
	BOOL m_fBound;
	CComPtr<IAutoComplete> m_pac;

public:


	// Constructors/destructors

	CCustomAutoComplete()
	{
		Clear();
		InternalInit();

	}

	CCustomAutoComplete(TCHAR ** p_ArrayList)
	{

		m_CurrList = (TCHAR**)malloc(sizeof(TCHAR *)*256);
		for(int i = 0; i <256; i++)
		{ 
			m_CurrList[i] = (TCHAR *)malloc(sizeof(TCHAR)*256);
			ZeroMemory(m_CurrList[i], sizeof(TCHAR)*256);
		}
		InternalInit();
		Clear();
		SetList(p_ArrayList);

	}
	
	
	~CCustomAutoComplete()
	{
		for(int i = 0; i <256; i++)
		{ 
			free(m_CurrList[i]); 
			m_CurrList[i] = NULL;
		}
		free(m_CurrList);
		
	}

public:

	// Implementation

	BOOL Bind(HWND p_hWndEdit, DWORD p_dwOptions = 0, LPCTSTR p_lpszFormatString = NULL)
	{

		ATLASSERT(::IsWindow(p_hWndEdit));

		if ((m_fBound) || (m_pac))
			return FALSE;


		HRESULT hr = S_OK;

		hr = m_pac.CoCreateInstance(CLSID_AutoComplete);

		if (SUCCEEDED(hr))
		{

			if (p_dwOptions)
			{
				CComQIPtr<IAutoComplete2> pAC2(m_pac);

				ATLASSERT(pAC2);

				hr = pAC2->SetOptions(p_dwOptions);			// This never fails?
				pAC2.Release();

			}

			hr = m_pac->Init(p_hWndEdit, this, NULL, p_lpszFormatString);

			if (SUCCEEDED(hr))
			{
				m_fBound = TRUE;
				return TRUE;
			}

		}
			
		
		return FALSE;


	}

	VOID Unbind()
	{

		if (!m_fBound)
			return;

		ATLASSERT(m_pac);

		if (m_pac)
		{
			m_pac.Release();
			m_fBound = FALSE;

		}
	}



	BOOL SetList(TCHAR ** p_ArrayList)
	{

		Clear();
		
		for(int i = 0; i < 256; i++)
		{
			_tcscpy(m_CurrList[i],p_ArrayList[i]);
		}
		return TRUE;

	}


	BOOL AddItem(TCHAR * p_Item)
	{
		
		for(int i = 0; i < 256; i++)
		{	
			if(!_tcscmp(p_Item, m_CurrList[i]))
				return FALSE; 	
		}
		_tcscpy(m_CurrList[m_nLastElement], p_Item);
		m_nLastElement++;
		return TRUE;

	}


	
	BOOL RemoveItem(TCHAR * p_RemoveItem)
	{

		return TRUE;
	}


	BOOL Clear()
	{
		for(int i = 0; i < 256; i++)
			ZeroMemory(m_CurrList[i],256);
		m_nLastElement = 0;
		m_nCurrentElement = 0;
		return TRUE;

	}


public:

	//
	//	IUnknown implementation
	//
	STDMETHODIMP_(ULONG) AddRef()
	{
		return ::InterlockedIncrement(reinterpret_cast<LONG*>(&m_nRefCount));
	}

	STDMETHODIMP_(ULONG) Release()
	{
		ULONG nCount = 0;
		nCount = (ULONG) ::InterlockedDecrement(reinterpret_cast<LONG*>(&m_nRefCount));

		if (nCount == 0)
			delete this;

		return nCount;

	}

	STDMETHODIMP QueryInterface(REFIID riid, void** ppvObject)
	{

		HRESULT hr = E_NOINTERFACE;
		
		if (ppvObject != NULL)
		{
			*ppvObject = NULL;

			if (IID_IUnknown == riid)
				*ppvObject = static_cast<IUnknown*>(this);

			if (IID_IEnumString == riid)
				*ppvObject = static_cast<IEnumString*>(this);

			if (*ppvObject != NULL)
			{
				hr = S_OK;
				((LPUNKNOWN)*ppvObject)->AddRef();
			}

		}
		else
		{
			hr = E_POINTER;
		}
		
		return hr;

	}

public:

	//
	//	IEnumString implementation
	//
	STDMETHODIMP Next(ULONG celt, LPOLESTR* rgelt, ULONG* pceltFetched)
	{
		HRESULT hr = S_FALSE;

		if (!celt)
			celt = 1;
		ULONG celtFetched = 0;
		pceltFetched = &celtFetched;
		for (ULONG i = 0; i < celt; i++)
		{

			if (m_nCurrentElement == (ULONG)m_nLastElement+1)
				break;

			rgelt[i] = (LPWSTR)::CoTaskMemAlloc((ULONG) sizeof(TCHAR) * (256));
			lstrcpy(rgelt[i],m_CurrList[m_nCurrentElement]);

			if (pceltFetched)
				celtFetched++;
			
			m_nCurrentElement++;
			
			if (i == celt)
				hr = S_OK;
		}

		

		return hr;
		

	}
 
	STDMETHODIMP Skip(ULONG celt)
	{
		m_nCurrentElement += celt;
		
		if (m_nCurrentElement > m_nLastElement)
			m_nCurrentElement = 0;

		return S_OK;

	}
 
	STDMETHODIMP Reset(void)
	{
			m_nCurrentElement = 0;
		return S_OK;
	}
 
	STDMETHODIMP Clone(IEnumString** ppenum)
	{
	
		if (!ppenum)
			return E_POINTER;
		
		CCustomAutoComplete* pnew = new CCustomAutoComplete();

		pnew->AddRef();
		*ppenum = pnew;

		return S_OK;
	}

private:

	// Internal implementation

	void InternalInit()
	{

		m_nCurrentElement = 0;
		m_nRefCount = 0;
		m_fBound = FALSE;
		m_nLastElement = 0;

	}

};

Here is how I use it...

	// Initialize Autocomplete object and source object
			
			IAutoComplete *pac;

			HRESULT hr = CoCreateInstance(CLSID_AutoComplete, 
                                NULL, 
                              CLSCTX_INPROC_SERVER,
                              IID_PPV_ARGS(&pac));

		// case

			IUnknown *punkSource;


			/* CUSTOM STRING CODE*/


		
			TCHAR **commandsArray = (TCHAR**)malloc(sizeof(TCHAR *)*256);

			for(int i = 0; i <256; i++)
			{ 
				commandsArray[i] = (TCHAR *)malloc(sizeof(TCHAR)*256);
				ZeroMemory(commandsArray[i], sizeof(TCHAR)*256);
			}

			_tcscpy(commandsArray[0],_T("CUBE <name>, <width>, <height>, <length>"));
			_tcscpy(commandsArray[1],_T("adasdasdas <name>, <width>, <height>, <length>"));
			_tcscpy(commandsArray[2],_T("JESUSs <name>, <width>, <height>, <length>"));
			_tcscpy(commandsArray[3],_T("RECTANGLE <name>, <width>, <height>, <length>"));
		   _tcscpy(commandsArray[4],_T("SKETCASDSAHD <name>, <width>, <height>, <length>"));
			_tcscpy(commandsArray[5],_T("WAASDASDASD"));
			
			CCustomAutoComplete *pes = new CCustomAutoComplete(commandsArray);
		
			hr = pes->QueryInterface(IID_PPV_ARGS(&punkSource));

			// initialize the IUnknown Interface
			
			hr = pes->QueryInterface(IID_PPV_ARGS(&punkSource));

			if(!SUCCEEDED(hr))
			{
					return 0;// ...
			}


			// release objects

			for(int i = 0; i <256; i++)
			{ 
				if(commandsArray[i])
					free(commandsArray[i]); 
				commandsArray[i] = NULL;
			}
			free(commandsArray);
			
			hr = pac->Init(GetDlgItem(hwndTabCtrl,IDC_CONSOLE), punkSource, NULL, NULL);
				
			IAutoComplete2 *pac2;

			hr = pac->QueryInterface(IID_PPV_ARGS(&pac2));

			if (SUCCEEDED(hr))
			{
				 hr = pac2->SetOptions(ACO_AUTOSUGGEST|ACO_AUTOAPPEND);
                       }

Here is another implementation that also does not work

	// Initialize Autocomplete object and source object
			
			IAutoComplete *pac;

			HRESULT hr = CoCreateInstance(CLSID_AutoComplete, 
                                NULL, 
                              CLSCTX_INPROC_SERVER,
                              IID_PPV_ARGS(&pac));

		// case

			IUnknown *punkSource;


			/* CUSTOM STRING CODE*/	
		
		
			
			
			// INITIALIZE STRINGS 
				  LPOLESTR newArr[6] = {_T("CUBE <name>, <width>, <height>, <length>"),
											_T("adasdasdas <name>, <width>, <height>, <length>"),
											_T("JESUSs <name>, <width>, <height>, <length>"),
											_T("RECTANGLE <name>, <width>, <height>, <length>"),
											_T("SKETCASDSAHD <name>, <width>, <height>, <length>"),
											_T("WAASDASDASD")};
	
		
		
			CComObject<CComEnumString> *pes = 0;
		   hr = CComObject<CComEnumString>::CreateInstance( &pes);   // CRASH HERE
		 	pes->AddRef();
			
			pes->Init(newArr,&newArr[6],NULL,AtlFlagNoCopy);
		
			// initialize the IUnknown Interface
			
			hr = pes->QueryInterface(IID_PPV_ARGS(&punkSource));

			if(!SUCCEEDED(hr))
			{
					return 0;// ...
			}


			// release objects

			for(int i = 0; i <256; i++)
			{ 
				if(commandsArray[i])
					free(commandsArray[i]); 
				commandsArray[i] = NULL;
			}
			free(commandsArray);
			
			hr = pac->Init(GetDlgItem(hwndTabCtrl,IDC_CONSOLE), punkSource, NULL, NULL);
				
			IAutoComplete2 *pac2;

			hr = pac->QueryInterface(IID_PPV_ARGS(&pac2));

			if (SUCCEEDED(hr))
			{
				 hr = pac2->SetOptions(ACO_AUTOSUGGEST|ACO_AUTOAPPEND);
			}

However the program crashes on the CreateInstance call as shown in the code....

I appreciate any help I can get on this....