C++ COpcString::IsEmpty方法代码示例

// Save
bool COpcXmlDocument::Save(const COpcString& cFilePath)
{
    HRESULT hResult = S_OK;

    VARIANT varFile;

    varFile.vt      = VT_BSTR;
    varFile.bstrVal = SysAllocString((LPCWSTR)((cFilePath.IsEmpty())?m_cFilePath:cFilePath));

    TRY
    {
        // save the file.
        hResult = m_ipDocument->save(varFile);

        if (FAILED(hResult))
        {
            THROW();
        }
    }

    CATCH_FINALLY
    {
        OpcVariantClear(&varFile);
    }

    return SUCCEEDED(hResult);
}

// AddNamespace
bool COpcXmlDocument::AddNamespace(const COpcString& cPrefix, const COpcString& cNamespace)
{
    // check for a valid root element.
    COpcXmlElement cElement(GetRoot());

    if (cElement == NULL)
    {
        return false;
    }

    // check for an invalid prefix
    if (cPrefix.IsEmpty())
    {
        return false;
    }

    // construct the new namespace attribute name.
    COpcString cAttributeName;

    cAttributeName += OPCXML_NAMESPACE_ATTRIBUTE;
    cAttributeName += ":";
    cAttributeName += cPrefix;

    // add or update the namespace string.
    cElement.SetAttribute(cAttributeName, cNamespace);

    return true;
}

// GetNamespaces
void COpcXmlDocument::GetNamespaces(COpcStringMap& cNamespaces)
{
    // clear the current set.
    cNamespaces.RemoveAll();

    // check for a valid root element.
    COpcXmlElement cElement(GetRoot());

    if (cElement == NULL)
    {
        return;
    }

    // add the namespace for the root element.
    COpcString cPrefix = cElement.GetPrefix();

    if (!cPrefix.IsEmpty())
    {
        cNamespaces[cPrefix] = cElement.GetNamespace();
    }

    // fetch the attributes from the root element.
    COpcXmlAttributeList cAttributes;

    if (cElement.GetAttributes(cAttributes) > 0)
    {
        for (UINT ii = 0; ii < cAttributes.GetSize(); ii++)
        {
            if (cAttributes[ii].GetPrefix() == OPCXML_NAMESPACE_ATTRIBUTE)
            {
                COpcString cName = cAttributes[ii].GetQualifiedName().GetName();

                // don't add the default namespace.
                if (!cName.IsEmpty())
                {
                    cNamespaces[cName] = cAttributes[ii].GetValue();
                }
            }
        }
    }
}

COpcTextReader::COpcTextReader(const COpcString& cBuffer)
:
    m_szBuf(NULL),
    m_uLength(0),
    m_uEndOfData(0)
{
    if (!cBuffer.IsEmpty())
    {
        LPCWSTR szBuf = (COpcString&)cBuffer;

        m_uLength = (szBuf != NULL)?wcslen(szBuf):0;
        m_szBuf   = (WCHAR*)OpcAlloc((m_uLength+1)*sizeof(WCHAR));

        wcsncpy(m_szBuf, szBuf, m_uLength);

        m_uEndOfData = m_uLength;
        m_szBuf[m_uEndOfData] = L'\0';
    }
} 

// GetItemID
COpcString COpcBrowseElement::GetItemID() const
{
    if (m_cItemID.IsEmpty())
    {
        COpcString cItemID;

        if (m_pParent != NULL)
        {
            cItemID += m_pParent->GetItemID();

            if (!cItemID.IsEmpty())
            {
                cItemID += m_pParent->GetSeparator();
            }
        }

        cItemID += m_cName;

        return cItemID;
    }

    return m_cItemID;
}

// Read
template<> bool OpcXml::Read(const COpcString& cString, DateTime& cValue)
{
    bool bResult = true;

    FILETIME cFileTime;

	// check for invalid date.
	if (cString.IsEmpty())
	{
		cValue = OpcMinDate();
		return true;
	}

    TRY
    {
        SYSTEMTIME cSystemTime; ZeroMemory(&cSystemTime, sizeof(cSystemTime));

        COpcText cText;
        COpcTextReader cReader(cString);

        // parse date fields.
        cText.SetType(COpcText::Delimited);
        cText.SetDelims(L"T");

        if (!cReader.GetNext(cText)) THROW_(bResult, false);

        if (!ToDate(cText, cSystemTime.wYear, cSystemTime.wMonth, cSystemTime.wDay))
        {
            THROW_(bResult, false);
        }

        // parse time fields.
        cText.SetType(COpcText::Delimited);
        cText.SetDelims(L"Z-+");
        cText.SetEofDelim();

        if (!cReader.GetNext(cText)) THROW_(bResult, false);

        bResult = ToTime(
            cText, 
            cSystemTime.wHour, 
            cSystemTime.wMinute, 
            cSystemTime.wSecond, 
            cSystemTime.wMilliseconds);

        if (!bResult)
        {
            THROW_(bResult, false);
        }

		// convert to a UTC file time.
		if (!SystemTimeToFileTime(&cSystemTime, &cFileTime))
		{
			THROW_(bResult, false);
		}

		if (cText.GetDelimChar() != _T('Z'))
		{
			// convert local system time to UTC file time.
			if (cText.GetEof())
			{
				FILETIME ftUtcTime;

				if (!OpcLocalTimeToUtcTime(cFileTime, ftUtcTime))
				{
					THROW_(bResult, false);
				}
				
				cFileTime = ftUtcTime;
			}

			// apply offset specified in the datetime string.
			else
			{
				bool bNegative = (cText.GetDelimChar() == _T('-'));

				// parse time fields.
				cText.SetType(COpcText::Delimited);
				cText.SetEofDelim();

				if (!cReader.GetNext(cText)) THROW_(bResult, false);

				SHORT sMinutes = 0;

				bResult = ToOffset(
					cText, 
					bNegative,
					sMinutes);

				if (!bResult)
				{
					THROW_(bResult, false);
				}

				// apply timezone offset.
				LONGLONG llTime = OpcToInt64(cFileTime);

				llTime -= ((LONGLONG)sMinutes)*60*10000000;

//.........这里部分代码省略.........

// Load
bool COpcXmlDocument::Load(const COpcString& cFilePath)
{
    HRESULT hResult = S_OK;

    VARIANT varFile;

    varFile.vt      = VT_BSTR;
    varFile.bstrVal = SysAllocString((LPCWSTR)cFilePath);

    TRY
    {
        // create new document instance.
        if (!Init())
        {
            THROW_(hResult, E_FAIL);
        }

        // load the file.
        VARIANT_BOOL bResult = VARIANT_FALSE;

        hResult = m_ipDocument->load(varFile, &bResult);

        if (FAILED(hResult))
        {
            THROW();
        }

        if (!bResult)
        {
            IXMLDOMParseError* ipError = NULL;

            hResult = m_ipDocument->get_parseError(&ipError);

            if (FAILED(hResult))
            {
                THROW_(hResult, E_FAIL);
            }

            BSTR bstrReason = NULL;

            hResult = ipError->get_reason(&bstrReason);

            if (SUCCEEDED(hResult))
            {
                SysFreeString(bstrReason);
            }

            ipError->Release();
        }

        // update default path.
        if (!cFilePath.IsEmpty()) m_cFilePath = cFilePath;
    }

    CATCH
    {
        Clear();
    }

    FINALLY
    {
        OpcVariantClear(&varFile);
    }

    return SUCCEEDED(hResult);
}

// Insert
COpcBrowseElement* COpcBrowseElement::Insert(const COpcString& cPath)
{   
    COpcString cName    = cPath;
    COpcString cSubPath = OPC_EMPTY_STRING;
    
    // check if multiple levels have been specified.
    do
    {
        UINT uIndex = cName.Find(GetSeparator());

        if (uIndex == -1)
        {
            break;
        }

        cSubPath = cName.SubStr(uIndex + GetSeparator().GetLength());
        cName    = cName.SubStr(0, uIndex);       
        
        if (!cName.IsEmpty())
        {
            break;
        }

        cName = cSubPath;
    }
    while (!cSubPath.IsEmpty());

    // invalid path specified.
    if (cName.IsEmpty())
    {
        return NULL;
    }

    // find out if node already exists.
    COpcBrowseElement* pNode = NULL;

    OPC_POS pos = m_cChildren.GetHeadPosition();

    while (pos != NULL)
    {
        pNode = m_cChildren.GetNext(pos);

        if (pNode->m_cName == cName)
        {
            // return existing node.
            if (cSubPath.IsEmpty())
            {
                return pNode;
            }

            // insert sub-path into existing node.
            return pNode->Insert(cSubPath);
        }
    }

    // create new node.
    pNode = CreateInstance();
    pNode->m_cName = cName;
    OPC_ASSERT(!pNode->m_cName.IsEmpty());
    
    COpcBrowseElement* pChild = pNode;
    
    if (!cSubPath.IsEmpty())
    {
        pChild = pNode->Insert(cSubPath);

        if (pChild == NULL)
        {
            delete pNode;
            return NULL;
        }
    }

    m_cChildren.AddTail(pNode);
    return pChild;
}