Java Code Examples for org.apache.xpath.XPath#SELECT

/**
 * Uses an XSL stylesheet document.
 * @throws TransformerConfigurationException if the baseIdentifier can not be resolved to a URL.
 */
public StylesheetRoot(ErrorListener errorListener) throws TransformerConfigurationException
{

  super(null);

  setStylesheetRoot(this);

  try
  {
    m_selectDefault = new XPath("node()", this, this, XPath.SELECT, errorListener);

    initDefaultRule(errorListener);
  }
  catch (TransformerException se)
  {
    throw new TransformerConfigurationException(XSLMessages.createMessage(XSLTErrorResources.ER_CANNOT_INIT_DEFAULT_TEMPLATES, null), se); //"Can't init default templates!", se);
  }
}
 

/**
 * Take the received string, which is an XML query expression, compile it, and
 * store the compiled query locally. Note that for now, we only support XPath
 * because that's what Xalan supports.
 * 
 * @param queryExpr
 *          The XPath expression to compile
 */
public void compileXQExpr(final String queryExpr, final String opName,
    final DocumentBuilder dBuilder) throws StandardException {
  try {

    /* The following XPath constructor compiles the expression
     * as part of the construction process.  We have to pass
     * in a PrefixResolver object in order to avoid NPEs when
     * invalid/unknown functions are used, so we just create
     * a dummy one, which means prefixes will not be resolved
     * in the query (Xalan will just throw an error if a prefix
     * is used).  In the future we may want to revisit this
     * to make it easier for users to query based on namespaces.
     */
    query = new XPath(queryExpr, null, new PrefixResolverDefault(
        dBuilder.newDocument()), XPath.SELECT);

  } catch (Throwable te) {

    /* Something went wrong during compilation of the
     * expression; wrap the error and re-throw it.
     * Note: we catch "Throwable" here to catch as many
     * Xalan-produced errors as possible in order to
     * minimize the chance of an uncaught Xalan error
     * (such as a NullPointerException) causing Derby
     * to fail in a more serious way.  In particular, an
     * uncaught Java exception like NPE can result in
     * Derby throwing "ERROR 40XT0: An internal error was
     * identified by RawStore module" for all statements on
     * the connection after the failure--which we clearly
     * don't want.  If we catch the error and wrap it,
     * though, the statement will fail but Derby will
     * continue to run as normal. 
     */
    throw StandardException.newException(SQLState.LANG_XML_QUERY_ERROR, te,
        opName, te.getMessage());

  }
}
 

/**
 * Take the received string, which is an XML query expression, compile it, and
 * store the compiled query locally. Note that for now, we only support XPath
 * because that's what Xalan supports.
 * 
 * @param queryExpr
 *          The XPath expression to compile
 */
public void compileXQExpr(final String queryExpr, final String opName,
    final DocumentBuilder dBuilder) throws StandardException {
  try {

    /* The following XPath constructor compiles the expression
     * as part of the construction process.  We have to pass
     * in a PrefixResolver object in order to avoid NPEs when
     * invalid/unknown functions are used, so we just create
     * a dummy one, which means prefixes will not be resolved
     * in the query (Xalan will just throw an error if a prefix
     * is used).  In the future we may want to revisit this
     * to make it easier for users to query based on namespaces.
     */
    query = new XPath(queryExpr, null, new PrefixResolverDefault(
        dBuilder.newDocument()), XPath.SELECT);

  } catch (Throwable te) {

    /* Something went wrong during compilation of the
     * expression; wrap the error and re-throw it.
     * Note: we catch "Throwable" here to catch as many
     * Xalan-produced errors as possible in order to
     * minimize the chance of an uncaught Xalan error
     * (such as a NullPointerException) causing Derby
     * to fail in a more serious way.  In particular, an
     * uncaught Java exception like NPE can result in
     * Derby throwing "ERROR 40XT0: An internal error was
     * identified by RawStore module" for all statements on
     * the connection after the failure--which we clearly
     * don't want.  If we catch the error and wrap it,
     * though, the statement will fail but Derby will
     * continue to run as normal. 
     */
    throw StandardException.newException(SQLState.LANG_XML_QUERY_ERROR, te,
        opName, te.getMessage());

  }
}
 

/**
 * Construct a simple AVT part.
 * 
 * @param val A pure string section of an AVT.
 * @param nsNode An object which can be used to determine the
 * Namespace Name (URI) for any Namespace prefix used in the XPath. 
 * Usually this is based on the context where the XPath was specified,
 * such as a node within a Stylesheet.
 * @param xpathProcessor XPath parser
 * @param factory XPath factory
 * @param liaison An XPathContext object, providing infomation specific
 * to this invocation and this thread. Maintains SAX output state, 
 * variables, error handler and so on, so the transformation/XPath 
 * object itself can be simultaneously invoked from multiple threads.
 *
 * @throws javax.xml.transform.TransformerException
 * TODO: Fix or remove this unused c'tor.
 */
public AVTPartXPath(
        String val, org.apache.xml.utils.PrefixResolver nsNode, 
        XPathParser xpathProcessor, XPathFactory factory, 
        XPathContext liaison)
          throws javax.xml.transform.TransformerException
{
  m_xpath = new XPath(val, null, nsNode, XPath.SELECT, liaison.getErrorListener());
}
 

/**
 * Process an expression string into an XPath.
 * Must be public for access by the AVT class.
 *
 * @param str A non-null reference to a valid or invalid XPath expression string.
 *
 * @return A non-null reference to an XPath object that represents the string argument.
 *
 * @throws javax.xml.transform.TransformerException if the expression can not be processed.
 * @see <a href="http://www.w3.org/TR/xslt#section-Expressions">Section 4 Expressions in XSLT Specification</a>
 */
public XPath createXPath(String str, ElemTemplateElement owningTemplate)
        throws javax.xml.transform.TransformerException
{
  ErrorListener handler = m_stylesheetProcessor.getErrorListener();
  XPath xpath = new XPath(str, owningTemplate, this, XPath.SELECT, handler, 
          m_funcTable);
  // Visit the expression, registering namespaces for any extension functions it includes.
  xpath.callVisitors(xpath, new ExpressionVisitor(getStylesheetRoot()));
  return xpath;
}