xpathparser.java

java1.6众多例子参考

   * Consume an expected token, throwing an exception if it
   * isn't there.
   *
   * @param expected The string to be expected.
   *
   * @throws javax.xml.transform.TransformerException
   */
  private final void consumeExpected(String expected)
          throws javax.xml.transform.TransformerException
  {

    if (tokenIs(expected))
    {
      nextToken();
    }
    else
    {
      error(XPATHErrorResources.ER_EXPECTED_BUT_FOUND, new Object[]{ expected,
                                                                     m_token });  //"Expected "+expected+", but found: "+m_token);

	  // Patch for Christina's gripe. She wants her errorHandler to return from
	  // this error and continue trying to parse, rather than throwing an exception.
	  // Without the patch, that put us into an endless loop.
		throw new XPathProcessorException(CONTINUE_AFTER_FATAL_ERROR);
	}
  }

  /**
   * Consume an expected token, throwing an exception if it
   * isn't there.
   *
   * @param expected the character to be expected.
   *
   * @throws javax.xml.transform.TransformerException
   */
  private final void consumeExpected(char expected)
          throws javax.xml.transform.TransformerException
  {

    if (tokenIs(expected))
    {
      nextToken();
    }
    else
    {
      error(XPATHErrorResources.ER_EXPECTED_BUT_FOUND,
            new Object[]{ String.valueOf(expected),
                          m_token });  //"Expected "+expected+", but found: "+m_token);

	  // Patch for Christina's gripe. She wants her errorHandler to return from
	  // this error and continue trying to parse, rather than throwing an exception.
	  // Without the patch, that put us into an endless loop.
		throw new XPathProcessorException(CONTINUE_AFTER_FATAL_ERROR);
    }
  }

  /**
   * Warn the user of a problem.
   *
   * @param msg An error msgkey that corresponds to one of the constants found 
   *            in {@link com.sun.org.apache.xpath.internal.res.XPATHErrorResources}, which is 
   *            a key for a format string.
   * @param args An array of arguments represented in the format string, which 
   *             may be null.
   *
   * @throws TransformerException if the current ErrorListoner determines to 
   *                              throw an exception.
   */
  void warn(String msg, Object[] args) throws TransformerException
  {

    String fmsg = XSLMessages.createXPATHWarning(msg, args);
    ErrorListener ehandler = this.getErrorListener();

    if (null != ehandler)
    {
      // TO DO: Need to get stylesheet Locator from here.
      ehandler.warning(new TransformerException(fmsg, m_sourceLocator));
    }
    else
    {
      // Should never happen.
      System.err.println(fmsg);
    }
  }

  /**
   * Notify the user of an assertion error, and probably throw an
   * exception.
   *
   * @param b  If false, a runtime exception will be thrown.
   * @param msg The assertion message, which should be informative.
   * 
   * @throws RuntimeException if the b argument is false.
   */
  private void assertion(boolean b, String msg)
  {

    if (!b)
    {
      String fMsg = XSLMessages.createXPATHMessage(
        XPATHErrorResources.ER_INCORRECT_PROGRAMMER_ASSERTION,
        new Object[]{ msg });

      throw new RuntimeException(fMsg);
    }
  }

  /**
   * Notify the user of an error, and probably throw an
   * exception.
   *
   * @param msg An error msgkey that corresponds to one of the constants found 
   *            in {@link com.sun.org.apache.xpath.internal.res.XPATHErrorResources}, which is 
   *            a key for a format string.
   * @param args An array of arguments represented in the format string, which 
   *             may be null.
   *
   * @throws TransformerException if the current ErrorListoner determines to 
   *                              throw an exception.
   */
  void error(String msg, Object[] args) throws TransformerException
  {

    String fmsg = XSLMessages.createXPATHMessage(msg, args);
    ErrorListener ehandler = this.getErrorListener();

    TransformerException te = new TransformerException(fmsg, m_sourceLocator);
    if (null != ehandler)
    {
      // TO DO: Need to get stylesheet Locator from here.
      ehandler.fatalError(te);
    }
    else
    {
      // System.err.println(fmsg);
      throw te;
    }
  }

  /**
   * This method is added to support DOM 3 XPath API.
   * <p>
   * This method is exactly like error(String, Object[]); except that
   * the underlying TransformerException is 
   * XpathStylesheetDOM3Exception (which extends TransformerException).
   * <p>
   * So older XPath code in Xalan is not affected by this. To older XPath code
   * the behavior of whether error() or errorForDOM3() is called because it is
   * always catching TransformerException objects and is oblivious to
   * the new subclass of XPathStylesheetDOM3Exception. Older XPath code 
   * runs as before.
   * <p>
   * However, newer DOM3 XPath code upon catching a TransformerException can
   * can check if the exception is an instance of XPathStylesheetDOM3Exception
   * and take appropriate action.
   * 
   * @param msg An error msgkey that corresponds to one of the constants found 
   *            in {@link com.sun.org.apache.xpath.internal.res.XPATHErrorResources}, which is 
   *            a key for a format string.
   * @param args An array of arguments represented in the format string, which 
   *             may be null.
   *
   * @throws TransformerException if the current ErrorListoner determines to 
   *                              throw an exception.
   */
  void errorForDOM3(String msg, Object[] args) throws TransformerException
  {

	String fmsg = XSLMessages.createXPATHMessage(msg, args);
	ErrorListener ehandler = this.getErrorListener();

	TransformerException te = new XPathStylesheetDOM3Exception(fmsg, m_sourceLocator);
	if (null != ehandler)
	{
	  // TO DO: Need to get stylesheet Locator from here.
	  ehandler.fatalError(te);
	}
	else
	{
	  // System.err.println(fmsg);
	  throw te;
	}
  }
  /**
   * Dump the remaining token queue.
   * Thanks to Craig for this.
   *
   * @return A dump of the remaining token queue, which may be appended to 
   *         an error message.
   */
  protected String dumpRemainingTokenQueue()
  {

    int q = m_queueMark;
    String returnMsg;

    if (q < m_ops.getTokenQueueSize())
    {
      String msg = "\n Remaining tokens: (";

      while (q < m_ops.getTokenQueueSize())
      {
        String t = (String) m_ops.m_tokenQueue.elementAt(q++);

        msg += (" '" + t + "'");
      }

      returnMsg = msg + ")";
    }
    else
    {
      returnMsg = "";
    }

    return returnMsg;
  }

  /**
   * Given a string, return the corresponding function token.
   *
   * @param key A local name of a function.
   *
   * @return   The function ID, which may correspond to one of the FUNC_XXX 
   *    values found in {@link com.sun.org.apache.xpath.internal.compiler.FunctionTable}, but may 
   *    be a value installed by an external module.
   */
  final int getFunctionToken(String key)
  {

    int tok;
    
    Object id;

    try
    {
      // These are nodetests, xpathparser treats them as functions when parsing
      // a FilterExpr. 
      id = Keywords.lookupNodeTest(key);
      if (null == id) id = m_functionTable.getFunctionID(key);
      tok = ((Integer) id).intValue();
    }
    catch (NullPointerException npe)
    {
      tok = -1;
    }
    catch (ClassCastException cce)
    {
      tok = -1;
    }

    return tok;
  }

  /**
   * Insert room for operation.  This will NOT set
   * the length value of the operation, but will update
   * the length value for the total expression.
   *
   * @param pos The position where the op is to be inserted.
   * @param length The length of the operation space in the op map.
   * @param op The op code to the inserted.
   */
  void insertOp(int pos, int length, int op)
  {

    int totalLen = m_ops.getOp(OpMap.MAPINDEX_LENGTH);

    for (int i = totalLen - 1; i >= pos; i--)
    {
      m_ops.setOp(i + length, m_ops.getOp(i));
    }

    m_ops.setOp(pos,op);
    m_ops.setOp(OpMap.MAPINDEX_LENGTH,totalLen + length);
  }

  /**
   * Insert room for operation.  This WILL set
   * the length value of the operation, and will update
   * the length value for the total expression.
   *
   * @param length The length of the operation.
   * @param op The op code to the inserted.
   */
  void appendOp(int length, int op)
  {

    int totalLen = m_ops.getOp(OpMap.MAPINDEX_LENGTH);

    m_ops.setOp(totalLen, op);
    m_ops.setOp(totalLen + OpMap.MAPINDEX_LENGTH, length);
    m_ops.setOp(OpMap.MAPINDEX_LENGTH, totalLen + length);
  }

  // ============= EXPRESSIONS FUNCTIONS =================

  /**
   *
   *
   * Expr  ::=  OrExpr
   *
   *
   * @throws javax.xml.transform.TransformerException
   */
  protected void Expr() throws javax.xml.transform.TransformerException
  {
    OrExpr();
  }

  /**
   *
   *
   * OrExpr  ::=  AndExpr
   * | OrExpr 'or' AndExpr
   *
   *
   * @throws javax.xml.transform.TransformerException
   */
  protected void OrExpr() throws javax.xml.transform.TransformerException
  {

    int opPos = m_ops.getOp(OpMap.MAPINDEX_LENGTH);

    AndExpr();

    if ((null != m_token) && tokenIs("or"))
    {
      nextToken();
      insertOp(opPos, 2, OpCodes.OP_OR);
      OrExpr();

      m_ops.setOp(opPos + OpMap.MAPINDEX_LENGTH,
        m_ops.getOp(OpMap.MAPINDEX_LENGTH) - opPos);
    }
  }

  /**
   *
   *
   * AndExpr  ::=  EqualityExpr
   * | AndExpr 'and' EqualityExpr
   *
   *
   * @throws javax.xml.transform.TransformerException
   */
  protected void AndExpr() throws javax.xml.transform.TransformerException
  {

    int opPos = m_ops.getOp(OpMap.MAPINDEX_LENGTH);

    EqualityExpr(-1);

    if ((null != m_token) && tokenIs("and"))
    {
      nextToken();
      insertOp(opPos, 2, OpCodes.OP_AND);
      AndExpr();

      m_ops.setOp(opPos + OpMap.MAPINDEX_LENGTH,
        m_ops.getOp(OpMap.MAPINDEX_LENGTH) - opPos);
    }
  }

  /**
   *
   * @returns an Object which is either a String, a Number, a Boolean, or a vector
   * of nodes.
   *
   * EqualityExpr  ::=  RelationalExpr
   * | EqualityExpr '=' RelationalExpr
   *
   *
   * @param addPos Position where expression is to be added, or -1 for append.
   *
   * @return the position at the end of the equality expression.
   *
   * @throws javax.xml.transform.TransformerException
   */
  protected int EqualityExpr(int addPos) throws javax.xml.transform.TransformerException
  {

    int opPos = m_ops.getOp(OpMap.MAPINDEX_LENGTH);

    if (-1 == addPos)
      addPos = opPos;

    RelationalExpr(-1);

    if (null != m_token)
    {
      if (tokenIs('!') && lookahead('=', 1))
      {
        nextToken();
        nextToken();
        insertOp(addPos, 2, OpCodes.OP_NOTEQUALS);

        int opPlusLeftHandLen = m_ops.getOp(OpMap.MAPINDEX_LENGTH) - addPos;

        addPos = EqualityExpr(addPos);
        m_ops.setOp(addPos + OpMap.MAPINDEX_LENGTH,
          m_ops.getOp(addPos + opPlusLeftHandLen + 1) + opPlusLeftHandLen);
        addPos += 2;
      }
      else if (tokenIs('='))
      {
        nextToken();
        insertOp(addPos, 2, OpCodes.OP_EQUALS);

        int opPlusLeftHandLen = m_ops.getOp(OpMap.MAPINDEX_LENGTH) - addPos;

        addPos = EqualityExpr(addPos);
        m_ops.setOp(addPos + OpMap.MAPINDEX_LENGTH,
          m_ops.getOp(addPos + opPlusLeftHandLen + 1) + opPlusLeftHandLen);
        addPos += 2;
      }
    }

    return addPos;
  }

  /**
   * .
   * @returns an Object which is either a String, a Number, a Boolean, or a vector
   * of nodes.
   *
   * RelationalExpr  ::=  AdditiveExpr
   * | RelationalExpr '<' AdditiveExpr
   * | RelationalExpr '>' AdditiveExpr
   * | RelationalExpr '<=' AdditiveExpr
   * | RelationalExpr '>=' AdditiveExpr
   *
   *
   * @param addPos Position where expression is to be added, or -1 for append.
   *
   * @return the position at the end of the relational expression.
   *
   * @throws javax.xml.transform.TransformerException
   */
  protected int RelationalExpr(int addPos) throws javax.xml.transform.TransformerException
  {

    int opPos = m_ops.getOp(OpMap.MAPINDEX_LENGTH);

    if (-1 == addPos)
      addPos = opPos;

    AdditiveExpr(-1);

    if (null != m_token)
    {
      if (tokenIs('<'))
      {
        nextToken();

        if (tokenIs('='))
        {
          nextToken();
          insertOp(addPos, 2, OpCodes.OP_LTE);
        }
        else
        {
          insertOp(addPos, 2, OpCodes.OP_LT);
        }

        int opPlusLeftHandLen = m_ops.getOp(OpMap.MAPINDEX_LENGTH) - addPos;

        addPos = RelationalExpr(addPos);
        m_ops.setOp(addPos + OpMap.MAPINDEX_LENGTH, 
          m_ops.getOp(addPos + opPlusLeftHandLen + 1) + opPlusLeftHandLen);
        addPos += 2;
      }
      else if (tokenIs('>'))
      {
        nextToken();

        if (tokenIs('='))
        {
          nextToken();
          insertOp(addPos, 2, OpCodes.OP_GTE);