apache/xpath/XPathException.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: XPathException.java 468655 2006-10-28 07:12:06Z minchau $
 */
package org.apache.xpath;

import javax.xml.transform.TransformerException;

import org.w3c.dom.Node;

/**
 * This class implements an exception object that all
 * XPath classes will throw in case of an error.  This class
 * extends TransformerException, and may hold other exceptions. In the
 * case of nested exceptions, printStackTrace will dump
 * all the traces of the nested exceptions, not just the trace
 * of this object.
 * @xsl.usage general
 */
public class XPathException extends TransformerException
{
    static final long serialVersionUID = 4263549717619045963L;

  /** The home of the expression that caused the error.
   *  @serial  */
  Object m_styleNode = null;

  /**
   * Get the stylesheet node from where this error originated.
   * @return The stylesheet node from where this error originated, or null.
   */
  public Object getStylesheetNode()
  {
    return m_styleNode;
  }

  /**
   * Set the stylesheet node from where this error originated.
   * @param styleNode The stylesheet node from where this error originated, or null.
   */
  public void setStylesheetNode(Object styleNode)
  {
    m_styleNode = styleNode;
  }


  /** A nested exception.
   *  @serial   */
  protected Exception m_exception;

  /**
   * Create an XPathException object that holds
   * an error message.
   * @param message The error message.
   */
  public XPathException(String message, ExpressionNode ex)
  {
    super(message);
    this.setLocator(ex);
    setStylesheetNode(getStylesheetNode(ex));
  }

  /**
   * Create an XPathException object that holds
   * an error message.
   * @param message The error message.
   */
  public XPathException(String message)
  {
    super(message);
  }


  /**
   * Get the XSLT ElemVariable that this sub-expression references.  In order for
   * this to work, the SourceLocator must be the owning ElemTemplateElement.
   * @return The dereference to the ElemVariable, or null if not found.
   */
  public org.w3c.dom.Node getStylesheetNode(ExpressionNode ex)
  {

    ExpressionNode owner = getExpressionOwner(ex);

    if (null != owner && owner instanceof org.w3c.dom.Node)
    {
		return ((org.w3c.dom.Node)owner);
    }
    return null;

  }

  /**
   * Get the first non-Expression parent of this node.
   * @return null or first ancestor that is not an Expression.
   */
  protected ExpressionNode getExpressionOwner(ExpressionNode ex)
  {
  	ExpressionNode parent = ex.exprGetParent();
  	while((null != parent) && (parent instanceof Expression))
  		parent = parent.exprGetParent();
  	return parent;
  }


  /**
   * Create an XPathException object that holds
   * an error message and the stylesheet node that
   * the error originated from.
   * @param message The error message.
   * @param styleNode The stylesheet node that the error originated from.
   */
  public XPathException(String message, Object styleNode)
  {

    super(message);

    m_styleNode = styleNode;
  }

  /**
   * Create an XPathException object that holds
   * an error message, the stylesheet node that
   * the error originated from, and another exception
   * that caused this exception.
   * @param message The error message.
   * @param styleNode The stylesheet node that the error originated from.
   * @param e The exception that caused this exception.
   */
  public XPathException(String message, Node styleNode, Exception e)
  {

    super(message);

    m_styleNode = styleNode;
    this.m_exception = e;
  }

  /**
   * Create an XPathException object that holds
   * an error message, and another exception
   * that caused this exception.
   * @param message The error message.
   * @param e The exception that caused this exception.
   */
  public XPathException(String message, Exception e)
  {

    super(message);

    this.m_exception = e;
  }

  /**
   * Print the the trace of methods from where the error
   * originated.  This will trace all nested exception
   * objects, as well as this object.
   * @param s The stream where the dump will be sent to.
   */
  public void printStackTrace(java.io.PrintStream s)
  {

    if (s == null)
      s = System.err;

    try
    {
      super.printStackTrace(s);
    }
    catch (Exception e){}

    Throwable exception = m_exception;

    for (int i = 0; (i < 10) && (null != exception); i++)
    {
      s.println("---------");
      exception.printStackTrace(s);

      if (exception instanceof TransformerException)
      {
        TransformerException se = (TransformerException) exception;
        Throwable prev = exception;

        exception = se.getException();

        if (prev == exception)
          break;
      }
      else
      {
        exception = null;
      }
    }
  }

  /**
   * Find the most contained message.
   *
   * @return The error message of the originating exception.
   */
  public String getMessage()
  {

    String lastMessage = super.getMessage();
    Throwable exception = m_exception;

    while (null != exception)
    {
      String nextMessage = exception.getMessage();

      if (null != nextMessage)
        lastMessage = nextMessage;

      if (exception instanceof TransformerException)
      {
        TransformerException se = (TransformerException) exception;
        Throwable prev = exception;

        exception = se.getException();

        if (prev == exception)
          break;
      }
      else
      {
        exception = null;
      }
    }

    return (null != lastMessage) ? lastMessage : "";
  }

  /**
   * Print the the trace of methods from where the error
   * originated.  This will trace all nested exception
   * objects, as well as this object.
   * @param s The writer where the dump will be sent to.
   */
  public void printStackTrace(java.io.PrintWriter s)
  {

    if (s == null)
      s = new java.io.PrintWriter(System.err);

    try
    {
      super.printStackTrace(s);
    }
    catch (Exception e){}


    boolean isJdk14OrHigher = false;
    try {
        Throwable.class.getMethod("getCause", (Class<?>) null);
        isJdk14OrHigher = true;
    } catch (NoSuchMethodException nsme) {
        // do nothing
    }

    // The printStackTrace method of the Throwable class in jdk 1.4
    // and higher will include the cause when printing the backtrace.
    // The following code is only required when using jdk 1.3 or lower
    if (!isJdk14OrHigher) {

      Throwable exception = m_exception;

      for (int i = 0; (i < 10) && (null != exception); i++)
      {
        s.println("---------");

        try
        {
          exception.printStackTrace(s);
        }
        catch (Exception e)
        {
          s.println("Could not print stack trace...");
        }

        if (exception instanceof TransformerException)
        {
          TransformerException se = (TransformerException) exception;
          Throwable prev = exception;

          exception = se.getException();

          if (prev == exception)
          {
            exception = null;

            break;
          }
        }
        else
        {
          exception = null;
        }
      }
    }
  }

  /**
   *  Return the embedded exception, if any.
   *  Overrides javax.xml.transform.TransformerException.getException().
   *
   *  @return The embedded exception, or null if there is none.
   */
  public Throwable getException()
  {
    return m_exception;
  }
}