package org.apache.torque;
   
   /*
    * 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.
   */
  
  import java.io.PrintStream;
  import java.io.PrintWriter;
  import java.io.StringWriter;
  import java.util.LinkedList;
  import java.util.StringTokenizer;
  
  /***
   * This is a base class of runtime exeptions thrown by Torque. <p>
   *
   * This class represents a non-checked type exception (see
   * {@link java.lang.RuntimeException}).
   * It is intended to ease the debugging by carrying on the information about the
   * exception which was caught and provoked throwing the current exception.
   * Catching and rethrowing may occur multiple times, and provided that all
   * exceptions except the first one are descendands of
   * <code>TorqueRuntimeException</code>, when the exception is finally printed
   * out using any of the <code>printStackTrace()</code> methods, the stacktrace
   * will contain the information about all exceptions thrown and caught on the
   * way.
   *
   * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
   * @version $Id: TorqueRuntimeException.java 584524 2007-10-14 10:25:43Z tfischer $
   */
  public class TorqueRuntimeException
      extends RuntimeException
  {
      /***
       * Serial version
       */
      private static final long serialVersionUID = -2997617341459640541L;
  
      /***
       * Holds the reference to the exception or error that caused
       * this exception to be thrown.
       */
      private Throwable nested = null;
  
      /***
       * Constructs a new <code>TorqueRuntimeException</code> without specified
       * detail message.
       */
      public TorqueRuntimeException()
      {
          super();
      }
  
      /***
       * Constructs a new <code>TorqueRuntimeException</code> with specified
       * detail message.
       *
       * @param msg the error message.
       */
      public TorqueRuntimeException(String msg)
      {
          super(msg);
      }
  
      /***
       * Constructs a new <code>TorqueRuntimeException</code> with specified
       * nested <code>Throwable</code>.
       *
       * @param nested the exception or error that caused this exception
       *               to be thrown.
       */
      public TorqueRuntimeException(Throwable nested)
      {
          super();
          this.nested = nested;
      }
  
      /***
       * Constructs a new <code>TorqueRuntimeException</code> with specified
       * detail message and nested <code>Throwable</code>.
       *
       * @param msg the error message.
       * @param nested the exception or error that caused this exception
       *               to be thrown.
       */
     public TorqueRuntimeException(String msg, Throwable nested)
     {
         super(msg);
         this.nested = nested;
     }
 
     /***
      * Prints the stack trace of this exception the the standar error stream.
      */
     public void printStackTrace()
     {
         synchronized (System.err)
         {
             printStackTrace(System.err);
         }
     }
 
     /***
      * Prints the stack trace of this exception to the specified print stream.
      *
      * @param out <code>PrintStream</code> to use for output
      */
     public void printStackTrace(PrintStream out)
     {
         synchronized (out)
         {
             PrintWriter pw = new PrintWriter(out, false);
             printStackTrace(pw);
             // flush the PrintWriter before it's GCed
             pw.flush();
         }
     }
 
     /***
      * Prints the stack trace of this exception to the specified print writer.
      *
      * @param out <code>PrintWriter</code> to use for output.
      */
     public void printStackTrace(PrintWriter out)
     {
         synchronized (out)
         {
             printStackTrace(out, 0);
         }
     }
 
     /***
      * Prints the stack trace of this exception skiping a specified number
      * of stack frames.
      *
      * @param out <code>PrintWriter</code> to use for output.
      * @param skip the numbere of stack frames to skip.
      */
     public void printStackTrace(PrintWriter out, int skip)
     {
         String[] st = captureStackTrace();
         if (nested != null)
         {
             if (nested instanceof TorqueRuntimeException)
             {
                 ((TorqueRuntimeException) nested)
                         .printStackTrace(out, st.length - 2);
             }
             else if (nested instanceof TorqueException)
             {
                 ((TorqueException) nested).printStackTrace(out);
             }
             else
             {
                 String[] nst = captureStackTrace(nested);
                 for (int i = 0; i < nst.length - st.length + 2; i++)
                 {
                     out.println(nst[i]);
                 }
             }
             out.print("rethrown as ");
         }
         for (int i = 0; i < st.length - skip; i++)
         {
             out.println(st[i]);
         }
     }
 
     /***
      * Captures the stack trace associated with this exception.
      *
      * @return an array of Strings describing stack frames.
      */
     private String[] captureStackTrace()
     {
         StringWriter sw = new StringWriter();
         super.printStackTrace(new PrintWriter(sw, true));
         return splitStackTrace(sw.getBuffer().toString());
     }
 
     /***
      * Captures the stack trace associated with a <code>Throwable</code>
      * object.
      *
      * @param t the <code>Throwable</code>.
      * @return an array of Strings describing stack frames.
      */
     private String[] captureStackTrace(Throwable t)
     {
         StringWriter sw = new StringWriter();
         t.printStackTrace(new PrintWriter(sw, true));
         return splitStackTrace(sw.getBuffer().toString());
     }
 
     /***
      * Splits the stack trace given as a newline separated string
      * into an array of stack frames.
      *
      * @param stackTrace the stack trace.
      * @return an array of Strings describing stack frames.
      */
     private String[] splitStackTrace(String stackTrace)
     {
         String linebreak = System.getProperty("line.separator");
         StringTokenizer st = new StringTokenizer(stackTrace, linebreak);
         LinkedList list = new LinkedList();
         while (st.hasMoreTokens())
         {
             list.add(st.nextToken());
         }
         return (String[]) list.toArray(new String[list.size()]); 
     }
 }