content: /*******************************************************************************
  * Copyright (c) 2009-2011 Luaj.org. All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  * 
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  ******************************************************************************/
  package org.luaj.vm2;
  
  
  /**
   * RuntimeException that is thrown and caught in response to a lua error. 
   * <p>
   * {@link LuaError} is used wherever a lua call to {@code error()} 
   * would be used within a script.
   * <p>
   * Since it is an unchecked exception inheriting from {@link RuntimeException},
   * Java method signatures do notdeclare this exception, althoug it can 
   * be thrown on almost any luaj Java operation.
   * This is analagous to the fact that any lua script can throw a lua error at any time.
   * <p>   
   */
  public class LuaError extends RuntimeException {
  	private static final long serialVersionUID = 1L;
  	
  	protected int level;
  	
  	protected String fileline;
  	
  	protected String traceback;
  	
  	protected Throwable cause;
  
  	public String getMessage() {
  		if (traceback != null)
  			return traceback;
  		String m = super.getMessage();
  		if (m == null)
  			return null;
  		if (fileline != null)
  			return fileline + " " + m;
  		return m;
  	}
  
  	/** Construct LuaError when a program exception occurs. 
  	 * <p> 
  	 * All errors generated from lua code should throw LuaError(String) instead.
  	 * @param cause the Throwable that caused the error, if known.  
  	 */
  	public LuaError(Throwable cause) {
  		super( "vm error: "+cause );
  		this.cause = cause;
  		this.level = 1;
  	}
  
  	/**
  	 * Construct a LuaError with a specific message.  
  	 *  
  	 * @param message message to supply
  	 */
  	public LuaError(String message) {
  		super( message );
  		this.level = 1;
  	}		
  
  	/**
  	 * Construct a LuaError with a message, and level to draw line number information from.
  	 * @param message message to supply
  	 * @param level where to supply line info from in call stack
  	 */
  	public LuaError(String message, int level) {
  		super( message );
  		this.level = level;
  	}	
  
  
  	/** 
  	 * Get the cause, if any.
  	 */
  	public Throwable getCause() {
  		return cause;
  	}
  
  
  }
  