src/main/java/org/luaj/vm3/LuaError.java

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package org.luaj.vm3;


/**
 * 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;
	}


}