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* Copyright (c) 2009-2011 Luaj.org. All rights reserved.
*
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* 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
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******************************************************************************/
package org.luaj.vm2.libs;

import org.luaj.vm2.LuaValue;
import org.luaj.vm2.Varargs;

/** Abstract base class for Java function implementations that take no arguments and 
 * return one value. 
 * <p>
 * Subclasses need only implement {@link LuaValue#call()} to complete this class, 
 * simplifying development.  
 * All other uses of {@link #call(LuaValue)}, {@link #invoke(Varargs)},etc, 
 * are routed through this method by this class.
 * <p>
 * If one or more arguments are required, or variable argument or variable return values, 
 * then use one of the related function
 * {@link OneArgFunction}, {@link TwoArgFunction}, {@link ThreeArgFunction}, or {@link VarArgFunction}.
 * <p>
 * See {@link LibFunction} for more information on implementation libraries and library functions.
 * @see #call()
 * @see LibFunction
 * @see OneArgFunction
 * @see TwoArgFunction
 * @see ThreeArgFunction
 * @see VarArgFunction
 */
abstract public class ZeroArgFunction extends LibFunction {

	abstract public LuaValue call();

	/** Default constructor */
	public ZeroArgFunction() {
	}
	
	public LuaValue call(LuaValue arg) {
		return call();
	}

	public LuaValue call(LuaValue arg1, LuaValue arg2) {
		return call();
	}

	public LuaValue call(LuaValue arg1, LuaValue arg2, LuaValue arg3) {
		return call();
	}

	public Varargs invoke(Varargs varargs) {
		return call();
	}
} 
