/*******************************************************************************
* Copyright (c) 2009 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.lib;

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

/** Abstract base class for Java function implementations that take two arguments and 
 * return one value. 
 * <p>
 * Subclasses need only implement {@link LuaValue#call(LuaValue,LuaValue)} to complete this class, 
 * simplifying development.  
 * All other uses of {@link #call()}, {@link #invoke(Varargs)},etc, 
 * are routed through this method by this class, 
 * dropping or extending arguments with {@code nil} values as required.
 * <p>
 * If more or less than two arguments are required,  
 * or variable argument or variable return values, 
 * then use one of the related function
 * {@link ZeroArgFunction}, {@link OneArgFunction}, {@link ThreeArgFunction}, or {@link VarArgFunction}.
 * <p>
 * See {@link LibFunction} for more information on implementation libraries and library functions.
 * @see #call(LuaValue,LuaValue)
 * @see LibFunction
 * @see ZeroArgFunction
 * @see OneArgFunction
 * @see ThreeArgFunction
 * @see VarArgFunction
 */
abstract public class TwoArgFunction extends LibFunction {

	abstract public LuaValue call(LuaValue arg1, LuaValue arg2);
	
	/** Default constructor */
	public TwoArgFunction() {
	}
	
	public final LuaValue call() {
		return call(NIL, NIL);
	}

	public final LuaValue call(LuaValue arg) {
		return call(arg, NIL);
	}

	public LuaValue call(LuaValue arg1, LuaValue arg2, LuaValue arg3) {
		return call(arg1, arg2);
	}
	
	public Varargs invoke(Varargs varargs) {
		return call(varargs.arg1(),varargs.arg(2));
	}
	
}