src/main/java/org/luaj/vm3/lib/TwoArgFunction.java

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package org.luaj.vm3.lib;

import org.luaj.vm3.LuaValue;
import org.luaj.vm3.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));
	}

}