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/*******************************************************************************
* 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
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* THE SOFTWARE.
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package nl.weeaboo.lua2.lib;

import static nl.weeaboo.lua2.vm.LuaNil.NIL;

import nl.weeaboo.lua2.io.LuaSerializable;
import nl.weeaboo.lua2.vm.LuaValue;
import nl.weeaboo.lua2.vm.Varargs;

/**
 * Abstract base class for Java function implementations that take two arguments and return one value.
 * 
 * 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.
 * 

 * 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}.
 * 
 * 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
 */
@LuaSerializable
public abstract class TwoArgFunction extends LibFunction {

    private static final long serialVersionUID = 4246903072049489129L;

    /** Default constructor. */
    public TwoArgFunction() {
    }

    /**
     * Constructor with specific environment
     *
     * @param env The environment to apply during constructon.
     */
    public TwoArgFunction(LuaValue env) {
        this.env = env;
    }

    @Override
    public abstract LuaValue call(LuaValue arg1, LuaValue arg2);

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

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

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

    @Override
    public final Varargs invoke(Varargs varargs) {
        return call(varargs.arg1(), varargs.arg(2));
    }

}