/*
* $Id: JavaFunction.java,v 1.6 2006/12/22 14:06:40 thiago Exp $
* Copyright (C) 2003-2007 Kepler Project.
*
* 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.keplerproject.luajava;
/**
* JavaFunction is a class that can be used to implement a Lua function in Java.
* JavaFunction is an abstract class, so in order to use it you must extend this
* class and implement the <code>execute</code> method. This <code>execute</code>
* method is the method that will be called when you call the function from Lua.
* To register the JavaFunction in Lua use the method <code>register(String name)</code>.
*/
public abstract class JavaFunction
{
/**
* This is the state in which this function will exist.
*/
protected LuaState L;
/**
* This method is called from Lua. Any parameters can be taken with
* <code>getParam</code>. A reference to the JavaFunctionWrapper itself is
* always the first parameter received. Values passed back as results
* of the function must be pushed onto the stack.
* @return The number of values pushed onto the stack.
*/
public abstract int execute() throws LuaException;
/**
* Constructor that receives a LuaState.
* @param L LuaState object associated with this JavaFunction object
*/
public JavaFunction(LuaState L)
{
this.L = L;
}
/**
* Returns a parameter received from Lua. Parameters are numbered from 1.
* A reference to the JavaFunction itself is always the first parameter
* received (the same as <code>this</code>).
* @param idx Index of the parameter.
* @return Reference to parameter.
* @see LuaObject
*/
public LuaObject getParam(int idx)
{
return L.getLuaObject(idx);
}
/**
* Register a JavaFunction with a given name. This method registers in a
* global variable the JavaFunction specified.
* @param name name of the function.
*/
public void register(String name) throws LuaException
{
synchronized (L)
{
L.pushJavaFunction(this);
L.setGlobal(name);
}
}
}