SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// Multi-Phasic Applications: SquirrelJME
//     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
// ---------------------------------------------------------------------------
// SquirrelJME is under the Mozilla Public License Version 2.0.
// See license.mkd for licensing and copyright information.
// ---------------------------------------------------------------------------

package cc.squirreljme.emulator;

import cc.squirreljme.jvm.mle.ReflectionShelf;
import cc.squirreljme.jvm.mle.brackets.TypeBracket;
import cc.squirreljme.jvm.mle.exceptions.MLECallError;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

/**
 * Emulation for {@link ReflectionShelf}.
 *
 * @since 2022/09/07
 */
public class EmulatedReflectionShelf
{
    /**
     * Invokes the main method of a give type.
     *
     * @param __type The type to look for the main method in.
     * @param __args The arguments to the call.
     * @throws MLECallError If any argument is {@code null}.
     * @throws Throwable Any exception thrown by the target.
     * @since 2022/09/07
     */
    public static void invokeMain(TypeBracket __type,
        String... __args)
        throws MLECallError, Throwable
    {
        if (__type == null || __args == null)
            throw new MLECallError("Null arguments.");
        
        // Go into the class
        Method mainMethod = null;
        try
        {
            // Find class
            Class<?> mainClass = ((EmulatedTypeBracket)__type).javaClass;
            
            // Find main method
            Method[] methods = mainClass.getMethods();
            for (int i = methods.length - 1; i >= 0; i--)
            {
                Method maybe = methods[i];
                int flags = maybe.getModifiers();
                
                // Needs to match everything
                if ((flags & (Modifier.PUBLIC | Modifier.STATIC)) ==
                    (Modifier.PUBLIC | Modifier.STATIC) &&
                    "main".equals(maybe.getName()) &&
                    maybe.getReturnType() == Void.TYPE &&
                    maybe.getParameterCount() == 1 &&
                    String[].class == maybe.getParameterTypes()[0])
                {
                    mainMethod = maybe;
                    break;
                }
            }
            
            // Not found?
            if (mainMethod == null)
                throw new MLECallError("No public static void " +
                    "main(String[]) in " + mainClass);
            
            // Invoke call
            mainMethod.setAccessible(true);
            mainMethod.invoke(null, (Object)__args);
        }
        catch (InvocationTargetException __e)
        {
            // Just throw what we wrapped around
            throw __e.getTargetException();
        }
        catch (IllegalAccessException __e)
        {
            throw new MLECallError("Cannot access main.", __e);
        }
    }
}