/***** BEGIN LICENSE BLOCK *****
 * Version: CPL 1.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Common Public
 * License Version 1.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.eclipse.org/legal/cpl-v10.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2002-2004 Jan Arne Petersen <jpetersen@uni-bonn.de>
 * Copyright (C) 2004-2006 Thomas E Enebo <enebo@acm.org>
 * Copyright (C) 2004 Stefan Matthias Aust <sma@3plus4.de>
 * 
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 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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package org.jruby;

import org.jruby.runtime.ClassIndex;
import org.jruby.runtime.ObjectAllocator;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.util.collections.SinglyLinkedList;

public class MetaClass extends RubyClass {

    public MetaClass(Ruby runtime, RubyClass superClass, ObjectAllocator allocator, SinglyLinkedList parentCRef) {
        super(runtime, runtime.getClass("Class"), superClass, allocator, parentCRef, null);
        
        this.index = ClassIndex.CLASS;
    }
 
    public boolean isSingleton() {
        return true;
    }

    protected RubyClass subclass() {
        throw getRuntime().newTypeError("can't make subclass of virtual class");
    }

    /**
     * If an object uses an anonymous class 'class << obj', then this grabs the original 
     * metaclass and not the one that get injected as a result of 'class << obj'.
     */
    public RubyClass getRealClass() {
        return getSuperClass().getRealClass();
    }
    
    public void methodAdded(RubySymbol symbol) {
        getAttachedObject().callMethod(getRuntime().getCurrentContext(), "singleton_method_added", symbol);
    }

    public IRubyObject getAttachedObject() {
    	// Though it may not be obvious, attachToObject is always called just after instance
    	// creation.  Kind of a brittle arrangement here...
        return getInstanceVariable("__attached__");
    }

    public IRubyObject allocateObject() {
        throw getRuntime().newTypeError("can't create instance of virtual class");
    }
}