/***** 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
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 *
 * 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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package org.jruby;

import java.lang.ref.SoftReference;

import org.jruby.runtime.builtin.IRubyObject;

public final class MetaClass extends RubyClass {
    
    private static final SoftReference<IRubyObject> NULL_SOFT_REF = new SoftReference<IRubyObject>(null);

    private SoftReference<IRubyObject> attached = NULL_SOFT_REF; 
    
    /** rb_class_boot (for MetaClasses) (in makeMetaClass(RubyClass))
     * 
     */
    public MetaClass(Ruby runtime, RubyClass superClass, IRubyObject attached) {
        super(runtime, superClass, false);
        this.attached = new SoftReference<IRubyObject>(attached);
        this.index = superClass.index; // use same ClassIndex as metaclass, since we're technically still of that type
    }

    @Override
    public boolean isSingleton() {
        return true;
    }

    /**
     * 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 superClass.getRealClass();
    }

    public final IRubyObject allocate(){
        throw runtime.newTypeError("can't create instance of virtual class");
    }

    public IRubyObject getAttached() {
        return attached.get();
    }

    public void setAttached(IRubyObject attached) {
        this.attached = new SoftReference<IRubyObject>(attached);
    }

}
