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/* Copyright (C) 2004 - 2005  db4objects Inc.  http://www.db4o.com

This file is part of the db4o open source object database.

db4o is free software; you can redistribute it and/or modify it under
the terms of version 2 of the GNU General Public License as published
by the Free Software Foundation and as clarified by db4objects' GPL 
interpretation policy, available at
http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
Suite 350, San Mateo, CA 94403, USA.

db4o is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place - Suite 330, Boston, MA  02111-1307, USA. */
package com.db4o;

import com.db4o.foundation.*;
import com.db4o.query.*;
import com.db4o.reflect.*;

/**
 *
 * Class constraint on queries
 * 
 */
public class QConClass extends QConObject{
	
	private transient ReflectClass _claxx;
	public String _className;
	public boolean i_equal;
	
	public QConClass(){
		// C/S
	}
	
	QConClass(Transaction a_trans, QCon a_parent, QField a_field, ReflectClass claxx){
		super(a_trans, a_parent, a_field, null);
		if(claxx != null){
			i_yapClass = a_trans.i_stream.getYapClass(claxx, true);
			if(claxx.equals(a_trans.i_stream.i_handlers.ICLASS_OBJECT)){
				i_yapClass = (YapClass)((YapClassPrimitive)i_yapClass).i_handler;
			}
		}
		_claxx = claxx;
	}
    
    public boolean canBeIndexLeaf(){
        return false;
    }
	
	boolean evaluate(QCandidate a_candidate){
		boolean res = true;
		ReflectClass claxx = a_candidate.classReflector();
		if(claxx == null){
			res = false;
		}else{
			res = i_equal ? _claxx.equals(claxx) : _claxx.isAssignableFrom(claxx);
		}
		return i_evaluator.not(res);
	}
	
	void evaluateSelf() {
		
		// optimization for simple class queries: 
		// No instantiation of objects, if not necessary.
		// Does not handle the special comparison of the
		// Compare interface.
		// 
		if(i_evaluator.isDefault()){
			if(i_orderID == 0 && ! hasJoins()){
				if(i_yapClass != null  && i_candidates.i_yapClass != null){
					if(i_yapClass.getHigherHierarchy(i_candidates.i_yapClass) == i_yapClass){
						return;
					}
				}
			}
		}
		i_candidates.filter(this);
	}
	
	public Constraint equal (){
		synchronized(streamLock()){
			i_equal = true;
			return this;
		}
	}
	
	boolean isNullConstraint() {
		return false;
	}
    
    String logObject() {
        if (Deploy.debugQueries) {
            if(_claxx != null){
                return _claxx.toString();
            }
        } 
        return "";
    }
    
    void marshall() {
        super.marshall();
        if(_claxx!=null) {
        	_className = _claxx.getName();
        }
    }
	
	public String toString(){
        if(! Debug4.prettyToStrings){
            return super.toString();
        }
		String str = "QConClass ";
		if(_claxx != null){
			str += _claxx.toString() + " ";
		}
		return str + super.toString();
	}
	
    void unmarshall(Transaction a_trans) {
        if (i_trans == null) {
            super.unmarshall(a_trans);
            if(_className!=null) {
            	_claxx = a_trans.reflector().forName(_className);
            }
        }
    }
    
}