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 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
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 *  Unless required by applicable law or agreed to in writing,
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package org.apache.cayenne.util;

import java.util.HashMap;
import java.util.Map;

import org.apache.cayenne.project.ProjectPath;

/**
 * A common superclass for specialized tree visitors. Can also be used as a noop
 * pass-through visitor for nodes that need no processing by themselves.
 * 
 * @author Andrus Adamchik
 */
// TODO, andrus, 4/24/2006 - move to Cayenne core in 2.0
public class BaseTreeVisitor implements HierarchicalTreeVisitor {

    protected Map childVisitors;
    protected boolean terminatingOnNoChildVisitor;

    public BaseTreeVisitor() {
        this.terminatingOnNoChildVisitor = true;
    }

    public boolean isTerminatingOnNoChildVisitor() {
        return terminatingOnNoChildVisitor;
    }

    public void setTerminatingOnNoChildVisitor(boolean terminatingOnNoChildVisitor) {
        this.terminatingOnNoChildVisitor = terminatingOnNoChildVisitor;
    }

    public HierarchicalTreeVisitor childVisitor(ProjectPath path, Class childType) {
        if (childVisitors == null) {
            return terminatingOnNoChildVisitor ? null : this;
        }

        HierarchicalTreeVisitor childVisitor = (HierarchicalTreeVisitor) childVisitors
                .get(childType.getName());
        return childVisitor != null ? childVisitor : terminatingOnNoChildVisitor
                ? null
                : this;
    }

    public void onFinishNode(ProjectPath path) {
    }

    public boolean onStartNode(ProjectPath path) {
        return true;
    }

    public void addChildVisitor(Class childClass, HierarchicalTreeVisitor visitor) {
        if (childVisitors == null) {
            childVisitors = new HashMap();
        }

        childVisitors.put(childClass.getName(), visitor);
    }
}
