/**************************************************************************************
 * Copyright (C) 2008 EsperTech, Inc. All rights reserved.                            *
 * http://esper.codehaus.org                                                          *
 * http://www.espertech.com                                                           *
 * ---------------------------------------------------------------------------------- *
 * The software in this package is published under the terms of the GPL license       *
 * a copy of which has been included with this distribution in the license.txt file.  *
 **************************************************************************************/
package com.espertech.esper.pattern;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Visitor class for printing out an evaluation state tree where each node is printed indented according
 * to its depth in the tree.
 */
public final class EvalStateNodePrinterVisitor implements EvalStateNodeVisitor
{
    private int level;

    public final Object visit(EvalStateNode node, Object data)
    {
        if (log.isDebugEnabled())
        {
            log.debug("visit " + indent(level++) + node.toString());
        }
        node.childrenAccept(this, data);
        level--;
        return data;
    }

    private static String indent(int level)
    {
        StringBuilder buffer = new StringBuilder();
        for (int i = 0; i < level; i++)
        {
            buffer.append("  ");
        }
        return buffer.toString();
    }

    private static final Log log = LogFactory.getLog(EvalStateNodePrinterVisitor.class);
}