/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file 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 with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j.pattern;

import org.apache.log4j.spi.LoggingEvent;

/**
 * Formats the event sequence number.
 *
 * @author Ceki G&uuml;lc&uuml;
 */
public class SequenceNumberPatternConverter extends LoggingEventPatternConverter {
    /**
     * Singleton.
     */
    private static final SequenceNumberPatternConverter INSTANCE = new SequenceNumberPatternConverter();

    /**
     * Private constructor.
     */
    private SequenceNumberPatternConverter() {
	super("Sequence Number", "sn");
    }

    /**
     * Obtains an instance of SequencePatternConverter.
     * 
     * @param options options, currently ignored, may be null.
     * @return instance of SequencePatternConverter.
     */
    public static SequenceNumberPatternConverter newInstance(final String[] options) {
	return INSTANCE;
    }

    /**
     * {@inheritDoc}
     */
    public void format(final LoggingEvent event, final StringBuffer toAppendTo) {
	toAppendTo.append("0");
    }
}
