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/*
 * 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;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * The class implements the pre log4j 1.3 org.apache.log4j.helpers.PatternConverter contract by delegating to the log4j
 * 1.3 pattern implementation.
 *
 * @author Curt Arnold
 */
public final class BridgePatternConverter extends org.apache.log4j.helpers.PatternConverter {
    /**
     * Pattern converters.
     */
    private LoggingEventPatternConverter[] patternConverters;

    /**
     * Field widths and alignment corresponding to pattern converters.
     */
    private FormattingInfo[] patternFields;

    /**
     * Does pattern process exceptions.
     */
    private boolean handlesExceptions;

    /**
     * Create a new instance.
     *
     * @param pattern pattern, may not be null.
     */
    public BridgePatternConverter(final String pattern) {
        next = null;
        handlesExceptions = false;

        List converters = new ArrayList();
        List fields = new ArrayList();
        Map converterRegistry = null;

        PatternParser.parse(pattern, converters, fields, converterRegistry, PatternParser.getPatternLayoutRules());

        patternConverters = new LoggingEventPatternConverter[converters.size()];
        patternFields = new FormattingInfo[converters.size()];

        int i = 0;
        Iterator converterIter = converters.iterator();
        Iterator fieldIter = fields.iterator();

        while (converterIter.hasNext()) {
            Object converter = converterIter.next();

            if (converter instanceof LoggingEventPatternConverter) {
                patternConverters[i] = (LoggingEventPatternConverter) converter;
                handlesExceptions |= patternConverters[i].handlesThrowable();
            } else {
                patternConverters[i] = new org.apache.log4j.pattern.LiteralPatternConverter("");
            }

            if (fieldIter.hasNext()) {
                patternFields[i] = (FormattingInfo) fieldIter.next();
            } else {
                patternFields[i] = FormattingInfo.getDefault();
            }

            i++;
        }
    }

    /**
     * {@inheritDoc}
     */
    protected String convert(final LoggingEvent event) {
        //
        // code should be unreachable.
        //
        StringBuffer sbuf = new StringBuffer();
        format(sbuf, event);

        return sbuf.toString();
    }

    /**
     * Format event to string buffer.
     *
     * @param sbuf string buffer to receive formatted event, may not be null.
     * @param e    event to format, may not be null.
     */
    public void format(final StringBuffer sbuf, final LoggingEvent e) {
        for (int i = 0; i < patternConverters.length; i++) {
            int startField = sbuf.length();
            patternConverters[i].format(e, sbuf);
            patternFields[i].format(startField, sbuf);
        }
    }

    /**
     * Will return false if any of the conversion specifiers in the pattern handles {@link Exception Exceptions}.
     *
     * @return true if the pattern formats any information from exceptions.
     */
    public boolean ignoresThrowable() {
        return !handlesExceptions;
    }
}