ConfigurableFTPFileEntryParserImpl.java

/*
 * 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.commons.net.ftp.parser;

import java.text.ParseException;
import java.util.Calendar;

import org.apache.commons.net.ftp.Configurable;
import org.apache.commons.net.ftp.FTPClientConfig;

/**
 * <p>
 * This abstract class implements the common timestamp parsing algorithm for all the concrete parsers. Classes derived from this one will parse file listings
 * via a supplied regular expression that pulls out the date portion as a separate string which is passed to the underlying {@link FTPTimestampParser delegate}
 * to handle parsing of the file timestamp.
 * <p>
 * This class also implements the {@link Configurable Configurable} interface to allow the parser to be configured from the outside.
 *
 * @since 1.4
 */
public abstract class ConfigurableFTPFileEntryParserImpl extends RegexFTPFileEntryParserImpl implements Configurable {

    private final FTPTimestampParser timestampParser;

    /**
     * constructor for this abstract class.
     *
     * @param regex Regular expression used main parsing of the file listing.
     */
    public ConfigurableFTPFileEntryParserImpl(final String regex) {
        super(regex);
        this.timestampParser = new FTPTimestampParserImpl();
    }

    /**
     * constructor for this abstract class.
     *
     * @param regex Regular expression used main parsing of the file listing.
     * @param flags the flags to apply, see {@link java.util.regex.Pattern#compile(String, int) Pattern#compile(String, int)}. Use 0 for none.
     * @since 3.4
     */
    public ConfigurableFTPFileEntryParserImpl(final String regex, final int flags) {
        super(regex, flags);
        this.timestampParser = new FTPTimestampParserImpl();
    }

    /**
     * Implements the {@link Configurable Configurable} interface. Configures this parser by delegating to the underlying Configurable FTPTimestampParser
     * implementation, ' passing it the supplied {@link FTPClientConfig FTPClientConfig} if that is non-null or a default configuration defined by each concrete
     * subclass.
     *
     * @param config the configuration to be used to configure this parser. If it is null, a default configuration defined by each concrete subclass is used
     *               instead.
     */
    @Override
    public void configure(final FTPClientConfig config) {
        if (this.timestampParser instanceof Configurable) {
            final FTPClientConfig defaultCfg = getDefaultConfiguration();
            if (config != null) {
                if (null == config.getDefaultDateFormatStr()) {
                    config.setDefaultDateFormatStr(defaultCfg.getDefaultDateFormatStr());
                }
                if (null == config.getRecentDateFormatStr()) {
                    config.setRecentDateFormatStr(defaultCfg.getRecentDateFormatStr());
                }
                ((Configurable) this.timestampParser).configure(config);
            } else {
                ((Configurable) this.timestampParser).configure(defaultCfg);
            }
        }
    }

    /**
     * Each concrete subclass must define this member to create a default configuration to be used when that subclass is instantiated without a
     * {@link FTPClientConfig FTPClientConfig} parameter being specified.
     *
     * @return the default configuration for the subclass.
     */
    protected abstract FTPClientConfig getDefaultConfiguration();

    /**
     * This method is called by the concrete parsers to delegate timestamp parsing to the timestamp parser.
     *
     * @param timestampStr the timestamp string pulled from the file listing by the regular expression parser, to be submitted to the
     *                     <code>timestampParser</code> for extracting the timestamp.
     * @return a <code>java.util.Calendar</code> containing results of the timestamp parse.
     * @throws ParseException on parse error
     */
    public Calendar parseTimestamp(final String timestampStr) throws ParseException {
        return this.timestampParser.parseTimestamp(timestampStr);
    }
}