    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018
    019package org.apache.commons.net.ftp.parser;
    020
    021import java.util.regex.MatchResult;
    022import java.util.regex.Matcher;
    023import java.util.regex.Pattern;
    024import java.util.regex.PatternSyntaxException;
    025
    026import org.apache.commons.net.ftp.FTPFileEntryParserImpl;
    027
    028/**
    029 * This abstract class implements both the older FTPFileListParser and
    030 * newer FTPFileEntryParser interfaces with default functionality.
    031 * All the classes in the parser subpackage inherit from this.
    032 *
    033 * This is the base class for all regular expression based FTPFileEntryParser classes
    034 *
    035 * @author Steve Cohen <scohen@apache.org>
    036 */
    037public abstract class RegexFTPFileEntryParserImpl extends
    038        FTPFileEntryParserImpl {
    039    /**
    040     * internal pattern the matcher tries to match, representing a file
    041     * entry
    042     */
    043    private Pattern pattern = null;
    044
    045    /**
    046     * internal match result used by the parser
    047     */
    048    private MatchResult result = null;
    049
    050    /**
    051     * Internal PatternMatcher object used by the parser.  It has protected
    052     * scope in case subclasses want to make use of it for their own purposes.
    053     */
    054    protected Matcher _matcher_ = null;
    055
    056    /**
    057     * The constructor for a RegexFTPFileEntryParserImpl object.
    058     *
    059     * @param regex  The regular expression with which this object is
    060     * initialized.
    061     *
    062     * @exception IllegalArgumentException
    063     * Thrown if the regular expression is unparseable.  Should not be seen in
    064     * normal conditions.  It it is seen, this is a sign that a subclass has
    065     * been created with a bad regular expression.   Since the parser must be
    066     * created before use, this means that any bad parser subclasses created
    067     * from this will bomb very quickly,  leading to easy detection.
    068     */
    069
    070    public RegexFTPFileEntryParserImpl(String regex) {
    071        super();
    072        setRegex(regex);
    073    }
    074
    075    /**
    076     * Convenience method delegates to the internal MatchResult's matches()
    077     * method.
    078     *
    079     * @param s the String to be matched
    080     * @return true if s matches this object's regular expression.
    081     */
    082
    083    public boolean matches(String s) {
    084        this.result = null;
    085        _matcher_ = pattern.matcher(s);
    086        if (_matcher_.matches()) {
    087            this.result = _matcher_.toMatchResult();
    088        }
    089        return null != this.result;
    090    }
    091
    092    /**
    093     * Convenience method
    094     *
    095     * @return the number of groups() in the internal MatchResult.
    096     */
    097
    098    public int getGroupCnt() {
    099        if (this.result == null) {
    100            return 0;
    101        }
    102        return this.result.groupCount();
    103    }
    104
    105    /**
    106     * Convenience method delegates to the internal MatchResult's group()
    107     * method.
    108     *
    109     * @param matchnum match group number to be retrieved
    110     *
    111     * @return the content of the <code>matchnum'th</code> group of the internal
    112     *         match or null if this method is called without a match having
    113     *         been made.
    114     */
    115    public String group(int matchnum) {
    116        if (this.result == null) {
    117            return null;
    118        }
    119        return this.result.group(matchnum);
    120    }
    121
    122    /**
    123     * For debugging purposes - returns a string shows each match group by
    124     * number.
    125     *
    126     * @return a string shows each match group by number.
    127     */
    128
    129    public String getGroupsAsString() {
    130        StringBuilder b = new StringBuilder();
    131        for (int i = 1; i <= this.result.groupCount(); i++) {
    132            b.append(i).append(") ").append(this.result.group(i)).append(
    133                    System.getProperty("line.separator"));
    134        }
    135        return b.toString();
    136    }
    137
    138    /**
    139     * Alter the current regular expression being utilised for entry parsing
    140     * and create a new {@link Pattern} instance.
    141     * @param regex The new regular expression
    142     * @return  true
    143     * @since 2.0
    144     * @throws PatternSyntaxException if the regex cannot be compiled
    145     */
    146    public boolean setRegex(String regex) {
    147        try {
    148            pattern = Pattern.compile(regex);
    149            return true;
    150        } catch (PatternSyntaxException pse) {
    151            throw new IllegalArgumentException("Unparseable regex supplied: "
    152                    + regex);
    153        }
    154    }
    155
    156}