    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 */
    035public abstract class RegexFTPFileEntryParserImpl extends
    036        FTPFileEntryParserImpl {
    037    /**
    038     * internal pattern the matcher tries to match, representing a file
    039     * entry
    040     */
    041    private Pattern pattern;
    042
    043    /**
    044     * internal match result used by the parser
    045     */
    046    private MatchResult result;
    047
    048    /**
    049     * Internal PatternMatcher object used by the parser.  It has protected
    050     * scope in case subclasses want to make use of it for their own purposes.
    051     */
    052    protected Matcher _matcher_;
    053
    054    /**
    055     * The constructor for a RegexFTPFileEntryParserImpl object.
    056     * The expression is compiled with flags = 0.
    057     *
    058     * @param regex  The regular expression with which this object is
    059     * initialized.
    060     *
    061     * @throws IllegalArgumentException
    062     * Thrown if the regular expression is unparseable.  Should not be seen in
    063     * normal conditions.  It it is seen, this is a sign that a subclass has
    064     * been created with a bad regular expression.   Since the parser must be
    065     * created before use, this means that any bad parser subclasses created
    066     * from this will bomb very quickly,  leading to easy detection.
    067     */
    068
    069    public RegexFTPFileEntryParserImpl(final String regex) {
    070        compileRegex(regex, 0);
    071    }
    072
    073    /**
    074     * The constructor for a RegexFTPFileEntryParserImpl object.
    075     *
    076     * @param regex  The regular expression with which this object is
    077     * initialized.
    078     * @param flags the flags to apply, see {@link Pattern#compile(String, int)}. Use 0 for none.
    079     *
    080     * @throws IllegalArgumentException
    081     * Thrown if the regular expression is unparseable.  Should not be seen in
    082     * normal conditions.  It it is seen, this is a sign that a subclass has
    083     * been created with a bad regular expression.   Since the parser must be
    084     * created before use, this means that any bad parser subclasses created
    085     * from this will bomb very quickly,  leading to easy detection.
    086     * @since 3.4
    087     */
    088    public RegexFTPFileEntryParserImpl(final String regex, final int flags) {
    089        compileRegex(regex, flags);
    090    }
    091
    092    /**
    093     * Convenience method delegates to the internal MatchResult's matches()
    094     * method.
    095     *
    096     * @param s the String to be matched
    097     * @return true if s matches this object's regular expression.
    098     */
    099
    100    public boolean matches(final String s) {
    101        this.result = null;
    102        _matcher_ = pattern.matcher(s);
    103        if (_matcher_.matches()) {
    104            this.result = _matcher_.toMatchResult();
    105        }
    106        return null != this.result;
    107    }
    108
    109    /**
    110     * Convenience method
    111     *
    112     * @return the number of groups() in the internal MatchResult.
    113     */
    114
    115    public int getGroupCnt() {
    116        if (this.result == null) {
    117            return 0;
    118        }
    119        return this.result.groupCount();
    120    }
    121
    122    /**
    123     * Convenience method delegates to the internal MatchResult's group()
    124     * method.
    125     *
    126     * @param matchnum match group number to be retrieved
    127     *
    128     * @return the content of the <code>matchnum'th</code> group of the internal
    129     *         match or null if this method is called without a match having
    130     *         been made.
    131     */
    132    public String group(final int matchnum) {
    133        if (this.result == null) {
    134            return null;
    135        }
    136        return this.result.group(matchnum);
    137    }
    138
    139    /**
    140     * For debugging purposes - returns a string shows each match group by
    141     * number.
    142     *
    143     * @return a string shows each match group by number.
    144     */
    145
    146    public String getGroupsAsString() {
    147        final StringBuilder b = new StringBuilder();
    148        for (int i = 1; i <= this.result.groupCount(); i++) {
    149            b.append(i).append(") ").append(this.result.group(i)).append(
    150                    System.getProperty("line.separator"));
    151        }
    152        return b.toString();
    153    }
    154
    155    /**
    156     * Alter the current regular expression being utilised for entry parsing
    157     * and create a new {@link Pattern} instance.
    158     * @param regex The new regular expression
    159     * @return  true
    160     * @since 2.0
    161     * @throws IllegalArgumentException if the regex cannot be compiled
    162     */
    163    public boolean setRegex(final String regex) {
    164        compileRegex(regex, 0);
    165        return true;
    166    }
    167
    168
    169    /**
    170     * Alter the current regular expression being utilised for entry parsing
    171     * and create a new {@link Pattern} instance.
    172     * @param regex The new regular expression
    173     * @param flags the flags to apply, see {@link Pattern#compile(String, int)}. Use 0 for none.
    174     * @return  true
    175     * @since 3.4
    176     * @throws IllegalArgumentException if the regex cannot be compiled
    177     */
    178    public boolean setRegex(final String regex, final int flags) {
    179        compileRegex(regex, flags);
    180        return true;
    181    }
    182
    183    /**
    184     * Compile the regex and store the {@link Pattern}.
    185     *
    186     * This is an internal method to do the work so the constructor does not
    187     * have to call an overrideable method.
    188     *
    189     * @param regex the expression to compile
    190     * @param flags the flags to apply, see {@link Pattern#compile(String, int)}. Use 0 for none.
    191     * @throws IllegalArgumentException if the regex cannot be compiled
    192     */
    193    private void compileRegex(final String regex, final int flags) {
    194        try {
    195            pattern = Pattern.compile(regex, flags);
    196        } catch (final PatternSyntaxException pse) {
    197            throw new IllegalArgumentException("Unparseable regex supplied: " + regex);
    198        }
    199    }
    200}