    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 = null;
    042
    043    /**
    044     * internal match result used by the parser
    045     */
    046    private MatchResult result = null;
    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_ = null;
    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        super();
    071        compileRegex(regex, 0);
    072    }
    073
    074    /**
    075     * The constructor for a RegexFTPFileEntryParserImpl object.
    076     *
    077     * @param regex  The regular expression with which this object is
    078     * initialized.
    079     * @param flags the flags to apply, see {@link Pattern#compile(String, int)}. Use 0 for none.
    080     *
    081     * @throws IllegalArgumentException
    082     * Thrown if the regular expression is unparseable.  Should not be seen in
    083     * normal conditions.  It it is seen, this is a sign that a subclass has
    084     * been created with a bad regular expression.   Since the parser must be
    085     * created before use, this means that any bad parser subclasses created
    086     * from this will bomb very quickly,  leading to easy detection.
    087     * @since 3.4
    088     */
    089    public RegexFTPFileEntryParserImpl(final String regex, final int flags) {
    090        super();
    091        compileRegex(regex, flags);
    092    }
    093
    094    /**
    095     * Convenience method delegates to the internal MatchResult's matches()
    096     * method.
    097     *
    098     * @param s the String to be matched
    099     * @return true if s matches this object's regular expression.
    100     */
    101
    102    public boolean matches(final String s) {
    103        this.result = null;
    104        _matcher_ = pattern.matcher(s);
    105        if (_matcher_.matches()) {
    106            this.result = _matcher_.toMatchResult();
    107        }
    108        return null != this.result;
    109    }
    110
    111    /**
    112     * Convenience method
    113     *
    114     * @return the number of groups() in the internal MatchResult.
    115     */
    116
    117    public int getGroupCnt() {
    118        if (this.result == null) {
    119            return 0;
    120        }
    121        return this.result.groupCount();
    122    }
    123
    124    /**
    125     * Convenience method delegates to the internal MatchResult's group()
    126     * method.
    127     *
    128     * @param matchnum match group number to be retrieved
    129     *
    130     * @return the content of the <code>matchnum'th</code> group of the internal
    131     *         match or null if this method is called without a match having
    132     *         been made.
    133     */
    134    public String group(final int matchnum) {
    135        if (this.result == null) {
    136            return null;
    137        }
    138        return this.result.group(matchnum);
    139    }
    140
    141    /**
    142     * For debugging purposes - returns a string shows each match group by
    143     * number.
    144     *
    145     * @return a string shows each match group by number.
    146     */
    147
    148    public String getGroupsAsString() {
    149        final StringBuilder b = new StringBuilder();
    150        for (int i = 1; i <= this.result.groupCount(); i++) {
    151            b.append(i).append(") ").append(this.result.group(i)).append(
    152                    System.getProperty("line.separator"));
    153        }
    154        return b.toString();
    155    }
    156
    157    /**
    158     * Alter the current regular expression being utilised for entry parsing
    159     * and create a new {@link Pattern} instance.
    160     * @param regex The new regular expression
    161     * @return  true
    162     * @since 2.0
    163     * @throws IllegalArgumentException if the regex cannot be compiled
    164     */
    165    public boolean setRegex(final String regex) {
    166        compileRegex(regex, 0);
    167        return true;
    168    }
    169
    170
    171    /**
    172     * Alter the current regular expression being utilised for entry parsing
    173     * and create a new {@link Pattern} instance.
    174     * @param regex The new regular expression
    175     * @param flags the flags to apply, see {@link Pattern#compile(String, int)}. Use 0 for none.
    176     * @return  true
    177     * @since 3.4
    178     * @throws IllegalArgumentException if the regex cannot be compiled
    179     */
    180    public boolean setRegex(final String regex, final int flags) {
    181        compileRegex(regex, flags);
    182        return true;
    183    }
    184
    185    /**
    186     * Compile the regex and store the {@link Pattern}.
    187     *
    188     * This is an internal method to do the work so the constructor does not
    189     * have to call an overrideable method.
    190     *
    191     * @param regex the expression to compile
    192     * @param flags the flags to apply, see {@link Pattern#compile(String, int)}. Use 0 for none.
    193     * @throws IllegalArgumentException if the regex cannot be compiled
    194     */
    195    private void compileRegex(final String regex, final int flags) {
    196        try {
    197            pattern = Pattern.compile(regex, flags);
    198        } catch (final PatternSyntaxException pse) {
    199            throw new IllegalArgumentException("Unparseable regex supplied: " + regex);
    200        }
    201    }
    202}