    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 */
    017package org.apache.commons.io.filefilter;
    018
    019import java.io.File;
    020import java.io.Serializable;
    021import java.nio.file.FileVisitResult;
    022import java.nio.file.Path;
    023import java.nio.file.attribute.BasicFileAttributes;
    024import java.util.function.Function;
    025import java.util.regex.Pattern;
    026
    027import org.apache.commons.io.IOCase;
    028
    029/**
    030 * Filters files using supplied regular expression(s).
    031 * <p>
    032 * See java.util.regex.Pattern for regex matching rules.
    033 * </p>
    034 * <h2>Using Classic IO</h2>
    035 * <p>
    036 * e.g.
    037 *
    038 * <pre>
    039 * File dir = new File(".");
    040 * FileFilter fileFilter = new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$");
    041 * File[] files = dir.listFiles(fileFilter);
    042 * for (String file : files) {
    043 *     System.out.println(file);
    044 * }
    045 * </pre>
    046 *
    047 * <h2>Using NIO</h2>
    048 *
    049 * <pre>
    050 * final Path dir = Paths.get("");
    051 * final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$"));
    052 * //
    053 * // Walk one dir
    054 * Files.<b>walkFileTree</b>(dir, Collections.emptySet(), 1, visitor);
    055 * System.out.println(visitor.getPathCounters());
    056 * System.out.println(visitor.getFileList());
    057 * //
    058 * visitor.getPathCounters().reset();
    059 * //
    060 * // Walk dir tree
    061 * Files.<b>walkFileTree</b>(dir, visitor);
    062 * System.out.println(visitor.getPathCounters());
    063 * System.out.println(visitor.getDirList());
    064 * System.out.println(visitor.getFileList());
    065 * </pre>
    066 *
    067 * @since 1.4
    068 */
    069public class RegexFileFilter extends AbstractFileFilter implements Serializable {
    070
    071    private static final long serialVersionUID = 4269646126155225062L;
    072
    073    /**
    074     * Compiles the given pattern source.
    075     *
    076     * @param pattern the source pattern.
    077     * @param flags the compilation flags.
    078     * @return a new Pattern.
    079     */
    080    private static Pattern compile(final String pattern, final int flags) {
    081        if (pattern == null) {
    082            throw new IllegalArgumentException("Pattern is missing");
    083        }
    084        return Pattern.compile(pattern, flags);
    085    }
    086
    087    /**
    088     * Converts IOCase to Pattern compilation flags.
    089     *
    090     * @param caseSensitivity case-sensitivity.
    091     * @return Pattern compilation flags.
    092     */
    093    private static int toFlags(final IOCase caseSensitivity) {
    094        return IOCase.isCaseSensitive(caseSensitivity) ? Pattern.CASE_INSENSITIVE : 0;
    095    }
    096
    097    /** The regular expression pattern that will be used to match file names. */
    098    private final Pattern pattern;
    099
    100    /** How convert a path to a string. */
    101    private final Function<Path, String> pathToString;
    102
    103    /**
    104     * Constructs a new regular expression filter for a compiled regular expression
    105     *
    106     * @param pattern regular expression to match.
    107     * @throws IllegalArgumentException if the pattern is null.
    108     */
    109    public RegexFileFilter(final Pattern pattern) {
    110        this(pattern, p -> p.getFileName().toString());
    111    }
    112
    113    /**
    114     * Constructs a new regular expression filter for a compiled regular expression
    115     *
    116     * @param pattern regular expression to match.
    117     * @param pathToString How convert a path to a string.
    118     * @throws IllegalArgumentException if the pattern is null.
    119     * @since 2.10.0
    120     */
    121    public RegexFileFilter(final Pattern pattern, final Function<Path, String> pathToString) {
    122        if (pattern == null) {
    123            throw new IllegalArgumentException("Pattern is missing");
    124        }
    125        this.pattern = pattern;
    126        this.pathToString = pathToString;
    127    }
    128
    129    /**
    130     * Constructs a new regular expression filter.
    131     *
    132     * @param pattern regular string expression to match
    133     * @throws IllegalArgumentException if the pattern is null
    134     */
    135    public RegexFileFilter(final String pattern) {
    136        this(pattern, 0);
    137    }
    138
    139    /**
    140     * Constructs a new regular expression filter with the specified flags.
    141     *
    142     * @param pattern regular string expression to match
    143     * @param flags pattern flags - e.g. {@link Pattern#CASE_INSENSITIVE}
    144     * @throws IllegalArgumentException if the pattern is null
    145     */
    146    public RegexFileFilter(final String pattern, final int flags) {
    147        this(compile(pattern, flags));
    148    }
    149
    150    /**
    151     * Constructs a new regular expression filter with the specified flags case sensitivity.
    152     *
    153     * @param pattern regular string expression to match
    154     * @param caseSensitivity how to handle case sensitivity, null means case-sensitive
    155     * @throws IllegalArgumentException if the pattern is null
    156     */
    157    public RegexFileFilter(final String pattern, final IOCase caseSensitivity) {
    158        this(compile(pattern, toFlags(caseSensitivity)));
    159    }
    160
    161    /**
    162     * Checks to see if the file name matches one of the regular expressions.
    163     *
    164     * @param dir the file directory (ignored)
    165     * @param name the file name
    166     * @return true if the file name matches one of the regular expressions
    167     */
    168    @Override
    169    public boolean accept(final File dir, final String name) {
    170        return pattern.matcher(name).matches();
    171    }
    172
    173    /**
    174     * Checks to see if the file name matches one of the regular expressions.
    175     *
    176     * @param path the path
    177     * @param attributes the path attributes
    178     * @return true if the file name matches one of the regular expressions
    179     */
    180    @Override
    181    public FileVisitResult accept(final Path path, final BasicFileAttributes attributes) {
    182        return toFileVisitResult(pattern.matcher(pathToString.apply(path)).matches(), path);
    183    }
    184
    185    /**
    186     * Returns a debug string.
    187     *
    188     * @since 2.10.0
    189     */
    190    @Override
    191    public String toString() {
    192        return "RegexFileFilter [pattern=" + pattern + "]";
    193    }
    194
    195}