    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.Objects;
    025import java.util.function.Function;
    026import java.util.regex.Pattern;
    027
    028import org.apache.commons.io.IOCase;
    029import org.apache.commons.io.file.PathUtils;
    030
    031/**
    032 * Filters files using supplied regular expression(s).
    033 * <p>
    034 * See java.util.regex.Pattern for regex matching rules.
    035 * </p>
    036 * <h2>Using Classic IO</h2>
    037 * <p>
    038 * e.g.
    039 *
    040 * <pre>
    041 * File dir = FileUtils.current();
    042 * FileFilter fileFilter = new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$");
    043 * File[] files = dir.listFiles(fileFilter);
    044 * for (String file : files) {
    045 *     System.out.println(file);
    046 * }
    047 * </pre>
    048 *
    049 * <h2>Using NIO</h2>
    050 *
    051 * <pre>
    052 * final Path dir = PathUtils.current();
    053 * final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$"));
    054 * //
    055 * // Walk one dir
    056 * Files.<b>walkFileTree</b>(dir, Collections.emptySet(), 1, visitor);
    057 * System.out.println(visitor.getPathCounters());
    058 * System.out.println(visitor.getFileList());
    059 * //
    060 * visitor.getPathCounters().reset();
    061 * //
    062 * // Walk dir tree
    063 * Files.<b>walkFileTree</b>(dir, visitor);
    064 * System.out.println(visitor.getPathCounters());
    065 * System.out.println(visitor.getDirList());
    066 * System.out.println(visitor.getFileList());
    067 * </pre>
    068 * <h2>Deprecating Serialization</h2>
    069 * <p>
    070 * <em>Serialization is deprecated and will be removed in 3.0.</em>
    071 * </p>
    072 *
    073 * @since 1.4
    074 */
    075public class RegexFileFilter extends AbstractFileFilter implements Serializable {
    076
    077    private static final long serialVersionUID = 4269646126155225062L;
    078
    079    /**
    080     * Compiles the given pattern source.
    081     *
    082     * @param pattern the source pattern.
    083     * @param flags the compilation flags.
    084     * @return a new Pattern.
    085     */
    086    private static Pattern compile(final String pattern, final int flags) {
    087        Objects.requireNonNull(pattern, "pattern");
    088        return Pattern.compile(pattern, flags);
    089    }
    090
    091    /**
    092     * Converts IOCase to Pattern compilation flags.
    093     *
    094     * @param ioCase case-sensitivity.
    095     * @return Pattern compilation flags.
    096     */
    097    private static int toFlags(final IOCase ioCase) {
    098        return IOCase.isCaseSensitive(ioCase) ? 0 : Pattern.CASE_INSENSITIVE;
    099    }
    100
    101    /** The regular expression pattern that will be used to match file names. */
    102    private final Pattern pattern;
    103
    104    /** How convert a path to a string. */
    105    private transient final Function<Path, String> pathToString;
    106
    107    /**
    108     * Constructs a new regular expression filter for a compiled regular expression
    109     *
    110     * @param pattern regular expression to match.
    111     * @throws NullPointerException if the pattern is null.
    112     */
    113    @SuppressWarnings("unchecked")
    114    public RegexFileFilter(final Pattern pattern) {
    115        this(pattern, (Function<Path, String> & Serializable) PathUtils::getFileNameString);
    116    }
    117
    118    /**
    119     * Constructs a new regular expression filter for a compiled regular expression
    120     *
    121     * @param pattern regular expression to match.
    122     * @param pathToString How convert a path to a string.
    123     * @throws NullPointerException if the pattern is null.
    124     * @since 2.10.0
    125     */
    126    public RegexFileFilter(final Pattern pattern, final Function<Path, String> pathToString) {
    127        Objects.requireNonNull(pattern, "pattern");
    128        this.pattern = pattern;
    129        this.pathToString = pathToString != null ? pathToString : Objects::toString;
    130    }
    131
    132    /**
    133     * Constructs a new regular expression filter.
    134     *
    135     * @param pattern regular string expression to match
    136     * @throws NullPointerException if the pattern is null
    137     */
    138    public RegexFileFilter(final String pattern) {
    139        this(pattern, 0);
    140    }
    141
    142    /**
    143     * Constructs a new regular expression filter with the specified flags.
    144     *
    145     * @param pattern regular string expression to match
    146     * @param flags pattern flags - e.g. {@link Pattern#CASE_INSENSITIVE}
    147     * @throws IllegalArgumentException if the pattern is null
    148     */
    149    public RegexFileFilter(final String pattern, final int flags) {
    150        this(compile(pattern, flags));
    151    }
    152
    153    /**
    154     * Constructs a new regular expression filter with the specified flags case sensitivity.
    155     *
    156     * @param pattern regular string expression to match
    157     * @param ioCase how to handle case sensitivity, null means case-sensitive
    158     * @throws IllegalArgumentException if the pattern is null
    159     */
    160    public RegexFileFilter(final String pattern, final IOCase ioCase) {
    161        this(compile(pattern, toFlags(ioCase)));
    162    }
    163
    164    /**
    165     * Checks to see if the file name matches one of the regular expressions.
    166     *
    167     * @param dir the file directory (ignored)
    168     * @param name the file name
    169     * @return true if the file name matches one of the regular expressions
    170     */
    171    @Override
    172    public boolean accept(final File dir, final String name) {
    173        return pattern.matcher(name).matches();
    174    }
    175
    176    /**
    177     * Checks to see if the file name matches one of the regular expressions.
    178     *
    179     * @param path the path
    180     * @param attributes the path attributes
    181     * @return true if the file name matches one of the regular expressions
    182     */
    183    @Override
    184    public FileVisitResult accept(final Path path, final BasicFileAttributes attributes) {
    185        final String result = pathToString.apply(path);
    186        return toFileVisitResult(result != null && pattern.matcher(result).matches());
    187    }
    188
    189    /**
    190     * Returns a debug string.
    191     *
    192     * @since 2.10.0
    193     */
    194    @Override
    195    public String toString() {
    196        return "RegexFileFilter [pattern=" + pattern + "]";
    197    }
    198
    199}