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