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.util.regex.Pattern;
022
023import org.apache.commons.io.IOCase;
024
025/**
026 * Filters files using supplied regular expression(s).
027 * <p>
028 * See java.util.regex.Pattern for regex matching rules.
029 * </p>
030 *
031 * <p>
032 * e.g.
033 * <pre>
034 * File dir = new File(".");
035 * FileFilter fileFilter = new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$");
036 * File[] files = dir.listFiles(fileFilter);
037 * for (int i = 0; i &lt; files.length; i++) {
038 *   System.out.println(files[i]);
039 * }
040 * </pre>
041 *
042 * @since 1.4
043 */
044public class RegexFileFilter extends AbstractFileFilter implements Serializable {
045
046    private static final long serialVersionUID = 4269646126155225062L;
047    /** The regular expression pattern that will be used to match file names */
048    private final Pattern pattern;
049
050    /**
051     * Construct a new regular expression filter.
052     *
053     * @param pattern regular string expression to match
054     * @throws IllegalArgumentException if the pattern is null
055     */
056    public RegexFileFilter(final String pattern) {
057        if (pattern == null) {
058            throw new IllegalArgumentException("Pattern is missing");
059        }
060
061        this.pattern = Pattern.compile(pattern);
062    }
063
064    /**
065     * Construct a new regular expression filter with the specified flags case sensitivity.
066     *
067     * @param pattern regular string expression to match
068     * @param caseSensitivity  how to handle case sensitivity, null means case-sensitive
069     * @throws IllegalArgumentException if the pattern is null
070     */
071    public RegexFileFilter(final String pattern, final IOCase caseSensitivity) {
072        if (pattern == null) {
073            throw new IllegalArgumentException("Pattern is missing");
074        }
075        int flags = 0;
076        if (caseSensitivity != null && !caseSensitivity.isCaseSensitive()) {
077            flags = Pattern.CASE_INSENSITIVE;
078        }
079        this.pattern = Pattern.compile(pattern, flags);
080    }
081
082    /**
083     * Construct a new regular expression filter with the specified flags.
084     *
085     * @param pattern regular string expression to match
086     * @param flags pattern flags - e.g. {@link Pattern#CASE_INSENSITIVE}
087     * @throws IllegalArgumentException if the pattern is null
088     */
089    public RegexFileFilter(final String pattern, final int flags) {
090        if (pattern == null) {
091            throw new IllegalArgumentException("Pattern is missing");
092        }
093        this.pattern = Pattern.compile(pattern, flags);
094    }
095
096    /**
097     * Construct a new regular expression filter for a compiled regular expression
098     *
099     * @param pattern regular expression to match
100     * @throws IllegalArgumentException if the pattern is null
101     */
102    public RegexFileFilter(final Pattern pattern) {
103        if (pattern == null) {
104            throw new IllegalArgumentException("Pattern is missing");
105        }
106
107        this.pattern = pattern;
108    }
109
110    /**
111     * Checks to see if the file name matches one of the regular expressions.
112     *
113     * @param dir   the file directory (ignored)
114     * @param name  the file name
115     * @return true if the file name matches one of the regular expressions
116     */
117    @Override
118    public boolean accept(final File dir, final String name) {
119        return pattern.matcher(name).matches();
120    }
121
122}