001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2025 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018///////////////////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.checks.whitespace;
021
022import java.io.File;
023
024import com.puppycrawl.tools.checkstyle.StatelessCheck;
025import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
026import com.puppycrawl.tools.checkstyle.api.FileText;
027
028/**
029 * <div>
030 * Checks that there are no tab characters ({@code '\t'}) in the source code.
031 * </div>
032 *
033 * <p>
034 * Rationale:
035 * </p>
036 * <ul>
037 * <li>
038 * Developers should not need to configure the tab width of their text editors in order
039 * to be able to read source code.
040 * </li>
041 * <li>
042 * From the Apache jakarta coding standards: In a distributed development environment,
043 * when the commit messages get sent to a mailing list, they are almost impossible to
044 * read if you use tabs.
045 * </li>
046 * </ul>
047 *
048 * <p>
049 * When the {@code FileTabCharacter} check is used with the default configuration,
050 * only the first instance of a tab character is reported.
051 * </p>
052 *
053 * <ul>
054 * <li>
055 * Property {@code eachLine} - Control whether to report on each line containing a tab,
056 * or just the first instance.
057 * Type is {@code boolean}.
058 * Default value is {@code false}.
059 * </li>
060 * <li>
061 * Property {@code fileExtensions} - Specify the file extensions of the files to process.
062 * Type is {@code java.lang.String[]}.
063 * Default value is {@code ""}.
064 * </li>
065 * </ul>
066 *
067 * <p>
068 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker}
069 * </p>
070 *
071 * <p>
072 * Violation Message Keys:
073 * </p>
074 * <ul>
075 * <li>
076 * {@code containsTab}
077 * </li>
078 * <li>
079 * {@code file.containsTab}
080 * </li>
081 * </ul>
082 *
083 * @since 5.0
084 */
085@StatelessCheck
086public class FileTabCharacterCheck extends AbstractFileSetCheck {
087
088    /**
089     * A key is pointing to the warning message text in "messages.properties"
090     * file.
091     */
092    public static final String MSG_CONTAINS_TAB = "containsTab";
093
094    /**
095     * A key is pointing to the warning message text in "messages.properties"
096     * file.
097     */
098    public static final String MSG_FILE_CONTAINS_TAB = "file.containsTab";
099
100    /** Control whether to report on each line containing a tab, or just the first instance. */
101    private boolean eachLine;
102
103    @Override
104    protected void processFiltered(File file, FileText fileText) {
105        int lineNum = 0;
106        for (int index = 0; index < fileText.size(); index++) {
107            final String line = fileText.get(index);
108            lineNum++;
109            final int tabPosition = line.indexOf('\t');
110            if (tabPosition != -1) {
111                if (eachLine) {
112                    log(lineNum, tabPosition, MSG_CONTAINS_TAB);
113                }
114                else {
115                    log(lineNum, tabPosition, MSG_FILE_CONTAINS_TAB);
116                    break;
117                }
118            }
119        }
120    }
121
122    /**
123     * Setter to control whether to report on each line containing a tab, or just the first
124     * instance.
125     *
126     * @param eachLine Whether report on each line containing a tab.
127     * @since 5.0
128     */
129    public void setEachLine(boolean eachLine) {
130        this.eachLine = eachLine;
131    }
132
133}