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 * Notes:
050 * When the {@code FileTabCharacter} check is used with the default configuration,
051 * only the first instance of a tab character is reported.
052 * </p>
053 *
054 * <ul>
055 * <li>
056 * Property {@code eachLine} - Control whether to report on each line containing a tab,
057 * or just the first instance.
058 * Type is {@code boolean}.
059 * Default value is {@code false}.
060 * </li>
061 * <li>
062 * Property {@code fileExtensions} - Specify the file extensions of the files to process.
063 * Type is {@code java.lang.String[]}.
064 * Default value is {@code ""}.
065 * </li>
066 * </ul>
067 *
068 * <p>
069 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker}
070 * </p>
071 *
072 * <p>
073 * Violation Message Keys:
074 * </p>
075 * <ul>
076 * <li>
077 * {@code containsTab}
078 * </li>
079 * <li>
080 * {@code file.containsTab}
081 * </li>
082 * </ul>
083 *
084 * @since 5.0
085 */
086@StatelessCheck
087public class FileTabCharacterCheck extends AbstractFileSetCheck {
088
089    /**
090     * A key is pointing to the warning message text in "messages.properties"
091     * file.
092     */
093    public static final String MSG_CONTAINS_TAB = "containsTab";
094
095    /**
096     * A key is pointing to the warning message text in "messages.properties"
097     * file.
098     */
099    public static final String MSG_FILE_CONTAINS_TAB = "file.containsTab";
100
101    /** Control whether to report on each line containing a tab, or just the first instance. */
102    private boolean eachLine;
103
104    @Override
105    protected void processFiltered(File file, FileText fileText) {
106        int lineNum = 0;
107        for (int index = 0; index < fileText.size(); index++) {
108            final String line = fileText.get(index);
109            lineNum++;
110            final int tabPosition = line.indexOf('\t');
111            if (tabPosition != -1) {
112                if (eachLine) {
113                    log(lineNum, tabPosition, MSG_CONTAINS_TAB);
114                }
115                else {
116                    log(lineNum, tabPosition, MSG_FILE_CONTAINS_TAB);
117                    break;
118                }
119            }
120        }
121    }
122
123    /**
124     * Setter to control whether to report on each line containing a tab, or just the first
125     * instance.
126     *
127     * @param eachLine Whether report on each line containing a tab.
128     * @since 5.0
129     */
130    public void setEachLine(boolean eachLine) {
131        this.eachLine = eachLine;
132    }
133
134}