001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2026 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 * @since 5.0
055 */
056@StatelessCheck
057public class FileTabCharacterCheck extends AbstractFileSetCheck {
058
059    /**
060     * A key is pointing to the warning message text in "messages.properties" file.
061     */
062    public static final String MSG_CONTAINS_TAB = "containsTab";
063
064    /**
065     * A key is pointing to the warning message text in "messages.properties" file.
066     */
067    public static final String MSG_FILE_CONTAINS_TAB = "file.containsTab";
068
069    /** Control whether to report on each line containing a tab, or just the first instance. */
070    private boolean eachLine;
071
072    /**
073     * Creates a new {@code FileTabCharacterCheck} instance.
074     */
075    public FileTabCharacterCheck() {
076        // no code by default
077    }
078
079    @Override
080    protected void processFiltered(File file, FileText fileText) {
081        int lineNum = 0;
082        for (int index = 0; index < fileText.size(); index++) {
083            final String line = fileText.get(index);
084            lineNum++;
085            final int tabPosition = line.indexOf('\t');
086            if (tabPosition != -1) {
087                if (eachLine) {
088                    log(lineNum, tabPosition, MSG_CONTAINS_TAB);
089                }
090                else {
091                    log(lineNum, tabPosition, MSG_FILE_CONTAINS_TAB);
092                    break;
093                }
094            }
095        }
096    }
097
098    /**
099     * Setter to control whether to report on each line containing a tab, or just the first
100     * instance.
101     *
102     * @param eachLine Whether report on each line containing a tab.
103     * @since 5.0
104     */
105    public void setEachLine(boolean eachLine) {
106        this.eachLine = eachLine;
107    }
108
109}