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"
061     * file.
062     */
063    public static final String MSG_CONTAINS_TAB = "containsTab";
064
065    /**
066     * A key is pointing to the warning message text in "messages.properties"
067     * file.
068     */
069    public static final String MSG_FILE_CONTAINS_TAB = "file.containsTab";
070
071    /** Control whether to report on each line containing a tab, or just the first instance. */
072    private boolean eachLine;
073
074    /**
075     * Creates a new {@code FileTabCharacterCheck} instance.
076     */
077    public FileTabCharacterCheck() {
078        // no code by default
079    }
080
081    @Override
082    protected void processFiltered(File file, FileText fileText) {
083        int lineNum = 0;
084        for (int index = 0; index < fileText.size(); index++) {
085            final String line = fileText.get(index);
086            lineNum++;
087            final int tabPosition = line.indexOf('\t');
088            if (tabPosition != -1) {
089                if (eachLine) {
090                    log(lineNum, tabPosition, MSG_CONTAINS_TAB);
091                }
092                else {
093                    log(lineNum, tabPosition, MSG_FILE_CONTAINS_TAB);
094                    break;
095                }
096            }
097        }
098    }
099
100    /**
101     * Setter to control whether to report on each line containing a tab, or just the first
102     * instance.
103     *
104     * @param eachLine Whether report on each line containing a tab.
105     * @since 5.0
106     */
107    public void setEachLine(boolean eachLine) {
108        this.eachLine = eachLine;
109    }
110
111}