001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 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;
021
022import com.puppycrawl.tools.checkstyle.StatelessCheck;
023import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026
027/**
028 * <p>
029 * Checks that long constants are defined with an upper ell. That is {@code 'L'}
030 * and not {@code 'l'}. This is in accordance with the Java Language Specification,
031 * <a href="https://docs.oracle.com/javase/specs/jls/se11/html/jls-3.html#jls-3.10.1">
032 * Section 3.10.1</a>.
033 * </p>
034 * <p>
035 * Rationale: The lower-case ell {@code 'l'} looks a lot like {@code 1}.
036 * </p>
037 * <p>
038 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
039 * </p>
040 * <p>
041 * Violation Message Keys:
042 * </p>
043 * <ul>
044 * <li>
045 * {@code upperEll}
046 * </li>
047 * </ul>
048 *
049 * @since 3.0
050 */
051@StatelessCheck
052public class UpperEllCheck extends AbstractCheck {
053
054    /**
055     * A key is pointing to the warning message text in "messages.properties"
056     * file.
057     */
058    public static final String MSG_KEY = "upperEll";
059
060    @Override
061    public int[] getDefaultTokens() {
062        return getRequiredTokens();
063    }
064
065    @Override
066    public int[] getAcceptableTokens() {
067        return getRequiredTokens();
068    }
069
070    @Override
071    public int[] getRequiredTokens() {
072        return new int[] {TokenTypes.NUM_LONG};
073    }
074
075    @Override
076    public void visitToken(DetailAST ast) {
077        if (ast.getText().endsWith("l")) {
078            log(ast, MSG_KEY);
079        }
080    }
081
082}