src/main/java/com/puppycrawl/tools/checkstyle/checks/naming/ConstantNameCheck.java

////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2017 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
////////////////////////////////////////////////////////////////////////////////

package com.puppycrawl.tools.checkstyle.checks.naming;

import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.ScopeUtils;

/**
 * <p>
 * Checks that constant names conform to a format specified
 * by the format property.
 * A <em>constant</em> is a <strong>static</strong> and <strong>final</strong>
 * field or an interface/annotation field, except
 * <strong>serialVersionUID</strong> and <strong>serialPersistentFields
 * </strong>.  The format is a regular expression
 * and defaults to <strong>^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$</strong>.
 * </p>
 * <p>
 * An example of how to configure the check is:
 * </p>
 * <pre>
 * &lt;module name="ConstantName"/&gt;
 * </pre>
 *
 * <p>
 * An example of how to configure the check for names that are only upper case
 * letters and digits is:
 * </p>
 * <pre>
 * &lt;module name="ConstantName"&gt;
 *    &lt;property name="format" value="^[A-Z][A-Z0-9]*$"/&gt;
 * &lt;/module&gt;
 * </pre>
 *
 *
 * @author Rick Giles
 */
public class ConstantNameCheck
    extends AbstractAccessControlNameCheck {
    /** Creates a new {@code ConstantNameCheck} instance. */
    public ConstantNameCheck() {
        super("^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$");
    }

    @Override
    public int[] getDefaultTokens() {
        return getRequiredTokens();
    }

    @Override
    public int[] getAcceptableTokens() {
        return getRequiredTokens();
    }

    @Override
    public int[] getRequiredTokens() {
        return new int[] {TokenTypes.VARIABLE_DEF};
    }

    @Override
    protected final boolean mustCheckName(DetailAST ast) {
        boolean returnValue = false;

        final DetailAST modifiersAST =
            ast.findFirstToken(TokenTypes.MODIFIERS);
        final boolean isStatic = modifiersAST.findFirstToken(TokenTypes.LITERAL_STATIC) != null;
        final boolean isFinal = modifiersAST.findFirstToken(TokenTypes.FINAL) != null;

        if (isStatic && isFinal && shouldCheckInScope(modifiersAST)
                || ScopeUtils.isInAnnotationBlock(ast)
                || ScopeUtils.isInInterfaceOrAnnotationBlock(ast)
                        && !ScopeUtils.isInCodeBlock(ast)) {
            // Handle the serialVersionUID and serialPersistentFields constants
            // which are used for Serialization. Cannot enforce rules on it. :-)
            final DetailAST nameAST = ast.findFirstToken(TokenTypes.IDENT);
            if (!"serialVersionUID".equals(nameAST.getText())
                && !"serialPersistentFields".equals(nameAST.getText())) {
                returnValue = true;
            }
        }

        return returnValue;
    }
}