001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2015 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.coding;
021
022import com.puppycrawl.tools.checkstyle.api.Check;
023import com.puppycrawl.tools.checkstyle.api.DetailAST;
024import com.puppycrawl.tools.checkstyle.api.TokenTypes;
025
026/**
027 * Ensures there is a package declaration.
028 * Rationale: Classes that live in the null package cannot be
029 * imported. Many novice developers are not aware of this.
030 *
031 * @author <a href="mailto:simon@redhillconsulting.com.au">Simon Harris</a>
032 * @author Oliver Burn
033 */
034public final class PackageDeclarationCheck extends Check {
035
036    /**
037     * A key is pointing to the warning message text in "messages.properties"
038     * file.
039     */
040    public static final String MSG_KEY = "missing.package.declaration";
041
042    /** Line number used to log violation when no AST nodes are present in file. */
043    private static final int DEFAULT_LINE_NUMBER = 1;
044
045    /** Is package defined. */
046    private boolean defined;
047
048    @Override
049    public int[] getDefaultTokens() {
050        return new int[] {TokenTypes.PACKAGE_DEF};
051    }
052
053    @Override
054    public int[] getRequiredTokens() {
055        return getDefaultTokens();
056    }
057
058    @Override
059    public int[] getAcceptableTokens() {
060        return new int[] {TokenTypes.PACKAGE_DEF};
061    }
062
063    @Override
064    public void beginTree(DetailAST ast) {
065        defined = false;
066    }
067
068    @Override
069    public void finishTree(DetailAST ast) {
070        if (!defined) {
071            int lineNumber = DEFAULT_LINE_NUMBER;
072            if (ast != null) {
073                lineNumber = ast.getLineNo();
074            }
075            log(lineNumber, MSG_KEY);
076        }
077    }
078
079    @Override
080    public void visitToken(DetailAST ast) {
081        defined = true;
082    }
083}