001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2019 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.naming;
021
022import java.util.regex.Pattern;
023
024import com.puppycrawl.tools.checkstyle.StatelessCheck;
025import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
026import com.puppycrawl.tools.checkstyle.api.DetailAST;
027import com.puppycrawl.tools.checkstyle.api.FullIdent;
028import com.puppycrawl.tools.checkstyle.api.TokenTypes;
029
030/**
031 * <p>
032 * Checks that package names conform to a format specified
033 * by the format property.
034 * </p>
035 * <p>
036 * The default value of {@code format} for module {@code PackageName} has been chosen to match
037 * the requirements in the
038 * <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-6.html#jls-6.5.3">
039 * Java Language specification</a>
040 * and the Sun coding conventions. However both underscores and uppercase letters are rather
041 * uncommon, so most configurations should probably assign value
042 * {@code ^[a-z]+(\.[a-z][a-z0-9]*)*$} to {@code format} for module {@code PackageName}.
043 * </p>
044 * <ul>
045 * <li>
046 * Property {@code format} - Specifies valid identifiers. Default value is
047 * {@code "^[a-z]+(\.[a-zA-Z_][a-zA-Z0-9_]*)*$"}.
048 * </li>
049 * </ul>
050 * <p>
051 * An example of how to configure the check is:
052 * </p>
053 * <pre>
054 * &lt;module name="PackageName"/&gt;
055 * </pre>
056 * <p>Code Example:</p>
057 * <pre>
058 * package com; // OK
059 * package COM; // violation, name 'COM' must match pattern '^[a-z]+(\.[a-zA-Z_][a-zA-Z0-9_]*)*$'
060 * package com.checkstyle.checks; // OK
061 * package com.A.checkstyle.checks; // OK
062 * package com.checkstyle1.checks; // OK
063 * package com.checkSTYLE.checks; // OK
064 * package com._checkstyle.checks_; // OK
065 * </pre>
066 * <p>
067 * An example of how to configure the check to ensure with packages start with a lowercase letter
068 * and only contains lowercase letters or numbers is:
069 * </p>
070 * <pre>
071 * &lt;module name=&quot;PackageName&quot;&gt;
072 *   &lt;property name=&quot;format&quot;
073 *     value=&quot;^[a-z]+(\.[a-z][a-z0-9]*)*$&quot;/&gt;
074 * &lt;/module&gt;
075 * </pre>
076 * <p>Code Example:</p>
077 * <pre>
078 * package com; // OK
079 * package COM; // violation, name 'COM' must match pattern '^[a-z]+(\.[a-z][a-z0-9]*)*$'
080 * package com.checkstyle.checks; // OK
081 * package com.A.checkstyle.checks; // violation, name 'com.A.checkstyle' must match
082 *                                  // pattern '^[a-z]+(\.[a-z][a-z0-9]*)*$'
083 * package com.checkstyle1.checks; // OK
084 * package com.checkSTYLE.checks; // violation, name 'com.checkSTYLE.checks' must
085 *                                // match pattern '^[a-z]+(\.[a-z][a-z0-9]*)*$'
086 * package com._checkstyle.checks_; // violation, name 'com._checkstyle.checks_' must match
087 *                                  // pattern '^[a-z]+(\.[a-z][a-z0-9]*)*$'
088 * </pre>
089 *
090 * @since 3.0
091 */
092@StatelessCheck
093public class PackageNameCheck
094    extends AbstractCheck {
095
096    /**
097     * A key is pointing to the warning message text in "messages.properties"
098     * file.
099     */
100    public static final String MSG_KEY = "name.invalidPattern";
101
102    /** Specifies valid identifiers. */
103    // Uppercase letters seem rather uncommon, but they're allowed in
104    // https://docs.oracle.com/javase/specs/
105    //  second_edition/html/packages.doc.html#40169
106    private Pattern format = Pattern.compile("^[a-z]+(\\.[a-zA-Z_][a-zA-Z0-9_]*)*$");
107
108    /**
109     * Setter to specifies valid identifiers.
110     * @param pattern the new pattern
111     */
112    public void setFormat(Pattern pattern) {
113        format = pattern;
114    }
115
116    @Override
117    public int[] getDefaultTokens() {
118        return getRequiredTokens();
119    }
120
121    @Override
122    public int[] getAcceptableTokens() {
123        return getRequiredTokens();
124    }
125
126    @Override
127    public int[] getRequiredTokens() {
128        return new int[] {TokenTypes.PACKAGE_DEF};
129    }
130
131    @Override
132    public void visitToken(DetailAST ast) {
133        final DetailAST nameAST = ast.getLastChild().getPreviousSibling();
134        final FullIdent full = FullIdent.createFullIdent(nameAST);
135        if (!format.matcher(full.getText()).find()) {
136            log(full.getDetailAst(),
137                MSG_KEY,
138                full.getText(),
139                format.pattern());
140        }
141    }
142
143}