001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2017 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.design;
021
022import java.util.Map;
023import java.util.SortedMap;
024import java.util.TreeMap;
025
026import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
027import com.puppycrawl.tools.checkstyle.api.DetailAST;
028import com.puppycrawl.tools.checkstyle.api.TokenTypes;
029import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
030
031/**
032 * Checks that each top-level class, interface
033 * or enum resides in a source file of its own.
034 * <p>
035 * Official description of a 'top-level' term:<a
036 * href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-7.html#jls-7.6">
037 * 7.6. Top Level Type Declarations</a>. If file doesn't contains
038 * public class, enum or interface, top-level type is the first type in file.
039 * </p>
040 * <p>
041 * An example of code with violations:
042 * </p>
043 * <pre>{@code
044 * public class Foo{
045 *     //methods
046 * }
047 *
048 * class Foo2{
049 *     //methods
050 * }
051 * }</pre>
052 * <p>
053 * An example of code without top-level public type:
054 * </p>
055 * <pre>{@code
056 * class Foo{ //top-level class
057 *     //methods
058 * }
059 *
060 * class Foo2{
061 *     //methods
062 * }
063 * }</pre>
064 * <p>
065 * An example of check's configuration:
066 * </p>
067 * <pre>
068 * &lt;module name="OneTopLevelClass"/&gt;
069 * </pre>
070 *
071 * <p>
072 * An example of code without violations:
073 * </p>
074 * <pre>{@code
075 * public class Foo{
076 *     //methods
077 * }
078 * }</pre>
079 *
080 * <p> ATTENTION: This Check does not support customization of validated tokens,
081 *  so do not use the "tokens" property.
082 * </p>
083 *
084 * @author maxvetrenko
085 */
086public class OneTopLevelClassCheck extends AbstractCheck {
087
088    /**
089     * A key is pointing to the warning message text in "messages.properties"
090     * file.
091     */
092    public static final String MSG_KEY = "one.top.level.class";
093
094    /**
095     * True if a java source file contains a type
096     * with a public access level modifier.
097     */
098    private boolean publicTypeFound;
099
100    /** Mapping between type names and line numbers of the type declarations.*/
101    private final SortedMap<Integer, String> lineNumberTypeMap = new TreeMap<>();
102
103    @Override
104    public int[] getDefaultTokens() {
105        return getAcceptableTokens();
106    }
107
108    // ZERO tokens as Check do Traverse of Tree himself, he does not need to subscribed to Tokens
109    @Override
110    public int[] getAcceptableTokens() {
111        return CommonUtils.EMPTY_INT_ARRAY;
112    }
113
114    @Override
115    public int[] getRequiredTokens() {
116        return getAcceptableTokens();
117    }
118
119    @Override
120    public void beginTree(DetailAST rootAST) {
121        publicTypeFound = false;
122        lineNumberTypeMap.clear();
123
124        DetailAST currentNode = rootAST;
125        while (currentNode != null) {
126            if (currentNode.getType() == TokenTypes.CLASS_DEF
127                    || currentNode.getType() == TokenTypes.ENUM_DEF
128                    || currentNode.getType() == TokenTypes.INTERFACE_DEF) {
129                if (isPublic(currentNode)) {
130                    publicTypeFound = true;
131                }
132                else {
133                    final String typeName = currentNode
134                            .findFirstToken(TokenTypes.IDENT).getText();
135                    lineNumberTypeMap.put(currentNode.getLineNo(), typeName);
136                }
137            }
138            currentNode = currentNode.getNextSibling();
139        }
140    }
141
142    @Override
143    public void finishTree(DetailAST rootAST) {
144        if (!lineNumberTypeMap.isEmpty()) {
145            if (!publicTypeFound) {
146                // skip first top-level type.
147                lineNumberTypeMap.remove(lineNumberTypeMap.firstKey());
148            }
149
150            for (Map.Entry<Integer, String> entry
151                    : lineNumberTypeMap.entrySet()) {
152                log(entry.getKey(), MSG_KEY, entry.getValue());
153            }
154        }
155    }
156
157    /**
158     * Checks if a type is public.
159     * @param typeDef type definition node.
160     * @return true if a type has a public access level modifier.
161     */
162    private static boolean isPublic(DetailAST typeDef) {
163        final DetailAST modifiers =
164                typeDef.findFirstToken(TokenTypes.MODIFIERS);
165        return modifiers.findFirstToken(TokenTypes.LITERAL_PUBLIC) != null;
166    }
167}