1 ////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code for adherence to a set of rules.
3 // Copyright (C) 2001-2019 the original author or authors.
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 ////////////////////////////////////////////////////////////////////////////////
19
20 package com.puppycrawl.tools.checkstyle.checks.coding;
21
22 import com.puppycrawl.tools.checkstyle.StatelessCheck;
23 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
24 import com.puppycrawl.tools.checkstyle.api.DetailAST;
25 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
26 import com.puppycrawl.tools.checkstyle.utils.CheckUtil;
27
28 /**
29 * <p>
30 * Checks that each variable declaration is in its own statement
31 * and on its own line.
32 * </p>
33 * <p>
34 * Rationale: <a
35 * href="https://checkstyle.org/styleguides/sun-code-conventions-19990420/CodeConventions.doc5.html#a2992">
36 * the SUN Code conventions chapter 6.1</a> recommends that
37 * declarations should be one per line.
38 * </p>
39 * <p>
40 * An example of how to configure the check is:
41 * </p>
42 * <pre>
43 * <module name="MultipleVariableDeclarations"/>
44 * </pre>
45 */
46 @StatelessCheck
47 public class MultipleVariableDeclarationsCheck extends AbstractCheck {
48
49 /**
50 * A key is pointing to the warning message text in "messages.properties"
51 * file.
52 */
53 public static final String MSG_MULTIPLE = "multiple.variable.declarations";
54
55 /**
56 * A key is pointing to the warning message text in "messages.properties"
57 * file.
58 */
59 public static final String MSG_MULTIPLE_COMMA = "multiple.variable.declarations.comma";
60
61 @Override
62 public int[] getAcceptableTokens() {
63 return getRequiredTokens();
64 }
65
66 @Override
67 public int[] getDefaultTokens() {
68 return getRequiredTokens();
69 }
70
71 @Override
72 public int[] getRequiredTokens() {
73 return new int[] {TokenTypes.VARIABLE_DEF};
74 }
75
76 @Override
77 public void visitToken(DetailAST ast) {
78 DetailAST nextNode = ast.getNextSibling();
79
80 if (nextNode != null) {
81 final boolean isCommaSeparated = nextNode.getType() == TokenTypes.COMMA;
82
83 if (isCommaSeparated
84 || nextNode.getType() == TokenTypes.SEMI) {
85 nextNode = nextNode.getNextSibling();
86 }
87
88 if (nextNode != null
89 && nextNode.getType() == TokenTypes.VARIABLE_DEF) {
90 final DetailAST firstNode = CheckUtil.getFirstNode(ast);
91 if (isCommaSeparated) {
92 // Check if the multiple variable declarations are in a
93 // for loop initializer. If they are, then no warning
94 // should be displayed. Declaring multiple variables in
95 // a for loop initializer is a good way to minimize
96 // variable scope. Refer Feature Request Id - 2895985
97 // for more details
98 if (ast.getParent().getType() != TokenTypes.FOR_INIT) {
99 log(firstNode, MSG_MULTIPLE_COMMA);
100 }
101 }
102 else {
103 final DetailAST lastNode = getLastNode(ast);
104 final DetailAST firstNextNode = CheckUtil.getFirstNode(nextNode);
105
106 if (firstNextNode.getLineNo() == lastNode.getLineNo()) {
107 log(firstNode, MSG_MULTIPLE);
108 }
109 }
110 }
111 }
112 }
113
114 /**
115 * Finds sub-node for given node maximum (line, column) pair.
116 * @param node the root of tree for search.
117 * @return sub-node with maximum (line, column) pair.
118 */
119 private static DetailAST getLastNode(final DetailAST node) {
120 DetailAST currentNode = node;
121 DetailAST child = node.getFirstChild();
122 while (child != null) {
123 final DetailAST newNode = getLastNode(child);
124 if (newNode.getLineNo() > currentNode.getLineNo()
125 || newNode.getLineNo() == currentNode.getLineNo()
126 && newNode.getColumnNo() > currentNode.getColumnNo()) {
127 currentNode = newNode;
128 }
129 child = child.getNextSibling();
130 }
131
132 return currentNode;
133 }
134
135 }