1 ////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code for adherence to a set of rules.
3 // Copyright (C) 2001-2015 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 package com.puppycrawl.tools.checkstyle.checks.blocks;
20
21 import com.puppycrawl.tools.checkstyle.api.DetailAST;
22 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
23 import com.puppycrawl.tools.checkstyle.checks.AbstractOptionCheck;
24
25 /**
26 * Checks for empty blocks. The policy to verify is specified using the {@link
27 * BlockOption} class and defaults to {@link BlockOption#STMT}.
28 *
29 * <p> By default the check will check the following blocks:
30 * {@link TokenTypes#LITERAL_WHILE LITERAL_WHILE},
31 * {@link TokenTypes#LITERAL_TRY LITERAL_TRY},
32 * {@link TokenTypes#LITERAL_FINALLY LITERAL_FINALLY},
33 * {@link TokenTypes#LITERAL_DO LITERAL_DO},
34 * {@link TokenTypes#LITERAL_IF LITERAL_IF},
35 * {@link TokenTypes#LITERAL_ELSE LITERAL_ELSE},
36 * {@link TokenTypes#LITERAL_FOR LITERAL_FOR},
37 * {@link TokenTypes#STATIC_INIT STATIC_INIT},
38 * {@link TokenTypes#LITERAL_SWITCH LITERAL_SWITCH}.
39 * </p>
40 *
41 * <p> An example of how to configure the check is:
42 * </p>
43 * <pre>
44 * <module name="EmptyBlock"/>
45 * </pre>
46 *
47 * <p> An example of how to configure the check for the {@link
48 * BlockOption#TEXT} policy and only try blocks is:
49 * </p>
50 *
51 * <pre>
52 * <module name="EmptyBlock">
53 * <property name="tokens" value="LITERAL_TRY"/>
54 * <property name="option" value="text"/>
55 * </module>
56 * </pre>
57 *
58 * @author Lars Kühne
59 */
60 public class EmptyBlockCheck
61 extends AbstractOptionCheck<BlockOption>
62 {
63 /**
64 * A key is pointing to the warning message text in "messages.properties"
65 * file.
66 */
67 public static final String MSG_KEY_BLOCK_NO_STMT = "block.noStmt";
68
69 /**
70 * A key is pointing to the warning message text in "messages.properties"
71 * file.
72 */
73 public static final String MSG_KEY_BLOCK_EMPTY = "block.empty";
74
75 /**
76 * Creates a new <code>EmptyBlockCheck</code> instance.
77 */
78 public EmptyBlockCheck()
79 {
80 super(BlockOption.STMT, BlockOption.class);
81 }
82
83 @Override
84 public int[] getDefaultTokens()
85 {
86 return new int[] {
87 TokenTypes.LITERAL_WHILE,
88 TokenTypes.LITERAL_TRY,
89 TokenTypes.LITERAL_FINALLY,
90 TokenTypes.LITERAL_DO,
91 TokenTypes.LITERAL_IF,
92 TokenTypes.LITERAL_ELSE,
93 TokenTypes.LITERAL_FOR,
94 TokenTypes.INSTANCE_INIT,
95 TokenTypes.STATIC_INIT,
96 TokenTypes.LITERAL_SWITCH,
97 //TODO: does this handle TokenTypes.LITERAL_SYNCHRONIZED?
98 };
99 }
100
101 @Override
102 public int[] getAcceptableTokens()
103 {
104 return new int[] {
105 TokenTypes.LITERAL_WHILE,
106 TokenTypes.LITERAL_TRY,
107 TokenTypes.LITERAL_CATCH,
108 TokenTypes.LITERAL_FINALLY,
109 TokenTypes.LITERAL_DO,
110 TokenTypes.LITERAL_IF,
111 TokenTypes.LITERAL_ELSE,
112 TokenTypes.LITERAL_FOR,
113 TokenTypes.INSTANCE_INIT,
114 TokenTypes.STATIC_INIT,
115 TokenTypes.LITERAL_SWITCH,
116 TokenTypes.LITERAL_CASE,
117 TokenTypes.LITERAL_SWITCH,
118 TokenTypes.LITERAL_DEFAULT,
119 TokenTypes.ARRAY_INIT,
120 //TODO: does this handle TokenTypes.LITERAL_SYNCHRONIZED?
121 };
122 }
123
124 @Override
125 public void visitToken(DetailAST ast)
126 {
127 final DetailAST slistToken = ast.findFirstToken(TokenTypes.SLIST);
128 final DetailAST leftCurly = slistToken != null
129 ? slistToken : ast.findFirstToken(TokenTypes.LCURLY);
130 if (leftCurly != null) {
131 if (getAbstractOption() == BlockOption.STMT) {
132 boolean emptyBlock;
133 if (leftCurly.getType() == TokenTypes.LCURLY) {
134 emptyBlock = leftCurly.getNextSibling().getType() != TokenTypes.CASE_GROUP;
135 }
136 else {
137 emptyBlock = leftCurly.getChildCount() <= 1;
138 }
139 if (emptyBlock) {
140 log(leftCurly.getLineNo(),
141 leftCurly.getColumnNo(),
142 MSG_KEY_BLOCK_NO_STMT,
143 ast.getText());
144 }
145 }
146 else if (getAbstractOption() == BlockOption.TEXT
147 && !hasText(leftCurly))
148 {
149 log(leftCurly.getLineNo(),
150 leftCurly.getColumnNo(),
151 MSG_KEY_BLOCK_EMPTY,
152 ast.getText());
153 }
154 }
155 }
156
157 /**
158 * @param slistAST a <code>DetailAST</code> value
159 * @return whether the SLIST token contains any text.
160 */
161 protected boolean hasText(final DetailAST slistAST)
162 {
163 boolean retVal = false;
164
165 final DetailAST rightCurly = slistAST.findFirstToken(TokenTypes.RCURLY);
166 final DetailAST rcurlyAST = rightCurly != null
167 ? rightCurly : slistAST.getParent().findFirstToken(TokenTypes.RCURLY);
168 if (rcurlyAST != null) {
169 final int slistLineNo = slistAST.getLineNo();
170 final int slistColNo = slistAST.getColumnNo();
171 final int rcurlyLineNo = rcurlyAST.getLineNo();
172 final int rcurlyColNo = rcurlyAST.getColumnNo();
173 final String[] lines = getLines();
174 if (slistLineNo == rcurlyLineNo) {
175 // Handle braces on the same line
176 final String txt = lines[slistLineNo - 1]
177 .substring(slistColNo + 1, rcurlyColNo);
178 if (txt.trim().length() != 0) {
179 retVal = true;
180 }
181 }
182 else {
183 // check only whitespace of first & last lines
184 if (lines[slistLineNo - 1]
185 .substring(slistColNo + 1).trim().length() != 0
186 || lines[rcurlyLineNo - 1]
187 .substring(0, rcurlyColNo).trim().length() != 0)
188 {
189 retVal = true;
190 }
191 else {
192 // check if all lines are also only whitespace
193 for (int i = slistLineNo; i < rcurlyLineNo - 1; i++) {
194 if (lines[i].trim().length() > 0) {
195 retVal = true;
196 break;
197 }
198 }
199 }
200 }
201 }
202 return retVal;
203 }
204 }