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Java > Open Source Codes > com > puppycrawl > tools > checkstyle > checks > blocks > AvoidNestedBlocksCheck


1 ////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code for adherence to a set of rules.
3 // Copyright (C) 2001-2005 Oliver Burn
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.Check;
22 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
23 import com.puppycrawl.tools.checkstyle.api.DetailAST;
24
25 /**
26  * Finds nested blocks.
27  *
28  * <p>
29  * For example this Check flags confusing code like
30  * </p>
31  * <pre>
32  * public void guessTheOutput()
33  * {
34  * int whichIsWich = 0;
35  * {
36  * int whichIsWhich = 2;
37  * }
38  * System.out.println("value = " + whichIsWhich);
39  * }
40  * </pre>
41  *
42  * and debugging / refactoring leftovers such as
43  *
44  * <pre>
45  * // if (someOldCondition)
46  * {
47  * System.out.println("unconditional");
48  * }
49  * </pre>
50  *
51  * <p>
52  * A case in a switch statement does not implicitly form a block.
53  * Thus to be able to introduce local variables that have case scope
54  * it is necessary to open a nested block. This is supported, set
55  * the allowInSwitchCase property to true and include all statements
56  * of the case in the block.
57  * </p>
58  *
59  * <pre>
60  * switch (a)
61  * {
62  * case 0:
63  * // Never OK, break outside block
64  * {
65  * x = 1;
66  * }
67  * break;
68  * case 1:
69  * // Never OK, statement outside block
70  * System.out.println("Hello");
71  * {
72  * x = 2;
73  * break;
74  * }
75  * case 1:
76  * // OK if allowInSwitchCase is true
77  * {
78  * System.out.println("Hello");
79  * x = 2;
80  * break;
81  * }
82  * }
83  * </pre>
84  *
85  * @author lkuehne
86  */
87 public class AvoidNestedBlocksCheck extends Check
88 {
89     /**
90      * Whether nested blocks are allowed if they are the
91      * only child of a switch case.
92      */
93     private boolean mAllowInSwitchCase;
94
95     /** {@inheritDoc} */
96     public int[] getDefaultTokens()
97     {
98         return new int[] {TokenTypes.SLIST};
99     }
100
101     /** {@inheritDoc} */
102     public void visitToken(DetailAST aAST)
103     {
104         final DetailAST parent = aAST.getParent();
105         if (parent.getType() == TokenTypes.SLIST) {
106             if (mAllowInSwitchCase
107                     && (parent.getParent().getType() == TokenTypes.CASE_GROUP)
108                     && (parent.getNumberOfChildren() == 1))
109             {
110                 return;
111             }
112             log(aAST.getLineNo(), aAST.getColumnNo(), "block.nested");
113         }
114     }
115
116     /**
117      * Setter for allowInSwitchCase property.
118      * @param aAllowInSwitchCase whether nested blocks are allowed
119      * if they are the only child of a switch case.
120      */
121     public void setAllowInSwitchCase(boolean aAllowInSwitchCase)
122     {
123         mAllowInSwitchCase = aAllowInSwitchCase;
124     }
125 }
126
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