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Java > Open Source Codes > net > sourceforge > pmd > rules > SimplifyBooleanReturns


1 /**
2  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
3  */
4 package net.sourceforge.pmd.rules;
5
6 import net.sourceforge.pmd.AbstractRule;
7 import net.sourceforge.pmd.ast.ASTBlock;
8 import net.sourceforge.pmd.ast.ASTBlockStatement;
9 import net.sourceforge.pmd.ast.ASTBooleanLiteral;
10 import net.sourceforge.pmd.ast.ASTIfStatement;
11 import net.sourceforge.pmd.ast.ASTReturnStatement;
12 import net.sourceforge.pmd.ast.ASTStatement;
13 import net.sourceforge.pmd.ast.SimpleNode;
14
15 public class SimplifyBooleanReturns extends AbstractRule {
16
17     public Object JavaDoc visit(ASTIfStatement node, Object JavaDoc data) {
18         // only deal with if..then..else stmts
19 if (node.jjtGetNumChildren() != 3) {
20             return super.visit(node, data);
21         }
22
23         // don't bother if either the if or the else block is empty
24 if (node.jjtGetChild(1).jjtGetNumChildren() == 0 || node.jjtGetChild(2).jjtGetNumChildren() == 0) {
25             return super.visit(node, data);
26         }
27
28         // first case:
29 // If
30 // Expr
31 // Statement
32 // ReturnStatement
33 // Statement
34 // ReturnStatement
35 // i.e.,
36 // if (foo)
37 // return true;
38 // else
39 // return false;
40
41         // second case
42 // If
43 // Expr
44 // Statement
45 // Block
46 // BlockStatement
47 // Statement
48 // ReturnStatement
49 // Statement
50 // Block
51 // BlockStatement
52 // Statement
53 // ReturnStatement
54 // i.e.,
55 // if (foo) {
56 // return true;
57 // } else {
58 // return false;
59 // }
60 if (node.jjtGetChild(1).jjtGetChild(0) instanceof ASTReturnStatement && node.jjtGetChild(2).jjtGetChild(0) instanceof ASTReturnStatement && terminatesInBooleanLiteral((SimpleNode) node.jjtGetChild(1).jjtGetChild(0)) && terminatesInBooleanLiteral((SimpleNode) node.jjtGetChild(2).jjtGetChild(0))) {
61             addViolation(data, node);
62         } else if (hasOneBlockStmt((SimpleNode) node.jjtGetChild(1)) && hasOneBlockStmt((SimpleNode) node.jjtGetChild(2)) && terminatesInBooleanLiteral((SimpleNode) node.jjtGetChild(1).jjtGetChild(0)) && terminatesInBooleanLiteral((SimpleNode) node.jjtGetChild(2).jjtGetChild(0))) {
63             addViolation(data, node);
64         }
65
66         return super.visit(node, data);
67     }
68
69     private boolean hasOneBlockStmt(SimpleNode node) {
70         return node.jjtGetChild(0) instanceof ASTBlock && node.jjtGetChild(0).jjtGetNumChildren() == 1 && node.jjtGetChild(0).jjtGetChild(0) instanceof ASTBlockStatement && node.jjtGetChild(0).jjtGetChild(0).jjtGetChild(0) instanceof ASTStatement && node.jjtGetChild(0).jjtGetChild(0).jjtGetChild(0).jjtGetChild(0) instanceof ASTReturnStatement;
71     }
72
73     private boolean terminatesInBooleanLiteral(SimpleNode node) {
74         return eachNodeHasOneChild(node) && (getLastChild(node) instanceof ASTBooleanLiteral);
75     }
76
77     private boolean eachNodeHasOneChild(SimpleNode node) {
78         if (node.jjtGetNumChildren() > 1) {
79             return false;
80         }
81         if (node.jjtGetNumChildren() == 0) {
82             return true;
83         }
84         return eachNodeHasOneChild((SimpleNode) node.jjtGetChild(0));
85     }
86
87     private SimpleNode getLastChild(SimpleNode node) {
88         if (node.jjtGetNumChildren() == 0) {
89             return node;
90         }
91         return getLastChild((SimpleNode) node.jjtGetChild(0));
92     }
93 }
94
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