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1   package net.sourceforge.pmd.rules.design;
2   
3   import net.sourceforge.pmd.AbstractRule;
4   import net.sourceforge.pmd.ast.ASTExpression;
5   import net.sourceforge.pmd.ast.ASTMethodDeclaration;
6   import net.sourceforge.pmd.ast.ASTName;
7   import net.sourceforge.pmd.ast.ASTPrimaryExpression;
8   import net.sourceforge.pmd.ast.ASTReturnStatement;
9   import net.sourceforge.pmd.symboltable.NameOccurrence;
10  import net.sourceforge.pmd.symboltable.VariableNameDeclaration;
11  
12  import java.util.Iterator;
13  import java.util.List;
14  import java.util.Map;
15  
16  public class UnnecessaryLocalBeforeReturn extends AbstractRule {
17  
18      public Object visit(ASTMethodDeclaration meth, Object data) {
19          // skip void/abstract/native method
20          if (meth.isVoid() || meth.isAbstract() || meth.isNative()) {
21              return data;
22          }
23          return super.visit(meth, data);
24      }
25  
26      public Object visit(ASTReturnStatement rtn, Object data) {
27          // skip returns of literals
28          ASTName name = (ASTName) rtn.getFirstChildOfType(ASTName.class);
29          if (name == null) {
30              return data;
31          }
32  
33          // skip 'complicated' expressions
34          if (rtn.findChildrenOfType(ASTExpression.class).size() > 1 || rtn.findChildrenOfType(ASTPrimaryExpression.class).size() > 1) {
35              return data;
36          }
37  
38          Map vars = name.getScope().getVariableDeclarations();
39          for (Iterator i = vars.keySet().iterator(); i.hasNext();) {
40              VariableNameDeclaration key = (VariableNameDeclaration) i.next();
41              List usages = (List) vars.get(key);
42              for (Iterator j = usages.iterator(); j.hasNext();) {
43                  NameOccurrence occ = (NameOccurrence) j.next();
44                  if (occ.getLocation().equals(name)) {
45                      // only check declarations that occur one line earlier
46                      if (key.getNode().getBeginLine() == name.getBeginLine() - 1) {
47                          String var = name.getImage();
48                          if (var.indexOf('.') != -1) {
49                              var = var.substring(0, var.indexOf('.'));
50                          }
51                          addViolation(data, rtn, var);
52                      }
53                  }
54              }
55          }
56          return data;
57      }
58  }