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1   package net.sourceforge.pmd.rules.design;
2   
3   import net.sourceforge.pmd.AbstractRule;
4   import net.sourceforge.pmd.ast.ASTEqualityExpression;
5   import net.sourceforge.pmd.ast.ASTInitializer;
6   import net.sourceforge.pmd.ast.ASTName;
7   import net.sourceforge.pmd.ast.Node;
8   import net.sourceforge.pmd.ast.SimpleNode;
9   import net.sourceforge.pmd.symboltable.VariableNameDeclaration;
10  
11  public class CompareObjectsWithEquals extends AbstractRule {
12  
13      private boolean hasName(Node n) {
14          return n.jjtGetNumChildren() > 0 && n.jjtGetChild(0) instanceof ASTName;
15      }
16  
17      public Object visit(ASTEqualityExpression node, Object data) {
18          // skip if either child is not a simple name
19          if (!hasName(((SimpleNode) node.jjtGetChild(0)).jjtGetChild(0)) || !hasName(((SimpleNode) node.jjtGetChild(1)).jjtGetChild(0))) {
20              return data;
21          }
22  
23          // skip if either is a qualified name
24          if (((SimpleNode) node.jjtGetChild(0).jjtGetChild(0).jjtGetChild(0)).getImage().indexOf(".") != -1
25                  || ((SimpleNode) node.jjtGetChild(1).jjtGetChild(0).jjtGetChild(0)).getImage().indexOf(".") != -1) {
26              return data;
27          }
28  
29          // skip static initializers... missing some cases here
30          if (!node.getParentsOfType(ASTInitializer.class).isEmpty()) {
31              return data;
32          }
33  
34          ASTName n0 = (ASTName) node.jjtGetChild(0).jjtGetChild(0).jjtGetChild(0);
35          ASTName n1 = (ASTName) node.jjtGetChild(1).jjtGetChild(0).jjtGetChild(0);
36  
37          if (n0.getNameDeclaration() instanceof VariableNameDeclaration && n1.getNameDeclaration() instanceof VariableNameDeclaration) {
38              VariableNameDeclaration nd0 = (VariableNameDeclaration) n0.getNameDeclaration();
39              VariableNameDeclaration nd1 = (VariableNameDeclaration) n1.getNameDeclaration();
40  
41              // skip array dereferences... this misses some cases
42              // FIXME catch comparisons btwn array elements of reference types
43              if (nd0.isArray() || nd1.isArray()) {
44                  return data;
45              }
46  
47              if (nd0.isReferenceType() && nd1.isReferenceType()) {
48                  addViolation(data, node);
49              }
50          }
51  
52          return data;
53      }
54  }