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1   /***
2    * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
3   */
4   package net.sourceforge.pmd.rules.design;
5   
6   import net.sourceforge.pmd.AbstractRule;
7   import net.sourceforge.pmd.RuleContext;
8   import net.sourceforge.pmd.ast.ASTClassDeclaration;
9   import net.sourceforge.pmd.ast.ASTCompilationUnit;
10  import net.sourceforge.pmd.ast.ASTConstructorDeclaration;
11  import net.sourceforge.pmd.ast.ASTFieldDeclaration;
12  import net.sourceforge.pmd.ast.ASTMethodDeclaration;
13  import net.sourceforge.pmd.ast.ASTUnmodifiedClassDeclaration;
14  
15  public class UseSingletonRule extends AbstractRule {
16  
17      private boolean isOK;
18      private int methodCount;
19  
20      public Object visit(ASTCompilationUnit cu, Object data) {
21          methodCount = 0;
22          isOK = false;
23          Object result = cu.childrenAccept(this, data);
24          if (!isOK && methodCount > 0) {
25              RuleContext ctx = (RuleContext) data;
26              ctx.getReport().addRuleViolation(createRuleViolation(ctx, cu.getBeginLine()));
27          }
28  
29          return result;
30      }
31  
32      public Object visit(ASTFieldDeclaration decl, Object data) {
33          isOK = true;
34          return data;
35      }
36  
37      public Object visit(ASTConstructorDeclaration decl, Object data) {
38          if (decl.isPrivate()) {
39              isOK = true;
40          }
41          return data;
42      }
43  
44      public Object visit(ASTUnmodifiedClassDeclaration decl, Object data) {
45          if (decl.jjtGetParent() instanceof ASTClassDeclaration && ((ASTClassDeclaration)decl.jjtGetParent()).isAbstract()) {
46              isOK = true;
47          }
48          return super.visit(decl, data);
49      }
50  
51      public Object visit(ASTMethodDeclaration decl, Object data) {
52          methodCount++;
53  
54          if (!isOK && !decl.isStatic()) {
55              isOK = true;
56          }
57  
58          return data;
59      }
60  
61  }