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1   /*
2    * Created on 14.07.2004
3    */
4   package net.sourceforge.pmd.lang.java.dfa;
5   
6   import java.util.ArrayList;
7   import java.util.HashSet;
8   import java.util.List;
9   import java.util.Map;
10  import java.util.Set;
11  
12  import net.sourceforge.pmd.lang.ast.Node;
13  import net.sourceforge.pmd.lang.dfa.DataFlowNode;
14  import net.sourceforge.pmd.lang.dfa.StartOrEndDataFlowNode;
15  import net.sourceforge.pmd.lang.dfa.VariableAccess;
16  import net.sourceforge.pmd.lang.java.ast.ASTClassOrInterfaceBodyDeclaration;
17  import net.sourceforge.pmd.lang.java.ast.ASTConstructorDeclaration;
18  import net.sourceforge.pmd.lang.java.ast.ASTFormalParameter;
19  import net.sourceforge.pmd.lang.java.ast.ASTMethodDeclaration;
20  import net.sourceforge.pmd.lang.java.ast.ASTVariableInitializer;
21  import net.sourceforge.pmd.lang.java.ast.JavaNode;
22  import net.sourceforge.pmd.lang.java.ast.JavaParserVisitorAdapter;
23  import net.sourceforge.pmd.lang.java.symboltable.NameOccurrence;
24  import net.sourceforge.pmd.lang.java.symboltable.VariableNameDeclaration;
25  
26  /**
27   * @author raik, Sven Jacob
28   *         <p/>
29   *         Searches for special nodes and computes based on the sequence, the type of
30   *         access of a variable.
31   */
32  public class VariableAccessVisitor extends JavaParserVisitorAdapter {
33  
34      public void compute(ASTMethodDeclaration node) {
35  	if (node.jjtGetParent() instanceof ASTClassOrInterfaceBodyDeclaration) {
36  	    this.computeNow(node);
37  	}
38      }
39  
40      public void compute(ASTConstructorDeclaration node) {
41  	this.computeNow(node);
42      }
43  
44      private void computeNow(Node node) {
45  	DataFlowNode inode = node.getDataFlowNode();
46  
47  	List<VariableAccess> undefinitions = markUsages(inode);
48  
49  	// all variables are first in state undefinition
50  	DataFlowNode firstINode = inode.getFlow().get(0);
51  	firstINode.setVariableAccess(undefinitions);
52  
53  	// all variables are getting undefined when leaving scope
54  	DataFlowNode lastINode = inode.getFlow().get(inode.getFlow().size() - 1);
55  	lastINode.setVariableAccess(undefinitions);
56      }
57  
58      private List<VariableAccess> markUsages(DataFlowNode inode) {
59  	// undefinitions was once a field... seems like it works fine as a local
60  	List<VariableAccess> undefinitions = new ArrayList<VariableAccess>();
61  	Set<Map<VariableNameDeclaration, List<NameOccurrence>>> variableDeclarations = collectDeclarations(inode);
62  	for (Map<VariableNameDeclaration, List<NameOccurrence>> declarations : variableDeclarations) {
63  	    for (Map.Entry<VariableNameDeclaration, List<NameOccurrence>> entry : declarations.entrySet()) {
64  		VariableNameDeclaration vnd = entry.getKey();
65  
66  		if (vnd.getAccessNodeParent() instanceof ASTFormalParameter) {
67  		    // no definition/undefinition/references for parameters
68  		    continue;
69  		} else if (((Node) vnd.getAccessNodeParent()).getFirstDescendantOfType(ASTVariableInitializer.class) != null) {
70  		    // add definition for initialized variables
71  		    addVariableAccess(vnd.getNode(), new VariableAccess(VariableAccess.DEFINITION, vnd.getImage()),
72  			    inode.getFlow());
73  		}
74  		undefinitions.add(new VariableAccess(VariableAccess.UNDEFINITION, vnd.getImage()));
75  
76  		for (NameOccurrence occurrence : entry.getValue()) {
77  		    addAccess(occurrence, inode);
78  		}
79  	    }
80  	}
81  	return undefinitions;
82      }
83  
84      private Set<Map<VariableNameDeclaration, List<NameOccurrence>>> collectDeclarations(DataFlowNode inode) {
85  	Set<Map<VariableNameDeclaration, List<NameOccurrence>>> decls = new HashSet<Map<VariableNameDeclaration, List<NameOccurrence>>>();
86  	Map<VariableNameDeclaration, List<NameOccurrence>> varDecls;
87  	for (int i = 0; i < inode.getFlow().size(); i++) {
88  	    DataFlowNode n = inode.getFlow().get(i);
89  	    if (n instanceof StartOrEndDataFlowNode) {
90  		continue;
91  	    }
92  	    varDecls = ((JavaNode)n.getNode()).getScope().getVariableDeclarations();
93  	    if (!decls.contains(varDecls)) {
94  		decls.add(varDecls);
95  	    }
96  	}
97  	return decls;
98      }
99  
100     private void addAccess(NameOccurrence occurrence, DataFlowNode inode) {
101 	if (occurrence.isOnLeftHandSide()) {
102 	    this.addVariableAccess(occurrence.getLocation(), new VariableAccess(VariableAccess.DEFINITION, occurrence
103 		    .getImage()), inode.getFlow());
104 	} else if (occurrence.isOnRightHandSide() || !occurrence.isOnLeftHandSide() && !occurrence.isOnRightHandSide()) {
105 	    this.addVariableAccess(occurrence.getLocation(), new VariableAccess(VariableAccess.REFERENCING, occurrence
106 		    .getImage()), inode.getFlow());
107 	}
108     }
109 
110     /**
111      * Adds a VariableAccess to a dataflow node.
112      * @param node location of the access of a variable
113      * @param va variable access to add
114      * @param flow dataflownodes that can contain the node.
115      */
116     private void addVariableAccess(Node node, VariableAccess va, List<DataFlowNode> flow) {
117 	// backwards to find the right inode (not a method declaration)
118 	for (int i = flow.size() - 1; i > 0; i--) {
119 	    DataFlowNode inode = flow.get(i);
120 	    if (inode.getNode() == null) {
121 		continue;
122 	    }
123 
124 	    List<? extends Node> children = inode.getNode().findDescendantsOfType(node.getClass());
125 	    for (Node n : children) {
126 		if (node.equals(n)) {
127 		    List<VariableAccess> v = new ArrayList<VariableAccess>();
128 		    v.add(va);
129 		    inode.setVariableAccess(v);
130 		    return;
131 		}
132 	    }
133 	}
134     }
135 
136 }