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1
5 package com.tc.object.walker;
6
7 import java.util.Collection  ;
8 import java.util.IdentityHashMap ;
9 import java.util.LinkedList ;
10 import java.util.Map ;
11
12 public class ObjectGraphWalker {
13
14 private final VisitedSet visited;
15 private final LinkedList backtrack = new LinkedList ();
16 private final Visitor visitor;
17 private final MemberValue root;
18 private int currentDepth = 0;
19 private final WalkTest walkTest;
20
21 public ObjectGraphWalker(Object root, WalkTest walkTest, Visitor visitor) {
22 if (root == null) { throw new IllegalArgumentException ("refusing to traverse null"); }
23 if (walkTest == null) { throw new NullPointerException ("null walk test"); }
24 if (visitor == null) { throw new NullPointerException ("null visitor"); }
25 this.root = MemberValue.rootValue(root);
26 this.visitor = visitor;
27 this.visited = new VisitedSet(this.root);
28 this.walkTest = walkTest;
29 }
30
31 public void walk() {
32 visitor.visitRootObject(root);
33 currentDepth++;
34
35 if (!walkTest.shouldTraverse(root)) { return; }
36
37 backtrack.addFirst(makeNode(root.getValueObject()));
38
39 while (backtrack.size() > 0) {
40 Node current = (Node) backtrack.getFirst();
41 visit(current);
42 }
43 }
44
45 private Node makeNode(Object o) {
46 if (o == null) { throw new NullPointerException (); }
47
48 if (o.getClass().isArray()) {
49 return new ArrayNode(o);
50 } else if (o instanceof Collection ) {
51 return new CollectionNode((Collection ) o);
52 } else if (o instanceof Map ) {
53 return new MapNode((Map ) o);
54 } else if (o instanceof MapEntry) {
55 return new MapEntryNode((MapEntry) o);
56 } else {
57 return new PlainNode(o);
58 }
59 }
60
61 private void visit(Node node) {
62 while (!node.done()) {
63 MemberValue value = node.next();
64
65 if (value instanceof MapEntry) {
66 MapEntry entry = (MapEntry) value;
67 visitor.visitMapEntry(entry.getIndex(), currentDepth);
68 currentDepth++;
69 backtrack.addFirst(makeNode(entry));
70 return;
71 }
72
73 Object o = value.getValueObject();
74
75 boolean shouldTraverse = walkTest.shouldTraverse(value);
76
77 if (shouldTraverse) {
78 visited.visit(value);
79 }
80
81 visitor.visitValue(value, currentDepth);
82
83 if (o != null && shouldTraverse && !value.isRepeated()) {
84 Node next = makeNode(o);
85 currentDepth++;
86 backtrack.addFirst(next);
87 return;
88 }
89 }
90
91 currentDepth--;
92 backtrack.removeFirst();
93 }
94
95 private static class VisitedSet {
96 private final IdentityHashMap visited = new IdentityHashMap ();
97
98 VisitedSet(MemberValue root) {
99 visit(root);
100 }
101
102 void visit(MemberValue value) {
103 Object o = value.getValueObject();
104
105 Integer id = (Integer ) visited.get(o);
106 if (id == null) {
107 id = new Integer (visited.size());
108 visited.put(o, id);
109 } else {
110 value.setRepeated(true);
111 }
112
113 value.setId(id.intValue());
114 }
115 }
116
117 }
118 |
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