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1 package com.thoughtworks.xstream.core;
2
3 import com.thoughtworks.xstream.alias.ClassMapper;
4 import com.thoughtworks.xstream.converters.Converter;
5 import com.thoughtworks.xstream.converters.ConverterLookup;
6 import com.thoughtworks.xstream.converters.basic.AbstractBasicConverter;
7 import com.thoughtworks.xstream.core.util.ObjectIdDictionary;
8 import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
9
10 public class ReferenceByIdMarshaller extends TreeMarshaller {
11
12 private ObjectIdDictionary references = new ObjectIdDictionary();
13 private IDGenerator idGenerator;
14
15 public static interface IDGenerator {
16 String  next();
17 }
18
19 public ReferenceByIdMarshaller(HierarchicalStreamWriter writer,
20 ConverterLookup converterLookup,
21 ClassMapper classMapper,
22 IDGenerator idGenerator) {
23 super(writer, converterLookup, classMapper);
24 this.idGenerator = idGenerator;
25 }
26
27 public ReferenceByIdMarshaller(HierarchicalStreamWriter writer,
28 ConverterLookup converterLookup,
29 ClassMapper classMapper) {
30 this(writer, converterLookup, classMapper, new SequenceGenerator(1));
31 }
32
33 public void convertAnother(Object item) {
34 Converter converter = converterLookup.lookupConverterForType(item.getClass());
35
36 if (isImmutableBasicType(converter)) {
37 converter.marshal(item, writer, this);
39 } else {
40 String idOfExistingReference = references.lookupId(item);
41 if (idOfExistingReference != null) {
42 writer.addAttribute("reference", idOfExistingReference);
43 } else {
44 String newId = idGenerator.next();
45 writer.addAttribute("id", newId);
46 references.associateId(item, newId);
47 converter.marshal(item, writer, this);
48 }
49 }
50 }
51
52 private boolean isImmutableBasicType(Converter converter) {
53 return converter instanceof AbstractBasicConverter;
54 }
55
56 }
57 |
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