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1 package org.hibernate.transform;
3
4 import java.util.ArrayList  ;
5 import java.util.HashSet ;
6 import java.util.List ;
7 import java.util.Set ;
8
9 import org.apache.commons.logging.Log;
10 import org.apache.commons.logging.LogFactory;
11
12
15 public class DistinctRootEntityResultTransformer implements ResultTransformer {
16
17 private static final Log log = LogFactory.getLog(DistinctRootEntityResultTransformer.class);
18
19 static final class Identity {
20 final Object entity;
21 Identity(Object entity) {
22 this.entity = entity;
23 }
24 public boolean equals(Object other) {
25 Identity that = (Identity) other;
26 return entity==that.entity;
27 }
28 public int hashCode() {
29 return System.identityHashCode(entity);
30 }
31 }
32
33 public Object transformTuple(Object [] tuple, String [] aliases) {
34 return tuple[ tuple.length-1 ];
35 }
36
37 public List transformList(List list) {
38 List result = new ArrayList ( list.size() );
39 Set distinct = new HashSet ();
40 for ( int i=0; i<list.size(); i++ ) {
41 Object entity = list.get(i);
42 if ( distinct.add( new Identity(entity) ) ) {
43 result.add(entity);
44 }
45 }
46 if ( log.isDebugEnabled() ) log.debug(
47 "transformed: " +
48 list.size() + " rows to: " +
49 result.size() + " distinct results"
50 );
51 return result;
52 }
53
54 }
55 |
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