ComCollection


1   package com4j;
2   
3   import java.util.Iterator  ;
4   import java.util.NoSuchElementException  ;
5   
6   /**
7    * Wraps IEnumVARIANT and implements {@link Iterator}.
8    *
9    * @author Kohsuke Kawaguchi
10   */
11  final class ComCollection<T> implements Iterator  <T> {
12  
13      private final IEnumVARIANT e;
14  
15      private Variant next;
16  
17  
18      /**
19       * The expected item type.
20       */
21      private final Class  <T> type;
22  
23      ComCollection(Class  <T> type, IEnumVARIANT e) {
24          this.e = e;
25          this.type = type;
26          fetch();
27      }
28  
29      public boolean hasNext() {
30          return next!=null;
31      }
32  
33      public T next() {
34          if(next==null)
35              throw new NoSuchElementException  ();
36          Variant v = next;
37          next = null;
38          fetch();
39  
40          Object   r;
41          try {
42  // ideally we'd like to use ChangeVariantType to do the conversion
43              // but for now let's just support interface types
44              if(Com4jObject.class.isAssignableFrom(type)) {
45                  r = v.object((Class  <? extends Com4jObject>)type);
46              } else
47                  throw new UnsupportedOperationException  ("I don't know how to handle "+type);
48          } finally {
49              v.clear();
50          }
51          return (T)r;
52      }
53  
54      public void remove() {
55          throw new UnsupportedOperationException  ();
56      }
57  
58      private void fetch() {
59          next = new Variant();
60          int r = e.next(1,next);
61          if(r==0) {
62              next = null;
63              e.dispose();
64          }
65      }
66  }
67
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