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Java > Open Source Codes > gnu > kawa > xml > DescendantOrSelfAxis


1 // Copyright (c) 2003 Per M.A. Bothner.
2 // This is free software; for terms and warranty disclaimer see ./COPYING.
3
4 package gnu.kawa.xml;
5 import gnu.lists.*;
6
7 /** Used to implement a descendant-or-self:: step in a path expression. */
8
9 public class DescendantOrSelfAxis extends TreeScanner
10 {
11   public static final DescendantOrSelfAxis anyNode =
12     new DescendantOrSelfAxis(NodeType.anyNodeTest);
13
14   private DescendantOrSelfAxis (NodePredicate type)
15   {
16     this.type = type;
17   }
18
19   public static DescendantOrSelfAxis make (NodePredicate type)
20   {
21     if (type == NodeType.anyNodeTest)
22       return anyNode;
23     return new DescendantOrSelfAxis(type);
24   }
25
26   public void scan (AbstractSequence seq, int ipos, PositionConsumer out)
27   {
28     if (type.isInstancePos(seq, ipos))
29       out.writePosition(seq, ipos);
30     if (! (seq instanceof TreeList))
31       { // AbstractSequence's nextMatching does not support descend. FIXME.
32 ipos = seq.firstChildPos(ipos);
33     while (ipos != 0)
34       {
35         scan(seq, ipos, out);
36         ipos = seq.nextPos(ipos);
37       }
38     return;
39       }
40     int limit = seq.nextPos(ipos);
41     int child = ipos;
42     for (;;)
43       {
44     child = seq.nextMatching(child, type, limit, true);
45     if (child == 0)
46       break;
47     out.writePosition(seq, child);
48       }
49   }
50 }
51
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