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Java > Open Source Codes > net > sf > saxon > sort > GroupIterator


1 package net.sf.saxon.sort;
2
3 import net.sf.saxon.om.SequenceIterator;
4 import net.sf.saxon.trans.XPathException;
5 import net.sf.saxon.value.AtomicValue;
6
7 /**
8  * A GroupIterator is an iterator that iterates over a sequence of groups.
9  * The normal methods such as next() and current() always deliver the leading item
10  * of the group. Additional methods are available to get the grouping key for the
11  * current group (only applicable to group-by and group-adjacent), and to get all the
12  * members of the current group.
13  */
14
15 public interface GroupIterator extends SequenceIterator {
16
17     /**
18      * Get the grouping key of the current group
19      * @return the current grouping key in the case of group-by or group-adjacent,
20      * or null in the case of group-starting-with and group-ending-with
21      */
22
23     public AtomicValue getCurrentGroupingKey();
24
25     /**
26      * Get an iterator over the members of the current group, in population
27      * order. This must always be a clean iterator, that is, an iterator that
28      * starts at the first item of the group.
29      * @return an iterator over all the members of the current group, in population
30      * order.
31      */
32
33     public SequenceIterator iterateCurrentGroup() throws XPathException;
34
35 }
36
37
38 //
39 // The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
40 // you may not use this file except in compliance with the License. You may obtain a copy of the
41 // License at http://www.mozilla.org/MPL/
42 //
43 // Software distributed under the License is distributed on an "AS IS" basis,
44 // WITHOUT WARRANTY OF ANY KIND, either express or implied.
45 // See the License for the specific language governing rights and limitations under the License.
46 //
47 // The Original Code is: all this file.
48 //
49 // The Initial Developer of the Original Code is Michael H. Kay
50 //
51 // Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
52 //
53 // Contributor(s): none
54 //
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