net.sf.saxon.expr.sort
Interface GroupIterator
- All Superinterfaces:
- SequenceIterator
- All Known Implementing Classes:
- GroupAdjacentIterator, GroupByIterator, GroupEndingIterator, GroupMatchingIterator, GroupStartingIterator, MergeGroupingIterator, SortedGroupIterator
public interface GroupIterator
- extends SequenceIterator
A GroupIterator is an iterator that iterates over a sequence of groups.
The normal methods such as next() and current() always deliver the leading item
of the group. Additional methods are available to get the grouping key for the
current group (only applicable to group-by and group-adjacent), and to get all the
members of the current group.
getCurrentGroupingKey
Value getCurrentGroupingKey()
- Get the grouping key of the current group
- Returns:
- the current grouping key in the case of group-by or group-adjacent,
or null in the case of group-starting-with and group-ending-with
iterateCurrentGroup
SequenceIterator<? extends Item> iterateCurrentGroup()
throws XPathException
- Get an iterator over the members of the current group, in population
order. This must always be a clean iterator, that is, an iterator that
starts at the first item of the group.
- Returns:
- an iterator over all the members of the current group, in population
order.
- Throws:
XPathException
- if a dynamic error occurs
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