net.sf.saxon.sort
Class GroupBySingletonIterator

java.lang.Object
  net.sf.saxon.sort.GroupByIterator
      net.sf.saxon.sort.GroupBySingletonIterator

All Implemented Interfaces:

LastPositionFinder, LookaheadIterator, SequenceIterator, GroupIterator

public class GroupBySingletonIterator
extends GroupByIterator

A variant of the GroupByIterator used for XQuery 1.1 grouping, where the grouping key is either a single atomic value or an empty sequence, and an empty sequence compares equal to an empty sequence.

Field Summary

Fields inherited from class net.sf.saxon.sort.GroupByIterator

comparer, groupKeys, groups, keyExpression

Fields inherited from interface net.sf.saxon.om.SequenceIterator

GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD

Constructor Summary

GroupBySingletonIterator(SequenceIterator population, Expression keyExpression, XPathContext keyContext, StringCollator collator)
Create a GroupByIterator

Method Summary

protected void

processItem(HashMap<ComparisonKey,List<Item>> index, Item item, XPathContext c2) Process one item in the population

Methods inherited from class net.sf.saxon.sort.GroupByIterator

close, current, getAnother, getCurrentGroup, getCurrentGroupingKey, getLastPosition, getProperties, hasNext, iterateCurrentGroup, next, position

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GroupBySingletonIterator

public GroupBySingletonIterator(SequenceIterator population,
                                Expression keyExpression,
                                XPathContext keyContext,
                                StringCollator collator)
                         throws XPathException

Create a GroupByIterator

Parameters:

population - iterator over the population to be grouped

keyExpression - the expression used to calculate the grouping key

keyContext - dynamic context for calculating the grouping key

collator - Collation to be used for comparing grouping keys

Throws:

XPathException

Method Detail

processItem

protected void processItem(HashMap<ComparisonKey,List<Item>> index,
                           Item item,
                           XPathContext c2)
                    throws XPathException

Process one item in the population

Overrides:

processItem in class GroupByIterator

Parameters:

index - the index of items

item - the item from the population to be processed

c2 - the XPath evaluation context

Throws:

XPathException