net.sf.saxon.expr.sort

Class SortedGroupIterator

java.lang.Object

net.sf.saxon.expr.sort.SortedIterator

net.sf.saxon.expr.sort.SortedGroupIterator

All Implemented Interfaces:

LastPositionFinder, GroupIterator, Sortable, SequenceIterator, LookaheadIterator

public class SortedGroupIterator
extends SortedIterator
implements GroupIterator

A SortedGroupIterator is a modified SortedIterator. It sorts a sequence of groups, and is itself a GroupIterator. The modifications retain extra information about the items being sorted. The items are each the leading item of a group, and as well as the item itself, the iterator preserves information about the group: specifically, an iterator over the items in the group, and the value of the grouping key (if any).

Field Summary

Fields inherited from class net.sf.saxon.expr.sort.SortedIterator

base, comparators, context, count, position, sortKeyEvaluator, values

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

GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD

Constructor Summary

Constructors

Constructor and Description
SortedGroupIterator(XPathContext context, GroupIterator base, SortKeyEvaluator sortKeyEvaluator, AtomicComparer[] comparators)

Method Summary

Methods

Modifier and Type	Method and Description
protected void	buildArray() Override the method that builds the array of values and sort keys.
AtomicSequence	getCurrentGroupingKey() Get the grouping key of the current group
ManualGroupIterator	getSnapShot(XPathContext context) Get a sequence which is a snapshot of this sequence at the current position
boolean	hasCurrentGroup() Ask whether this iterator has a current group
boolean	hasCurrentGroupingKey() Ask whether this iterator has a current grouping key
SequenceIterator	iterateCurrentGroup() Get an iterator over the members of the current group, in population order.
Item	next() Get the next item, in sorted order
void	setGroupSlot(int groupSlot) Set a local variable slot to hold the value of the current group
void	setKeySlot(int keySlot) Set a local variable slot to hold the value of the current grouping key

Methods inherited from class net.sf.saxon.expr.sort.SortedIterator

close, compare, current, getAnother, getLength, getProperties, hasNext, position, setHostLanguage, swap

Methods inherited from class java.lang.Object

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

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

close, current, getAnother, getProperties, position

Constructor Detail

SortedGroupIterator

public SortedGroupIterator(XPathContext context,
                   GroupIterator base,
                   SortKeyEvaluator sortKeyEvaluator,
                   AtomicComparer[] comparators)

Method Detail

setGroupSlot

public void setGroupSlot(int groupSlot)

Description copied from interface: GroupIterator

Set a local variable slot to hold the value of the current group

Specified by:

setGroupSlot in interface GroupIterator

Parameters:

groupSlot - the stack frame position of the variable holding the current group

setKeySlot

public void setKeySlot(int keySlot)

Description copied from interface: GroupIterator

Set a local variable slot to hold the value of the current grouping key

Specified by:

setKeySlot in interface GroupIterator

Parameters:

keySlot - the stack frame position of the variable holding the current grouping key

buildArray

protected void buildArray()
                   throws XPathException

Override the method that builds the array of values and sort keys.

Overrides:

buildArray in class SortedIterator

Throws:

XPathException

next

public Item next()
          throws XPathException

Description copied from class: SortedIterator

Get the next item, in sorted order

Specified by:

next in interface SequenceIterator

Overrides:

next in class SortedIterator

Returns:

the next item, or null if there are no more items. Once a call on next() has returned null, no further calls should be made. The preferred action for an iterator if subsequent calls on next() are made is to return null again, and all implementations within Saxon follow this rule.

Throws:

XPathException - if an error occurs retrieving the next item

getCurrentGroupingKey

public AtomicSequence getCurrentGroupingKey()

Description copied from interface: GroupIterator

Get the grouping key of the current group

Specified by:

getCurrentGroupingKey in interface GroupIterator

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

public SequenceIterator iterateCurrentGroup()
                                     throws XPathException

Description copied from interface: GroupIterator

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.

Specified by:

iterateCurrentGroup in interface GroupIterator

Returns:

an iterator over all the members of the current group, in population order.

Throws:

XPathException - if a dynamic error occurs

hasCurrentGroup

public boolean hasCurrentGroup()

Description copied from interface: GroupIterator

Ask whether this iterator has a current group

Specified by:

hasCurrentGroup in interface GroupIterator

Returns:

false if the controlling xsl:for-each-group element binds a group variable, true if it delivers results using the current-group() function

hasCurrentGroupingKey

public boolean hasCurrentGroupingKey()

Description copied from interface: GroupIterator

Ask whether this iterator has a current grouping key

Specified by:

hasCurrentGroupingKey in interface GroupIterator

Returns:

false if the controlling xsl:for-each-group element binds a grouping-key variable, true if it delivers results using the current-grouping-key() function

getSnapShot

public ManualGroupIterator getSnapShot(XPathContext context)
                                throws XPathException

Description copied from interface: GroupIterator

Get a sequence which is a snapshot of this sequence at the current position

Specified by:

getSnapShot in interface GroupIterator

Throws:

XPathException