net.sf.saxon.expr.sort

Class GroupMatchingIterator

java.lang.Object

net.sf.saxon.expr.sort.GroupMatchingIterator

All Implemented Interfaces:

GroupIterator, SequenceIterator, LookaheadIterator

Direct Known Subclasses:

GroupEndingIterator, GroupStartingIterator

public abstract class GroupMatchingIterator
extends Object
implements LookaheadIterator, GroupIterator

A GroupMatchingIterator contains code shared between GroupStartingIterator and GroupEndingIterator

Field Summary

Fields

Modifier and Type	Field and Description
protected XPathContext	baseContext
protected Item	current
protected List	currentMembers
protected Item	next
protected Pattern	pattern
protected FocusIterator	population
protected int	position
protected XPathContext	runningContext

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

ATOMIZING, GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD

Constructor Summary

Constructors

Constructor and Description
GroupMatchingIterator()

Method Summary

Methods

Modifier and Type	Method and Description
protected abstract void	advance()
void	close() Close the iterator.
AtomicSequence	getCurrentGroupingKey() Get the grouping key of the current group
int	getProperties() Get properties of this iterator, as a bit-significant integer.
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
boolean	hasNext() Determine whether there are more items to come.
SequenceIterator	iterateCurrentGroup() Get an iterator over the members of the current group, in population order.
Item	next() Get the next item in the sequence.

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

getAnother

Field Detail

population

protected FocusIterator population

pattern

protected Pattern pattern

baseContext

protected XPathContext baseContext

runningContext

protected XPathContext runningContext

currentMembers

protected List currentMembers

next

protected Item next

current

protected Item current

position

protected int position

Constructor Detail

GroupMatchingIterator

public GroupMatchingIterator()

Method Detail

advance

protected abstract void advance()
                         throws XPathException

Throws:

XPathException

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()

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.

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

hasNext

public boolean hasNext()

Description copied from interface: LookaheadIterator

Determine whether there are more items to come. Note that this operation is stateless and it is not necessary (or usual) to call it before calling next(). It is used only when there is an explicit need to tell if we are at the last element.

This method must not be called unless the result of getProperties() on the iterator includes the bit setting SequenceIterator.LOOKAHEAD

Specified by:

hasNext in interface LookaheadIterator

Returns:

true if there are more items in the sequence

next

public Item next()
          throws XPathException

Description copied from interface: SequenceIterator

Get the next item in the sequence. This method changes the state of the iterator, in particular it affects the result of subsequent calls of position() and current().

Specified by:

next in interface SequenceIterator

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

close

public void close()

Description copied from interface: SequenceIterator

Close the iterator. This indicates to the supplier of the data that the client does not require any more items to be delivered by the iterator. This may enable the supplier to release resources. After calling close(), no further calls on the iterator should be made; if further calls are made, the effect of such calls is undefined.

(Currently, closing an iterator is important only when the data is being "pushed" in another thread. Closing the iterator terminates that thread and means that it needs to do no additional work. Indeed, failing to close the iterator may cause the push thread to hang waiting for the buffer to be emptied.)

Specified by:

close in interface SequenceIterator

getProperties

public int getProperties()

Description copied from interface: SequenceIterator

Get properties of this iterator, as a bit-significant integer.

Specified by:

getProperties in interface SequenceIterator

Returns:

the properties of this iterator. This will be some combination of properties such as SequenceIterator.GROUNDED, SequenceIterator.LAST_POSITION_FINDER, and SequenceIterator.LOOKAHEAD. It is always acceptable to return the value zero, indicating that there are no known special properties. It is acceptable for the properties of the iterator to change depending on its state.

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