net.sf.saxon.sort
Class GroupAdjacentIterator

java.lang.Object
  |
  +--net.sf.saxon.sort.GroupAdjacentIterator
All Implemented Interfaces:
GroupIterator, LookaheadIterator, SequenceIterator

public class GroupAdjacentIterator
extends java.lang.Object
implements GroupIterator, LookaheadIterator

A GroupAdjacentIterator iterates over a sequence of groups defined by xsl:for-each-group group-adjacent="x". The groups are returned in order of first appearance.


Constructor Summary
GroupAdjacentIterator(SequenceIterator population, Expression keyExpression, XPathContext keyContext, java.text.Collator collator)
           
 
Method Summary
 Item current()
          Get the current value in the sequence (the one returned by the most recent call on next()).
 SequenceIterator getAnother()
          Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence.
 AtomicValue getCurrentGroupingKey()
          Get the grouping key of the current group
 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.
 int position()
          Get the current position.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

GroupAdjacentIterator

public GroupAdjacentIterator(SequenceIterator population,
                             Expression keyExpression,
                             XPathContext keyContext,
                             java.text.Collator collator)
                      throws XPathException
Method Detail

getCurrentGroupingKey

public AtomicValue 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.

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.

Specified by:
hasNext in interface LookaheadIterator
Returns:
true if there are more nodes

next

public Item next()
          throws XPathException
Description copied from interface: SequenceIterator
Get the next item in the sequence.

Specified by:
next in interface SequenceIterator
Returns:
the next item, or null if there are no more items.
Throws:
XPathException - if an error occurs retrieving the next item

current

public Item current()
Description copied from interface: SequenceIterator
Get the current value in the sequence (the one returned by the most recent call on next()). This will be null before the first call of next().

Specified by:
current in interface SequenceIterator
Returns:
the current item, the one most recently returned by a call on next(); or null, if next() has not been called, or if the end of the sequence has been reached.

position

public int position()
Description copied from interface: SequenceIterator
Get the current position. This will be zero before the first call on next(), otherwise it will be the number of times that next() has been called.

Specified by:
position in interface SequenceIterator
Returns:
the current position, the position of the item returned by the most recent call of next()

getAnother

public SequenceIterator getAnother()
                            throws XPathException
Description copied from interface: SequenceIterator
Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence.

Specified by:
getAnother in interface SequenceIterator
Returns:
a SequenceIterator that iterates over the same items, positioned before the first item
Throws:
XPathException - if any error occurs