public class GroupAdjacentIterator extends Object implements GroupIterator, LookaheadIterator
Each step of this iterator advances to the first item of the next group, leaving the members of that group in a saved list.
GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD
Constructor and Description |
---|
GroupAdjacentIterator(SequenceIterator population,
Expression keyExpression,
XPathContext baseContext,
StringCollator collator) |
Modifier and Type | Method and Description |
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void |
close()
Close the iterator.
|
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.
|
Value |
getCurrentGroupingKey()
Get the grouping key of the current group
|
int |
getProperties()
Get properties of this iterator, as a bit-significant integer.
|
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.
|
public GroupAdjacentIterator(SequenceIterator population, Expression keyExpression, XPathContext baseContext, StringCollator collator) throws XPathException
XPathException
public Value getCurrentGroupingKey()
GroupIterator
getCurrentGroupingKey
in interface GroupIterator
public SequenceIterator iterateCurrentGroup()
GroupIterator
iterateCurrentGroup
in interface GroupIterator
public boolean hasNext()
LookaheadIterator
SequenceIterator.LOOKAHEAD
hasNext
in interface LookaheadIterator
public Item next() throws XPathException
SequenceIterator
next
in interface SequenceIterator
XPathException
- if an error occurs retrieving the next itempublic Item current()
SequenceIterator
current
in interface SequenceIterator
public int position()
SequenceIterator
This method does not change the state of the iterator.
position
in interface SequenceIterator
public void close()
SequenceIterator
(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.)
close
in interface SequenceIterator
public SequenceIterator getAnother() throws XPathException
SequenceIterator
This method allows access to all the items in the sequence without disturbing the current position of the iterator. Internally, its main use is in evaluating the last() function.
This method does not change the state of the iterator.
getAnother
in interface SequenceIterator
XPathException
- if any error occurspublic int getProperties()
getProperties
in interface SequenceIterator
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.