public class OneItemGoneIterator extends Object implements SequenceIterator, LastPositionFinder, GroundedIterator, LookaheadIterator
This avoids the cost of calling getAnother() to re-read the first item (which itself can be an expensive operation, for example if it involves calling a user function).
GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD
Constructor and Description |
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OneItemGoneIterator(SequenceIterator baseIterator)
Create an iterator that delivers all the items that the base iterator delivers, even
though the first item of the base iterator has already been read
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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.
|
int |
getLastPosition()
Get the last position (that is, the number of items in the sequence).
|
int |
getProperties()
Get properties of this iterator, as a bit-significant integer.
|
boolean |
hasNext()
Determine whether there are more items to come.
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GroundedValue |
materialize()
Return a GroundedValue containing all the items in the sequence returned by this
SequenceIterator.
|
Item |
next()
Get the next item in the sequence.
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int |
position()
Get the current position.
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public OneItemGoneIterator(SequenceIterator baseIterator)
baseIterator
- the base iterator, whose current position must be 1public Item next() throws XPathException
next
in interface SequenceIterator
XPathException
- if an error occurs retrieving the next itempublic Item current()
current
in interface SequenceIterator
public int position()
position
in interface SequenceIterator
public void close()
(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
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.public int getLastPosition() throws XPathException
SequenceIterator.LAST_POSITION_FINDER
getLastPosition
in interface LastPositionFinder
XPathException
public GroundedValue materialize() throws XPathException
materialize
in interface GroundedIterator
XPathException
public boolean hasNext()
SequenceIterator.LOOKAHEAD
hasNext
in interface LookaheadIterator