public class UnionEnumeration extends Object implements SequenceIterator, LookaheadIterator
ATOMIZING, GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD
Constructor and Description |
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UnionEnumeration(SequenceIterator p1,
SequenceIterator p2,
ItemOrderComparer comparer)
Create the iterator.
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Modifier and Type | Method and Description |
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void |
close()
Close the iterator.
|
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 |
getProperties()
Get properties of this iterator, as a bit-significant integer.
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boolean |
hasNext()
Determine whether there are more items to come.
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NodeInfo |
next()
Get the next item in the sequence.
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public UnionEnumeration(SequenceIterator p1, SequenceIterator p2, ItemOrderComparer comparer) throws XPathException
p1
- iterator over the first operand sequence (in document order)p2
- iterator over the second operand sequencecomparer
- used to test whether nodes are in document order. Different versions
are used for intra-document and cross-document operationsXPathException
- if an error occurs reading the first item of either operandpublic boolean hasNext()
LookaheadIterator
SequenceIterator.LOOKAHEAD
hasNext
in interface LookaheadIterator
public NodeInfo next() throws XPathException
SequenceIterator
next
in interface SequenceIterator
XPathException
- if an error occurs retrieving the next itempublic 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.
Some implementations of this method may regenerate the input sequence, creating new nodes with different identity from the original. This is not recommended, but is hard to prevent. This causes no problem for the primary usage of this method to support the last() function, but it has been known to cause trouble in other situations.
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.Copyright (c) 2004-2014 Saxonica Limited. All rights reserved.