net.sf.saxon.om
public interface SequenceIterator
A SequenceIterator keeps track of the current Item and the current position. The objects returned by the SequenceIterator will always be either nodes (class NodeInfo) or singleton values (class AtomicValue): these are represented collectively by the interface Item.
This interface forms part of the public Saxon API. The JavaDoc "since" flag is used from release 8.4 onwards to indicate methods that are considered to be a stable part of the API. Methods without a "since" flag should not be regarded as a stable part of the API.
Note that the stability of this interface applies to classes that use the interface, not to classes that implement it. The interface may be extended in future to add new methods.
Since: 8.4
Field Summary | |
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static int | GROUNDED
Property value: the iterator is "grounded". |
static int | LAST_POSITION_FINDER
Property value: the iterator knows the number of items that it will deliver.
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static int | LOOKAHEAD
Property value: the iterator knows whether there are more items still to come. |
Method Summary | |
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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.
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int | getProperties()
Get properties of this iterator, as a bit-significant integer. |
Item | next()
Get the next item in the sequence. |
int | position()
Get the current position. |
(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.)
Since: 9.1
Returns: the current item, the one most recently returned by a call on next(). Returns null if next() has not been called, or if the end of the sequence has been reached.
Since: 8.4
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.
Returns: a SequenceIterator that iterates over the same items, positioned before the first item
Throws: XPathException if any error occurs
Since: 8.4
Returns: the properties of this iterator. This will be some combination of properties such as GROUNDED, LAST_POSITION_FINDER, and 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.
Since: 8.6
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
Since: 8.4
This method does not change the state of the iterator.
Returns: the current position, the position of the item returned by the most recent call of next(). This is 1 after next() has been successfully called once, 2 after it has been called twice, and so on. If next() has never been called, the method returns zero. If the end of the sequence has been reached, the value returned will always be <= 0; the preferred value is -1.
Since: 8.4