public final class MultithreadedContextMappingIterator extends Object implements SequenceIterator
|Constructor and Description|
Construct an Iterator that will apply a specified action expression to each Item returned by the current iterator of the supplied dynamic context.
|Modifier and Type||Method and Description|
Close the iterator.
Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence.
Get properties of this iterator, as a bit-significant integer.
Get the next item in the sequence.
public MultithreadedContextMappingIterator(Expression action, XPathContextMinor context, int threads) throws XPathException
action- the mapping expression to be applied
context- the processing context. The action expression is applied to each item returned by context.getCurrentIterator() in turn.
threads- the number of threads to be used (in addition to the base evaluation thread) These threads are used to evaluate the action expression. The current thread is used to evaluate the base iterator and to gather the results of invoking the action expressions in the right order.
public Item next() throws XPathException
XPathException- if an error occurs retrieving the next item
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.)
public SequenceIterator getAnother() throws XPathException
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.
public int getProperties()
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.
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