public class MappingIterator extends java.lang.Object implements SequenceIterator
This is a powerful class. It is used, with different mapping functions, in a great variety of ways. It underpins the way that "for" expressions and path expressions are evaluated, as well as sequence expressions. It is also used in the implementation of the document(), key(), and id() functions.
|Constructor and Description|
Construct a MappingIterator that will apply a specified MappingFunction to each Item returned by the base iterator.
|Modifier and Type||Method and Description|
Close the iterator.
Get the next item in the sequence.
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
public MappingIterator(SequenceIterator base, MappingFunction action)
base- the base iterator, which must deliver items of type F
action- the mapping function to be applied
public Item next() throws XPathException
XPathException- if an error occurs retrieving the next item
public void close()
For example, the iterator returned by the unparsed-text-lines() function has a close() method that causes the underlying input stream to be closed, whether or not the file has been read to completion.
Closing an iterator is important 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.
Copyright (c) 2004-2020 Saxonica Limited. All rights reserved.