public class ItemCheckingIterator extends java.lang.Object implements SequenceIterator, LookaheadIterator, LastPositionFinder
Constructor and Description |
---|
ItemCheckingIterator(SequenceIterator base,
java.util.function.Consumer<Item> action)
Construct an ItemCheckingIterator that will apply a specified DummyItemMappingFunction to
each Item returned by the base iterator.
|
Modifier and Type | Method and Description |
---|---|
void |
close()
Close the iterator.
|
void |
discharge()
Calling this method instructs the iterator to release any resources it holds, while still
remaining able to deliver the remaining items in the sequence.
|
int |
getLength()
Get the last position (that is, the number of items in the sequence).
|
boolean |
hasNext()
Determine whether there are more items to come.
|
Item |
next()
Get the next item in the sequence.
|
boolean |
supportsGetLength()
Ask whether this iterator supports use of the
LastPositionFinder.getLength() method. |
boolean |
supportsHasNext()
Ask whether the hasNext() method can be called.
|
public ItemCheckingIterator(SequenceIterator base, java.util.function.Consumer<Item> action)
base
- the base iteratoraction
- the mapping function to be applied.public boolean supportsHasNext()
LookaheadIterator
supportsHasNext
in interface LookaheadIterator
LookaheadIterator.hasNext()
method is availablepublic boolean hasNext()
LookaheadIterator
This method must not be called unless the result of LookaheadIterator.supportsHasNext()
is true.
hasNext
in interface LookaheadIterator
public Item next()
SequenceIterator
next
in interface SequenceIterator
public void close()
SequenceIterator
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.
Closing an iterator is not necessary if the iterator is read to completion: if a call
on SequenceIterator.next()
returns null, the iterator will be closed automatically. An explicit
call on SequenceIterator.close()
is needed only when iteration is abandoned prematurely.
close
in interface java.io.Closeable
close
in interface java.lang.AutoCloseable
close
in interface SequenceIterator
public void discharge()
SequenceIterator
SequenceIterator.close()
will be called when no more items are needed.discharge
in interface SequenceIterator
public boolean supportsGetLength()
LastPositionFinder
LastPositionFinder.getLength()
method. This
method should always be called before calling LastPositionFinder.getLength()
, because an iterator
that implements this interface may support use of LastPositionFinder.getLength()
in some situations
and not in otherssupportsGetLength
in interface LastPositionFinder
LastPositionFinder.getLength()
method can be called to determine the length
of the underlying sequence.public int getLength()
LastPositionFinder
LastPositionFinder.supportsGetLength()
has been called
and has returned true.getLength
in interface LastPositionFinder
Copyright (c) 2004-2022 Saxonica Limited. All rights reserved.