- All Implemented Interfaces:
- Direct Known Subclasses:
public abstract class AbstractBlockIterator extends java.lang.Object implements SequenceIteratorIterate over the instructions in a sequence of instructions (or an XPath comma expression), concatenating the result of each instruction into a single combined sequence. This abstract class has concrete subclasses handling the interpreted and compiled cases
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description
close()Close the iterator.
init(int size, XPathContext context)Initializer for use from bytecode
next()Get the next item in the sequence.
public AbstractBlockIterator(int size, XPathContext context)
public void init(int size, XPathContext context)Initializer for use from bytecode
size- the size
context- the XPath context
public Item next()Get the next item in the sequence.
public abstract SequenceIterator getNthChildIterator(int n) throws XPathException
public void close()Description copied from interface:
SequenceIteratorClose the iterator. This indicates to the supplier of the data that the client does not require any more items to be delivered by the iterator. This may enable the supplier to release resources. After calling close(), no further calls on the iterator should be made; if further calls are made, the effect of such calls is undefined.
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.
It is not possible to guarantee that an iterator that is not read to completion or will be closed. For example, if a lazy-evaluated variable
$varis passed to a user-written function, the function may access
$varonly; we have no way of knowing whether further items will be read. For this reason, any
SequenceIteratorthat holds resources which need to be closed should use the
Cleaner, and resources held by a
SequenceIteratorshould be registered with the
Cleaner; if the
SequenceIteratoris then garbage-collected without being closed, the
Cleanerwill ensure that the underlying resources are closed. (An example of a
SequenceIteratorthat uses this mechanism is the