Package net.sf.saxon.om

Class MemoSequence.ProgressiveIterator

java.lang.Object

net.sf.saxon.om.MemoSequence.ProgressiveIterator

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, LastPositionFinder, SequenceIterator, GroundedIterator

Enclosing class:

MemoSequence

public static final class MemoSequence.ProgressiveIterator
extends java.lang.Object
implements SequenceIterator, LastPositionFinder, GroundedIterator

A ProgressiveIterator starts by reading any items already held in the reservoir; when the reservoir is exhausted, it reads further items from the inputIterator, copying them into the reservoir as they are read.

Constructor Summary

Constructors

Constructor	Description
ProgressiveIterator(MemoSequence container)	Create a ProgressiveIterator

Method Summary

Modifier and Type	Method	Description
void	close()	Close the iterator.
int	getLength()	Get the last position (that is, the number of items in the sequence)
MemoSequence	getMemoSequence()	Get the containing MemoSequence
GroundedValue	getResidue()	Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position.
boolean	isActuallyGrounded()	Ask if the iterator is actually grounded.
GroundedValue	materialize()	Return a value containing all the items in the sequence returned by this SequenceIterator
Item	next()	Get the next item in the sequence.
boolean	supportsGetLength()	Ask whether this iterator supports use of the LastPositionFinder.getLength() method.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ProgressiveIterator

public ProgressiveIterator(MemoSequence container)

Create a ProgressiveIterator

Parameters:

container - the containing MemoSequence

Method Detail

getMemoSequence

public MemoSequence getMemoSequence()

Get the containing MemoSequence

Returns:

the containing MemoSequence

next

public Item next()

Description copied from interface: SequenceIterator

Get the next item in the sequence. This method changes the state of the iterator.

Specified by:

next in interface SequenceIterator

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.

supportsGetLength

public boolean supportsGetLength()

Description copied from interface: LastPositionFinder

Ask whether this iterator supports use of the 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 others

Specified by:

supportsGetLength in interface LastPositionFinder

Returns:

true if the LastPositionFinder.getLength() method can be called to determine the length of the underlying sequence.

getLength

public int getLength()

Get the last position (that is, the number of items in the sequence)

Specified by:

getLength in interface LastPositionFinder

Returns:

the number of items in the sequence

isActuallyGrounded

public boolean isActuallyGrounded()

Description copied from interface: GroundedIterator

Ask if the iterator is actually grounded. This method must be called before calling GroundedIterator.materialize() or GroundedIterator.getResidue(), because the iterator might be grounded under some conditions and not others (usually when it delegates to another iterator)

Specified by:

isActuallyGrounded in interface GroundedIterator

Returns:

true if this iterator is grounded

materialize

public GroundedValue materialize()

Return a value containing all the items in the sequence returned by this SequenceIterator

Specified by:

materialize in interface GroundedIterator

Returns:

the corresponding value

getResidue

public GroundedValue getResidue()

Description copied from interface: GroundedIterator

Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position. This should be an "in-memory" value, not a Closure. This method does not change the state of the iterator (in particular, it does not consume the iterator).

Specified by:

getResidue in interface GroundedIterator

Returns:

the corresponding Value

close

public void close()

Close 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 next() returns null, the iterator will be closed automatically. An explicit call on close() is needed only when iteration is abandoned prematurely.

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface SequenceIterator

Since:

9.1. Default implementation added in 9.9.