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<T>, GroundedIterator<T>

Enclosing class:

MemoSequence<T extends Item<?>>

public final class MemoSequence.ProgressiveIterator
extends java.lang.Object
implements SequenceIterator<T>, LastPositionFinder, GroundedIterator<T>

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.

Field Summary

Fields inherited from interface net.sf.saxon.om.SequenceIterator

ATOMIZING, GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD

Constructor Summary

Constructors

Constructor and Description
ProgressiveIterator() Create a ProgressiveIterator

Method Summary

Modifier and Type	Method and 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
int	getProperties() Get properties of this iterator, as a bit-significant integer.
GroundedValue<T>	getResidue() Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position.
GroundedValue<T>	materialize() Return a value containing all the items in the sequence returned by this SequenceIterator
T	next() Get the next item in the sequence.

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.saxon.om.SequenceIterator

forEachOrFail

Constructor Detail

ProgressiveIterator

public ProgressiveIterator()

Create a ProgressiveIterator

Method Detail

getMemoSequence

public MemoSequence getMemoSequence()

Get the containing MemoSequence

next

public T next()
       throws XPathException

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<T extends Item<?>>

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.

Throws:

XPathException - if an error occurs retrieving the next item

close

public void close()

Description copied from interface: SequenceIterator

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.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface SequenceIterator<T extends Item<?>>

getLength

public int getLength()
              throws XPathException

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

Throws:

XPathException - if an error occurs evaluating the sequence in order to determine the number of items

materialize

public GroundedValue<T> materialize()
                             throws XPathException

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

Specified by:

materialize in interface SequenceIterator<T extends Item<?>>

Specified by:

materialize in interface GroundedIterator<T extends Item<?>>

Returns:

the corresponding value

Throws:

XPathException - if reading the SequenceIterator throws an error

getResidue

public GroundedValue<T> getResidue()
                            throws XPathException

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<T extends Item<?>>

Returns:

the corresponding Value

Throws:

XPathException - in the cases of subclasses (such as the iterator over a MemoClosure) which cause evaluation of expressions while materializing the value.

getProperties

public int getProperties()

Get properties of this iterator, as a bit-significant integer.

Specified by:

getProperties in interface SequenceIterator<T extends Item<?>>

Returns:

the properties of this iterator. This will be some combination of properties such as SequenceIterator.GROUNDED and SequenceIterator.LAST_POSITION_FINDER. It is always acceptable to return the value zero, indicating that there are no known special properties.