Package com.saxonica.ee.bytecode.iter

Class OneToOneMappingIterator

java.lang.Object

com.saxonica.ee.bytecode.iter.OneToOneMappingIterator

All Implemented Interfaces:

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

public abstract class OneToOneMappingIterator
extends java.lang.Object
implements SequenceIterator, LookaheadIterator, LastPositionFinder

Abstract iterator that performs a one-to-one mapping from the items in the input sequence to the items in the output sequence; the mapping operation is defined by the map() action implemented in the subclass.

Nested Class Summary

Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator

SequenceIterator.Property

Field Summary

Fields

Modifier and Type	Field	Description
protected XPathContext	context

Constructor Summary

Constructors

Constructor	Description
OneToOneMappingIterator()

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).
java.util.EnumSet<SequenceIterator.Property>	getProperties()	Get properties of this iterator, as a bit-significant integer.
boolean	hasNext()	Determine whether there are more items to come.
protected abstract Item	map(Item baseItem)	Abstract method to be supplied in subclasses to map an item from the input sequence to an item in the output sequence
Item	next()	Get the next item in the sequence.
void	setSequence(SequenceIterator base, XPathContext context)

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, materialize

Field Detail

context

protected XPathContext context

Constructor Detail

OneToOneMappingIterator

public OneToOneMappingIterator()

Method Detail

setSequence

public void setSequence(SequenceIterator base,
                        XPathContext context)

hasNext

public boolean hasNext()

Description copied from interface: LookaheadIterator

Determine whether there are more items to come. Note that this operation is stateless and it is not necessary (or usual) to call it before calling next(). It is used only when there is an explicit need to tell if we are at the last element.

This method must not be called unless the result of getProperties() on the iterator includes the property SequenceIterator.Property.LOOKAHEAD

Specified by:

hasNext in interface LookaheadIterator

Returns:

true if there are more items in the sequence

next

public Item 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

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

map

protected abstract Item map(Item baseItem)
                     throws XPathException

Abstract method to be supplied in subclasses to map an item from the input sequence to an item in the output sequence

Parameters:

baseItem - the item in the input (base) sequence

Returns:

the corresponding item in the output sequence. Must not be null

Throws:

XPathException - if the mapping function fails

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.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface SequenceIterator

getLength

public int getLength()
              throws XPathException

Description copied from interface: LastPositionFinder

Get the last position (that is, the number of items in the sequence). This method is non-destructive: it does not change the state of the iterator. The result is undefined if the next() method of the iterator has already returned null. This method must not be called unless the result of getProperties() on the iterator includes the bit setting SequenceIterator.Property.LAST_POSITION_FINDER

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

getProperties

public java.util.EnumSet<SequenceIterator.Property> getProperties()

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

Specified by:

getProperties in interface SequenceIterator

Returns:

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