Package net.sf.saxon.tree.iter

Class SingletonIterator<T extends Item>

java.lang.Object

net.sf.saxon.tree.iter.SingletonIterator<T>

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, LastPositionFinder, SequenceIterator, GroundedIterator, LookaheadIterator, ReversibleIterator, UnfailingIterator

Direct Known Subclasses:

SingleAtomicIterator

public class SingletonIterator<T extends Item>
extends java.lang.Object
implements SequenceIterator, UnfailingIterator, ReversibleIterator, LastPositionFinder, GroundedIterator, LookaheadIterator

SingletonIterator: an iterator over a sequence of zero or one values

Nested Class Summary

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

SequenceIterator.Property

Constructor Summary

Constructors

Constructor	Description
SingletonIterator(T value)	Private constructor: external classes should use the factory method

Method Summary

Modifier and Type	Method	Description
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.
GroundedValue	getResidue()	Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position.
SingletonIterator<T>	getReverseIterator()	Get a new SequenceIterator that returns the same items in reverse order.
T	getValue()
boolean	hasNext()	Determine whether there are more items to come.
static <T extends Item> UnfailingIterator	makeIterator(T item)	Factory method.
GroundedValue	materialize()	Return a Value containing all the items in the sequence returned by this SequenceIterator
T	next()	Get the next item in the sequence.
static <T extends Item> SingletonIterator<T>	rawIterator(T item)	Factory method for use when it is known the item will not be null

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

close, forEachOrFail

Methods inherited from interface net.sf.saxon.tree.iter.UnfailingIterator

forEach, toList

Constructor Detail

SingletonIterator

public SingletonIterator(T value)

Private constructor: external classes should use the factory method

Parameters:

value - the item to iterate over

Method Detail

makeIterator

public static <T extends Item> UnfailingIterator makeIterator(T item)

Factory method.

Parameters:

item - the item to iterate over

Returns:

a SingletonIterator over the supplied item, or an EmptyIterator if the supplied item is null.

rawIterator

public static <T extends Item> SingletonIterator<T> rawIterator(T item)

Factory method for use when it is known the item will not be null

Parameters:

item - the item to iterate over; must not be null

Returns:

a SingletonIterator over the supplied item

hasNext

public boolean hasNext()

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.

Specified by:

hasNext in interface LookaheadIterator

Returns:

true if there are more items

next

public T 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

Specified by:

next in interface UnfailingIterator

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.

getLength

public int getLength()

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

getReverseIterator

public SingletonIterator<T> getReverseIterator()

Description copied from interface: ReversibleIterator

Get a new SequenceIterator that returns the same items in reverse order. If this SequenceIterator is an AxisIterator, then the returned SequenceIterator must also be an AxisIterator.

Specified by:

getReverseIterator in interface ReversibleIterator

Returns:

an iterator over the items in reverse order

getValue

public T getValue()

materialize

public GroundedValue materialize()

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

Specified by:

materialize in interface GroundedIterator

Specified by:

materialize in interface SequenceIterator

Returns:

the corresponding Value. If the value is a closure or a function call package, it will be evaluated and expanded.

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

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.