Package net.sf.saxon.tree.iter
Class SingletonIterator<T extends Item>
java.lang.Object
net.sf.saxon.tree.iter.SingletonIterator<T>
- All Implemented Interfaces:
Closeable
,AutoCloseable
,LastPositionFinder
,SequenceIterator
,GroundedIterator
,LookaheadIterator
,ReversibleIterator
,UnfailingIterator
- Direct Known Subclasses:
SingleAtomicIterator
public class SingletonIterator<T extends Item>
extends Object
implements SequenceIterator, UnfailingIterator, ReversibleIterator, LastPositionFinder, GroundedIterator, LookaheadIterator
SingletonIterator: an iterator over a sequence of zero or one values
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Nested Class Summary
Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator
SequenceIterator.Property
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Field Summary
Fields -
Constructor Summary
ConstructorsConstructorDescriptionSingletonIterator
(T value) Private constructor: external classes should use the factory method -
Method Summary
Modifier and TypeMethodDescriptionint
Get the last position (that is, the number of items in the sequence).Get properties of this iterator, as a bit-significant integer.Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position.Get a new SequenceIterator that returns the same items in reverse order.getValue()
boolean
hasNext()
Determine whether there are more items to come.static <T extends Item>
UnfailingIteratormakeIterator
(T item) Factory method.Return a Value containing all the items in the sequence returned by this SequenceIteratornext()
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 nullMethods 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
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Field Details
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gone
boolean gone
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Constructor Details
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SingletonIterator
Private constructor: external classes should use the factory method- Parameters:
value
- the item to iterate over
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Method Details
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makeIterator
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.
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rawIterator
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
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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 interfaceLookaheadIterator
- Returns:
- true if there are more items
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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 interfaceSequenceIterator
- Specified by:
next
in interfaceUnfailingIterator
- 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.
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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 settingSequenceIterator.Property.LAST_POSITION_FINDER
- Specified by:
getLength
in interfaceLastPositionFinder
- Returns:
- the number of items in the sequence
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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 interfaceReversibleIterator
- Returns:
- an iterator over the items in reverse order
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getValue
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materialize
Return a Value containing all the items in the sequence returned by this SequenceIterator- Specified by:
materialize
in interfaceGroundedIterator
- Specified by:
materialize
in interfaceSequenceIterator
- Returns:
- the corresponding Value. If the value is a closure or a function call package, it will be evaluated and expanded.
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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 interfaceGroundedIterator
- Returns:
- the corresponding Value
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getProperties
Get properties of this iterator, as a bit-significant integer.- Specified by:
getProperties
in interfaceSequenceIterator
- Returns:
- the properties of this iterator. This will be some combination of
properties such as
SequenceIterator.Property.GROUNDED
,SequenceIterator.Property.LAST_POSITION_FINDER
, andSequenceIterator.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.
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