Package net.sf.saxon.om
Class SingletonIterator
- java.lang.Object
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- net.sf.saxon.om.SingletonIterator
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- All Implemented Interfaces:
LastPositionFinder
,ReversibleIterator
,AtomizableIterator
,AxisIterator
,GroundedIterator
,LookaheadIterator
,SequenceIterator
public class SingletonIterator extends java.lang.Object implements AxisIterator, ReversibleIterator, LastPositionFinder, GroundedIterator, LookaheadIterator, AtomizableIterator
SingletonIterator: an iterator over a sequence of zero or one values
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Field Summary
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Fields inherited from interface net.sf.saxon.om.SequenceIterator
ATOMIZABLE, GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description Item
current()
Get the current item in the sequence.SequenceIterator
getAnother()
Get another iterator over the same sequence of items, positioned at the start of the sequence.int
getLastPosition()
Get the last position (that is, the number of items in the sequence).int
getProperties()
Get properties of this iterator, as a bit-significant integer.SequenceIterator
getReverseIterator()
Get a new SequenceIterator that returns the same items in reverse order.Item
getValue()
boolean
hasNext()
Determine whether there are more items to come.static AxisIterator
makeIterator(Item item)
Factory method.Value
materialize()
Return a Value containing all the items in the sequence returned by this SequenceIteratorItem
next()
Get the next item in the sequence.int
position()
Return the current position in the sequence.void
setIsAtomizing(boolean atomizing)
Indicate that any nodes returned in the sequence will be atomized.
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Method Detail
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makeIterator
public static AxisIterator makeIterator(Item 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.
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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
public Item next()
Description copied from interface:AxisIterator
Get the next item in the sequence.- Specified by:
next
in interfaceAxisIterator
- Specified by:
next
in interfaceSequenceIterator
- Returns:
- the next Item. If there are no more nodes, return null.
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current
public Item current()
Description copied from interface:AxisIterator
Get the current item in the sequence.- Specified by:
current
in interfaceAxisIterator
- Specified by:
current
in interfaceSequenceIterator
- Returns:
- the current item, that is, the item most recently returned by next()
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position
public int position()
Return the current position in the sequence.- Specified by:
position
in interfaceAxisIterator
- Specified by:
position
in interfaceSequenceIterator
- Returns:
- 0 before the first call on next(); 1 before the second call on next(); -1 after the second call on next().
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getLastPosition
public int getLastPosition()
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.LAST_POSITION_FINDER
- Specified by:
getLastPosition
in interfaceLastPositionFinder
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getAnother
public SequenceIterator getAnother()
Description copied from interface:AxisIterator
Get another iterator over the same sequence of items, positioned at the start of the sequence. It must be possible to call this method at any time, whether none, some, or all of the items in the original iterator have been read. The method is non-destructive: it does not change the state of the original iterator.- Specified by:
getAnother
in interfaceAxisIterator
- Specified by:
getAnother
in interfaceSequenceIterator
- Returns:
- a new iterator over the same sequence
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getReverseIterator
public SequenceIterator 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
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getValue
public Item getValue()
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materialize
public Value materialize()
Return a Value containing all the items in the sequence returned by this SequenceIterator- Specified by:
materialize
in interfaceGroundedIterator
- 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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setIsAtomizing
public void setIsAtomizing(boolean atomizing)
Indicate that any nodes returned in the sequence will be atomized. This means that if it wishes to do so, the implementation can return the typed values of the nodes rather than the nodes themselves. The implementation is free to ignore this hint.This implementation attempts atomization of a singleton node if it is untyped. This avoids adding an iterator to iterate over the value in the common case where the typed value of the node is a single atomic value.
- Specified by:
setIsAtomizing
in interfaceAtomizableIterator
- Parameters:
atomizing
- true if the caller of this iterator will atomize any nodes that are returned, and is therefore willing to accept the typed value of the nodes instead of the nodes themselves.
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getProperties
public int 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.GROUNDED
,SequenceIterator.LAST_POSITION_FINDER
, andSequenceIterator.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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