org.exist.xquery.value
Class EmptySequence

java.lang.Object
  org.exist.xquery.value.AbstractSequence
      org.exist.xquery.value.EmptySequence

All Implemented Interfaces:

Sequence

public class EmptySequence
extends AbstractSequence

Field Summary

Fields inherited from interface org.exist.xquery.value.Sequence

EMPTY_SEQUENCE

Constructor Summary

EmptySequence()

Method Summary

void	add(Item item) Add an item to the current sequence.
AtomicValue	convertTo(int requiredType) Try to convert the sequence into an atomic value.
int	getItemCount() Returns the number of items contained in the sequence.
int	getItemType() Return the primary type to which all items in this sequence belong.
boolean	hasOne() Returns whether the sequence has just one item or not.
boolean	isEmpty() Returns whether the sequence is empty or not.
Item	itemAt(int pos) Returns the item located at the specified position within this sequence.
SequenceIterator	iterate() Returns an iterator over all items in the sequence.
void	removeDuplicates() Explicitely remove all duplicate nodes from this sequence.
MemoryNodeSet	toMemNodeSet() Convert the sequence into an in-memory node set.
NodeSet	toNodeSet() Convert the sequence into a NodeSet.
String	toString()
SequenceIterator	unorderedIterator() Returns an iterator over all items in the sequence.

Methods inherited from class org.exist.xquery.value.AbstractSequence

addAll, clearContext, conversionPreference, effectiveBooleanValue, getCardinality, getCollectionIterator, getDocumentSet, getState, getStringValue, hasChanged, hasMany, isCacheable, isCached, isPersistentSet, nodeMoved, setIsCached, setSelfAsContext, toJavaObject

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

EmptySequence

public EmptySequence()

Method Detail

getItemType

public int getItemType()

Description copied from interface: Sequence

Return the primary type to which all items in this sequence belong. This is Type.NODE for node sets, Type.ITEM for other sequences with mixed items.

Specified by:

getItemType in interface Sequence

Specified by:

getItemType in class AbstractSequence

Returns:

the primary type of the items in this sequence.

iterate

public SequenceIterator iterate()
                         throws XPathException

Description copied from interface: Sequence

Returns an iterator over all items in the sequence. The items are returned in document order where applicable.

Specified by:

iterate in interface Sequence

Specified by:

iterate in class AbstractSequence

Throws:

XPathException - TODO

unorderedIterator

public SequenceIterator unorderedIterator()
                                   throws XPathException

Description copied from interface: Sequence

Returns an iterator over all items in the sequence. The returned items may - but need not - to be in document order.

Specified by:

unorderedIterator in interface Sequence

Specified by:

unorderedIterator in class AbstractSequence

Throws:

XPathException

getItemCount

public int getItemCount()

Description copied from interface: Sequence

Returns the number of items contained in the sequence. Call this method only when necessary, since it can be resource consuming.

Specified by:

getItemCount in interface Sequence

Specified by:

getItemCount in class AbstractSequence

Returns:

The number of items in the sequence

itemAt

public Item itemAt(int pos)

Description copied from interface: Sequence

Returns the item located at the specified position within this sequence. Items are counted beginning at 0.

Specified by:

itemAt in interface Sequence

Specified by:

itemAt in class AbstractSequence

isEmpty

public boolean isEmpty()

Description copied from interface: Sequence

Returns whether the sequence is empty or not.

Specified by:

isEmpty in interface Sequence

Specified by:

isEmpty in class AbstractSequence

Returns:

true is the sequence is empty

hasOne

public boolean hasOne()

Description copied from interface: Sequence

Returns whether the sequence has just one item or not.

Specified by:

hasOne in interface Sequence

Specified by:

hasOne in class AbstractSequence

Returns:

true is the sequence has just one item

add

public void add(Item item)
         throws XPathException

Description copied from interface: Sequence

Add an item to the current sequence. An XPathException may be thrown if the item's type is incompatible with this type of sequence (e.g. if the sequence is a node set). The sequence may or may not allow duplicate values.

Specified by:

add in interface Sequence

Specified by:

add in class AbstractSequence

Throws:

XPathException

convertTo

public AtomicValue convertTo(int requiredType)
                      throws XPathException

Description copied from interface: Sequence

Try to convert the sequence into an atomic value. The target type should be specified by using one of the constants defined in class Type. An XPathException is thrown if the conversion is impossible.

Specified by:

convertTo in interface Sequence

Overrides:

convertTo in class AbstractSequence

Parameters:

requiredType - one of the type constants defined in class Type

Throws:

XPathException

toNodeSet

public NodeSet toNodeSet()
                  throws XPathException

Description copied from interface: Sequence

Convert the sequence into a NodeSet. If the sequence contains items which are not nodes, an XPathException is thrown.

Throws:

XPathException - if the sequence contains items which are not nodes.

toMemNodeSet

public MemoryNodeSet toMemNodeSet()
                           throws XPathException

Description copied from interface: Sequence

Convert the sequence into an in-memory node set. If the sequence contains items which are not nodes, an XPathException is thrown. For persistent node sets, this method will return null. Call Sequence.isPersistentSet() to check if the sequence is a persistent node set.

Throws:

XPathException - if the sequence contains items which are not nodes or is a persistent node set

removeDuplicates

public void removeDuplicates()

Description copied from interface: Sequence

Explicitely remove all duplicate nodes from this sequence.

toString

public String toString()

Overrides:

toString in class AbstractSequence