net.axyana.qizxopen.xquery
Class Empty

java.lang.Object
  net.axyana.qizxopen.xquery.dt.BaseValue
      net.axyana.qizxopen.xquery.Empty

All Implemented Interfaces:

java.io.Serializable, XQItem, XQValue

public class Empty

extends net.axyana.qizxopen.xquery.dt.BaseValue

The empty sequence (unique instance).

See Also:

Serialized Form

Field Summary

static XQValue

sequence

Fields inherited from interface net.axyana.qizxopen.xquery.XQItem

INCOMPARABLE

Constructor Summary

Empty()

Method Summary

XQItem	asAtom() Gets the current item with atomization.
XQValue	bornAgain() Returns a new version of the sequence in its initial state.
int	compareTo(XQItem that, EvalContext context) Compares two items.
net.axyana.qizxopen.util.time.Duration	getDuration() Gets the item as a Duration value.
XQItem	getItem() Gets the current item (undefined result if end of sequence reached).
net.axyana.qizxopen.util.time.DateTimeBase	getMoment() Gets the item as a Duration value.
XQItemType	getType() Returns the type description.
boolean	isNode() Tests whether the item is a Node.
boolean	next() Attempts to get the next atomic item.

Methods inherited from class net.axyana.qizxopen.xquery.dt.BaseValue

deepEqual, getBoolean, getDecimal, getDouble, getFloat, getInteger, getNode, getString, hasQuickIndex, nextCollection, quickCount, quickIndex, setLazy, worthExpanding

Methods inherited from class java.lang.Object

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

Field Detail

sequence

public static XQValue sequence

Constructor Detail

Empty

public Empty()

Method Detail

getType

public XQItemType getType()

Description copied from interface: XQItem

Returns the type description.

next

public boolean next()

Description copied from interface: XQValue

Attempts to get the next atomic item. If true is returned, the item value is available through one of the specialized accessors.

bornAgain

public XQValue bornAgain()

Description copied from interface: XQValue

Returns a new version of the sequence in its initial state. Value objects are in principle immutable, but due to the iterative implementation style (see the XQValue.next() method), this is not actually true. Therefore when a value is used several times (in particular the value of a variable), there is a need for "regeneration".

NOTE: this needs not be a deep copy, because only the state of the iterator is concerned, not the underlying data.

isNode

public boolean isNode()

Description copied from interface: XQItem

Tests whether the item is a Node.

getItem

public XQItem getItem()
               throws XQTypeException

Description copied from interface: XQValue

Gets the current item (undefined result if end of sequence reached).

Throws:

XQTypeException

asAtom

public XQItem asAtom()
              throws XQTypeException

Description copied from interface: XQValue

Gets the current item with atomization. If the current item is a Node, it is transparently transformed into a sequence of atomic values (in the future schema-aware implementation), or simply to its string value (in XQuery Basic).

Throws:

XQTypeException

compareTo

public int compareTo(XQItem that,
                     EvalContext context)

Description copied from interface: XQItem

Compares two items.

getDuration

public net.axyana.qizxopen.util.time.Duration getDuration()
                                                   throws XQEvalException

Description copied from interface: XQItem

Gets the item as a Duration value.

Throws:

XQEvalException

getMoment

public net.axyana.qizxopen.util.time.DateTimeBase getMoment()
                                                     throws XQEvalException

Description copied from interface: XQItem

Gets the item as a Duration value.

Throws:

XQEvalException