org.exist.xquery.value
Class PreorderedValueSequence

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

All Implemented Interfaces:

Sequence

public class PreorderedValueSequence

extends AbstractSequence

A sequence that sorts its items in the order specified by the order specs of an "order by" clause. Used by ForExpr. For better performance, the whole input sequence is sorted in one single step. However, this only works if every order expression returns a result of type node.

Author:

wolf

Field Summary

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

EMPTY_SEQUENCE

Constructor Summary

PreorderedValueSequence(OrderSpec[] specs, Sequence input, int contextId)

Method Summary

void	add(Item item) Add an item to the current sequence.
void	clearContext(int contextId) For every item in the sequence, clear any context-dependant information that is stored during query processing.
int	getItemType() Return the primary type to which all items in this sequence belong.
int	getLength() Returns the number of items contained in the sequence.
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.
NodeSet	toNodeSet() Convert the sequence into a NodeSet.
SequenceIterator	unorderedIterator() Returns an iterator over all items in the sequence.

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

addAll, conversionPreference, convertTo, effectiveBooleanValue, getCardinality, getDocumentSet, getStringValue, isCached, isPersistentSet, setIsCached, setSelfAsContext, toJavaObject, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

PreorderedValueSequence

public PreorderedValueSequence(OrderSpec[] specs,
                               Sequence input,
                               int contextId)
                        throws XPathException

Method Detail

clearContext

public void clearContext(int contextId)

Description copied from interface: Sequence

For every item in the sequence, clear any context-dependant information that is stored during query processing. This feature is used for node sets, which may store information about their context node.

Specified by:

clearContext in interface Sequence

Overrides:

clearContext in class AbstractSequence

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

iterate

public SequenceIterator iterate()

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

unorderedIterator

public SequenceIterator unorderedIterator()

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

getLength

public int getLength()

Description copied from interface: Sequence

Returns the number of items contained in the sequence.

Specified by:

getLength in interface Sequence

Specified by:

getLength in class AbstractSequence

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

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

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.

Returns:

Throws:

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

removeDuplicates

public void removeDuplicates()

Description copied from interface: Sequence

Explicitely remove all duplicate nodes from this sequence.