org.treetank.service.xml.xpath

Class ExpressionSingle

java.lang.Object

org.treetank.service.xml.xpath.ExpressionSingle

public class ExpressionSingle
extends Object

ExpresseionSingle

This class builds an execution chain to execute a XPath query. All added axis are build together by using NestedAxis.

Constructor Summary

Constructors

Constructor and Description
ExpressionSingle(INodeReadTrx pRtx) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(AbsAxis mAx) Adds a new Axis to the expression chain.
AbsAxis	getExpr() Returns a chain to execute the query.
int	getSize() Returns the number of axis in this expression.
boolean	isDupOrd(AbsAxis ax) Determines for a given string representation of an axis, whether this axis leads to duplicates in the result sequence or not.
boolean	isOrdered()

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionSingle

public ExpressionSingle(INodeReadTrx pRtx)

Constructor. Initializes the internal state.

Method Detail

add

public void add(AbsAxis mAx)

Adds a new Axis to the expression chain. The first axis that is added has to be stored till a second axis is added. When the second axis is added, it is nested with the first one and builds the execution chain.

Parameters:

mAx - ach The axis to add.

getExpr

public AbsAxis getExpr()

Returns a chain to execute the query. If there is only one axis added, the chain was not build yet, so only this axis is returned.

Returns:

The query execution chain

getSize

public int getSize()

Returns the number of axis in this expression.

Returns:

size of the expression

isDupOrd

public boolean isDupOrd(AbsAxis ax)

Determines for a given string representation of an axis, whether this axis leads to duplicates in the result sequence or not. Furthermore it determines the new state for the order state that specifies, if the result sequence is in document order. This method is implemented according to the automata in [Hidders, J., Michiels, P., "Avoiding Unnecessary Ordering Operations in XPath", 2003]

Parameters:

ax - name of the current axis

Returns:

true, if expression is still duplicate free

isOrdered

public boolean isOrdered()

Returns:

true, if the result is in document order