lux.xpath

Class Predicate

java.lang.Object

lux.xpath.AbstractExpression

lux.xpath.Predicate

All Implemented Interfaces:

Visitable

public class Predicate
extends AbstractExpression

Nested Class Summary

Nested classes/interfaces inherited from class lux.xpath.AbstractExpression

AbstractExpression.Type

Field Summary

Fields inherited from class lux.xpath.AbstractExpression

subs, sup

Constructor Summary

Constructors

Constructor and Description
Predicate(AbstractExpression base, AbstractExpression filter)

Method Summary

Methods

Modifier and Type	Method and Description
AbstractExpression	accept(ExpressionVisitor visitor)
boolean	geq(AbstractExpression other)
AbstractExpression	getBase()
AbstractExpression	getFilter()
int	getPrecedence()
AbstractExpression	getRoot()
boolean	isDocumentOrdered()
boolean	isRestrictive() An expression is restrictive when any empty sub implies the expression is empty.
boolean	matchDown(AbstractExpression fieldExpr, AbstractExpression fromExpr) Traverse downwards, comparing with fromExpr for equivalence until one bottoms out, ignoring fromExpr (since it has already been checked).
void	setFilter(AbstractExpression filter)
void	toString(StringBuilder buf) Each subclass must implement the toString(StringBuilder) method by rendering itself as a syntatically valid XPath/XQuery expression in the given buffer.

Methods inherited from class lux.xpath.AbstractExpression

acceptSubs, appendSub, deepEquals, equivalent, getBindingContext, getLastContextStep, getSubs, getSuper, getTail, getType, isAbsolute, propEquals, propGreaterEqual, replaceRoot, setSubs, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

Predicate

public Predicate(AbstractExpression base,
         AbstractExpression filter)

Method Detail

toString

public void toString(StringBuilder buf)

Description copied from class: AbstractExpression

Each subclass must implement the toString(StringBuilder) method by rendering itself as a syntatically valid XPath/XQuery expression in the given buffer.

Specified by:

toString in class AbstractExpression

getBase

public final AbstractExpression getBase()

Returns:

the base of the predicate expression (the part that is tested by the predicate filter)

getFilter

public final AbstractExpression getFilter()

Returns:

the filter of the predicate expression (the part that tests the base expression)

setFilter

public final void setFilter(AbstractExpression filter)

accept

public AbstractExpression accept(ExpressionVisitor visitor)

getPrecedence

public int getPrecedence()

Specified by:

getPrecedence in class AbstractExpression

Returns:

19

getRoot

public AbstractExpression getRoot()

Overrides:

getRoot in class AbstractExpression

Returns:

the root of this expression: this will either be a Root(/), a function returning document nodes, or null.

isDocumentOrdered

public boolean isDocumentOrdered()

Overrides:

isDocumentOrdered in class AbstractExpression

Returns:

whether this expression is proven to return results in document order. This method returns true iff all its subs return true, or it has none. Warning: incorrect results may occur if document-ordering is falsely asserted.

isRestrictive

public boolean isRestrictive()

Description copied from class: AbstractExpression

An expression is restrictive when any empty sub implies the expression is empty. In other words, restrictive expressions only return results when all of their subs are non-empty. Eg: and, intersect, predicate, path step.

Overrides:

isRestrictive in class AbstractExpression

Returns:

whether this expression is restrictive

geq

public boolean geq(AbstractExpression other)

Overrides:

geq in class AbstractExpression

Parameters:

other - another expression

Returns:

whether the two expressions are s.t. this expr is non-empty whenever (for whichever contexts) the other one is.

matchDown

public boolean matchDown(AbstractExpression fieldExpr,
                AbstractExpression fromExpr)

Description copied from class: AbstractExpression

Traverse downwards, comparing with fromExpr for equivalence until one bottoms out, ignoring fromExpr (since it has already been checked).

Overrides:

matchDown in class AbstractExpression

Returns:

whether fieldExpr >= queryExpr