org.basex.query.xpath.expr
Class DualExpr

java.lang.Object
  org.basex.query.xpath.expr.Expr
      org.basex.query.xpath.expr.DualExpr

Direct Known Subclasses:

Calculation, Comparison

public abstract class DualExpr
extends Expr

Abstract Expression with two arguments.

Author:

Workgroup DBIS, University of Konstanz 2005-07, ISC License, Christian Gruen

Field Summary

Expr	expr1 First Expression.
Expr	expr2 Second Expression.

Constructor Summary

DualExpr()

Method Summary

boolean	usesPos() Checks whether this Expression (or its children) make use of the position parameter.
boolean	usesSize() Checks whether this Expression (or its children) make use of the setsize parameter.

Methods inherited from class org.basex.query.xpath.expr.Expr

compile, eval, indexEquivalent, indexSizes, returnedValue, sameAs, toString

Methods inherited from class java.lang.Object

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

Field Detail

expr1

public Expr expr1

First Expression.

expr2

public Expr expr2

Second Expression.

Constructor Detail

DualExpr

public DualExpr()

Method Detail

usesPos

public final boolean usesPos()

Description copied from class: Expr

Checks whether this Expression (or its children) make use of the position parameter. If not this allows some nice optimizations.

Specified by:

usesPos in class Expr

Returns:

whether position is used

usesSize

public final boolean usesSize()

Description copied from class: Expr

Checks whether this Expression (or its children) make use of the setsize parameter. If not this allows early predicate evaluation.

Specified by:

usesSize in class Expr

Returns:

whether setsize is used