org.basex.query.xpath.internal
Class InternalExpr

java.lang.Object
  org.basex.query.xpath.expr.Expr
      org.basex.query.xpath.internal.InternalExpr

Direct Known Subclasses:

AllOf, FTIndex, IndexAccess, IndexMatch, OneOf, Range

public abstract class InternalExpr
extends Expr

Abstract class for internal (optimized) XPath expressions.

Author:

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

Constructor Summary

InternalExpr()

Method Summary

Expr	compile(XPContext ctx) Tries to optimize the Expression.
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

eval, indexEquivalent, indexSizes, returnedValue, sameAs, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

InternalExpr

public InternalExpr()

Method Detail

compile

public final Expr compile(XPContext ctx)

Description copied from class: Expr

Tries to optimize the Expression.

Specified by:

compile in class Expr

Parameters:

ctx - expression context

Returns:

optimized Expression

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