org.basex.query.xpath.internal
Class InternalExpr

java.lang.Object
  extended by org.basex.query.ExprInfo
      extended by org.basex.query.xpath.expr.Expr
          extended by org.basex.query.xpath.internal.InternalExpr
Direct Known Subclasses:
AllOf, IndexAccess, IndexMatch, OneOf, Range, RangeAccess

public abstract class InternalExpr
extends Expr

Abstract class for internal (optimized) XPath expressions.

Author:
Workgroup DBIS, University of Konstanz 2005-08, ISC License, Christian Gruen

Constructor Summary
InternalExpr()
           
 
Method Summary
 Expr comp(XPContext ctx)
          Optimizes 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
 
Methods inherited from class org.basex.query.ExprInfo
color, info, name, plan, toString
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

InternalExpr

public InternalExpr()
Method Detail

comp

public final Expr comp(XPContext ctx)
Description copied from class: Expr
Optimizes the expression.

Specified by:
comp in class Expr
Parameters:
ctx - expression context
Returns:
optimized Expression

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

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