org.basex.query.xpath.locpath
Class PredSimple

java.lang.Object
  org.basex.query.ExprInfo
      org.basex.query.xpath.locpath.Pred
          org.basex.query.xpath.locpath.PredSimple

public final class PredSimple
extends Pred

XPath predicate.

Author:

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

Field Summary

Expr	expr Predicate expression.

Constructor Summary

PredSimple(Expr exp)
Constructor.

Method Summary

Expr	indexEquivalent(XPContext ctx, Step step, boolean seq) Returns an equivalent expression which accesses an index structure.
int	indexSizes(XPContext ctx, Step curr, int min) Returns the number of results if this query is evaluated by an index.
void	plan(Serializer ser) Recursively sends the abstract syntax of this expression to the specified serializer.
boolean	sameAs(Pred pred) Compares the predicate for equality.
java.lang.String	toString()

Methods inherited from class org.basex.query.xpath.locpath.Pred

color

Methods inherited from class org.basex.query.ExprInfo

info, name

Methods inherited from class java.lang.Object

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

Field Detail

expr

public Expr expr

Predicate expression.

Constructor Detail

PredSimple

public PredSimple(Expr exp)

Constructor.

Parameters:

exp - Expression to evaluate

Method Detail

indexEquivalent

public Expr indexEquivalent(XPContext ctx,
                            Step step,
                            boolean seq)
                     throws QueryException

Description copied from class: Pred

Returns an equivalent expression which accesses an index structure.

Parameters:

ctx - root

step - location step

seq - flag for sequential evaluation

Returns:

Equivalent index-expression or null

Throws:

QueryException - evaluation exception

indexSizes

public int indexSizes(XPContext ctx,
                      Step curr,
                      int min)

Description copied from class: Pred

Returns the number of results if this query is evaluated by an index. If Integer.MAX_VALUE is returned, no index access is possible.

Parameters:

ctx - root

curr - the current location step

min - current minimum index hits

Returns:

number of expected results

sameAs

public boolean sameAs(Pred pred)

Description copied from class: Pred

Compares the predicate for equality.

Parameters:

pred - predicate to be compared

Returns:

result of check

toString

public java.lang.String toString()

Specified by:

toString in class ExprInfo

plan

public void plan(Serializer ser)
          throws java.io.IOException

Description copied from class: ExprInfo

Recursively sends the abstract syntax of this expression to the specified serializer.

Specified by:

plan in class ExprInfo

Parameters:

ser - serializer

Throws:

java.io.IOException - exception