org.basex.query.xpath.internal
Class OneOf

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

public final class OneOf
extends InternalExpr

This Expression assembles a number of similar comparisons of which one has to evluate true.

Author:

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

Constructor Summary

OneOf(LocPath p, Item[] v, Comp c)
Constructor.

Method Summary

Bool	eval(XPContext ctx) Evaluates the expression with the specified context set.
Expr	indexEquivalent(XPContext ctx, Step curr) For predicate optimization.
int	indexSizes(XPContext ctx, Step curr, int min) For predicate optimization.
java.lang.String	toString()

Methods inherited from class org.basex.query.xpath.internal.InternalExpr

compile, usesPos, usesSize

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

returnedValue, sameAs

Methods inherited from class java.lang.Object

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

Constructor Detail

OneOf

public OneOf(LocPath p,
             Item[] v,
             Comp c)

Constructor.

Parameters:

p - location path

v - second expression to compare with first

c - comparator

Method Detail

eval

public Bool eval(XPContext ctx)
          throws EvalException

Description copied from class: Expr

Evaluates the expression with the specified context set. Additionally provides a context

Specified by:

eval in class Expr

Parameters:

ctx - query context

Returns:

resulting XPathValue

Throws:

EvalException - evaluation exception

indexEquivalent

public Expr indexEquivalent(XPContext ctx,
                            Step curr)

Description copied from class: Expr

For predicate optimization. If possible return an expression yielding the same results using the index. This may not do any changes to the current expression.

Overrides:

indexEquivalent in class Expr

Parameters:

ctx - root

curr - the LocationStep this Expression is a predicate of

Returns:

Equivalent index-expression or null

indexSizes

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

Description copied from class: Expr

For predicate optimization. If possible return the number of entries an index returns. This may not do any changes to the current expression.

Overrides:

indexSizes in class Expr

Parameters:

ctx - root

curr - the LocationStep this Expression is a predicate of

min - current minimum size

Returns:

Equivalent index-expression or null

toString

public java.lang.String toString()

Specified by:

toString in class Expr