org.basex.query.xpath.expr
Class Path

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

public final class Path
extends Expr

Path Expression. This Expression represents a relative location path operating on a nodeset (return value of expression).

Author:

Workgroup DBIS, University of Konstanz 2005-07, ISC License, Tim Petrowsky

Field Summary

Expr	expr Expression to be evaluated.
Expr	path Location path.

Constructor Summary

Path(Expr e, Expr p)
Constructor for a relative location path.

Method Summary

Expr	compile(XPContext ctx) Tries to optimize the Expression.
NodeSet	eval(XPContext ctx) Evaluates the expression with the specified context set.
java.lang.String	toString()
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

indexEquivalent, indexSizes, returnedValue, sameAs

Methods inherited from class java.lang.Object

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

Field Detail

expr

public Expr expr

Expression to be evaluated.

path

public Expr path

Location path.

Constructor Detail

Path

public Path(Expr e,
            Expr p)

Constructor for a relative location path.

Parameters:

e - Expression evaluating to a nodeset

p - Location Path (or maybe other Expression after optimization)

Method Detail

compile

public Expr compile(XPContext ctx)
             throws EvalException

Description copied from class: Expr

Tries to optimize the Expression.

Specified by:

compile in class Expr

Parameters:

ctx - expression context

Returns:

optimized Expression

Throws:

EvalException - evaluation exception

eval

public NodeSet 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

toString

public java.lang.String toString()

Specified by:

toString in class Expr

usesPos

public 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 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