org.basex.query.xpath.expr
Class Unary

java.lang.Object
  org.basex.query.ExprInfo
      org.basex.query.xpath.expr.Expr
          org.basex.query.xpath.expr.Unary

public final class Unary
extends Expr

XPath Unary Expression. The result of this expression is the change of the sign of a number.

Author:

Workgroup DBIS, University of Konstanz 2005-08, ISC License, Tim Petrowsky

Constructor Summary

Unary(Expr e)
Constructor.

Method Summary

Expr	comp(XPContext ctx) Optimizes the expression.
Dbl	eval(XPContext ctx) Evaluates the expression with the specified context set.
void	plan(Serializer ser) Recursively sends the abstract syntax of this expression to the specified serializer.
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 org.basex.query.ExprInfo

color, info, name

Methods inherited from class java.lang.Object

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

Constructor Detail

Unary

public Unary(Expr e)

Constructor.

Parameters:

e - expression evaluating to a node set.

Method Detail

comp

public Expr comp(XPContext ctx)
          throws QueryException

Description copied from class: Expr

Optimizes the expression.

Specified by:

comp in class Expr

Parameters:

ctx - expression context

Returns:

optimized Expression

Throws:

QueryException - evaluation exception

eval

public Dbl eval(XPContext ctx)
         throws QueryException

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:

QueryException - evaluation exception

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

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

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