org.basex.query.xpath.expr
Class Unary

java.lang.Object
  extended by org.basex.query.ExprInfo
      extended by org.basex.query.xpath.expr.Expr
          extended by 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