org.apache.openjpa.kernel.exps
Class IsEmptyExpression

java.lang.Object
  org.apache.openjpa.kernel.exps.Exp
      org.apache.openjpa.kernel.exps.IsEmptyExpression

All Implemented Interfaces:

Serializable, Expression

 class IsEmptyExpression
extends Exp

Expression to test for an empty Collection.

Author:

Abe White

Constructor Summary

IsEmptyExpression(Val val)
Constructor.

Method Summary

void	acceptVisit(ExpressionVisitor visitor) Accept a visit from a tree visitor.
protected boolean	eval(Collection candidates, StoreContext ctx, Object[] params) Evaluate the expression for the given group.
protected boolean	eval(Object candidate, Object orig, StoreContext ctx, Object[] params) Evaluate the expression for the given context candidate and original candidate.

Methods inherited from class org.apache.openjpa.kernel.exps.Exp

evaluate, evaluate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IsEmptyExpression

public IsEmptyExpression(Val val)

Constructor. Provide collection/map value to test.

Method Detail

eval

protected boolean eval(Object candidate,
                       Object orig,
                       StoreContext ctx,
                       Object[] params)

Description copied from class: Exp

Evaluate the expression for the given context candidate and original candidate.

Overrides:

eval in class Exp

eval

protected boolean eval(Collection candidates,
                       StoreContext ctx,
                       Object[] params)

Description copied from class: Exp

Evaluate the expression for the given group.

Overrides:

eval in class Exp

acceptVisit

public void acceptVisit(ExpressionVisitor visitor)

Description copied from interface: Expression

Accept a visit from a tree visitor.

Specified by:

acceptVisit in interface Expression

Overrides:

acceptVisit in class Exp