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Hibernate's core ORM functionality
/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* License: GNU Lesser General Public License (LGPL), version 2.1 or later.
* See the lgpl.txt file in the root directory or .
*/
package org.hibernate.query.criteria.internal.predicate;
import java.io.Serializable;
import javax.persistence.criteria.Expression;
import org.hibernate.query.criteria.internal.CriteriaBuilderImpl;
import org.hibernate.query.criteria.internal.ParameterRegistry;
import org.hibernate.query.criteria.internal.Renderable;
import org.hibernate.query.criteria.internal.compile.RenderingContext;
import org.hibernate.query.criteria.internal.expression.UnaryOperatorExpression;
/**
* Defines a {@link javax.persistence.criteria.Predicate} for checking the
* nullness state of an expression, aka an IS [NOT] NULL predicate.
*
* The NOT NULL form can be built by calling the constructor and then
* calling {@link #not}.
*
* @author Steve Ebersole
*/
public class NullnessPredicate
extends AbstractSimplePredicate
implements UnaryOperatorExpression, Serializable {
private final Expression operand;
/**
* Constructs the affirmitive form of nullness checking (IS NULL). To
* construct the negative form (IS NOT NULL) call {@link #not} on the
* constructed instance.
*
* @param criteriaBuilder The query builder from whcih this originates.
* @param operand The expression to check.
*/
public NullnessPredicate(CriteriaBuilderImpl criteriaBuilder, Expression operand) {
super( criteriaBuilder );
this.operand = operand;
}
@Override
public Expression getOperand() {
return operand;
}
@Override
public void registerParameters(ParameterRegistry registry) {
Helper.possibleParameter( getOperand(), registry );
}
@Override
public String render(boolean isNegated, RenderingContext renderingContext) {
return ( (Renderable) operand ).render( renderingContext ) + check( isNegated );
}
private String check(boolean negated) {
return negated ? " is not null" : " is null";
}
}