core/api/src/main/java/org/apache/zest/api/query/grammar/AssociationNullSpecification.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.zest.api.query.grammar;

import org.apache.zest.api.association.Association;
import org.apache.zest.api.composite.Composite;

/**
 * Association null Specification.
 */
public class AssociationNullSpecification<T>
    extends ExpressionSpecification
{
    private AssociationFunction<T> association;

    public AssociationNullSpecification( AssociationFunction<T> association )
    {
        this.association = association;
    }

    public AssociationFunction<T> association()
    {
        return association;
    }

    @Override
    public boolean satisfiedBy( Composite item )
    {
        try
        {
            Association<T> assoc = association.map( item );

            if( assoc == null )
            {
                return true;
            }

            return assoc.get() == null;
        }
        catch( IllegalArgumentException e )
        {
            return true;
        }
    }

    @Override
    public String toString()
    {
        return association.toString() + "is null";
    }
}