core/spi/src/main/java/org/apache/polygene/spi/entitystore/helpers/DefaultNamedAssociationState.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.polygene.spi.entitystore.helpers;

import java.util.Iterator;
import java.util.Map;
import java.util.Objects;
import org.apache.polygene.api.entity.EntityReference;
import org.apache.polygene.spi.entity.NamedAssociationState;

/**
 * Default implementation of NamedAssociationState.
 * Backed by HashMap.
 */
public final class DefaultNamedAssociationState
    implements NamedAssociationState
{
    private final DefaultEntityState entityState;
    private final Map<String, EntityReference> references;

    public DefaultNamedAssociationState( DefaultEntityState entityState, Map<String, EntityReference> references )
    {
        this.entityState = entityState;
        this.references = references;
    }

    @Override
    public int count()
    {
        return references.size();
    }

    @Override
    public boolean containsName( String name )
    {
        return references.containsKey( name );
    }

    @Override
    public boolean put( String name, EntityReference entityReference )
    {
        Objects.requireNonNull(name, "name");
        Objects.requireNonNull(entityReference, "entityReference");
        EntityReference oldReference = references.put( name, entityReference );
        if( entityReference.equals( oldReference ) )
        {
            return false;
        }
        entityState.markUpdated();
        return true;
    }

    @Override
    public boolean remove( String name )
    {
        if( references.remove( name ) == null )
        {
            return false;
        }
        entityState.markUpdated();
        return true;
    }

    @Override
    public boolean clear()
    {
        if( !references.isEmpty() )
        {
            references.clear();
            entityState.markUpdated();
            return true;
        }
        return false;
    }

    @Override
    public EntityReference get( String name )
    {
        return references.get( name );
    }

    @Override
    public String nameOf( EntityReference entityReference )
    {
        for( Map.Entry<String, EntityReference> entry : references.entrySet() )
        {
            if( entry.getValue().equals( entityReference ) )
            {
                return entry.getKey();
            }
        }
        return null;
    }

    @Override
    public Iterator<String> iterator()
    {
        final Iterator<String> iter = references.keySet().iterator();
        return new Iterator<String>()
        {
            private String current;

            @Override
            public boolean hasNext()
            {
                return iter.hasNext();
            }

            @Override
            public String next()
            {
                current = iter.next();
                return current;
            }

            @Override
            public void remove()
            {
                iter.remove();
                entityState.markUpdated();
            }
        };
    }
}