# DefaultNamedAssociationState.java

    /*
     * Copyright (c) 2011-2013, Niclas Hedhman. All Rights Reserved.
     * Copyright (c) 2014, Paul Merlin. All Rights Reserved.
     *
     * Licensed  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.qi4j.spi.entitystore.helpers;

    import java.util.Iterator;
    import java.util.Map;
    import org.qi4j.api.entity.EntityReference;
    import org.qi4j.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 )
        {
            if( references.put( name, entityReference ) == null )
            {
                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 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();
                }
            };
        }
    }