001    /*
002     * JBoss, Home of Professional Open Source.
003     * Copyright 2008, Red Hat Middleware LLC, and individual contributors
004     * as indicated by the @author tags. See the copyright.txt file in the
005     * distribution for a full listing of individual contributors. 
006     *
007     * This is free software; you can redistribute it and/or modify it
008     * under the terms of the GNU Lesser General Public License as
009     * published by the Free Software Foundation; either version 2.1 of
010     * the License, or (at your option) any later version.
011     *
012     * This software is distributed in the hope that it will be useful,
013     * but WITHOUT ANY WARRANTY; without even the implied warranty of
014     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015     * Lesser General Public License for more details.
016     *
017     * You should have received a copy of the GNU Lesser General Public
018     * License along with this software; if not, write to the Free
019     * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
020     * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
021     */
022    package org.jboss.dna.graph.properties.basic;
023    
024    import java.util.Iterator;
025    import java.util.NoSuchElementException;
026    import net.jcip.annotations.Immutable;
027    import org.jboss.dna.graph.properties.Name;
028    
029    /**
030     * An immutable version of a property that has exactly 1 value. This is done for efficiency of the in-memory representation, since
031     * many properties will have just a single value, while others will have multiple values.
032     * 
033     * @author Randall Hauch
034     */
035    @Immutable
036    public class BasicSingleValueProperty extends BasicProperty {
037    
038        protected final Object value;
039    
040        /**
041         * Create a property with a single value
042         * 
043         * @param name the property name
044         * @param value the property value (which may be null)
045         */
046        public BasicSingleValueProperty( Name name,
047                                         Object value ) {
048            super(name);
049            this.value = value;
050        }
051    
052        /**
053         * {@inheritDoc}
054         */
055        public boolean isEmpty() {
056            return false;
057        }
058    
059        /**
060         * {@inheritDoc}
061         */
062        public boolean isMultiple() {
063            return false;
064        }
065    
066        /**
067         * {@inheritDoc}
068         */
069        public boolean isSingle() {
070            return true;
071        }
072    
073        /**
074         * {@inheritDoc}
075         */
076        public int size() {
077            return 1;
078        }
079    
080        /**
081         * {@inheritDoc}
082         */
083        public Iterator<Object> iterator() {
084            return new ValueIterator();
085        }
086    
087        protected class ValueIterator implements Iterator<Object> {
088    
089            private boolean done = false;
090    
091            protected ValueIterator() {
092            }
093    
094            /**
095             * {@inheritDoc}
096             */
097            public boolean hasNext() {
098                return !done;
099            }
100    
101            /**
102             * {@inheritDoc}
103             */
104            public Object next() {
105                if (!done) {
106                    done = true;
107                    return BasicSingleValueProperty.this.value;
108                }
109                throw new NoSuchElementException();
110            }
111    
112            /**
113             * {@inheritDoc}
114             */
115            public void remove() {
116                throw new UnsupportedOperationException();
117            }
118    
119        }
120    
121    }