001    // Copyright 2007, 2009 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.internal.services;
016    
017    import org.apache.tapestry5.Binding;
018    import org.apache.tapestry5.internal.bindings.AbstractBinding;
019    import org.apache.tapestry5.ioc.Location;
020    
021    /**
022     * Wraps a {@link StringProvider} as a read-only {@link Binding}.
023     */
024    public class AttributeExpansionBinding extends AbstractBinding
025    {
026        private final StringProvider provider;
027    
028        public AttributeExpansionBinding(Location location, StringProvider provider)
029        {
030            super(location);
031    
032            this.provider = provider;
033        }
034    
035        public Object get()
036        {
037            return provider.provideString();
038        }
039    
040        /**
041         * Returns false. Expansions reference properties that may change arbitrarily.
042         */
043        @Override
044        public boolean isInvariant()
045        {
046            return false;
047        }
048    }