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
015package org.apache.tapestry5.internal.services;
016
017import org.apache.tapestry5.Binding;
018import org.apache.tapestry5.commons.Location;
019import org.apache.tapestry5.internal.bindings.AbstractBinding;
020
021/**
022 * Wraps a {@link StringProvider} as a read-only {@link Binding}.
023 */
024public 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}