001    // Copyright 2011 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.ioc.internal;
016    
017    import org.apache.tapestry5.ioc.ObjectLocator;
018    import org.apache.tapestry5.ioc.services.TypeCoercer;
019    
020    /**
021     * A proxy for the {@link TypeCoercer}
022     * 
023     * @since 5.3
024     */
025    public final class TypeCoercerProxyImpl implements TypeCoercerProxy
026    {
027        private final ObjectLocator locator;
028    
029        private TypeCoercer delegate;
030    
031        public TypeCoercerProxyImpl(ObjectLocator locator)
032        {
033            this.locator = locator;
034        }
035    
036        private TypeCoercer delegate()
037        {
038            if (delegate == null)
039                delegate = locator.getService(TypeCoercer.class);
040    
041            return delegate;
042        }
043    
044        public <S, T> T coerce(S input, Class<T> targetType)
045        {
046            if (targetType.isInstance(input))
047                return targetType.cast(input);
048    
049            return delegate().coerce(input, targetType);
050        }
051    
052    }