001    // Copyright 2007 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.services;
016    
017    import org.apache.tapestry5.ioc.AnnotationProvider;
018    import org.apache.tapestry5.ioc.ObjectLocator;
019    import org.apache.tapestry5.ioc.ObjectProvider;
020    import org.apache.tapestry5.ioc.annotations.IntermediateType;
021    import org.apache.tapestry5.ioc.annotations.Symbol;
022    import org.apache.tapestry5.ioc.services.Builtin;
023    import org.apache.tapestry5.ioc.services.SymbolSource;
024    import org.apache.tapestry5.ioc.services.TypeCoercer;
025    
026    /**
027     * Performs an injection based on a {@link Symbol} annotation.
028     */
029    public class SymbolObjectProvider implements ObjectProvider
030    {
031        private final SymbolSource symbolSource;
032    
033        private final TypeCoercer typeCoercer;
034    
035        public SymbolObjectProvider(@Builtin SymbolSource symbolSource,
036    
037                                    @Builtin TypeCoercer typeCoercer)
038        {
039            this.symbolSource = symbolSource;
040            this.typeCoercer = typeCoercer;
041        }
042    
043        public <T> T provide(Class<T> objectType, AnnotationProvider annotationProvider, ObjectLocator locator)
044        {
045            Symbol annotation = annotationProvider.getAnnotation(Symbol.class);
046    
047            if (annotation == null) return null;
048    
049            Object value = symbolSource.valueForSymbol(annotation.value());
050    
051            IntermediateType it = annotationProvider.getAnnotation(IntermediateType.class);
052    
053            if (it != null) value = typeCoercer.coerce(value, it.value());
054    
055            return typeCoercer.coerce(value, objectType);
056        }
057    
058    }