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.services.TypeCoercer;
018    
019    /**
020     * A simplified version of {@link TypeCoercer} used to defer the instantiation of the actual TypeCoercer
021     * service until necessary.
022     * 
023     * @since 5.3
024     */
025    public interface TypeCoercerProxy
026    {
027        /**
028         * Returns input cast to targetType if input is an instance of target type, otherwise delegates
029         * to {@link TypeCoercer#coerce(Object, Class)}.
030         * 
031         * @param <S>
032         * @param <T>
033         * @param input
034         *            value to be coerced
035         * @param targetType
036         *            desired type of value
037         * @return the value, coerced
038         * @throws RuntimeException
039         *             if the input can not be coerced
040         */
041        <S, T> T coerce(S input, Class<T> targetType);
042    
043    }