    001    // Copyright 2006, 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.services.Coercion;
    018
    019    /**
    020     * Combines two coercions to create a coercsion through an intermediate type.
    021     *
    022     * @param <S> The source (input) type
    023     * @param <I> The intermediate type
    024     * @param <T> The target (output) type
    025     */
    026    public class CompoundCoercion<S, I, T> implements Coercion<S, T>
    027    {
    028        private final Coercion<S, I> op1;
    029
    030        private final Coercion<I, T> op2;
    031
    032        public CompoundCoercion(Coercion<S, I> op1, Coercion<I, T> op2)
    033        {
    034            this.op1 = op1;
    035            this.op2 = op2;
    036        }
    037
    038        public T coerce(S input)
    039        {
    040            // Run the input through the first operation (S --> I), then run the result of that through
    041            // the second operation (I --> T).
    042
    043            I intermediate = op1.coerce(input);
    044
    045            return op2.coerce(intermediate);
    046        }
    047
    048        @Override
    049        public String toString()
    050        {
    051            return String.format("%s, %s", op1, op2);
    052        }
    053    }