    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
    015package org.apache.tapestry5.commons.internal.services;
    016
    017import org.apache.tapestry5.commons.services.Coercion;
    018
    019/**
    020 * Combines two coercions to create a coercion 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 */
    026public 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    @Override
    039    public T coerce(S input)
    040    {
    041        // Run the input through the first operation (S --> I), then run the result of that through
    042        // the second operation (I --> T).
    043
    044        I intermediate = op1.coerce(input);
    045
    046        return op2.coerce(intermediate);
    047    }
    048
    049    @Override
    050    public String toString()
    051    {
    052        return String.format("%s, %s", op1, op2);
    053    }
    054}