    001    // Copyright 2010, 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.func;
    016
    017    /**
    018     * Interface for operation {@link Flow#map(Mapper)} to define how Flow elements are mapped from one type
    019     * to another (or otherwise transformed).
    020     * <p>
    021     * This changed in 5.3 from an abstract base class to an interface.
    022     *
    023     * @since 5.2.0
    024     * @param <S>
    025     *            type of source flow
    026     * @param <T>
    027     *            type of target (output) flow
    028     */
    029    public interface Mapper<S, T>
    030    {
    031        /**
    032         * Implemented in subclasses to map an element from the source flow to an element of the target
    033         * flow.
    034         */
    035        T map(S element);
    036    }