001// Licensed under the Apache License, Version 2.0 (the "License");
002// you may not use this file except in compliance with the License.
003// You may obtain a copy of the License at
004//
005// http://www.apache.org/licenses/LICENSE-2.0
006//
007// Unless required by applicable law or agreed to in writing, software
008// distributed under the License is distributed on an "AS IS" BASIS,
009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
010// See the License for the specific language governing permissions and
011// limitations under the License.
012
013package org.apache.tapestry5.func;
014
015/**
016 * Interface for operation {@link Flow#map(Mapper)} to define how Flow elements are mapped from one type
017 * to another (or otherwise transformed).
018 *
019 * This changed in 5.3 from an abstract base class to an interface.
020 * 
021 * @since 5.2.0
022 * @param <S>
023 *            type of source flow
024 * @param <T>
025 *            type of target (output) flow
026 */
027public interface Mapper<S, T>
028{
029    /**
030     * Implemented in subclasses to map an element from the source flow to an element of the target
031     * flow.
032     */
033    T map(S element);
034}