    001// Copyright 2010 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.func;
    016
    017/**
    018 * A reducer takes an accumulator value and a single value from a collection and computes a new
    019 * accumulator value.
    020 * <A> type of accumulator
    021 * <T> type of collection value
    022 *
    023 * @since 5.2.0
    024 */
    025public interface Reducer<A, T>
    026{
    027    /**
    028     * Run a computation using the current value of the accumulator and an element (from a Flow),
    029     * and return the new accumulator.
    030     */
    031    A reduce(A accumulator, T element);
    032}