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}