    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.collections4;
    018
    019/**
    020 * Defines a functor interface implemented by classes that do something.
    021 * <p>
    022 * A {@code Closure} represents a block of code which is executed from
    023 * inside some block, function or iteration. It operates an input object.
    024 * </p>
    025 * <p>
    026 * Standard implementations of common closures are provided by
    027 * {@link ClosureUtils}. These include method invocation and for/while loops.
    028 * </p>
    029 *
    030 * @param <T> the type that the closure acts on
    031 * @since 1.0
    032 */
    033@FunctionalInterface
    034public interface Closure<T> {
    035
    036    /**
    037     * Performs an action on the specified input object.
    038     *
    039     * @param input  the input to execute on
    040     * @throws ClassCastException (runtime) if the input is the wrong class
    041     * @throws IllegalArgumentException (runtime) if the input is invalid
    042     * @throws FunctorException (runtime) if any other error occurs
    043     */
    044    void execute(T input);
    045
    046}