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</code> 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}