001/**
002 * The MIT License (MIT)
003 *
004 * Copyright (c) 2018 nobark (tools4j), Marco Terzer, Anton Anufriev
005 *
006 * Permission is hereby granted, free of charge, to any person obtaining a copy
007 * of this software and associated documentation files (the "Software"), to deal
008 * in the Software without restriction, including without limitation the rights
009 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
010 * copies of the Software, and to permit persons to whom the Software is
011 * furnished to do so, subject to the following conditions:
012 *
013 * The above copyright notice and this permission notice shall be included in all
014 * copies or substantial portions of the Software.
015 *
016 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
017 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
018 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
019 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
020 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
021 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
022 * SOFTWARE.
023 */
024package org.tools4j.nobark.loop;
025
026/**
027 * Step is similar to {@link Runnable} but returns true if substantial work has been performed.  Steps can for instance
028 * be used as building blocks in a {@link Loop}.
029 */
030public interface Step {
031    /**
032     * Executes this step and returns true if substantial work was performed.
033     *
034     * @return true if work was performed
035     */
036    boolean perform();
037
038    /**
039     * Step performing a no-OP; the implementation returns false indicating that no work was performed.
040     */
041    Step NO_OP = ComposableStep.NO_OP;
042}