code: ///////////////////////////////////////////////////////////////////////////
  //                   __                _      _   ________               //
  //                  / /   ____  ____ _(_)____/ | / / ____/               //
  //                 / /   / __ \/ __ `/ / ___/  |/ / / __                 //
  //                / /___/ /_/ / /_/ / / /__/ /|  / /_/ /                 //
  //               /_____/\____/\__, /_/\___/_/ |_/\____/                  //
  //                           /____/                                      //
  //                                                                       //
  //               The Next Generation Logic Library                       //
  //                                                                       //
  ///////////////////////////////////////////////////////////////////////////
  //                                                                       //
  //  Copyright 2015-20xx Christoph Zengler                                //
  //                                                                       //
  //  Licensed under the Apache License, Version 2.0 (the "License");      //
  //  you may not use this file except in compliance with the License.     //
  //  You may obtain a copy of the License at                              //
  //                                                                       //
  //  http://www.apache.org/licenses/LICENSE-2.0                           //
  //                                                                       //
  //  Unless required by applicable law or agreed to in writing, software  //
  //  distributed under the License is distributed on an "AS IS" BASIS,    //
  //  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or      //
  //  implied.  See the License for the specific language governing        //
  //  permissions and limitations under the License.                       //
  //                                                                       //
  ///////////////////////////////////////////////////////////////////////////
  
  package org.logicng.handlers;
  
  import org.logicng.datastructures.Assignment;
  
  /**
   * A MaxSAT handler which cancels the solving process after a given timeout.
   * @version 2.1.0
   * @since 1.0
   */
  public class TimeoutMaxSATHandler extends TimeoutHandler implements MaxSATHandler {
  
      private TimeoutSATHandler satHandler;
      private int currentLb;
      private int currentUb;
  
      /**
       * Constructs a new timeout handler with a given timeout and a timeout type.
       * The interpretation of the timeout depends on the timeout type:
       * <ul>
       *     <li>{@link TimerType#SINGLE_TIMEOUT}: The timeout is started when {@link Handler#started()} is called.
       *     Further calls to {@link Handler#started()} have no effect on the timeout. Thus, the timeout can only be started once.</li>
       *     <li>{@link TimerType#RESTARTING_TIMEOUT}: The timeout is restarted when {@link Handler#started()} is called.</li>
       *     <li>{@link TimerType#FIXED_END}: Timeout which is interpreted as fixed point in time (in milliseconds)
       *     at which the computation should be aborted. The method {@link Handler#started()} must still be called,
       *     but does not have an effect on the timeout.</li>
       * </ul>
       * Note that it might take a few milliseconds more until the solver is actually canceled, since the handler depends
       * on the solvers call to {@code foundApproximation()} or {@link SATHandler#detectedConflict()}.
       * @param timeout the timeout in milliseconds, its meaning is defined by the timeout type
       * @param type    the type of the timer, must not be {@code null}
       */
      public TimeoutMaxSATHandler(final long timeout, final TimerType type) {
          super(timeout, type);
          this.currentLb = -1;
          this.currentUb = -1;
      }
  
      /**
       * Constructs a new timeout handler with a given timeout and uses the timeout type {@link TimerType#SINGLE_TIMEOUT}.
       * Thus, the timeout is started when {@link Handler#started()} is called and
       * further calls to {@link Handler#started()} have no effect on the timeout.
       * @param timeout the timeout in milliseconds
       */
      public TimeoutMaxSATHandler(final long timeout) {
          super(timeout);
      }
  
      @Override
      public void started() {
          super.started();
          if (this.satHandler == null || this.type == TimerType.RESTARTING_TIMEOUT) {
              this.satHandler = new TimeoutSATHandler(this.designatedEnd, TimerType.FIXED_END);
          }
          this.currentLb = -1;
          this.currentUb = -1;
      }
  
      @Override
      public boolean aborted() {
          return super.aborted() || Handler.aborted(this.satHandler);
      }
  
      /**
       * Returns a SAT handler which can be used to cancel internal SAT calls of the model enumeration process.
       * Note that this handler will only be available after the first call to {@link #started()}.
       * @return the SAT handler
       */
      @Override
      public SATHandler satHandler() {
          return this.satHandler;
      }
  
      @Override
      public boolean foundLowerBound(final int lowerBound, final Assignment model) {
          this.currentLb = lowerBound;
          return !timeLimitExceeded();
      }
  
      @Override
      public boolean foundUpperBound(final int upperBound, final Assignment model) {
          this.currentUb = upperBound;
          return !timeLimitExceeded();
      }
  
      @Override
      public void finishedSolving() {
          // nothing to do here
      }
  
      @Override
      public int lowerBoundApproximation() {
          return this.currentLb;
      }
  
      @Override
      public int upperBoundApproximation() {
          return this.currentUb;
      }
  }
  