1   /* Contributed in the public domain.
2    * Licensed to CS GROUP (CS) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * CS licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *   http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.orekit.propagation.events;
18  
19  import org.hipparchus.CalculusFieldElement;
20  import org.orekit.propagation.FieldSpacecraftState;
21  import org.orekit.propagation.events.handlers.FieldContinueOnEvent;
22  import org.orekit.propagation.events.handlers.FieldEventHandler;
23  import org.orekit.time.FieldAbsoluteDate;
24  
25  /**
26   * An event detector that negates the sign on another event detector's {@link
27   * FieldEventDetector#g(FieldSpacecraftState) g} function.
28   *
29   * @since 12.0
30   * @param <T> type of the field element
31   * @author Evan Ward
32   * @author Luc Maisonobe
33   */
34  public class FieldNegateDetector<T extends CalculusFieldElement<T>>  extends FieldAbstractDetector<FieldNegateDetector<T>, T>
35          implements FieldDetectorModifier<T> {
36  
37      /** the delegate event detector. */
38      private final FieldEventDetector<T> original;
39  
40      /**
41       * Create a new event detector that negates an existing event detector.
42       *
43       * <p> This detector will be initialized with the same {@link
44       * FieldEventDetector#getMaxCheckInterval()}, {@link FieldEventDetector#getThreshold()}, and
45       * {@link FieldEventDetector#getMaxIterationCount()} as {@code original}. Initially this
46       * detector will use the {@link FieldContinueOnEvent} event handler.
47       *
48       * @param original detector.
49       */
50      public FieldNegateDetector(final FieldEventDetector<T> original) {
51          this(original.getDetectionSettings(), new FieldContinueOnEvent<>(), original);
52      }
53  
54      /**
55       * Protected constructor.
56       *
57       * @param detectionSettings event detection settings.
58       * @param newHandler   event handler.
59       * @param original     event detector.
60       * @since 13.0
61       */
62      protected FieldNegateDetector(final FieldEventDetectionSettings<T> detectionSettings,
63                                    final FieldEventHandler<T> newHandler,
64                                    final FieldEventDetector<T> original) {
65          super(detectionSettings, newHandler);
66          this.original = original;
67      }
68  
69      /**
70       * Get the delegate event detector.
71       * @return the delegate event detector
72       */
73      public FieldEventDetector<T> getOriginal() {
74          return original;
75      }
76  
77      @Override
78      public FieldEventDetector<T> getDetector() {
79          return getOriginal();
80      }
81  
82      @Override
83      public void init(final FieldSpacecraftState<T> s0, final FieldAbsoluteDate<T> t) {
84          super.init(s0, t);
85          getDetector().init(s0, t);
86      }
87  
88      @Override
89      public T g(final FieldSpacecraftState<T> s) {
90          return original.g(s).negate();
91      }
92  
93      @Override
94      protected FieldNegateDetector<T> create(final FieldEventDetectionSettings<T> detectionSettings,
95                                              final FieldEventHandler<T> newHandler) {
96          return new FieldNegateDetector<>(detectionSettings, newHandler, original);
97      }
98  
99  }