1   /* Copyright 2002-2019 CS Systèmes d'Information
2    * Licensed to CS Systèmes d'Information (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.sampling;
18  
19  import org.orekit.propagation.SpacecraftState;
20  import org.orekit.time.AbsoluteDate;
21  
22  /** This interface is a space-dynamics aware fixed size step handler.
23   *
24   * <p>It mirrors the <code>FixedStepHandler</code> interface from <a
25   * href="https://hipparchus.org/">Hipparchus</a> but provides
26   * a space-dynamics interface to the methods.</p>
27   * @author Luc Maisonobe
28   */
29  @FunctionalInterface
30  public interface OrekitFixedStepHandler {
31  
32      /** Initialize step handler at the start of a propagation.
33       * <p>
34       * This method is called once at the start of the propagation. It
35       * may be used by the step handler to initialize some internal data
36       * if needed.
37       * </p>
38       * <p>
39       * The default implementation does nothing
40       * </p>
41       * @param s0 initial state
42       * @param t target time for the integration
43            * @deprecated as of 9.0, replaced by {@link #init(SpacecraftState, AbsoluteDate, double)}
44       */
45      @Deprecated
46      default void init(SpacecraftState s0, AbsoluteDate t) {
47          // nothing by default
48      }
49  
50      /** Initialize step handler at the start of a propagation.
51       * <p>
52       * This method is called once at the start of the propagation. It
53       * may be used by the step handler to initialize some internal data
54       * if needed.
55       * </p>
56       * <p>
57       * The default implementation currently calls the deprecated
58       * {@link #init(SpacecraftState, AbsoluteDate)} which does nothing by
59       * default. When that method is removed the default implementation will do
60       * nothing.
61       * </p>
62       * @param s0 initial state
63       * @param t target time for the integration
64       * @param step the duration in seconds of the fixed step. This value is
65       *             positive even if propagation is backwards.
66            * @since 9.0
67       */
68      default void init(SpacecraftState s0, AbsoluteDate t, double step) {
69          // as of 9.0, the default implementation calls the DEPRECATED version
70          // without a step size, which does nothing by default but may have
71          // been overridden by users
72          // When the deprecated version is removed, the default implementation
73          // will do nothing
74          init(s0, t);
75      }
76  
77      /** Handle the current step.
78       * @param currentState current state at step time
79       * @param isLast if true, this is the last integration step
80       */
81      void handleStep(SpacecraftState currentState, boolean isLast);
82  
83  }