FieldTransformGenerator.java
- /* Copyright 2002-2017 CS Systèmes d'Information
- * Licensed to CS Systèmes d'Information (CS) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * CS licenses this file to You 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.orekit.frames;
- import java.util.ArrayList;
- import java.util.List;
- import org.hipparchus.Field;
- import org.hipparchus.RealFieldElement;
- import org.orekit.errors.OrekitException;
- import org.orekit.errors.OrekitExceptionWrapper;
- import org.orekit.time.AbsoluteDate;
- import org.orekit.time.FieldAbsoluteDate;
- import org.orekit.utils.GenericTimeStampedCache;
- import org.orekit.utils.TimeStampedGenerator;
- /** Generator to use field transforms in {@link GenericTimeStampedCache}.
- * @see GenericTimeStampedCache
- * @since 9.0
- * @author Luc Maisonobe
- */
- public class FieldTransformGenerator<T extends RealFieldElement<T>> implements TimeStampedGenerator<FieldTransform<T>> {
- /** Field to which the elements belong. */
- private final Field<T> field;
- /** Number of neighbors. */
- private int neighborsSize;
- /** Underlying provider. */
- private final TransformProvider provider;
- /** Step size. */
- private final double step;
- /** simple constructor.
- * @param field field to which the elements belong
- * @param neighborsSize number of neighbors
- * @param provider underlying provider
- * @param step step size
- */
- public FieldTransformGenerator(final Field<T> field,
- final int neighborsSize,
- final TransformProvider provider,
- final double step) {
- this.field = field;
- this.neighborsSize = neighborsSize;
- this.provider = provider;
- this.step = step;
- }
- /** {@inheritDoc} */
- public List<FieldTransform<T>> generate(final AbsoluteDate existingDate, final AbsoluteDate date) {
- try {
- final FieldAbsoluteDate<T> fieldDate = new FieldAbsoluteDate<>(field, date);
- final List<FieldTransform<T>> generated = new ArrayList<>();
- if (existingDate == null) {
- // no prior existing transforms, just generate a first set
- for (int i = 0; i < neighborsSize; ++i) {
- generated.add(provider.getTransform(fieldDate.shiftedBy(i * step)));
- }
- } else {
- // some transforms have already been generated
- // add the missing ones up to specified date
- FieldAbsoluteDate<T> t = new FieldAbsoluteDate<>(field, existingDate);
- if (date.compareTo(t.toAbsoluteDate()) > 0) {
- // forward generation
- do {
- t = t.shiftedBy(step);
- generated.add(generated.size(), provider.getTransform(t));
- } while (t.compareTo(fieldDate) <= 0);
- } else {
- // backward generation
- do {
- t = t.shiftedBy(-step);
- generated.add(0, provider.getTransform(t));
- } while (t.compareTo(fieldDate) >= 0);
- }
- }
- // return the generated transforms
- return generated;
- } catch (OrekitException oe) {
- throw new OrekitExceptionWrapper(oe);
- }
- }
- }