1   /* Copyright 2002-2026 CS GROUP
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.utils;
18  
19  import org.hipparchus.util.RyuDouble;
20  import org.orekit.time.DateTimeComponents;
21  
22  /** Formatter used to produce strings from data with high accuracy.
23   * <p>
24   * When producing test output from computed data, we want the shortest
25   * decimal representation of a floating point number that maintains
26   * round-trip safety. That is, a correct parser can recover the exact
27   * original number.
28   * </p>
29   * <p>
30   * For efficiency, this class uses the {@link RyuDouble Ryū} algorithm
31   * for producing shortest string representation with round-trip safety.
32   * </p>
33   * @author Luc Maisonobe
34   * @since 11.0
35   */
36  public class AccurateFormatter implements Formatter {
37  
38      /** Low switch level for exponential format in dates (will never be reached due to {@link #LOW_TRUNCATION}). */
39      private static final int LOW_EXP = -18;
40  
41      /** Truncation level for seconds, to avoid scientific format. */
42      private static final double LOW_TRUNCATION = 1.0e-15;
43  
44      /** Public constructor.
45       */
46      public AccurateFormatter() {
47          // nothing to do
48      }
49  
50      /** Formats to full accuracy.
51       * {@inheritDoc}
52       */
53      @Override
54      public String toString(final double value) {
55          return RyuDouble.doubleToString(value);
56      }
57  
58      /** Formats the seconds variable with maximum precision needed.
59       * {@inheritDoc}
60       */
61      @Override
62      public String toString(final int year, final int month, final int day,
63                             final int hour, final int minute, final double seconds) {
64          final double truncated = seconds < LOW_TRUNCATION ? 0.0 : seconds;
65          final String s = RyuDouble.doubleToString(truncated, LOW_EXP, RyuDouble.DEFAULT_HIGH_EXP);
66          return String.format(STANDARDIZED_LOCALE, DATE_FORMAT,
67                               year, month, day,
68                               hour, minute, s.charAt(1) == '.' ? "0" + s : s);
69      }
70  
71      /**
72       * Format date time components to make use of attosecond accuracy from {@link org.orekit.time.TimeOffset}.
73       * It relies on the {@link DateTimeComponents#toStringWithoutUtcOffset()} method to display date time.
74       *
75       * @param dt date time components to be formatted
76       * @return date formatted to match the following format [yyyy-MM-ddTHH:mm:ss.S#]
77       * @since 13.1.6
78       */
79      @Override
80      public String toString(final DateTimeComponents dt) {
81          return dt.toStringWithoutUtcOffset();
82      }
83  }