UnitsCache.java

  1. /* Copyright 2002-2023 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.units;

  18. import java.util.HashMap;
  19. import java.util.Map;

  20. /** Cache for parsed units.
  21.  * @author Luc Maisonobe
  22.  * @since 11.0
  23.  */
  24. public class UnitsCache {

  25.     /** Parsed units cache. */
  26.     private final Map<String, Unit> cache;

  27.     /** Simple constructor.
  28.      */
  29.     public UnitsCache() {
  30.         this.cache = new HashMap<>();
  31.     }

  32.     /** Get units from a string specification.
  33.      * <p>
  34.      * Parsing is performed only the first time a specification is
  35.      * encountered, so the cache speeds up cases where the same
  36.      * units is encountered many times (for example when parsing
  37.      * CCSDS messages with many entries).
  38.      * </p>
  39.      * @param specification units specification (may be null)
  40.      * @return parsed units ({@link Unit#NONE} if specification is null)
  41.      */
  42.     public Unit getUnits(final String specification) {

  43.         if (specification == null) {
  44.             return Unit.NONE;
  45.         }

  46.         Unit cached = cache.get(specification);
  47.         if (cached == null) {
  48.             cached = Unit.parse(specification);
  49.             cache.put(specification, cached);
  50.         }

  51.         return cached;

  52.     }

  53. }