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1   package org.opentrafficsim.kpi.sampling.indicator;
2   
3   import java.util.List;
4   
5   import org.djunits.value.vdouble.scalar.Time;
6   import org.djunits.value.vdouble.scalar.base.DoubleScalarInterface;
7   import org.djutils.exceptions.Throw;
8   import org.opentrafficsim.kpi.interfaces.GtuDataInterface;
9   import org.opentrafficsim.kpi.sampling.Query;
10  import org.opentrafficsim.kpi.sampling.TrajectoryGroup;
11  
12  /**
13   * Abstract indicator which stores the last calculated value and returns it in {@code getValue()} for an equal query, start time
14   * and end time.
15   * <p>
16   * Copyright (c) 2013-2020 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
17   * BSD-style license. See <a href="http://opentrafficsim.org/node/13">OpenTrafficSim License</a>.
18   * <p>
19   * @version $Revision$, $LastChangedDate$, by $Author$, initial version 1 okt. 2016 <br>
20   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
21   * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
22   * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
23   * @param <T> class of the value
24   */
25  public abstract class AbstractIndicator<T extends DoubleScalarInterface>
26  {
27  
28      /** Last query. */
29      private Query<?> lastQuery;
30  
31      /** Last start time. */
32      private Time lastStartTime;
33  
34      /** Last end time. */
35      private Time lastEndTime;
36  
37      /** Last value. */
38      private T lastValue;
39  
40      /**
41       * Get value for given query over time interval, returning earlier calculated value if possible. This method uses
42       * {@code Time.ZERO} as start time.
43       * @param query Query&lt;G&gt;; query
44       * @param endTime Time; start time of interval to calculate indicator over
45       * @param trajectoryGroups List&lt;TrajectoryGroup&lt;G&gt;&gt;; group of trajectories to calculate the indicator for
46       * @param <G> gtu data type
47       * @return value for given query
48       */
49      public final <G extends GtuDataInterface> T getValue(final Query<G> query, final Time endTime,
50              final List<TrajectoryGroup<G>> trajectoryGroups)
51      {
52          return getValue(query, Time.ZERO, endTime, trajectoryGroups);
53      }
54  
55      /**
56       * Get value for given query over time interval, returning earlier calculated value if possible.
57       * @param query Query&lt;G&gt;; query
58       * @param startTime Time; start time of interval to calculate indicator over
59       * @param endTime Time; start time of interval to calculate indicator over
60       * @param trajectoryGroups List&lt;TrajectoryGroup&lt;G&gt;&gt;; group of trajectories to calculate the indicator for
61       * @param <G> gtu data type
62       * @return value for given query
63       */
64      public final <G extends GtuDataInterface> T getValue(final Query<G> query, final Time startTime, final Time endTime,
65              final List<TrajectoryGroup<G>> trajectoryGroups)
66      {
67          Throw.whenNull(query, "Query may not be null.");
68          Throw.whenNull(startTime, "Start time may not be null.");
69          Throw.whenNull(endTime, "End time may not be null.");
70          if (this.lastQuery == null || !this.lastQuery.equals(query) || !this.lastStartTime.equals(startTime)
71                  || !this.lastEndTime.equals(endTime))
72          {
73              this.lastQuery = query;
74              this.lastStartTime = startTime;
75              this.lastEndTime = endTime;
76              this.lastValue = calculate(query, startTime, endTime, trajectoryGroups);
77          }
78          return this.lastValue;
79      }
80  
81      /**
82       * Calculate value for given trajectory group.
83       * @param query Query&lt;G&gt;; query
84       * @param startTime Time; start time of interval to calculate indicator over
85       * @param endTime Time; start time of interval to calculate indicator over
86       * @param trajectoryGroups List&lt;TrajectoryGroup&lt;G&gt;&gt;; group of trajectories to calculate the indicator for
87       * @param <G> gtu data type
88       * @return value for given trajectory group
89       */
90      protected abstract <G extends GtuDataInterface> T calculate(final Query<G> query, final Time startTime, final Time endTime,
91              final List<TrajectoryGroup<G>> trajectoryGroups);
92  
93  }