How to use

newValuesOf

method

in

org.diirt.datasource.ExpressionLanguage

/**
 * Returns up to 1,000 new values generated by the expression source rate.
 * <p>
 * You are strongly encouraged to use {@link #newValuesOf(org.diirt.datasource.expression.SourceRateExpression, int) }
 * to set a limit that is appropriate for your application.
 *
 * @param <T> type being read
 * @param expression source rate expression
 * @return a new expression
 */
public static <T> DesiredRateExpression<List<T>>
    newValuesOf(SourceRateExpression<T> expression) {
  return newValuesOf(expression, 1000);
}

/**
 * Returns all the new values generated by the expression source rate.
 *
 * @param <T> type being read
 * @param expressions source rate expressions
 * @return a new expression
 */
public static <T> DesiredRateExpressionList<List<T>>
    newValuesOf(SourceRateExpressionList<T> expressions) {
  DesiredRateExpressionList<List<T>> list = new DesiredRateExpressionListImpl<List<T>>();
  for (SourceRateExpression<T> expression : expressions.getSourceRateExpressions()) {
    list.and(newValuesOf(expression));
  }
  return list;
}

PVReader<List<VNumber>> reader = PVManager.read(ExpressionLanguage.newValuesOf(vNumber("ramp()")))
    .readListener(new PVReaderListener<List<VNumber>>() {
      @Override

public void b2_readAllValues() {
  // Read channel "channelName" up to every 100 ms, and get all
  // the new values from the last notification.
  PVReader<List<Object>> pvReader = PVManager
    .read(newValuesOf(channel("channelName")))
    .readListener(new PVReaderListener<List<Object>>() {
      @Override
      public void pvChanged(PVReaderEvent<List<Object>> event) {
        // Do something with each value
        for (Object newValue : event.getPvReader().getValue()) {
          System.out.println(newValue);
        }
      }
    })
    .maxRate(ofMillis(100));
  // Remember to close
  pvReader.close();
  // newValuesOf limits the values in the queue, to protect memory
  // consumption in problematic circumstances. The default is 1000 elements,
  // which you can override. See all options in the ExpressionLanguage class.
}

/**
 * Aggregates the sample at the scan rate and takes the average.
 *
 * @param doublePv the expression to take the average of; can't be null
 * @return an expression representing the average of the expression
 */
public static DesiredRateExpression<VDouble> averageOf(SourceRateExpression<VDouble> doublePv) {
  DesiredRateExpression<List<VDouble>> queue = newValuesOf(doublePv);
  return new DesiredRateExpressionImpl<VDouble>(queue,
      new AverageAggregator(queue.getFunction()), "avg(" + doublePv.getName() + ")");
}

/**
 * Aggregates the sample at the scan rate and calculates statistical information.
 *
 * @param doublePv the expression to calculate the statistics information on; can't be null
 * @return an expression representing the statistical information of the expression
 */
public static DesiredRateExpression<VStatistics> statisticsOf(SourceRateExpression<VDouble> doublePv) {
  DesiredRateExpression<List<VDouble>> queue = newValuesOf(doublePv);
  return new DesiredRateExpressionImpl<VStatistics>(queue,
      new StatisticsDoubleAggregator(queue.getFunction()), "stats(" + doublePv.getName() + ")");
}