Method next

src/query/expression/ExpressionIterator.java:323–358

Fetches the next set of data and computes a value for the expression. Make sure to call #compile() first. And make sure to call #hasNext() before calling this. @return A link to the data points for this result set @throws IllegalDataException if there wasn't any data left in any of t

(final long timestamp)

   * @throws JexlException if something went pear shaped processing the expression
   */
  public ExpressionDataPoint[] next(final long timestamp) {
    
    // fetch the timestamp ONCE to save some cycles.
    // final long timestamp = iterator.nextTimestamp();
    iterator.next();
    
    // set aside a couple of addresses for the variables
    double val;
    double result;
    for (int i = 0; i < iterator.getSeriesSize(); i++) {
      // this here is why life sucks. there MUST be a better way to bind variables
      for (final String variable : names) {
        if (iteration_results.get(variable)[i] == null) {
          context.set(variable, results.get(variable).getFillPolicy().getValue());
        } else {
          val = iteration_results.get(variable)[i].toDouble();
          if (Double.isNaN(val)) {
            context.set(variable, results.get(variable).getFillPolicy().getValue());
          } else {
            context.set(variable, val);
          }
        }
      }
      final Object output = expression.execute(context);
      if (output instanceof Double) {
        result = (Double) output;
      } else if (output instanceof Boolean) {
        result = (((Boolean) output) ? 1 : 0);
      } else {
        throw new IllegalStateException("Expression returned a result of type: " 
            + output.getClass().getName() + " for " + this);
      }
      dps[i].reset(timestamp, result);
    }
    return dps;
  }
  
  /** @return a list of expression results. You can keep this list and check the 
   * results on each call to {@link #next(int)} */