execute method

@override List execute(List results, Map<String, dynamic> passed)

The iterable, nested function that evaluates the entire FHIRPath expression one object at a time

Implementation

@override
List execute(List results, Map<String, dynamic> passed) {
  final executedBefore = before.execute(results.toList(), passed);
  final executedAfter = after.execute(results.toList(), passed);
  if (executedBefore.isEmpty || executedAfter.isEmpty) {
    return [];
  } else if (executedBefore.length != 1 || executedAfter.length != 1) {
    throw FhirPathEvaluationException(
      'Math Operators require each operand to result in a '
      'single object. The "-" operator was passed the following:\n'
      'Operand 1: $executedBefore\n'
      'Operand 2: $executedAfter',
      operation: '-',
      collection: results,
    );
  } else {
    switch (executedBefore.first.runtimeType) {
      case int:
        {
          if (executedAfter.first is num) {
            return [
              (executedBefore.first as int) - (executedAfter.first as num),
            ];
          }
          break;
        }
      case double:
        {
          if (executedAfter.first is num) {
            return [
              (executedBefore.first as double) - (executedAfter.first as num),
            ];
          }
          break;
        }
      case ValidatedQuantity:
        {
          if (executedAfter.first is ValidatedQuantity) {
            return [
              (executedBefore.first as ValidatedQuantity) -
                  (executedAfter.first as ValidatedQuantity),
            ];
          }
          break;
        }
      case FhirDateTime:
        {
          if (executedAfter.first is ValidatedQuantity &&
              (executedAfter.first as ValidatedQuantity).isDuration) {
            return [
              (executedBefore.first -
                      extendedDurationFromValidatedQuantity(
                        executedAfter.first as ValidatedQuantity,
                      ))
                  .toString(),
            ];
          }
          break;
        }
      case FhirDate:
        {
          if (executedAfter.first is ValidatedQuantity &&
              (executedAfter.first as ValidatedQuantity).isDuration) {
            return [
              (executedBefore.first -
                      extendedDurationFromValidatedQuantity(
                        executedAfter.first as ValidatedQuantity,
                      ))
                  .toString(),
            ];
          }
          break;
        }
      case FhirTime:
        {
          if (executedAfter.first is ValidatedQuantity &&
              (executedAfter.first as ValidatedQuantity).isDuration) {
            return [
              subtractFromFhirTime(
                executedBefore.first,
                (executedAfter.first as ValidatedQuantity),
              ).toString(),
            ];
          }
          break;
        }
      case String:
        {
          if (executedAfter.first is ValidatedQuantity &&
              (executedAfter.first as ValidatedQuantity).isDuration) {
            if (FhirDateTime(executedBefore.first).isValid) {
              return [
                (FhirDateTime(executedBefore.first) -
                        extendedDurationFromValidatedQuantity(
                          executedAfter.first,
                        ))
                    .toString(),
              ];
            } else if (FhirTime(executedBefore.first).isValid) {
              return [
                subtractFromFhirTime(
                  FhirTime(executedBefore.first),
                  executedAfter.first as ValidatedQuantity,
                ).toString(),
              ];
            }
          }
          break;
        }
      default:
        break;
    }
    throw FhirPathEvaluationException(
      'The "-" operator only accepts Integers, Decimals and '
      'Quantities, but was passed the following:\n'
      'Operand 1: ${executedBefore.first} (${executedBefore.first.runtimeType})\n'
      'Operand 2: ${executedAfter.first} (${executedAfter.first.runtimeType})',
      operation: '-',
      collection: results,
    );
  }
}