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 FhirPathQuantity:
        {
          if (executedAfter.first is FhirPathQuantity) {
            return [
              (executedBefore.first as FhirPathQuantity) -
                  (executedAfter.first as FhirPathQuantity)
            ];
          }
          break;
        }
      case FhirDateTime:
        {
          if (executedAfter.first is FhirPathQuantity) {
            return [
              (executedAfter.first as FhirPathQuantity)
                  .subtract(executedBefore.first)
                  .toString()
            ];
          }
          break;
        }
      case FhirDate:
        {
          if (executedAfter.first is FhirPathQuantity) {
            return [
              (executedAfter.first as FhirPathQuantity)
                  .subtract(executedBefore.first)
                  .toString()
            ];
          }
          break;
        }
      case FhirTime:
        {
          if (executedAfter.first is FhirPathQuantity) {
            return [
              (executedAfter.first as FhirPathQuantity)
                  .subtract(executedBefore.first)
                  .toString()
            ];
          }
          break;
        }
      case String:
        {
          if (executedAfter.first is FhirPathQuantity) {
            if (FhirDateTime(executedBefore.first).isValid) {
              return [
                (executedAfter.first as FhirPathQuantity)
                    .subtract(FhirDateTime(executedBefore.first))
                    .toString()
              ];
            } else if (FhirTime(executedBefore.first).isValid) {
              return [
                (executedAfter.first as FhirPathQuantity)
                    .subtract(FhirTime(executedBefore.first))
                    .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);
  }
}