convertArguments static method

List<Object?> convertArguments(Object function, List<Object?> arguments, TypeConverter converter)

arguments converted with converter to the parameter types of function where they do not fit, like Spring's ReflectionHelper.convertAllArguments; the list is returned as it is when nothing changes: #half(3) with a double parameter gets 3.0, 'abc'.substring('1') gets 1, 'abc'.charAt(1.0) gets 1. Dart has no reflection, so the parameter types are probed: int, double, num, String and bool parameters of the first maxConvertedArity positional parameters convert; an argument that cannot be converted is passed as it is (the call then fails as usual).

Implementation

static List<Object?> convertArguments(
  Object function,
  List<Object?> arguments,
  TypeConverter converter,
) {
  final (Function target, int count, int converted) = switch (function) {
    VarargsFunction(:final function, :final fixedArity) => (
      function,
      fixedArity + 1,
      fixedArity,
    ),
    final Function function => (function, arguments.length, arguments.length),
    _ => (_noFunction, 0, 0),
  };
  if (count > maxConvertedArity || converted > arguments.length) {
    return arguments;
  }
  List<Object?>? result;
  for (var i = 0; i < converted; i++) {
    final value = arguments[i];
    if (value == null || _accepts<Object?>(target, count, i)) {
      continue;
    }
    final Type? type;
    if (_accepts<int>(target, count, i) &&
        _accepts<double>(target, count, i)) {
      type = value is num ? null : num;
    } else if (_accepts<double>(target, count, i)) {
      type = value is double ? null : double;
    } else if (_accepts<int>(target, count, i)) {
      type = value is int ? null : int;
    } else if (_accepts<String>(target, count, i)) {
      type = value is String ? null : String;
    } else if (_accepts<bool>(target, count, i)) {
      type = value is bool ? null : bool;
    } else {
      type = null;
    }
    if (type == null) {
      continue;
    }
    try {
      final convertedValue = type == num
          ? _toNum(value, converter)
          : converter.convertValue(value, type);
      (result ??= [...arguments])[i] = convertedValue;
    } on Exception {
      // Not convertible: the call reports the mismatch.
    }
  }
  return result ?? arguments;
}