isSubtypeOf method

@override bool isSubtypeOf(RuntimeType other, { Object? value, })

Checks if this type is a subtype of other.

Implementation

@override
bool isSubtypeOf(RuntimeType other, {Object? value}) {
  if (other is FunctionRuntimeType) {
    // An untyped function type matches any function and vice-versa.
    if (_isUntyped || other._isUntyped) return true;
    // Return type is covariant.
    if (!_runtimeTypeCompatible(returnType, other.returnType)) return false;
    // Required positional parameters must line up 1:1 (contravariant).
    if (positionalParameterTypes.length !=
        other.positionalParameterTypes.length) {
      return false;
    }
    for (var i = 0; i < positionalParameterTypes.length; i++) {
      if (!_runtimeTypeCompatible(
          other.positionalParameterTypes[i], positionalParameterTypes[i])) {
        return false;
      }
    }
    // Named parameters: every named parameter the supertype declares must be
    // present here with a contravariant-compatible type.
    for (final entry in other.namedParameterTypes.entries) {
      final mine = namedParameterTypes[entry.key];
      if (mine == null) return false;
      if (!_runtimeTypeCompatible(entry.value, mine)) return false;
    }
    return true;
  }
  // Every function is a `Function` and an `Object`.
  return _isWildcardTypeName(other.name) || other.name == 'Function';
}