bool DescriptorBuilder::ValidateMapEntry()

in cdk/extra/protobuf/protobuf-3.19.6/src/google/protobuf/descriptor.cc [6794:6864]
59 lines of code
35 McCabe index (conditional complexity)

bool DescriptorBuilder::ValidateMapEntry(FieldDescriptor* field,
                                         const FieldDescriptorProto& proto) {
  const Descriptor* message = field->message_type();
  if (  // Must not contain extensions, extension range or nested message or
        // enums
      message->extension_count() != 0 ||
      field->label() != FieldDescriptor::LABEL_REPEATED ||
      message->extension_range_count() != 0 ||
      message->nested_type_count() != 0 || message->enum_type_count() != 0 ||
      // Must contain exactly two fields
      message->field_count() != 2 ||
      // Field name and message name must match
      message->name() != ToCamelCase(field->name(), false) + "Entry" ||
      // Entry message must be in the same containing type of the field.
      field->containing_type() != message->containing_type()) {
    return false;
  }

  const FieldDescriptor* key = message->map_key();
  const FieldDescriptor* value = message->map_value();
  if (key->label() != FieldDescriptor::LABEL_OPTIONAL || key->number() != 1 ||
      key->name() != "key") {
    return false;
  }
  if (value->label() != FieldDescriptor::LABEL_OPTIONAL ||
      value->number() != 2 || value->name() != "value") {
    return false;
  }

  // Check key types are legal.
  switch (key->type()) {
    case FieldDescriptor::TYPE_ENUM:
      AddError(field->full_name(), proto, DescriptorPool::ErrorCollector::TYPE,
               "Key in map fields cannot be enum types.");
      break;
    case FieldDescriptor::TYPE_FLOAT:
    case FieldDescriptor::TYPE_DOUBLE:
    case FieldDescriptor::TYPE_MESSAGE:
    case FieldDescriptor::TYPE_GROUP:
    case FieldDescriptor::TYPE_BYTES:
      AddError(
          field->full_name(), proto, DescriptorPool::ErrorCollector::TYPE,
          "Key in map fields cannot be float/double, bytes or message types.");
      break;
    case FieldDescriptor::TYPE_BOOL:
    case FieldDescriptor::TYPE_INT32:
    case FieldDescriptor::TYPE_INT64:
    case FieldDescriptor::TYPE_SINT32:
    case FieldDescriptor::TYPE_SINT64:
    case FieldDescriptor::TYPE_STRING:
    case FieldDescriptor::TYPE_UINT32:
    case FieldDescriptor::TYPE_UINT64:
    case FieldDescriptor::TYPE_FIXED32:
    case FieldDescriptor::TYPE_FIXED64:
    case FieldDescriptor::TYPE_SFIXED32:
    case FieldDescriptor::TYPE_SFIXED64:
      // Legal cases
      break;
      // Do not add a default, so that the compiler will complain when new types
      // are added.
  }

  if (value->type() == FieldDescriptor::TYPE_ENUM) {
    if (value->enum_type()->value(0)->number() != 0) {
      AddError(field->full_name(), proto, DescriptorPool::ErrorCollector::TYPE,
               "Enum value in map must define 0 as the first value.");
    }
  }

  return true;
}