Method is_signed

cpp/src/parquet/types.cc:1687–1689

}

bool IntLogicalType::is_signed() const {
  return (dynamic_cast<const LogicalType::Impl::Int&>(*impl_)).is_signed();
}

class LogicalType::Impl::Null final : public LogicalType::Impl::Incompatible,
                                      public LogicalType::Impl::UniversalApplicable {