std::string::substr may cause std::out_of_range exception
std::stoull and std::stoll may cause std::invalid_argument exception
both will cause php terminated.

related method:
bdict::parse
bint::parse
bstr::parse
bitem::escape_key  -> used by bdict::search
bitem::get_current_key  -> used by bdict/blist  del_path get_path set_path