sqlite3のエラーコードに対応するerror_categoryの実装を考えてみた。

sqlite3_error_category.cpp

#include <system_error>

const std::error_category& sqlite3_error_category()
{
	class sqlite3_error_category : public std::error_category
	{
		virtual const char* name() const noexcept override
		{
			return "sqlite3";
		}

		virtual std::string message(int ev) const override
		{
			return sqlite3_errstr(ev);
		}

		virtual std::error_condition default_error_condition(int ev) const noexcept override
		{
			switch (ev)
			{
				 case 0: return std::error_condition(); // SQLITE_OK
				 //case SQLITE_PERM: return std::error_condition(std::errc::operation_not_permitted); // EPERM
				 case SQLITE_ABORT: return std::error_condition(std::errc::operation_canceled); //E ECANCELED
				 case SQLITE_BUSY: return std::error_condition(std::errc::device_or_resource_busy); // EBUSY
				 case SQLITE_NOMEM: return std::error_condition(std::errc::not_enough_memory); // ENOMEM
				 case SQLITE_INTERRUPT: return std::error_condition(std::errc::operation_canceled); //E ECANCELED
				 case SQLITE_IOERR: return std::error_condition(std::errc::io_error); // EIO
				 case SQLITE_FULL: return std::error_condition(std::errc::no_space_on_device); // ENOSPC
				 //case SQLITE_TOOBIG: return std::error_condition(std::errc::argument_list_too_long); // E2BIG
				 //case SQLITE_AUTH: return std::error_condition(std::errc::permission_denied); // EACCES
				 //case SQLITE_RANGE: return std::error_condition(std::errc::result_out_of_range); // ERANGE
				 default: return std::error_condition(ev, sqlite3_error_category());
			}
		}
	};

	static const sqlite3_error_category category;
	return category;
}