Edit: derived_handler.h
/* Copyright (c) 2016, 2017 MariaDB This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #ifndef DERIVED_HANDLER_INCLUDED #define DERIVED_HANDLER_INCLUDED #include "mariadb.h" #include "sql_priv.h" class TMP_TABLE_PARAM; typedef class st_select_lex_unit SELECT_LEX_UNIT; /** @class derived_handler This interface class is to be used for execution of queries that specify derived table by foreign engines */ class derived_handler { public: THD *thd; handlerton *ht; TABLE_LIST *derived; /* Temporary table where all results should be stored in record[0] The table has a field for every item from the select list of the specification of derived. */ TABLE *table; /* The parameters if the temporary table used at its creation */ TMP_TABLE_PARAM *tmp_table_param; SELECT_LEX_UNIT *unit; // Specifies the derived table SELECT_LEX *select; // The first select of the specification derived_handler(THD *thd_arg, handlerton *ht_arg) : thd(thd_arg), ht(ht_arg), derived(0),table(0), tmp_table_param(0), unit(0), select(0) {} virtual ~derived_handler() = default; /* Functions to scan data. All these returns 0 if ok, error code in case of error */ /* Initialize the process of producing rows of the derived table */ virtual int init_scan()= 0; /* Put the next produced row of the derived in table->record[0] and return 0. Return HA_ERR_END_OF_FILE if there are no more rows, return other error number in case of fatal error. */ virtual int next_row()= 0; /* End prodicing rows */ virtual int end_scan()=0; /* Report errors */ virtual void print_error(int error, myf errflag); void set_derived(TABLE_LIST *tbl); }; #endif /* DERIVED_HANDLER_INCLUDED */
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