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+/*
+ Copyright (c) 2018, 2019 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 SELECT_HANDLER_INCLUDED
+#define SELECT_HANDLER_INCLUDED
+
+#include "mariadb.h"
+#include "sql_priv.h"
+
+/**
+ @class select_handler
+
+ This interface class is to be used for execution of select queries
+ by foreign engines
+*/
+
+class select_handler
+{
+ public:
+ THD *thd;
+ handlerton *ht;
+
+ SELECT_LEX *select; // Select to be excuted
+
+ /*
+ Temporary table where all results should be stored in record[0]
+ The table has a field for every item from the select_lex::item_list.
+ The table is actually never filled. Only its record buffer is used.
+ */
+ TABLE *table;
+ List<Item> result_columns;
+
+ bool is_analyze;
+
+ bool send_result_set_metadata();
+ bool send_data();
+
+ select_handler(THD *thd_arg, handlerton *ht_arg);
+
+ virtual ~select_handler();
+
+ int execute();
+
+ virtual bool prepare();
+
+ static TABLE *create_tmp_table(THD *thd, SELECT_LEX *sel);
+
+protected:
+ /*
+ Functions to scan the select result set.
+ All these returns 0 if ok, error code in case of error.
+ */
+
+ /* Initialize the process of producing rows of result set */
+ virtual int init_scan() = 0;
+
+ /*
+ Put the next produced row of the result set 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;
+
+ /* Finish scanning */
+ virtual int end_scan() = 0;
+
+ /* Report errors */
+ virtual void print_error(int error, myf errflag);
+
+ bool send_eof();
+};
+
+#endif /* SELECT_HANDLER_INCLUDED */