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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 */