Hiding internal pointers of SELECT_LEX structures

sql/item_subselect.cc

@@ -108,7 +108,7 @@ bool Item_subselect::fix_fields(THD *thd,TABLE_LIST *tables)
 		   (ORDER*) select_lex->group_list.first,
 		   select_lex->having,
 		   (ORDER*) 0, select_lex, 
-		   (SELECT_LEX_UNIT*) select_lex->master))
+		   select_lex->master_unit()))
     return 1;
   thd->lex.select= save_select;
   return 0;

sql/item_sum.cc

@@ -965,7 +965,7 @@ bool Item_sum_count_distinct::setup(THD *thd)
   if (!(table= create_tmp_table(thd, tmp_table_param, list, (ORDER*) 0, 1,
 				0, 0,
 				select_lex->options | thd->options,
-				(SELECT_LEX_UNIT*) select_lex->master)))
+				select_lex->master_unit())))
     return 1;
   table->file->extra(HA_EXTRA_NO_ROWS);		// Don't update rows
   table->no_rows=1;

sql/sql_derived.cc

@@ -34,7 +34,7 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
     TODO: make derived tables with union inside (now only 1 SELECT may be
     procesed)
   */
-  SELECT_LEX *sl= (SELECT_LEX*)unit->slave;
+  SELECT_LEX *sl= unit->first_select();
   List<Item> item_list;
   TABLE *table;
   int res;

sql/sql_lex.cc

@@ -1021,17 +1021,18 @@ bool st_select_lex_unit::create_total_list_n_last_return(THD *thd, st_lex *lex,
   TABLE_LIST *slave_list_first=0, **slave_list_last= &slave_list_first;
   TABLE_LIST **new_table_list= *result, *aux;
   SELECT_LEX *sl= (SELECT_LEX*)slave;
-  for (; sl; sl= (SELECT_LEX*)sl->next)
+  for (; sl; sl= sl->next_select())
   {
     // check usage of ORDER BY in union
-    if (sl->order_list.first && sl->next && !sl->braces)
+    if (sl->order_list.first && sl->next_select() && !sl->braces)
     {
       net_printf(&thd->net,ER_WRONG_USAGE,"UNION","ORDER BY");
       return 1;
     }
-    if (sl->slave)
-      if (((SELECT_LEX_UNIT *)
-	   sl->slave)->create_total_list_n_last_return(thd, lex,
+    for (SELECT_LEX_UNIT *inner=  sl->first_inner_unit();
+	 inner;
+	 inner= inner->next_unit())
+      if (inner->create_total_list_n_last_return(thd, lex,
 						 &slave_list_last))
 	return 1;
     if ((aux= (TABLE_LIST*) sl->table_list.first))

sql/sql_lex.h

@@ -186,11 +186,15 @@ enum sub_select_type {UNSPECIFIED_TYPE,UNION_TYPE, INTERSECT_TYPE,
     Base class for st_select_lex (SELECT_LEX) & 
     st_select_lex_unit (SELECT_LEX_UNIT)
 */
-struct st_select_lex_node {
-  enum sub_select_type linkage;
+class st_select_lex_node {
+protected:
   st_select_lex_node *next, **prev,   /* neighbor list */
     *master, *slave,                  /* vertical links */
     *link_next, **link_prev;          /* list of whole SELECT_LEX */
+public:
+  ulong options;
+  enum sub_select_type linkage;
+  //uint sort_default;
   SQL_LIST order_list;                /* ORDER clause */
   ha_rows select_limit, offset_limit; /* LIMIT clause parameters */
   void init_query();
@@ -207,9 +211,10 @@ private:
    SELECT_LEX_UNIT - unit of selects (UNION, INTERSECT, ...) group 
    SELECT_LEXs
 */
-struct st_lex;
-struct st_select_lex;
-struct st_select_lex_unit: public st_select_lex_node {
+class st_lex;
+class st_select_lex;
+class st_select_lex_unit: public st_select_lex_node {
+public:
   /*
     Pointer to 'last' select or pointer to unit where stored
     global parameters for union
@@ -219,8 +224,11 @@ struct st_select_lex_unit: public st_select_lex_node {
   ha_rows select_limit_cnt, offset_limit_cnt;
   void init_query();
   bool create_total_list(THD *thd, st_lex *lex, TABLE_LIST **result);
+  st_select_lex* outer_select() { return (st_select_lex*) master; }
   st_select_lex* first_select() { return (st_select_lex*) slave; }
   st_select_lex_unit* next_unit() { return (st_select_lex_unit*) next; }
+
+  friend void mysql_init_query(THD *thd);
 private:
   bool create_total_list_n_last_return(THD *thd, st_lex *lex,
 				       TABLE_LIST ***result);
@@ -230,10 +238,10 @@ typedef struct st_select_lex_unit SELECT_LEX_UNIT;
 /*
   SELECT_LEX - store information of parsed SELECT_LEX statment
 */
-struct st_select_lex: public st_select_lex_node {
+class st_select_lex: public st_select_lex_node {
+public:
   char *db, *db1, *table1, *db2, *table2;      	/* For outer join using .. */
   Item *where, *having;                         /* WHERE & HAVING clauses */
-  ulong options;
   List<List_item>     expr_list;
   List<List_item>     when_list;                /* WHEN clause */
   SQL_LIST	      table_list, group_list;   /* FROM & GROUP BY clauses */
@@ -241,14 +249,32 @@ struct st_select_lex: public st_select_lex_node {
   List<String>        interval_list, use_index, *use_index_ptr,
 		      ignore_index, *ignore_index_ptr;
   List<Item_func_match> ftfunc_list;
-  uint in_sum_expr, sort_default;
+  uint in_sum_expr;
   bool	create_refs, 
     braces,   /* SELECT ... UNION (SELECT ... ) <- this braces */
     depended; /* depended from outer select subselect */
   void init_query();
   void init_select();
-  st_select_lex* outer_select() { return (st_select_lex*) master->master; }
+  st_select_lex_unit* master_unit() { return (st_select_lex_unit*) master; }
+  st_select_lex_unit* first_inner_unit() 
+  { 
+    return (st_select_lex_unit*) slave; 
+  }
+  st_select_lex* outer_select() 
+  { 
+    return (st_select_lex*) master_unit()->outer_select(); 
+  }
   st_select_lex* next_select() { return (st_select_lex*) next; }
+  st_select_lex*  next_select_in_list() 
+  {
+    return (st_select_lex*) link_next;
+  }
+  st_select_lex_node** next_select_in_list_addr()
+  {
+    return &link_next;
+  }
+
+  friend void mysql_init_query(THD *thd);
 };
 typedef struct st_select_lex SELECT_LEX;
 

sql/sql_parse.cc

@@ -65,7 +65,7 @@ static void decrease_user_connections(UC *uc);
 static bool check_db_used(THD *thd,TABLE_LIST *tables);
 static bool check_merge_table_access(THD *thd, char *db, TABLE_LIST *tables);
 static bool check_dup(const char *db, const char *name, TABLE_LIST *tables);
-static void mysql_init_query(THD *thd);
+void mysql_init_query(THD *thd);
 static void remove_escape(char *name);
 static void refresh_status(void);
 static bool append_file_to_dir(THD *thd, char **filename_ptr,
@@ -1246,7 +1246,7 @@ mysql_execute_command(void)
 					   cursor))
 	DBUG_VOID_RETURN;
   }
-  if ((lex->select_lex.link_next && 
+  if ((lex->select_lex.next_select_in_list() && 
        lex->unit.create_total_list(thd, lex, &tables)) ||
       (table_rules_on && tables && thd->slave_thread &&
        !tables_ok(thd,tables)))
@@ -2664,7 +2664,7 @@ bool my_yyoverflow(short **yyss, YYSTYPE **yyvs, int *yystacksize)
 	Initialize global thd variables needed for query
 ****************************************************************************/
 
-static void
+void
 mysql_init_query(THD *thd)
 {
   DBUG_ENTER("mysql_init_query");
@@ -2720,8 +2720,8 @@ mysql_new_select(LEX *lex, bool move_down)
   else
     select_lex->include_neighbour(lex->select);
     
-  ((SELECT_LEX_UNIT*)select_lex->master)->global_parameters= select_lex;
-  select_lex->include_global(&lex->select->link_next);
+  select_lex->master_unit()->global_parameters= select_lex;
+  select_lex->include_global(lex->select->next_select_in_list_addr());
   lex->select= select_lex;
   return 0;
 }

sql/sql_select.cc

@@ -156,12 +156,12 @@ int handle_select(THD *thd, LEX *lex, select_result *result)
 {
   int res;
   register SELECT_LEX *select_lex = &lex->select_lex;
-  if (select_lex->link_next)
+  if (select_lex->next_select_in_list())
   {
     /* Fix tables 'to-be-unioned-from' list to point at opened tables */
     for (SELECT_LEX *sl= select_lex;
 	 sl;
-	 sl= (SELECT_LEX*)sl->link_next)
+	 sl= sl->next_select_in_list())
     {
       for (TABLE_LIST *cursor= (TABLE_LIST *)sl->table_list.first;
 	   cursor;
@@ -169,7 +169,7 @@ int handle_select(THD *thd, LEX *lex, select_result *result)
 	cursor->table= cursor->table_list->table;
     }
   }
-  if (select_lex->next)
+  if (select_lex->next_select())
     res=mysql_union(thd,lex,result);
   else
     res=mysql_select(thd,(TABLE_LIST*) select_lex->table_list.first,
@@ -7275,7 +7275,7 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
 	result->send_error(0,NullS);
     }
   }
-  if (!join->thd->lex.select->next)
+  if (!join->thd->lex.select->next_select())
   {
     save_lock=thd->lock;
     thd->lock=(MYSQL_LOCK *)0;

sql/sql_union.cc

@@ -104,7 +104,7 @@ int mysql_union(THD *thd, LEX *lex,select_result *result)
   }
   union_result->save_time_stamp=!describe;
 
-  for (sl= &lex->select_lex; sl; sl= (SELECT_LEX*) sl->next)
+  for (sl= &lex->select_lex; sl; sl= sl->next_select())
   {
     lex->select=sl;
     unit->offset_limit_cnt= sl->offset_limit;

sql/sql_yacc.yy

@@ -1477,8 +1477,8 @@ select_init:
             SELECT_LEX * sel=Select;
 	    sel->braces=true;
             /* select in braces, can't contain global parameters */
-            ((SELECT_LEX_UNIT*)sel->master)->global_parameters=
-              sel->master;
+            sel->master_unit()->global_parameters=
+              	sel->master_unit();
           } union_opt
 
 
@@ -2186,8 +2186,8 @@ join_table:
         | '(' SELECT_SYM select_part3 ')' opt_table_alias 
 	{
 	  LEX *lex=Lex;
-	  SELECT_LEX_UNIT *unit= (SELECT_LEX_UNIT*) lex->select->master;
-	  lex->select= (SELECT_LEX*) unit->master;
+	  SELECT_LEX_UNIT *unit= lex->select->master_unit();
+	  lex->select= unit->outer_select();
 	  if (!($$= add_table_to_list(new Table_ident(unit),
 	                              $5,0,TL_UNLOCK)))
 	    YYABORT;
@@ -2325,7 +2325,7 @@ order_clause:
 	  LEX *lex=Lex;
 	  if (lex->sql_command == SQLCOM_MULTI_UPDATE)
 	    YYABORT;
-	  lex->select->sort_default=1;
+	  /*lex->select->sort_default=1;*/
 	} order_list
 
 order_list:
@@ -3859,13 +3859,13 @@ optional_order_or_limit:
     LEX *lex=Lex;
     if (!lex->select->braces)
      YYABORT;
-    ((SELECT_LEX_UNIT*)lex->select->master)->global_parameters= 
-      lex->select->master;
+    lex->select->master_unit()->global_parameters= 
+      lex->select->master_unit();
     /*
       Following type conversion looks like hack, but all that need SELECT_LEX 
       fields always check linkage type.
     */
-    lex->select= (SELECT_LEX*)lex->select->master;
+    lex->select= (SELECT_LEX*)lex->select->master_unit();
     lex->select->select_limit=lex->thd->default_select_limit;
   }
   opt_order_clause limit_clause
@@ -3898,5 +3898,5 @@ subselect_end:
   ')'
   {
     LEX *lex=Lex;
-    lex->select = (SELECT_LEX*)lex->select->master->master;
+    lex->select = lex->select->outer_select();
   }