diff options
Diffstat (limited to 'sql/item_subselect.cc')
| -rw-r--r-- | sql/item_subselect.cc | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc index f3f840bdaa9..e2004356821 100644 --- a/sql/item_subselect.cc +++ b/sql/item_subselect.cc @@ -51,6 +51,10 @@ Item_subselect::Item_subselect(): void Item_subselect::init(st_select_lex *select_lex, select_subselect *result) { + /* + Please see Item_singlerow_subselect::invalidate_and_restore_select_lex(), + which depends on alterations to the parse tree implemented here. + */ DBUG_ENTER("Item_subselect::init"); DBUG_PRINT("enter", ("select_lex: 0x%lx", (long) select_lex)); @@ -91,6 +95,12 @@ void Item_subselect::init(st_select_lex *select_lex, DBUG_VOID_RETURN; } +st_select_lex * +Item_subselect::get_select_lex() +{ + return unit->first_select(); +} + void Item_subselect::cleanup() { DBUG_ENTER("Item_subselect::cleanup"); @@ -307,6 +317,26 @@ Item_singlerow_subselect::Item_singlerow_subselect(st_select_lex *select_lex) DBUG_VOID_RETURN; } +st_select_lex * +Item_singlerow_subselect::invalidate_and_restore_select_lex() +{ + DBUG_ENTER("Item_singlerow_subselect::invalidate_and_restore_select_lex"); + st_select_lex *result= get_select_lex(); + + DBUG_ASSERT(result); + + /* + This code restore the parse tree in it's state before the execution of + Item_singlerow_subselect::Item_singlerow_subselect(), + and in particular decouples this object from the SELECT_LEX, + so that the SELECT_LEX can be used with a different flavor + or Item_subselect instead, as part of query rewriting. + */ + unit->item= NULL; + + DBUG_RETURN(result); +} + Item_maxmin_subselect::Item_maxmin_subselect(THD *thd_param, Item_subselect *parent, st_select_lex *select_lex, |