diff options
Diffstat (limited to 'sql/item.cc')
| -rw-r--r-- | sql/item.cc | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/sql/item.cc b/sql/item.cc index b6dfb97d128..5a15baa67c1 100644 --- a/sql/item.cc +++ b/sql/item.cc @@ -159,6 +159,46 @@ bool Item_ident::remove_dependence_processor(byte * arg) } +/* + Store the pointer to this item field into a list if not already there. + + SYNOPSIS + Item_field::collect_item_field_processor() + arg pointer to a List<Item_field> + + DESCRIPTION + The method is used by Item::walk to collect all unique Item_field objects + from a tree of Items into a set of items represented as a list. + + IMPLEMENTATION + Item_cond::walk() and Item_func::walk() stop the evaluation of the + processor function for its arguments once the processor returns + true.Therefore in order to force this method being called for all item + arguments in a condition the method must return false. + + RETURN + false on success (force the evaluation of collect_item_field_processor + for the subsequent items.) + true o/w (stop evaluation of subsequent items.) +*/ + +bool Item_field::collect_item_field_processor(byte *arg) +{ + DBUG_ENTER("Item_field::collect_item_field_processor"); + DBUG_PRINT("info", ("%s", field->field_name ? field->field_name : "noname")); + List<Item_field> *item_list= (List<Item_field>*) arg; + List_iterator<Item_field> item_list_it(*item_list); + Item_field *curr_item; + while ((curr_item= item_list_it++)) + { + if (curr_item->eq(this, 1)) + DBUG_RETURN(false); /* Already in the set. */ + } + item_list->push_back(this); + DBUG_RETURN(false); +} + + bool Item::check_cols(uint c) { if (c != 1) |