Adding Type_std_attributes to reduce some duplicate code.

TODO: move some methods from Item to Type_std_attributes.

Author: Alexander Barkov

sql/item.cc

@@ -412,13 +412,11 @@ int Item::save_str_value_in_field(Field *field, String *result)
 
 Item::Item():
   is_expensive_cache(-1), rsize(0), name(0), orig_name(0), name_length(0),
-  fixed(0), is_autogenerated_name(TRUE),
-  collation(&my_charset_bin, DERIVATION_COERCIBLE)
+  fixed(0), is_autogenerated_name(TRUE)
 {
   marker= 0;
-  maybe_null=null_value=with_sum_func=with_field=unsigned_flag=0;
+  maybe_null=null_value=with_sum_func=with_field=0;
   in_rollup= 0;
-  decimals= 0; max_length= 0;
   with_subselect= 0;
   cmp_context= IMPOSSIBLE_RESULT;
    /* Initially this item is not attached to any JOIN_TAB. */
@@ -451,26 +449,23 @@ Item::Item():
   tables.
 */
 Item::Item(THD *thd, Item *item):
+  Type_std_attributes(item),
   join_tab_idx(item->join_tab_idx),
   is_expensive_cache(-1),
   rsize(0),
   str_value(item->str_value),
   name(item->name),
   orig_name(item->orig_name),
-  max_length(item->max_length),
   name_length(item->name_length),
-  decimals(item->decimals),
   marker(item->marker),
   maybe_null(item->maybe_null),
   in_rollup(item->in_rollup),
   null_value(item->null_value),
-  unsigned_flag(item->unsigned_flag),
   with_sum_func(item->with_sum_func),
   with_field(item->with_field),
   fixed(item->fixed),
   is_autogenerated_name(item->is_autogenerated_name),
   with_subselect(item->has_subquery()),
-  collation(item->collation),
   cmp_context(item->cmp_context)
 {
   next= thd->free_list;				// Put in free list
@@ -3713,17 +3708,14 @@ void Item_param::print(String *str, enum_query_type query_type)
 void
 Item_param::set_param_type_and_swap_value(Item_param *src)
 {
-  unsigned_flag= src->unsigned_flag;
+  Type_std_attributes::set(src);
   param_type= src->param_type;
   set_param_func= src->set_param_func;
   item_type= src->item_type;
   item_result_type= src->item_result_type;
 
-  collation.set(src->collation);
   maybe_null= src->maybe_null;
   null_value= src->null_value;
-  max_length= src->max_length;
-  decimals= src->decimals;
   state= src->state;
   value= src->value;
 
@@ -6965,17 +6957,14 @@ bool Item_ref::fix_fields(THD *thd, Item **reference)
 
 void Item_ref::set_properties()
 {
-  max_length= (*ref)->max_length;
+  Type_std_attributes::set(*ref);
   maybe_null= (*ref)->maybe_null;
-  decimals=   (*ref)->decimals;
-  collation.set((*ref)->collation);
   /*
     We have to remember if we refer to a sum function, to ensure that
     split_sum_func() doesn't try to change the reference.
   */
   with_sum_func= (*ref)->with_sum_func;
   with_field= (*ref)->with_field;
-  unsigned_flag= (*ref)->unsigned_flag;
   fixed= 1;
   if (alias_name_used)
     return;
@@ -7415,13 +7404,10 @@ Item_cache_wrapper::Item_cache_wrapper(Item *item_arg)
 :orig_item(item_arg), expr_cache(NULL), expr_value(NULL)
 {
   DBUG_ASSERT(orig_item->fixed);
-  max_length= orig_item->max_length;
+  Type_std_attributes::set(orig_item);
   maybe_null= orig_item->maybe_null;
-  decimals=   orig_item->decimals;
-  collation.set(orig_item->collation);
   with_sum_func= orig_item->with_sum_func;
   with_field= orig_item->with_field;
-  unsigned_flag= orig_item->unsigned_flag;
   name= item_arg->name;
   name_length= item_arg->name_length;
   with_subselect=  orig_item->with_subselect;

sql/item.h

@@ -118,7 +118,7 @@ class DTCollation {
     derivation= derivation_arg;
     set_repertoire_from_charset(collation_arg);
   }
-  void set(DTCollation &dt)
+  void set(const DTCollation &dt)
   { 
     collation= dt.collation;
     derivation= dt.derivation;
@@ -546,7 +546,48 @@ class String_copier_for_item: public String_copier
 };
 
 
-class Item {
+/**
+  A class to store type attributes for the standard data types.
+  Does not include attributes for the extended data types
+  such as ENUM, SET, GEOMETRY.
+*/
+class Type_std_attributes
+{
+public:
+  DTCollation collation;
+  uint decimals;
+  /*
+    The maximum value length in characters multiplied by collation->mbmaxlen.
+    Almost always it's the maximum value length in bytes.
+  */
+  uint32 max_length;
+  bool unsigned_flag;
+  Type_std_attributes()
+   :collation(&my_charset_bin, DERIVATION_COERCIBLE),
+    decimals(0), max_length(0), unsigned_flag(false)
+  { }
+  Type_std_attributes(const Type_std_attributes *other)
+   :collation(other->collation),
+    decimals(other->decimals),
+    max_length(other->max_length),
+    unsigned_flag(other->unsigned_flag)
+  { }
+  void set(const Type_std_attributes *other)
+  {
+    *this= *other;
+  }
+  void set(const Field *field)
+  {
+    decimals= field->decimals();
+    max_length= field->field_length;
+    collation.set(field->charset());
+    unsigned_flag= MY_TEST(field->flags & UNSIGNED_FLAG);
+  }
+};
+
+
+class Item: public Type_std_attributes
+{
   Item(const Item &);			/* Prevent use of these */
   void operator=(Item &);
   /**
@@ -614,24 +655,17 @@ class Item {
      @see Query_arena::free_list
    */
   Item *next;
-  /*
-    The maximum value length in characters multiplied by collation->mbmaxlen.
-    Almost always it's the maximum value length in bytes.
-  */
-  uint32 max_length;
   /*
     TODO: convert name and name_length fields into LEX_STRING to keep them in
     sync (see bug #11829681/60295 etc). Then also remove some strlen(name)
     calls.
   */
   uint name_length;                     /* Length of name */
-  uint decimals;
   int8 marker;
   bool maybe_null;			/* If item may be null */
   bool in_rollup;                       /* If used in GROUP BY list
                                            of a query with ROLLUP */ 
   bool null_value;			/* if item is null */
-  bool unsigned_flag;
   bool with_sum_func;                   /* True if item contains a sum func */
   /**
     True if any item except Item_sum contains a field. Set during parsing.
@@ -643,7 +677,6 @@ class Item {
   bool with_subselect;                  /* If this item is a subselect or some
                                            of its arguments is or contains a
                                            subselect */
-  DTCollation collation;
   Item_result cmp_context;              /* Comparison context */
   // alloc & destruct is done as start of select using sql_alloc
   Item();
@@ -4149,14 +4182,11 @@ class Item_copy :public Item
   {
     item= i;
     null_value=maybe_null=item->maybe_null;
-    decimals=item->decimals;
-    max_length=item->max_length;
+    Type_std_attributes::set(item);
     name=item->name;
     cached_field_type= item->field_type();
     cached_result_type= item->result_type();
-    unsigned_flag= item->unsigned_flag;
     fixed= item->fixed;
-    collation.set(item->collation);
   }
 
 public:
@@ -4608,10 +4638,7 @@ class Item_cache: public Item_basic_constant
   virtual bool setup(Item *item)
   {
     example= item;
-    max_length= item->max_length;
-    decimals= item->decimals;
-    collation.set(item->collation);
-    unsigned_flag= item->unsigned_flag;
+    Type_std_attributes::set(item);
     if (item->type() == FIELD_ITEM)
       cached_field= ((Item_field *)item)->field;
     return 0;

sql/item_cmpfunc.cc

@@ -2654,13 +2654,10 @@ void Item_func_if::fix_after_pullout(st_select_lex *new_parent, Item **ref)
 
 void Item_func_if::cache_type_info(Item *source)
 {
-  collation.set(source->collation);
+  Type_std_attributes::set(source);
   cached_field_type=  source->field_type();
   cached_result_type= source->result_type();
-  decimals=           source->decimals;
-  max_length=         source->max_length;
   maybe_null=         source->maybe_null;
-  unsigned_flag=      source->unsigned_flag;
 }
 
 

sql/item_func.cc

@@ -6645,11 +6645,8 @@ void Item_func_sp::fix_length_and_dec()
   DBUG_ENTER("Item_func_sp::fix_length_and_dec");
 
   DBUG_ASSERT(sp_result_field);
-  decimals= sp_result_field->decimals();
-  max_length= sp_result_field->field_length;
-  collation.set(sp_result_field->charset());
+  Type_std_attributes::set(sp_result_field);
   maybe_null= 1;
-  unsigned_flag= MY_TEST(sp_result_field->flags & UNSIGNED_FLAG);
 
   DBUG_VOID_RETURN;
 }
@@ -6999,9 +6996,6 @@ my_decimal *Item_func_last_value::val_decimal(my_decimal *decimal_value)
 void Item_func_last_value::fix_length_and_dec()
 {
   last_value=          args[arg_count -1];
-  decimals=            last_value->decimals;
-  max_length=          last_value->max_length;
-  collation.set(last_value->collation.collation);
+  Type_std_attributes::set(last_value);
   maybe_null=          last_value->maybe_null;
-  unsigned_flag=       last_value->unsigned_flag;
 }