changes based on partial revie of task 577 (SCRUM)

sql/item.cc:
  Fixed Item usual constructor to call current_thd only once.
  Fixed copy constructor to receive THD pointer via arguments.
  added comments
  removed counter-1 and unnessesary initializaton of counter
sql/item.h:
  Fixed copy constructor to receive THD pointer via arguments.
  Renamed get_same to copy_or_same.
  THD pointetr added to copy_or_same and get_tmp_table_item.
sql/item_cmpfunc.cc:
  fixed layout
  fixed direct call of destructor
sql/item_func.cc:
  fiex layout
  THD pointetr added to get_tmp_table_item.
sql/item_func.h:
  THD pointetr added to get_tmp_table_item.
sql/item_sum.cc:
  Fixed copy constructor to receive THD pointer via arguments.
  Renamed get_same to copy_or_same.
  THD pointetr added to copy_or_same and get_tmp_table_item.
sql/item_sum.h:
  fixed layout
  Fixed copy constructor to receive THD pointer via arguments.
  Renamed get_same to copy_or_same.
  THD pointetr added to copy_or_same and get_tmp_table_item.
sql/item_uniq.h:
  Fixed copy constructor to receive THD pointer via arguments.
  Renamed get_same to copy_or_same.
  THD pointetr added to copy_or_same and get_tmp_table_item.
sql/sql_base.cc:
  count from 0
sql/sql_select.cc:
  removed counter-1 and unnessesary initializaton of counter
  THD pointetr added to get_tmp_table_item and change_to_use_tmp_fields.

sql/item_sum.h

@@ -55,7 +55,7 @@ public:
   }
   Item_sum(List<Item> &list);
   //Copy constructor, need to perform subselects with temporary tables
-  Item_sum(Item_sum &item);
+  Item_sum(THD *thd, Item_sum &item);
   ~Item_sum() { result_field=0; }
 
   enum Type type() const { return SUM_FUNC_ITEM; }
@@ -77,7 +77,7 @@ public:
   void print(String *str);
   void fix_num_length_and_dec();
   virtual bool setup(THD *thd) {return 0;}
-  Item * get_tmp_table_item();
+  Item *get_tmp_table_item(THD *thd);
 };
 
 
@@ -88,7 +88,7 @@ public:
   Item_sum_num(Item *item_par) :Item_sum(item_par) {}
   Item_sum_num(Item *a, Item* b) :Item_sum(a,b) {}
   Item_sum_num(List<Item> &list) :Item_sum(list) {}
-  Item_sum_num(Item_sum_num &item) :Item_sum(item) {}
+  Item_sum_num(THD *thd, Item_sum_num &item) :Item_sum(thd, item) {}
   bool fix_fields(THD *, TABLE_LIST *, Item **);
   longlong val_int() { return (longlong) val(); } /* Real as default */
   String *val_str(String*str);
@@ -104,7 +104,7 @@ class Item_sum_int :public Item_sum_num
 public:
   Item_sum_int(Item *item_par) :Item_sum_num(item_par) {}
   Item_sum_int(List<Item> &list) :Item_sum_num(list) {}
-  Item_sum_int(Item_sum_int &item) :Item_sum_num(item) {}
+  Item_sum_int(THD *thd, Item_sum_int &item) :Item_sum_num(thd, item) {}
   double val() { return (double) val_int(); }
   String *val_str(String*str);
   enum Item_result result_type () const { return INT_RESULT; }
@@ -118,7 +118,8 @@ class Item_sum_sum :public Item_sum_num
 
   public:
   Item_sum_sum(Item *item_par) :Item_sum_num(item_par),sum(0.0) {}
-  Item_sum_sum(Item_sum_sum &item) :Item_sum_num(item), sum(item.sum) {}
+  Item_sum_sum(THD *thd, Item_sum_sum &item) 
+    :Item_sum_num(thd, item), sum(item.sum) {}
   enum Sumfunctype sum_func () const {return SUM_FUNC;}
   void reset();
   bool add();
@@ -126,7 +127,7 @@ class Item_sum_sum :public Item_sum_num
   void reset_field();
   void update_field(int offset);
   const char *func_name() const { return "sum"; }
-  Item * get_same() { return new Item_sum_sum(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_sum(thd, *this); }
 };
 
 
@@ -139,9 +140,9 @@ class Item_sum_count :public Item_sum_int
   Item_sum_count(Item *item_par)
     :Item_sum_int(item_par),count(0),used_table_cache(~(table_map) 0)
   {}
-  Item_sum_count(Item_sum_count &item): Item_sum_int(item),
-					count(item.count),
-					used_table_cache(item.used_table_cache)
+  Item_sum_count(THD *thd, Item_sum_count &item)
+    :Item_sum_int(thd, item), count(item.count),
+     used_table_cache(item.used_table_cache)
   {}
   table_map used_tables() const { return used_table_cache; }
   bool const_item() const { return !used_table_cache; }
@@ -153,7 +154,7 @@ class Item_sum_count :public Item_sum_int
   void reset_field();
   void update_field(int offset);
   const char *func_name() const { return "count"; }
-  Item * get_same() { return new Item_sum_count(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_count(thd, *this); }
 };
 
 
@@ -206,15 +207,15 @@ class Item_sum_count_distinct :public Item_sum_int
      tmp_table_param(0), tree(&tree_base), original(0), use_tree(0),
      always_null(0)
   { quick_group= 0; }
-  Item_sum_count_distinct(Item_sum_count_distinct &item):
-    Item_sum_int(item), table(item.table),
-    used_table_cache(item.used_table_cache),
-    field_lengths(item.field_lengths), tmp_table_param(item.tmp_table_param),
-    tree(item.tree), original(&item), key_length(item.key_length),
-    max_elements_in_tree(item.max_elements_in_tree),
-    rec_offset(item.rec_offset), use_tree(item.use_tree),
-    always_null(item.always_null)
-    {}
+  Item_sum_count_distinct(THD *thd, Item_sum_count_distinct &item)
+    :Item_sum_int(thd, item), table(item.table),
+     used_table_cache(item.used_table_cache),
+     field_lengths(item.field_lengths), tmp_table_param(item.tmp_table_param),
+     tree(item.tree), original(&item), key_length(item.key_length),
+     max_elements_in_tree(item.max_elements_in_tree),
+     rec_offset(item.rec_offset), use_tree(item.use_tree),
+     always_null(item.always_null)
+  {}
   ~Item_sum_count_distinct();
   table_map used_tables() const { return used_table_cache; }
   enum Sumfunctype sum_func () const { return COUNT_DISTINCT_FUNC; }
@@ -225,7 +226,10 @@ class Item_sum_count_distinct :public Item_sum_int
   void update_field(int offset) { return ; }	// Never called
   const char *func_name() const { return "count_distinct"; }
   bool setup(THD *thd);
-  Item * get_same() { return new Item_sum_count_distinct(*this); }
+  Item *copy_or_same(THD* thd) 
+  {
+    return new Item_sum_count_distinct(thd, *this);
+  }
 };
 
 
@@ -257,8 +261,8 @@ class Item_sum_avg :public Item_sum_num
 
   public:
   Item_sum_avg(Item *item_par) :Item_sum_num(item_par),count(0) {}
-  Item_sum_avg(Item_sum_avg &item)
-    :Item_sum_num(item), sum(item.sum), count(item.count) {}
+  Item_sum_avg(THD *thd, Item_sum_avg &item)
+    :Item_sum_num(thd, item), sum(item.sum), count(item.count) {}
   enum Sumfunctype sum_func () const {return AVG_FUNC;}
   void reset();
   bool add();
@@ -268,7 +272,7 @@ class Item_sum_avg :public Item_sum_num
   Item *result_item(Field *field)
   { return new Item_avg_field(this); }
   const char *func_name() const { return "avg"; }
-  Item * get_same() { return new Item_sum_avg(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_avg(thd, *this); }
 };
 
 class Item_sum_variance;
@@ -309,8 +313,8 @@ class Item_sum_variance : public Item_sum_num
 
   public:
   Item_sum_variance(Item *item_par) :Item_sum_num(item_par),count(0) {}
-  Item_sum_variance(Item_sum_variance &item):
-    Item_sum_num(item), sum(item.sum), sum_sqr(item.sum_sqr),
+  Item_sum_variance(THD *thd, Item_sum_variance &item):
+    Item_sum_num(thd, item), sum(item.sum), sum_sqr(item.sum_sqr),
     count(item.count) {}
   enum Sumfunctype sum_func () const { return VARIANCE_FUNC; }
   void reset();
@@ -321,7 +325,7 @@ class Item_sum_variance : public Item_sum_num
   Item *result_item(Field *field)
   { return new Item_variance_field(this); }
   const char *func_name() const { return "variance"; }
-  Item * get_same() { return new Item_sum_variance(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_variance(thd, *this); }
 };
 
 class Item_sum_std;
@@ -366,8 +370,8 @@ class Item_sum_hybrid :public Item_sum
   Item_sum_hybrid(Item *item_par,int sign) :Item_sum(item_par),cmp_sign(sign),
     used_table_cache(~(table_map) 0)
   {}
-  Item_sum_hybrid(Item_sum_hybrid &item):
-    Item_sum(item), value(item.value), tmp_value(item.tmp_value),
+  Item_sum_hybrid(THD *thd, Item_sum_hybrid &item):
+    Item_sum(thd, item), value(item.value), tmp_value(item.tmp_value),
     sum(item.sum), sum_int(item.sum_int), hybrid_type(item.hybrid_type),
     cmp_sign(item.cmp_sign), used_table_cache(used_table_cache) {}
   bool fix_fields(THD *, TABLE_LIST *, Item **);
@@ -401,12 +405,12 @@ class Item_sum_min :public Item_sum_hybrid
 {
 public:
   Item_sum_min(Item *item_par) :Item_sum_hybrid(item_par,1) {}
-  Item_sum_min(Item_sum_min &item) :Item_sum_hybrid(item) {}
+  Item_sum_min(THD *thd, Item_sum_min &item) :Item_sum_hybrid(thd, item) {}
   enum Sumfunctype sum_func () const {return MIN_FUNC;}
 
   bool add();
   const char *func_name() const { return "min"; }
-  Item * get_same() { return new Item_sum_min(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_min(thd, *this); }
 };
 
 
@@ -414,12 +418,12 @@ class Item_sum_max :public Item_sum_hybrid
 {
 public:
   Item_sum_max(Item *item_par) :Item_sum_hybrid(item_par,-1) {}
-  Item_sum_max(Item_sum_max &item) :Item_sum_hybrid(item) {}
+  Item_sum_max(THD *thd, Item_sum_max &item) :Item_sum_hybrid(thd, item) {}
   enum Sumfunctype sum_func () const {return MAX_FUNC;}
 
   bool add();
   const char *func_name() const { return "max"; }
-  Item * get_same() { return new Item_sum_max(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_max(thd, *this); }
 };
 
 
@@ -431,8 +435,8 @@ class Item_sum_bit :public Item_sum_int
   public:
   Item_sum_bit(Item *item_par,ulonglong reset_arg)
     :Item_sum_int(item_par),reset_bits(reset_arg),bits(reset_arg) {}
-  Item_sum_bit(Item_sum_bit &item):
-    Item_sum_int(item), reset_bits(item.reset_bits), bits(item.bits) {}
+  Item_sum_bit(THD *thd, Item_sum_bit &item):
+    Item_sum_int(thd, item), reset_bits(item.reset_bits), bits(item.bits) {}
   enum Sumfunctype sum_func () const {return SUM_BIT_FUNC;}
   void reset();
   longlong val_int();
@@ -444,11 +448,11 @@ class Item_sum_or :public Item_sum_bit
 {
   public:
   Item_sum_or(Item *item_par) :Item_sum_bit(item_par,LL(0)) {}
-  Item_sum_or(Item_sum_or &item) :Item_sum_bit(item) {}
+  Item_sum_or(THD *thd, Item_sum_or &item) :Item_sum_bit(thd, item) {}
   bool add();
   void update_field(int offset);
   const char *func_name() const { return "bit_or"; }
-  Item * get_same() { return new Item_sum_or(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_or(thd, *this); }
 };
 
 
@@ -456,11 +460,11 @@ class Item_sum_and :public Item_sum_bit
 {
   public:
   Item_sum_and(Item *item_par) :Item_sum_bit(item_par, ~(ulonglong) LL(0)) {}
-  Item_sum_and(Item_sum_and &item) :Item_sum_bit(item) {}
+  Item_sum_and(THD *thd, Item_sum_and &item) :Item_sum_bit(thd, item) {}
   bool add();
   void update_field(int offset);
   const char *func_name() const { return "bit_and"; }
-  Item * get_same() { return new Item_sum_and(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_and(thd, *this); }
 };
 
 /*
@@ -478,7 +482,8 @@ public:
   Item_udf_sum( udf_func *udf_arg, List<Item> &list )
     :Item_sum( list ), udf(udf_arg)
   { quick_group=0;}
-  Item_udf_sum(Item_udf_sum &item) :Item_sum(item), udf(item.udf) {}
+  Item_udf_sum(THD *thd, Item_udf_sum &item)
+    :Item_sum(thd, item), udf(item.udf) {}
   ~Item_udf_sum() {}
   const char *func_name() const { return udf.name(); }
   bool fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
@@ -502,13 +507,14 @@ class Item_sum_udf_float :public Item_udf_sum
   Item_sum_udf_float(udf_func *udf_arg) :Item_udf_sum(udf_arg) {}
   Item_sum_udf_float(udf_func *udf_arg, List<Item> &list)
     :Item_udf_sum(udf_arg,list) {}
-  Item_sum_udf_float(Item_sum_udf_float &item): Item_udf_sum(item) {}
+  Item_sum_udf_float(THD *thd, Item_sum_udf_float &item)
+    :Item_udf_sum(thd, item) {}
   ~Item_sum_udf_float() {}
   longlong val_int() { return (longlong) Item_sum_udf_float::val(); }
   double val();
   String *val_str(String*str);
   void fix_length_and_dec() { fix_num_length_and_dec(); }
-  Item * get_same() { return new Item_sum_udf_float(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_udf_float(thd, *this); }
 };
 
 
@@ -518,14 +524,15 @@ public:
   Item_sum_udf_int(udf_func *udf_arg) :Item_udf_sum(udf_arg) {}
   Item_sum_udf_int(udf_func *udf_arg, List<Item> &list)
     :Item_udf_sum(udf_arg,list) {}
-  Item_sum_udf_int(Item_sum_udf_int &item): Item_udf_sum(item) {}
+  Item_sum_udf_int(THD *thd, Item_sum_udf_int &item)
+    :Item_udf_sum(thd, item) {}
   ~Item_sum_udf_int() {}
   longlong val_int();
   double val() { return (double) Item_sum_udf_int::val_int(); }
   String *val_str(String*str);
   enum Item_result result_type () const { return INT_RESULT; }
   void fix_length_and_dec() { decimals=0; max_length=21; }
-  Item * get_same() { return new Item_sum_udf_int(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_udf_int(thd, *this); }
 };
 
 
@@ -535,7 +542,8 @@ public:
   Item_sum_udf_str(udf_func *udf_arg) :Item_udf_sum(udf_arg) {}
   Item_sum_udf_str(udf_func *udf_arg, List<Item> &list)
     :Item_udf_sum(udf_arg,list) {}
-  Item_sum_udf_str(Item_sum_udf_str &item): Item_udf_sum(item) {}
+  Item_sum_udf_str(THD *thd, Item_sum_udf_str &item)
+    :Item_udf_sum(thd, item) {}
   ~Item_sum_udf_str() {}
   String *val_str(String *);
   double val()
@@ -553,7 +561,7 @@ public:
   }
   enum Item_result result_type () const { return STRING_RESULT; }
   void fix_length_and_dec();
-  Item * get_same() { return new Item_sum_udf_str(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_udf_str(thd, *this); }
 };
 
 #else /* Dummy functions to get sql_yacc.cc compiled */
@@ -563,14 +571,15 @@ class Item_sum_udf_float :public Item_sum_num
  public:
   Item_sum_udf_float(udf_func *udf_arg) :Item_sum_num() {}
   Item_sum_udf_float(udf_func *udf_arg, List<Item> &list) :Item_sum_num() {}
-  Item_sum_udf_float(Item_sum_udf_float &item): Item_sum_num(item) {}
+  Item_sum_udf_float(THD *thd, Item_sum_udf_float &item)
+    :Item_sum_num(thd, item) {}
   ~Item_sum_udf_float() {}
   enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
   double val() { return 0.0; }
   void reset() {}
   bool add() { return 0; }  
   void update_field(int offset) {}
-  Item * get_same() { return new Item_sum_udf_float(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_udf_float(thd, *this); }
 };
 
 
@@ -579,7 +588,8 @@ class Item_sum_udf_int :public Item_sum_num
 public:
   Item_sum_udf_int(udf_func *udf_arg) :Item_sum_num() {}
   Item_sum_udf_int(udf_func *udf_arg, List<Item> &list) :Item_sum_num() {}
-  Item_sum_udf_int(Item_sum_udf_int &item): Item_sum_num(item) {}
+  Item_sum_udf_int(THD *thd, Item_sum_udf_int &item)
+    :Item_sum_num(thd, item) {}
   ~Item_sum_udf_int() {}
   enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
   longlong val_int() { return 0; }
@@ -587,7 +597,7 @@ public:
   void reset() {}
   bool add() { return 0; }  
   void update_field(int offset) {}
-  Item * get_same() { return new Item_sum_udf_int(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_udf_int(thd, *this); }
 };
 
 
@@ -596,7 +606,8 @@ class Item_sum_udf_str :public Item_sum_num
 public:
   Item_sum_udf_str(udf_func *udf_arg) :Item_sum_num() {}
   Item_sum_udf_str(udf_func *udf_arg, List<Item> &list)  :Item_sum_num() {}
-  Item_sum_udf_str(Item_sum_udf_str &item): Item_sum_num(item) {}
+  Item_sum_udf_str(THD *thd, Item_sum_udf_str &item)
+    :Item_sum_num(thd, item) {}
   ~Item_sum_udf_str() {}
   String *val_str(String *) { null_value=1; return 0; }
   double val() { null_value=1; return 0.0; }
@@ -607,7 +618,7 @@ public:
   void reset() {}
   bool add() { return 0; }  
   void update_field(int offset) {}
-  Item * get_same() { return new Item_sum_udf_str(*this); }
+  Item *copy_or_same(THD* thd) { return new Item_sum_udf_str(thd, *this); }
 };
 
 #endif /* HAVE_DLOPEN */