parse negative numbers into one item

use Item->neg to convert generate negative Item_num's
instead of Item_func_neg(Item_num).

Based on the following commit:

  Author: Monty <monty@mariadb.org>
  Date:   Mon May 30 22:44:00 2016 +0300

    Make negative number their own token
    The negation (-) operator will call Item->neg() one underlying numeric constants
    and remove itself (like the NOT() function does today for other NOT functions.

    This simplifies things
    - -1 is not anymore an expression but a basic_const_item
      - improves optimizer
      - DEFAULT -1 doesn't need special handling anymore
      - When we add DEFAULT expressions, -1 will be treated exactly like 1
    - printing of items doesn't anymore put braces around all negative numbers

    Other things fixed:
    - Fixed that longlong converted to decimal's has a more appropriate size
    - Fixed that "-0.0" read into a decimal is interpreted as 0.0

1 files changed, 6 insertions, 10 deletions

diff --git a/sql/item.h b/sql/item.h
index 67d683b15ff..22e44719706 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -1846,6 +1846,8 @@ public:
   /* how much position should be reserved for Exists2In transformation */
   virtual uint exists2in_reserved_items() { return 0; };
 
+  virtual Item *neg(THD *thd);
+
   /**
     Inform the item that it is located under a NOT, which is a top-level item.
   */
@@ -2261,7 +2263,6 @@ class Item_num: public Item_basic_constant
 {
 public:
   Item_num(THD *thd): Item_basic_constant(thd) { collation.set_numeric(); }
-  virtual Item_num *neg(THD *thd)= 0;
   Item *safe_charset_converter(THD *thd, CHARSET_INFO *tocs);
   bool check_partition_func_processor(uchar *int_arg) { return FALSE;}
   bool check_vcol_func_processor(uchar *arg) { return FALSE;}
@@ -2834,7 +2835,7 @@ public:
   bool basic_const_item() const { return 1; }
   Item *clone_item(THD *thd);
   virtual void print(String *str, enum_query_type query_type);
-  Item_num *neg(THD *thd) { value= -value; return this; }
+  Item *neg(THD *thd);
   uint decimal_precision() const
   { return (uint) (max_length - MY_TEST(value < 0)); }
   bool eq(const Item *item, bool binary_cmp) const
@@ -2855,7 +2856,7 @@ public:
   String *val_str(String*);
   Item *clone_item(THD *thd);
   virtual void print(String *str, enum_query_type query_type);
-  Item_num *neg(THD *thd);
+  Item *neg(THD *thd);
   uint decimal_precision() const { return max_length; }
 };
 
@@ -2899,12 +2900,7 @@ public:
   bool basic_const_item() const { return 1; }
   Item *clone_item(THD *thd);
   virtual void print(String *str, enum_query_type query_type);
-  Item_num *neg(THD *thd)
-  {
-    my_decimal_neg(&decimal_value);
-    unsigned_flag= !decimal_value.sign();
-    return this;
-  }
+  Item *neg(THD *thd);
   uint decimal_precision() const { return decimal_value.precision(); }
   bool eq(const Item *, bool binary_cmp) const;
   void set_decimal_value(my_decimal *value_par);
@@ -2954,7 +2950,7 @@ public:
   my_decimal *val_decimal(my_decimal *);
   bool basic_const_item() const { return 1; }
   Item *clone_item(THD *thd);
-  Item_num *neg(THD *thd) { value= -value; return this; }
+  Item *neg(THD *thd);
   virtual void print(String *str, enum_query_type query_type);
   bool eq(const Item *item, bool binary_cmp) const
   { return real_eq(value, item); }