MDEV-16874 Implement class Item_handled_func

mysql-test/main/func_time.result

@@ -1716,7 +1716,6 @@ min(timestampadd(month, 1>'', from_days('%Z')))
 NULL
 Warnings:
 Warning	1292	Truncated incorrect INTEGER value: '%Z'
-Warning	1292	Truncated incorrect DOUBLE value: ''
 Warning	1292	Incorrect datetime value: '0000-00-00'
 SET timestamp=UNIX_TIMESTAMP('2001-01-01 00:00:00');
 create table t1(a time);

sql/item_func.h

@@ -40,8 +40,6 @@ class Item_func :public Item_func_or_sum,
 {
   void sync_with_sum_func_and_with_field(List<Item> &list);
 protected:
-  String *val_str_from_val_str_ascii(String *str, String *str2);
-
   virtual bool check_arguments() const
   {
     return check_argument_types_scalar(0, arg_count);
@@ -188,6 +186,8 @@ class Item_func :public Item_func_or_sum,
     update_null_value();
     return null_value; 
   }
+  String *val_str_from_val_str_ascii(String *str, String *str2);
+
   void signal_divide_by_null();
   friend class udf_handler;
   Field *create_field_for_create_select(TABLE *table)
@@ -450,6 +450,64 @@ class Item_hybrid_func: public Item_func,
 };
 
 
+class Item_handled_func: public Item_func
+{
+public:
+  class Handler
+  {
+  public:
+    virtual ~Handler() { }
+    virtual String *val_str(Item_handled_func *, String *) const= 0;
+    virtual String *val_str_ascii(Item_handled_func *, String *) const= 0;
+    virtual double val_real(Item_handled_func *) const= 0;
+    virtual longlong val_int(Item_handled_func *) const= 0;
+    virtual my_decimal *val_decimal(Item_handled_func *, my_decimal *) const= 0;
+    virtual bool get_date(Item_handled_func *, MYSQL_TIME *, ulonglong fuzzydate) const= 0;
+    virtual const Type_handler *return_type_handler() const= 0;
+    virtual bool fix_length_and_dec(Item_handled_func *) const= 0;
+  };
+protected:
+  const Handler *m_func_handler;
+public:
+  Item_handled_func(THD *thd, Item *a)
+   :Item_func(thd, a), m_func_handler(NULL) { }
+  Item_handled_func(THD *thd, Item *a, Item *b)
+   :Item_func(thd, a, b), m_func_handler(NULL) { }
+  void set_func_handler(const Handler *handler)
+  {
+    m_func_handler= handler;
+  }
+  const Type_handler *type_handler() const
+  {
+    return m_func_handler->return_type_handler();
+  }
+  String *val_str(String *to)
+  {
+    return m_func_handler->val_str(this, to);
+  }
+  String *val_str_ascii(String *to)
+  {
+    return m_func_handler->val_str_ascii(this, to);
+  }
+  double val_real()
+  {
+    return m_func_handler->val_real(this);
+  }
+  longlong val_int()
+  {
+    return m_func_handler->val_int(this);
+  }
+  my_decimal *val_decimal(my_decimal *to)
+  {
+    return m_func_handler->val_decimal(this, to);
+  }
+  bool get_date(MYSQL_TIME *to, ulonglong fuzzydate)
+  {
+    return m_func_handler->get_date(this, to, fuzzydate);
+  }
+};
+
+
 /**
   Functions that at fix_fields() time determine the returned field type,
   trying to preserve the exact data type of the arguments.

sql/sql_type.h

@@ -367,6 +367,11 @@ class Temporal_with_date: protected MYSQL_TIME
   {
     make_from_item(thd, item, flags);
   }
+public:
+  bool check_date_with_warn(ulonglong flags)
+  {
+    return ::check_date_with_warn(this, flags, MYSQL_TIMESTAMP_ERROR);
+  }
 };