MDEV-11344 Split Arg_comparator::set_compare_func() into virtual methods in Type_handler

This patch:
- Introduces a new virtuial method Type_handler::set_comparator_func
  and moves pieces of the code from the switch in
  Arg_comparator::set_compare_func into the corresponding
  Type_handler_xxx::set_comparator_func.
- Adds Type_handler::get_handler_by_cmp_type()
- Moves Type_handler_hybrid_field_type::get_handler_by_result_type() to
  a static method Type_handler::get_handler_by_result_type(),
  for symmetry with similar methods:
  * Type_handler::get_handler_by_field_type()
  * Type_handler::get_handler_by_real_type()
  * Type_handler::get_handler_by_cmp_type()
- Introduces Type_handler_row, to unify the code for the scalar
  data types and the ROW data type (currently for comparison purposes only).
- Adds public type_handler_row, as it's now needed in item_row.h
- Makes type_handler_null public, as it's now needed in item_cmpfunc.h
  Note, other type_handler_xxx will become public as well later.
- Removes the global variable Arg_comparator::comparator_matrix,
  as it's not needed any more.

sql/item_cmpfunc.cc

@@ -522,102 +522,72 @@ void Item_bool_rowready_func2::fix_length_and_dec()
 }
 
 
-int Arg_comparator::set_compare_func(Item_func_or_sum *item, Item_result type)
+/**
+  Prepare the comparator (set the comparison function) for comparing
+  items *a1 and *a2 in the context of 'type'.
+
+  @param[in]      owner_arg  Item, peforming the comparison (e.g. Item_func_eq)
+  @param[in,out]  a1         first argument to compare
+  @param[in,out]  a2         second argument to compare
+  @param[in]      type       type context to compare in
+
+  Both *a1 and *a2 can be replaced by this method - typically by constant
+  items, holding the cached converted value of the original (constant) item.
+*/
+
+int Arg_comparator::set_cmp_func(Item_func_or_sum *owner_arg,
+                                 Item **a1, Item **a2)
 {
-  owner= item;
-  func= comparator_matrix[type]
-                         [is_owner_equal_func()];
+  thd= current_thd;
+  owner= owner_arg;
+  set_null= set_null && owner_arg;
+  a= a1;
+  b= a2;
+  m_compare_handler= Type_handler::get_handler_by_cmp_type(item_cmp_type(*a1,
+                                                                         *a2));
+  return m_compare_handler->set_comparator_func(this);
+}
 
-  switch (type) {
-  case TIME_RESULT:
-    m_compare_collation= &my_charset_numeric;
-    break;
-  case ROW_RESULT:
-  {
+
+bool Arg_comparator::set_cmp_func_for_row_arguments()
+{
   uint n= (*a)->cols();
   if (n != (*b)->cols())
   {
     my_error(ER_OPERAND_COLUMNS, MYF(0), n);
     comparators= 0;
-      return 1;
+    return true;
   }
   if (!(comparators= new Arg_comparator[n]))
-      return 1;
+    return true;
   for (uint i=0; i < n; i++)
   {
     if ((*a)->element_index(i)->cols() != (*b)->element_index(i)->cols())
     {
       my_error(ER_OPERAND_COLUMNS, MYF(0), (*a)->element_index(i)->cols());
-	return 1;
+      return true;
     }
     if (comparators[i].set_cmp_func(owner, (*a)->addr(i),
                                            (*b)->addr(i), set_null))
-        return 1;
-    }
-    break;
-  }
-  case INT_RESULT:
-  {
-    if (func == &Arg_comparator::compare_int_signed)
-    {
-      if ((*a)->unsigned_flag)
-        func= (((*b)->unsigned_flag)?
-               &Arg_comparator::compare_int_unsigned :
-               &Arg_comparator::compare_int_unsigned_signed);
-      else if ((*b)->unsigned_flag)
-        func= &Arg_comparator::compare_int_signed_unsigned;
-    }
-    else if (func== &Arg_comparator::compare_e_int)
-    {
-      if ((*a)->unsigned_flag ^ (*b)->unsigned_flag)
-        func= &Arg_comparator::compare_e_int_diff_signedness;
-    }
-    break;
-  }
-  case STRING_RESULT:
-  case DECIMAL_RESULT:
-    break;
-  case REAL_RESULT:
-  {
-    if ((*a)->decimals < NOT_FIXED_DEC && (*b)->decimals < NOT_FIXED_DEC)
-    {
-      precision= 5 / log_10[MY_MAX((*a)->decimals, (*b)->decimals) + 1];
-      if (func == &Arg_comparator::compare_real)
-        func= &Arg_comparator::compare_real_fixed;
-      else if (func == &Arg_comparator::compare_e_real)
-        func= &Arg_comparator::compare_e_real_fixed;
-    }
-    break;
-  }
+      return true;
   }
-  return 0;
+  return false;
 }
 
 
-/**
-  Prepare the comparator (set the comparison function) for comparing
-  items *a1 and *a2 in the context of 'type'.
-
-  @param[in]      owner_arg  Item, peforming the comparison (e.g. Item_func_eq)
-  @param[in,out]  a1         first argument to compare
-  @param[in,out]  a2         second argument to compare
-  @param[in]      type       type context to compare in
+bool Arg_comparator::set_cmp_func_row()
+{
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_row :
+                                &Arg_comparator::compare_row;
+  return set_cmp_func_for_row_arguments();
+}
 
-  Both *a1 and *a2 can be replaced by this method - typically by constant
-  items, holding the cached converted value of the original (constant) item.
-*/
 
-int Arg_comparator::set_cmp_func(Item_func_or_sum *owner_arg,
-                                 Item **a1, Item **a2)
+bool Arg_comparator::set_cmp_func_string()
 {
-  thd= current_thd;
-  owner= owner_arg;
-  set_null= set_null && owner_arg;
-  a= a1;
-  b= a2;
-  m_compare_type= item_cmp_type(*a1, *a2);
-
-  if (m_compare_type == STRING_RESULT &&
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_string :
+                                &Arg_comparator::compare_string;
+  if (compare_type() == STRING_RESULT &&
       (*a)->result_type() == STRING_RESULT &&
       (*b)->result_type() == STRING_RESULT)
   {
@@ -626,12 +596,18 @@ int Arg_comparator::set_cmp_func(Item_func_or_sum *owner_arg,
       generated item, like in natural join
     */
     if (owner->agg_arg_charsets_for_comparison(&m_compare_collation, a, b))
-      return 1;
+      return true;
   }
+  a= cache_converted_constant(thd, a, &a_cache, compare_type());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type());
+  return false;
+}
 
-  if (m_compare_type == TIME_RESULT)
-  {
+
+bool Arg_comparator::set_cmp_func_temporal()
+{
   enum_field_types f_type= a[0]->field_type_for_temporal_comparison(b[0]);
+  m_compare_collation= &my_charset_numeric;
   if (f_type == MYSQL_TYPE_TIME)
   {
     func= is_owner_equal_func() ? &Arg_comparator::compare_e_time :
@@ -642,21 +618,65 @@ int Arg_comparator::set_cmp_func(Item_func_or_sum *owner_arg,
     func= is_owner_equal_func() ? &Arg_comparator::compare_e_datetime :
                                   &Arg_comparator::compare_datetime;
   }
-    return 0;
-  }
+  return false;
+}
+
 
-  if (m_compare_type == INT_RESULT &&
-      (*a)->field_type() == MYSQL_TYPE_YEAR &&
+bool Arg_comparator::set_cmp_func_int()
+{
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_int :
+                                &Arg_comparator::compare_int_signed;
+  if ((*a)->field_type() == MYSQL_TYPE_YEAR &&
       (*b)->field_type() == MYSQL_TYPE_YEAR)
   {
-    m_compare_type= TIME_RESULT;
     func= is_owner_equal_func() ? &Arg_comparator::compare_e_datetime :
                                   &Arg_comparator::compare_datetime;
   }
+  else if (func == &Arg_comparator::compare_int_signed)
+  {
+    if ((*a)->unsigned_flag)
+      func= (((*b)->unsigned_flag)?
+             &Arg_comparator::compare_int_unsigned :
+             &Arg_comparator::compare_int_unsigned_signed);
+    else if ((*b)->unsigned_flag)
+      func= &Arg_comparator::compare_int_signed_unsigned;
+  }
+  else if (func== &Arg_comparator::compare_e_int)
+  {
+    if ((*a)->unsigned_flag ^ (*b)->unsigned_flag)
+      func= &Arg_comparator::compare_e_int_diff_signedness;
+  }
+  a= cache_converted_constant(thd, a, &a_cache, compare_type());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type());
+  return false;
+}
+
 
-  a= cache_converted_constant(thd, a, &a_cache, m_compare_type);
-  b= cache_converted_constant(thd, b, &b_cache, m_compare_type);
-  return set_compare_func(owner_arg, m_compare_type);
+bool Arg_comparator::set_cmp_func_real()
+{
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_real :
+                                &Arg_comparator::compare_real;
+  if ((*a)->decimals < NOT_FIXED_DEC && (*b)->decimals < NOT_FIXED_DEC)
+  {
+    precision= 5 / log_10[MY_MAX((*a)->decimals, (*b)->decimals) + 1];
+    if (func == &Arg_comparator::compare_real)
+      func= &Arg_comparator::compare_real_fixed;
+    else if (func == &Arg_comparator::compare_e_real)
+      func= &Arg_comparator::compare_e_real_fixed;
+  }
+  a= cache_converted_constant(thd, a, &a_cache, compare_type());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type());
+  return false;
+}
+
+
+bool Arg_comparator::set_cmp_func_decimal()
+{
+  func= is_owner_equal_func() ? &Arg_comparator::compare_e_decimal :
+                                &Arg_comparator::compare_decimal;
+  a= cache_converted_constant(thd, a, &a_cache, compare_type());
+  b= cache_converted_constant(thd, b, &b_cache, compare_type());
+  return false;
 }
 
 

sql/item_cmpfunc.h

@@ -47,7 +47,7 @@ typedef int (*Item_field_cmpfunc)(Item *f1, Item *f2, void *arg);
 class Arg_comparator: public Sql_alloc
 {
   Item **a, **b;
-  Item_result m_compare_type;
+  const Type_handler *m_compare_handler;
   CHARSET_INFO *m_compare_collation;
   arg_cmp_func func;
   Item_func_or_sum *owner;
@@ -58,7 +58,7 @@ class Arg_comparator: public Sql_alloc
   THD *thd;
   Item *a_cache, *b_cache;         // Cached values of a and b items
                                    //   when one of arguments is NULL.
-  int set_compare_func(Item_func_or_sum *owner, Item_result type);
+
   int set_cmp_func(Item_func_or_sum *owner_arg, Item **a1, Item **a2);
 
   int compare_temporal(enum_field_types type);
@@ -68,17 +68,26 @@ class Arg_comparator: public Sql_alloc
   /* Allow owner function to use string buffers. */
   String value1, value2;
 
-  Arg_comparator(): m_compare_type(STRING_RESULT),
+  Arg_comparator():
+    m_compare_handler(&type_handler_null),
     m_compare_collation(&my_charset_bin),
     set_null(TRUE), comparators(0), thd(0),
     a_cache(0), b_cache(0) {};
   Arg_comparator(Item **a1, Item **a2): a(a1), b(a2),
-    m_compare_type(STRING_RESULT),
+    m_compare_handler(&type_handler_null),
     m_compare_collation(&my_charset_bin),
     set_null(TRUE), comparators(0), thd(0),
     a_cache(0), b_cache(0) {};
 
 public:
+  bool set_cmp_func_for_row_arguments();
+  bool set_cmp_func_row();
+  bool set_cmp_func_string();
+  bool set_cmp_func_temporal();
+  bool set_cmp_func_int();
+  bool set_cmp_func_real();
+  bool set_cmp_func_decimal();
+
   inline int set_cmp_func(Item_func_or_sum *owner_arg,
 			  Item **a1, Item **a2, bool set_null_arg)
   {
@@ -110,13 +119,13 @@ class Arg_comparator: public Sql_alloc
 
   Item** cache_converted_constant(THD *thd, Item **value, Item **cache,
                                   Item_result type);
-  static arg_cmp_func comparator_matrix [6][2];
   inline bool is_owner_equal_func()
   {
     return (owner->type() == Item::FUNC_ITEM &&
            ((Item_func*)owner)->functype() == Item_func::EQUAL_FUNC);
   }
-  Item_result compare_type() const { return m_compare_type; }
+  const Type_handler *compare_type_handler() const { return m_compare_handler; }
+  Item_result compare_type() const { return m_compare_handler->cmp_type(); }
   CHARSET_INFO *compare_collation() const { return m_compare_collation; }
   Arg_comparator *subcomparators() const { return comparators; }
   void cleanup()

sql/item_row.h

@@ -56,6 +56,7 @@ class Item_row: public Item,
   {}
 
   enum Type type() const { return ROW_ITEM; };
+  const Type_handler *type_handler() const { return &type_handler_row; }
   void illegal_method_call(const char *);
   bool is_null() { return null_value; }
   void make_field(THD *thd, Send_field *)

sql/mysqld.cc

@@ -309,14 +309,6 @@ static my_bool opt_autocommit; ///< for --autocommit command-line option
 */
 static my_bool opt_verbose= 0;
 
-arg_cmp_func Arg_comparator::comparator_matrix[6][2] =
-{{&Arg_comparator::compare_string,     &Arg_comparator::compare_e_string},
- {&Arg_comparator::compare_real,       &Arg_comparator::compare_e_real},
- {&Arg_comparator::compare_int_signed, &Arg_comparator::compare_e_int},
- {&Arg_comparator::compare_row,        &Arg_comparator::compare_e_row},
- {&Arg_comparator::compare_decimal,    &Arg_comparator::compare_e_decimal},
- {&Arg_comparator::compare_datetime,   &Arg_comparator::compare_e_datetime}};
-
 /* Timer info to be used by the SQL layer */
 MY_TIMER_INFO sys_timer_info;
 

sql/sql_type.cc

@@ -39,7 +39,6 @@ static Type_handler_timestamp   type_handler_timestamp;
 static Type_handler_timestamp2  type_handler_timestamp2;
 static Type_handler_olddecimal  type_handler_olddecimal;
 static Type_handler_newdecimal  type_handler_newdecimal;
-static Type_handler_null        type_handler_null;
 static Type_handler_string      type_handler_string;
 static Type_handler_varchar     type_handler_varchar;
 static Type_handler_tiny_blob   type_handler_tiny_blob;
@@ -53,6 +52,10 @@ static Type_handler_enum        type_handler_enum;
 static Type_handler_set         type_handler_set;
 
 
+Type_handler_null        type_handler_null;
+Type_handler_row         type_handler_row;
+
+
 /**
   This method is used by:
   - Item_user_var_as_out_param::field_type()
@@ -99,18 +102,17 @@ Type_handler_string_result::type_handler_adjusted_to_max_octet_length(
 
 
 const Type_handler *
-Type_handler_hybrid_field_type::get_handler_by_result_type(Item_result type)
-                                                           const
+Type_handler::get_handler_by_cmp_type(Item_result type)
 {
   switch (type) {
   case REAL_RESULT:       return &type_handler_double;
   case INT_RESULT:        return &type_handler_longlong;
   case DECIMAL_RESULT:    return &type_handler_newdecimal;
   case STRING_RESULT:     return &type_handler_long_blob;
-  case TIME_RESULT:
-  case ROW_RESULT:
-    DBUG_ASSERT(0);
+  case TIME_RESULT:       return &type_handler_datetime;
+  case ROW_RESULT:        return &type_handler_row;
   }
+  DBUG_ASSERT(0);
   return &type_handler_string;
 }
 
@@ -684,3 +686,39 @@ int Type_handler_int_result::Item_save_in_field(Item *item, Field *field,
 {
   return item->save_int_in_field(field, no_conversions);
 }
+
+
+/***********************************************************************/
+
+bool Type_handler_row::set_comparator_func(Arg_comparator *cmp) const
+{
+  return cmp->set_cmp_func_row();
+}
+
+bool Type_handler_int_result::set_comparator_func(Arg_comparator *cmp) const
+{
+  return cmp->set_cmp_func_int();
+}
+
+bool Type_handler_real_result::set_comparator_func(Arg_comparator *cmp) const
+{
+  return cmp->set_cmp_func_real();
+}
+
+bool Type_handler_decimal_result::set_comparator_func(Arg_comparator *cmp) const
+{
+  return cmp->set_cmp_func_decimal();
+}
+
+bool Type_handler_string_result::set_comparator_func(Arg_comparator *cmp) const
+{
+  return cmp->set_cmp_func_string();
+}
+
+bool Type_handler_temporal_result::set_comparator_func(Arg_comparator *cmp) const
+{
+  return cmp->set_cmp_func_temporal();
+}
+
+
+/*************************************************************************/

sql/sql_type.h

@@ -27,6 +27,7 @@ class Field;
 class Item;
 class Type_std_attributes;
 class Sort_param;
+class Arg_comparator;
 struct TABLE;
 struct SORT_FIELD_ATTR;
 
@@ -221,6 +222,16 @@ class Type_handler
   static const Type_handler *string_type_handler(uint max_octet_length);
   static const Type_handler *get_handler_by_field_type(enum_field_types type);
   static const Type_handler *get_handler_by_real_type(enum_field_types type);
+  static const Type_handler *get_handler_by_cmp_type(Item_result type);
+  static const Type_handler *get_handler_by_result_type(Item_result type)
+  {
+    /*
+      As result_type() returns STRING_RESULT for temporal Items,
+      type should never be equal to TIME_RESULT here.
+    */
+    DBUG_ASSERT(type != TIME_RESULT);
+    return get_handler_by_cmp_type(type);
+  }
   virtual enum_field_types field_type() const= 0;
   virtual enum_field_types real_field_type() const { return field_type(); }
   virtual Item_result result_type() const= 0;
@@ -275,6 +286,59 @@ class Type_handler
 
   virtual int Item_save_in_field(Item *item, Field *field,
                                  bool no_conversions) const= 0;
+  virtual bool set_comparator_func(Arg_comparator *cmp) const= 0;
+};
+
+
+/*
+  Special handler for ROW
+*/
+class Type_handler_row: public Type_handler
+{
+public:
+  virtual ~Type_handler_row() {}
+  enum_field_types field_type() const
+  {
+    DBUG_ASSERT(0);
+    return MYSQL_TYPE_NULL;
+  };
+  Item_result result_type() const
+  {
+    return ROW_RESULT;
+  }
+  Item_result cmp_type() const
+  {
+    return ROW_RESULT;
+  }
+  Field *make_num_distinct_aggregator_field(MEM_ROOT *, const Item *) const
+  {
+    DBUG_ASSERT(0);
+    return NULL;
+  }
+  Field *make_conversion_table_field(TABLE *TABLE,
+                                     uint metadata,
+                                     const Field *target) const
+  {
+    DBUG_ASSERT(0);
+    return NULL;
+  }
+  void make_sort_key(uchar *to, Item *item,
+                     const SORT_FIELD_ATTR *sort_field,
+                     Sort_param *param) const
+  {
+    DBUG_ASSERT(0);
+  }
+  void sortlength(THD *thd, const Type_std_attributes *item,
+                            SORT_FIELD_ATTR *attr) const
+  {
+    DBUG_ASSERT(0);
+  }
+  int Item_save_in_field(Item *item, Field *field, bool no_conversions) const
+  {
+    DBUG_ASSERT(0);
+    return 1;
+  }
+  bool set_comparator_func(Arg_comparator *cmp) const;
 };
 
 
@@ -292,6 +356,7 @@ class Type_handler_real_result: public Type_handler
                   const Type_std_attributes *item,
                   SORT_FIELD_ATTR *attr) const;
   int Item_save_in_field(Item *item, Field *field, bool no_conversions) const;
+  bool set_comparator_func(Arg_comparator *cmp) const;
 };
 
 
@@ -308,6 +373,7 @@ class Type_handler_decimal_result: public Type_handler
                   const Type_std_attributes *item,
                   SORT_FIELD_ATTR *attr) const;
   int Item_save_in_field(Item *item, Field *field, bool no_conversions) const;
+  bool set_comparator_func(Arg_comparator *cmp) const;
 };
 
 
@@ -324,6 +390,7 @@ class Type_handler_int_result: public Type_handler
                   const Type_std_attributes *item,
                   SORT_FIELD_ATTR *attr) const;
   int Item_save_in_field(Item *item, Field *field, bool no_conversions) const;
+  bool set_comparator_func(Arg_comparator *cmp) const;
 };
 
 
@@ -338,6 +405,7 @@ class Type_handler_temporal_result: public Type_handler
   void sortlength(THD *thd,
                   const Type_std_attributes *item,
                   SORT_FIELD_ATTR *attr) const;
+  bool set_comparator_func(Arg_comparator *cmp) const;
 };
 
 
@@ -356,6 +424,7 @@ class Type_handler_string_result: public Type_handler
                   const Type_std_attributes *item,
                   SORT_FIELD_ATTR *attr) const;
   int Item_save_in_field(Item *item, Field *field, bool no_conversions) const;
+  bool set_comparator_func(Arg_comparator *cmp) const;
 };
 
 
@@ -704,7 +773,6 @@ class Type_handler_set: public Type_handler_string_result
 class Type_handler_hybrid_field_type
 {
   const Type_handler *m_type_handler;
-  const Type_handler *get_handler_by_result_type(Item_result type) const;
 public:
   Type_handler_hybrid_field_type();
   Type_handler_hybrid_field_type(const Type_handler *handler)
@@ -730,13 +798,13 @@ class Type_handler_hybrid_field_type
   }
   const Type_handler *set_handler_by_result_type(Item_result type)
   {
-    return (m_type_handler= get_handler_by_result_type(type));
+    return (m_type_handler= Type_handler::get_handler_by_result_type(type));
   }
   const Type_handler *set_handler_by_result_type(Item_result type,
                                                  uint max_octet_length,
                                                  CHARSET_INFO *cs)
   {
-    m_type_handler= get_handler_by_result_type(type);
+    m_type_handler= Type_handler::get_handler_by_result_type(type);
     return m_type_handler=
       m_type_handler->type_handler_adjusted_to_max_octet_length(max_octet_length,
                                                                 cs);
@@ -766,4 +834,7 @@ class Type_handler_hybrid_real_field_type:
 };
 
 
+extern Type_handler_row   type_handler_row;
+extern Type_handler_null  type_handler_null;
+
 #endif /* SQL_TYPE_H_INCLUDED */