MDEV-10772 Introduce Item_param::CONVERSION_INFO

Author: Alexander Barkov

sql/item.cc

@@ -3412,6 +3412,32 @@ bool Item_param::set_longdata(const char *str, ulong length)
 }
 
 
+void Item_param::CONVERSION_INFO::set(THD *thd, CHARSET_INFO *fromcs)
+{
+  CHARSET_INFO *tocs= thd->variables.collation_connection;
+
+  character_set_of_placeholder= fromcs;
+  character_set_client= thd->variables.character_set_client;
+  /*
+    Setup source and destination character sets so that they
+    are different only if conversion is necessary: this will
+    make later checks easier.
+  */
+  uint32 dummy_offset;
+  final_character_set_of_str_value=
+    String::needs_conversion(0, fromcs, tocs, &dummy_offset) ?
+    tocs : fromcs;
+}
+
+
+bool Item_param::CONVERSION_INFO::convert(THD *thd, String *str)
+{
+  return thd->convert_string(str,
+                             character_set_of_placeholder,
+                             final_character_set_of_str_value);
+}
+
+
 /**
   Set parameter value from user variable value.
 
@@ -3451,20 +3477,7 @@ bool Item_param::set_from_user_var(THD *thd, const user_var_entry *entry)
       break;
     case STRING_RESULT:
     {
-      CHARSET_INFO *fromcs= entry->charset();
-      CHARSET_INFO *tocs= thd->variables.collation_connection;
-      uint32 dummy_offset;
-
-      value.cs_info.character_set_of_placeholder= fromcs;
-      value.cs_info.character_set_client= thd->variables.character_set_client;
-      /*
-        Setup source and destination character sets so that they
-        are different only if conversion is necessary: this will
-        make later checks easier.
-      */
-      value.cs_info.final_character_set_of_str_value=
-        String::needs_conversion(0, fromcs, tocs, &dummy_offset) ?
-        tocs : fromcs;
+      value.cs_info.set(thd, entry->charset());
       /*
         Exact value of max_length is not known unless data is converted to
         charset of connection, so we have to set it later.
@@ -3775,21 +3788,7 @@ bool Item_param::convert_str_value(THD *thd)
   bool rc= FALSE;
   if (state == STRING_VALUE || state == LONG_DATA_VALUE)
   {
-    /*
-      Check is so simple because all charsets were set up properly
-      in setup_one_conversion_function, where typecode of
-      placeholder was also taken into account: the variables are different
-      here only if conversion is really necessary.
-    */
-    if (value.cs_info.final_character_set_of_str_value !=
-        value.cs_info.character_set_of_placeholder)
-    {
-      rc= thd->convert_string(&str_value,
-                              value.cs_info.character_set_of_placeholder,
-                              value.cs_info.final_character_set_of_str_value);
-    }
-    else
-      str_value.set_charset(value.cs_info.final_character_set_of_str_value);
+    rc= value.cs_info.convert_if_needed(thd, &str_value);
     /* Here str_value is guaranteed to be in final_character_set_of_str_value */
 
     /*

sql/item.h

@@ -2727,6 +2727,47 @@ class Item_param :public Item_basic_value,
     DECIMAL_VALUE
   } state;
 
+  struct CONVERSION_INFO
+  {
+    /*
+      Character sets conversion info for string values.
+      Character sets of client and connection defined at bind time are used
+      for all conversions, even if one of them is later changed (i.e.
+      between subsequent calls to mysql_stmt_execute).
+    */
+    CHARSET_INFO *character_set_client;
+    CHARSET_INFO *character_set_of_placeholder;
+    /*
+      This points at character set of connection if conversion
+      to it is required (i. e. if placeholder typecode is not BLOB).
+      Otherwise it's equal to character_set_client (to simplify
+      check in convert_str_value()).
+    */
+    CHARSET_INFO *final_character_set_of_str_value;
+  private:
+    bool needs_conversion() const
+    {
+      return final_character_set_of_str_value !=
+             character_set_of_placeholder;
+    }
+    bool convert(THD *thd, String *str);
+  public:
+    void set(THD *thd, CHARSET_INFO *cs);
+    bool convert_if_needed(THD *thd, String *str)
+    {
+      /*
+        Check is so simple because all charsets were set up properly
+        in setup_one_conversion_function, where typecode of
+        placeholder was also taken into account: the variables are different
+        here only if conversion is really necessary.
+      */
+      if (needs_conversion())
+        return convert(thd, str);
+      str->set_charset(final_character_set_of_str_value);
+      return false;
+    }
+  };
+
   /*
     A buffer for string and long data values. Historically all allocated
     values returned from val_str() were treated as eligible to
@@ -2743,24 +2784,7 @@ class Item_param :public Item_basic_value,
   {
     longlong integer;
     double   real;
-    /*
-      Character sets conversion info for string values.
-      Character sets of client and connection defined at bind time are used
-      for all conversions, even if one of them is later changed (i.e.
-      between subsequent calls to mysql_stmt_execute).
-    */
-    struct CONVERSION_INFO
-    {
-      CHARSET_INFO *character_set_client;
-      CHARSET_INFO *character_set_of_placeholder;
-      /*
-        This points at character set of connection if conversion
-        to it is required (i. e. if placeholder typecode is not BLOB).
-        Otherwise it's equal to character_set_client (to simplify
-        check in convert_str_value()).
-      */
-      CHARSET_INFO *final_character_set_of_str_value;
-    } cs_info;
+    CONVERSION_INFO cs_info;
     MYSQL_TIME     time;
   } value;