MDEV-30695 Refactor case folding data types in Asian collations

This is a non-functional change and should not change the server behavior. Casefolding information is now stored in items of a new data type MY_CASEFOLD_CHARACTER: typedef struct casefold_info_char_t { uint32 toupper; uint32 tolower; } MY_CASEFOLD_CHARACTER; Before this change, casefolding tables for Asian collations were stored in: typedef struct unicase_info_char_st { uint32 toupper; uint32 tolower; uint32 sort; } MY_UNICASE_CHARACTER; The "sort" member was not used in the code handling Asian collations, it only wasted space. (it's only used by Unicode _general_ci and _general_mysql500_ci collations). Unicode collations (at least UCA and _bin) should also be refactored later, but under terms of a separate task.

Author: abarkov

include/m_ctype.h

@@ -80,10 +80,26 @@ typedef const struct my_charset_handler_st MY_CHARSET_HANDLER;
 typedef const struct my_collation_handler_st MY_COLLATION_HANDLER;
 
 typedef const struct unicase_info_st MY_UNICASE_INFO;
+typedef const struct casefold_info_st MY_CASEFOLD_INFO;
 typedef const struct uni_ctype_st MY_UNI_CTYPE;
 typedef const struct my_uni_idx_st MY_UNI_IDX;
 typedef uint16 decimal_digits_t;
 
+
+typedef struct casefold_info_char_t
+{
+ uint32 toupper;
+ uint32 tolower;
+} MY_CASEFOLD_CHARACTER;
+
+
+struct casefold_info_st
+{
+ my_wc_t maxchar;
+ MY_CASEFOLD_CHARACTER **page;
+};
+
+
 typedef struct unicase_info_char_st
 {
  uint32 toupper;
@@ -755,6 +771,7 @@ struct charset_info_st
  MY_UCA_INFO *uca;
  const uint16 *tab_to_uni;
  MY_UNI_IDX *tab_from_uni;
+ MY_CASEFOLD_INFO *casefold;
  MY_UNICASE_INFO *caseinfo;
  const uchar *state_map;
  const uchar *ident_map;

strings/conf_to_src.c

@@ -408,6 +408,7 @@ void dispcset(FILE *f,CHARSET_INFO *cs)
  }
 
  fprintf(f," NULL, /* from_uni */\n");
+ fprintf(f," NULL, /* casefold */\n");
  fprintf(f," &my_unicase_default, /* caseinfo */\n");
  fprintf(f," NULL, /* state map */\n");
  fprintf(f," NULL, /* ident map */\n");