WL#1175: more default_week_formats for iso compatibility

New formats added for 'week()' function and 'default_week_format' option(4 - 7).
Next formats is supported now:
*Value* *Meaning*
  `0'     Week starts on Sunday; First Sunday of the year starts week 1.
  	  Week() returns 0-53.
  `1'     Week starts on Monday; Weeks numbered according to ISO 8601:1988.
	  Week() returns 0-53.
  `2'     Week starts on Sunday; First Sunday of the year starts week 1.
  	  Week() returns 1-53.
  `3'     Week starts on Monday; Weeks numbered according to ISO 8601:1988.
	  Week() returns 1-53.
  `4'     Week starts on Sunday; Weeks numbered according to ISO 8601:1988.
	  Week() returns 0-53.
  `5'     Week starts on Monday;  First Monday of the year starts week 1.
  	  Week() returns 0-53.
  `6'     Week starts on Sunday; Weeks numbered according to ISO 8601:1988.
	  Week() returns 1-53.
  `7'     Week starts on Monday;  First Monday of the year starts week 1.
  	  Week() returns 1-53.

4 files changed, 108 insertions, 38 deletions

diff --git a/sql/item_timefunc.cc b/sql/item_timefunc.cc
index caea79314de..f2b4a041b6c 100644
--- a/sql/item_timefunc.cc
+++ b/sql/item_timefunc.cc
@@ -175,27 +175,51 @@ longlong Item_func_second::val_int()
 }
 
 
-/*
-  Returns the week of year.
+uint week_mode(uint mode)
+{
+  uint week_format= (mode & 7);
+  if (!(week_format & WEEK_MONDAY_FIRST))
+    week_format^= WEEK_FIRST_WEEKDAY;
+  return week_format;
+}
 
-  The bits in week_format has the following meaning:
-    0	If not set:	USA format: Sunday is first day of week
-        If set:		ISO format: Monday is first day of week
-    1   If not set:	Week is in range 0-53
-    	If set		Week is in range 1-53.
+/*
+  The bits in week_format(for calc_week() function) has the following meaning:
+   WEEK_MONDAY_FIRST (0)  If not set	Sunday is first day of week
+      		   	  If set	Monday is first day of week
+   WEEK_YEAR (1)	  If not set	Week is in range 0-53
+
+   	Week 0 is returned for the the last week of the previous year (for
+	a date at start of january) In this case one can get 53 for the
+	first week of next year.  This flag ensures that the week is
+	relevant for the given year. Note that this flag is only
+	releveant if WEEK_JANUARY is not set.
+
+			  If set	 Week is in range 1-53.
+
+	In this case one may get week 53 for a date in January (when
+	the week is that last week of previous year) and week 1 for a
+	date in December.
+
+  WEEK_FIRST_WEEKDAY (2)  If not set	Weeks are numbered according
+			   		to ISO 8601:1988
+			  If set	The week that contains the first
+					'first-day-of-week' is week 1.
+	
+	ISO 8601:1988 means that if the week containing January 1 has
+	four or more days in the new year, then it is week 1;
+	Otherwise it is the last week of the previous year, and the
+	next week is week 1.
 */
 
 longlong Item_func_week::val_int()
 {
   uint year;
-  uint week_format;
   TIME ltime;
   if (get_arg0_date(&ltime,0))
     return 0;
-  week_format= (uint) args[1]->val_int();
-  return (longlong) calc_week(&ltime, 
-			      (week_format & 2) != 0,
-			      (week_format & 1) == 0,
+  return (longlong) calc_week(&ltime,
+			      week_mode((uint) args[1]->val_int()),
 			      &year);
 }
 
@@ -206,7 +230,9 @@ longlong Item_func_yearweek::val_int()
   TIME ltime;
   if (get_arg0_date(&ltime,0))
     return 0;
-  week=calc_week(&ltime, 1, (args[1]->val_int() & 1) == 0, &year);
+  week= calc_week(&ltime, 
+		  (week_mode((uint) args[1]->val_int()) | WEEK_YEAR),
+		  &year);
   return week+year*100;
 }
 
@@ -844,7 +870,10 @@ String *Item_func_date_format::val_str(String *str)
       case 'u':
       {
 	uint year;
-	sprintf(intbuff,"%02d",calc_week(&l_time, 0, (*ptr) == 'U', &year));
+	sprintf(intbuff,"%02d",
+		calc_week(&l_time, 
+			  ((*ptr) == 'U' ? 
+			   WEEK_FIRST_WEEKDAY : WEEK_MONDAY_FIRST) , &year));
 	str->append(intbuff);
       }
       break;
@@ -852,7 +881,11 @@ String *Item_func_date_format::val_str(String *str)
       case 'V':
       {
 	uint year;
-	sprintf(intbuff,"%02d",calc_week(&l_time, 1, (*ptr) == 'V', &year));
+	sprintf(intbuff,"%02d",
+		calc_week(&l_time,
+			  ((*ptr) == 'V' ? WEEK_YEAR | WEEK_FIRST_WEEKDAY :
+			   WEEK_YEAR | WEEK_MONDAY_FIRST),
+			  &year));
 	str->append(intbuff);
       }
       break;
@@ -860,7 +893,10 @@ String *Item_func_date_format::val_str(String *str)
       case 'X':
       {
 	uint year;
-	(void) calc_week(&l_time, 1, (*ptr) == 'X', &year);
+	(void) calc_week(&l_time,
+			 ((*ptr) == 'X' ? WEEK_YEAR | WEEK_FIRST_WEEKDAY :
+			  WEEK_YEAR | WEEK_MONDAY_FIRST),
+			 &year);
 	sprintf(intbuff,"%04d",year);
 	str->append(intbuff);
       }
diff --git a/sql/mysql_priv.h b/sql/mysql_priv.h
index adb7831896c..04529919990 100644
--- a/sql/mysql_priv.h
+++ b/sql/mysql_priv.h
@@ -247,6 +247,11 @@ void debug_sync_point(const char* lock_name, uint lock_timeout);
 #define tmp_file_prefix "#sql"			/* Prefix for tmp tables */
 #define tmp_file_prefix_length 4
 
+/* Flags for calc_week() function.  */
+#define WEEK_MONDAY_FIRST    1
+#define WEEK_YEAR            2
+#define WEEK_FIRST_WEEKDAY   4
+
 struct st_table;
 class THD;
 
@@ -806,8 +811,7 @@ ha_rows filesort(TABLE *form,struct st_sort_field *sortorder, uint s_length,
 void change_double_for_sort(double nr,byte *to);
 int get_quick_record(SQL_SELECT *select);
 int calc_weekday(long daynr,bool sunday_first_day_of_week);
-uint calc_week(TIME *ltime, bool with_year, bool sunday_first_day_of_week,
-	       uint *year);
+uint calc_week(TIME *l_time, uint week_behaviour, uint *year);
 void find_date(char *pos,uint *vek,uint flag);
 TYPELIB *convert_strings_to_array_type(my_string *typelibs, my_string *end);
 TYPELIB *typelib(List<String> &strings);
diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index e5ddbfe7a33..84287a6cba1 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -4105,7 +4105,7 @@ this value; if zero (the default): when the size exceeds max_binlog_size. \
     "The default week format used by WEEK() functions.",
     (gptr*) &global_system_variables.default_week_format, 
     (gptr*) &max_system_variables.default_week_format, 
-    0, GET_ULONG, REQUIRED_ARG, 0, 0, 3L, 0, 1, 0},
+    0, GET_ULONG, REQUIRED_ARG, 0, 0, 7L, 0, 1, 0},
   {0, 0, 0, 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0}
 };
 
diff --git a/sql/time.cc b/sql/time.cc
index 321a8ba16e5..bf218fa58ab 100644
--- a/sql/time.cc
+++ b/sql/time.cc
@@ -175,42 +175,72 @@ uint calc_days_in_year(uint year)
     366 : 365;
 }
 
-/* Calculate week.  If 'with_year' is not set, then return a week 0-53, where
-   0 means that it's the last week of the previous year.
-   If 'with_year' is set then the week will always be in the range 1-53 and
-   the year out parameter will contain the year for the week */
 
-uint calc_week(TIME *l_time, bool with_year, bool sunday_first_day_of_week,
-	       uint *year)
+/*
+  The bits in week_format has the following meaning:
+   WEEK_MONDAY_FIRST (0)  If not set	Sunday is first day of week
+      		   	  If set	Monday is first day of week
+   WEEK_YEAR (1)	  If not set	Week is in range 0-53
+
+   	Week 0 is returned for the the last week of the previous year (for
+	a date at start of january) In this case one can get 53 for the
+	first week of next year.  This flag ensures that the week is
+	relevant for the given year. Note that this flag is only
+	releveant if WEEK_JANUARY is not set.
+
+			  If set	 Week is in range 1-53.
+
+	In this case one may get week 53 for a date in January (when
+	the week is that last week of previous year) and week 1 for a
+	date in December.
+
+  WEEK_FIRST_WEEKDAY (2)  If not set	Weeks are numbered according
+			   		to ISO 8601:1988
+			  If set	The week that contains the first
+					'first-day-of-week' is week 1.
+	
+	ISO 8601:1988 means that if the week containing January 1 has
+	four or more days in the new year, then it is week 1;
+	Otherwise it is the last week of the previous year, and the
+	next week is week 1.
+*/
+
+uint calc_week(TIME *l_time, uint week_behaviour, uint *year)
 {
   uint days;
   ulong daynr=calc_daynr(l_time->year,l_time->month,l_time->day);
   ulong first_daynr=calc_daynr(l_time->year,1,1);
-  uint weekday=calc_weekday(first_daynr,sunday_first_day_of_week);
+  bool monday_first= test(week_behaviour & WEEK_MONDAY_FIRST);
+  bool week_year= test(week_behaviour & WEEK_YEAR);
+  bool first_weekday= test(week_behaviour & WEEK_FIRST_WEEKDAY);
+
+  uint weekday=calc_weekday(first_daynr, !monday_first);
   *year=l_time->year;
-  if (l_time->month == 1 && l_time->day <= 7-weekday &&
-      ((!sunday_first_day_of_week && weekday >= 4) ||
-       (sunday_first_day_of_week && weekday != 0)))
+
+  if (l_time->month == 1 && l_time->day <= 7-weekday)
   {
-    /* Last week of the previous year */
-    if (!with_year)
+    if (!week_year && 
+	(first_weekday && weekday != 0 ||
+	 !first_weekday && weekday >= 4))
       return 0;
-    with_year=0;				// Don't check the week again
+    week_year= 1;
     (*year)--;
     first_daynr-= (days=calc_days_in_year(*year));
     weekday= (weekday + 53*7- days) % 7;
   }
-  if ((sunday_first_day_of_week && weekday != 0) ||
-      (!sunday_first_day_of_week && weekday >= 4))
+
+  if ((first_weekday && weekday != 0) ||
+      (!first_weekday && weekday >= 4))
     days= daynr - (first_daynr+ (7-weekday));
   else
     days= daynr - (first_daynr - weekday);
-  if (with_year && days >= 52*7)
+
+  if (week_year && days >= 52*7)
   {
-    /* Check if we are on the first week of the next year (or week 53) */
     weekday= (weekday + calc_days_in_year(*year)) % 7;
-    if (weekday < 4)
-    {					// We are at first week on next year
+    if (!first_weekday && weekday < 4 ||
+	first_weekday && weekday == 0)
+    {
       (*year)++;
       return 1;
     }