[RFC][PATCH v3 05/11] Implement the %OB specifier - alternative month names (bug 10871)

[Rafal Luzynski <digitalfreak at lingonborough dot com>]

Some languages (Slavic, Baltic, etc.) require a genitive case of the
month name when formatting a full date (with the day number) while
they require a nominative case when referring to the month standalone.

strftime() now implements a %OB format specifier which generates an
alternative month name.  For the languages which require both nominative
and genitive case of the month names it is expected that it outputs
the alternative month name which should be a nominative (sic!) case
or whatever is appropriate when formatting the month names standalone
(without a day).  For those languages %B will return the basic month
name but from now it is expected to be a genitive case or whatever is
appropriate when formatting full dates (including both day and month).
This means that all applications using %B to retrieve the month
name standalone should use %OB from now.  For those languages which
do not use different (nominative and genitive) cases of the month
name or do not yet have their locales updated %OB will retrieve
the same string as %B so moving to %OB will be harmless as long
as the version of glibc which supports this feature is used.

strptime() now accepts both nominative and genitive month names.

[BZ #10871]
* time/strftime_l.c: %OB format for alternative month names added.
* time/strptime_l.c: alternative month names also recognized.
---
 time/strftime_l.c | 12 ++++++++++--
 time/strptime_l.c | 28 ++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/time/strftime_l.c b/time/strftime_l.c
index 1205035..4d54e23 100644
--- a/time/strftime_l.c
+++ b/time/strftime_l.c
@@ -492,6 +492,9 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T
*format,
 # define f_month \
   ((const CHAR_T *) (tp->tm_mon < 0 || tp->tm_mon > 11			     \
 		     ? "?" : _NL_CURRENT (LC_TIME, NLW(MON_1) + tp->tm_mon)))
+# define f_altmonth \
+  ((const CHAR_T *) (tp->tm_mon < 0 || tp->tm_mon > 11			     \
+		     ? "?" : _NL_CURRENT (LC_TIME, NLW(ALTMON_1) + tp->tm_mon)))
 # define ampm \
   ((const CHAR_T *) _NL_CURRENT (LC_TIME, tp->tm_hour > 11		      \
 				 ? NLW(PM_STR) : NLW(AM_STR)))
@@ -507,6 +510,7 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T
*format,
 		   ? "?" : month_name[tp->tm_mon])
 #  define a_wkday f_wkday
 #  define a_month f_month
+#  define f_altmonth (L_(""))
 #  define ampm (L_("AMPM") + 2 * (tp->tm_hour > 11))
 
   size_t aw_len = 3;
@@ -775,7 +779,7 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T
*format,
 #endif
 
 	case L_('B'):
-	  if (modifier != 0)
+	  if (modifier == L_('E'))
 	    goto bad_format;
 	  if (change_case)
 	    {
@@ -783,7 +787,11 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const
CHAR_T *format,
 	      to_lowcase = 0;
 	    }
 #if defined _NL_CURRENT || !HAVE_STRFTIME
-	  cpy (STRLEN (f_month), f_month);
+	  /* Use f_altmonth only if f_altmonth is provided.  */
+	  if (f_altmonth[0] && modifier == L_('O'))
+	    cpy (STRLEN (f_altmonth), f_altmonth);
+	  else
+	    cpy (STRLEN (f_month), f_month);
 	  break;
 #else
 	  goto underlying_strftime;
diff --git a/time/strptime_l.c b/time/strptime_l.c
index 3a56947..6d5520e 100644
--- a/time/strptime_l.c
+++ b/time/strptime_l.c
@@ -124,6 +124,8 @@ extern const struct __locale_data _nl_C_LC_TIME
attribute_hidden;
   (&_nl_C_LC_TIME.values[_NL_ITEM_INDEX (ABDAY_1)].string)
 # define month_name (&_nl_C_LC_TIME.values[_NL_ITEM_INDEX (MON_1)].string)
 # define ab_month_name (&_nl_C_LC_TIME.values[_NL_ITEM_INDEX (ABMON_1)].string)
+# define alt_month_name \
+  (&_nl_C_LC_TIME.values[_NL_ITEM_INDEX (ALTMON_1)].string)
 # define HERE_D_T_FMT (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (D_T_FMT)].string)
 # define HERE_D_FMT (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (D_FMT)].string)
 # define HERE_AM_STR (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (AM_STR)].string)
@@ -403,6 +405,22 @@ __strptime_internal (const char *rp, const char *fmt,
struct tm *tmp,
 	      if (s.decided !=raw)
 		{
 		  trp = rp;
+#ifdef _LIBC
+		  /* First check if the alt month is provided.  */
+		  if (_NL_CURRENT (LC_TIME, ALTMON_1 + cnt)
+		      && * (_NL_CURRENT (LC_TIME, ALTMON_1 + cnt))
+		      && match_string (_NL_CURRENT (LC_TIME, ALTMON_1 + cnt), trp)
+		      && trp > rp_longest)
+		    {
+		      rp_longest = trp;
+		      cnt_longest = cnt;
+		      if (s.decided == not
+			  && strcmp (_NL_CURRENT (LC_TIME, ALTMON_1 + cnt),
+				     alt_month_name[cnt]))
+			decided_longest = loc;
+		    }
+		  trp = rp;
+#endif
 		  if (match_string (_NL_CURRENT (LC_TIME, MON_1 + cnt), trp)
 		      && trp > rp_longest)
 		    {
@@ -429,6 +447,12 @@ __strptime_internal (const char *rp, const char *fmt,
struct tm *tmp,
 	      if (s.decided != loc
 		  && (((trp = rp, match_string (month_name[cnt], trp))
 		       && trp > rp_longest)
+#ifdef _LIBC
+		      || ((trp = rp, alt_month_name[cnt]
+			  && alt_month_name[cnt][0]
+			  && match_string (alt_month_name[cnt], trp))
+			  && trp > rp_longest)
+#endif
 		      || ((trp = rp, match_string (ab_month_name[cnt], trp))
 			  && trp > rp_longest)))
 		{
@@ -1016,6 +1040,10 @@ __strptime_internal (const char *rp, const char *fmt,
struct tm *tmp,
 	case 'O':
 	  switch (*fmt++)
 	    {
+	    case 'B':
+	      /* Undo the increment and continue.  */
+	      fmt--;
+	      break;
 	    case 'd':
 	    case 'e':
 	      /* Match day of month using alternate numeric symbols.  */
-- 
2.7.4