[glib] gdatetime: Extend the '%z' timezone format

[Kalev Lember <klember src gnome org>]

commit 8fd7f58aeef89f60ca16b8350e6dd0bd34ab5ed1
Author: Kalev Lember <kalevlember gmail com>
Date:   Fri Aug 30 21:24:56 2013 +0200

    gdatetime: Extend the '%z' timezone format
    
    Implement gnulib strftime extensions for the '%z' numeric timezone
    format. These are also supported and documented by GNU date(1):
    
    %z     +hhmm numeric time zone (e.g., -0400)
    
    %:z    +hh:mm numeric time zone (e.g., -04:00)
    
    %::z   +hh:mm:ss numeric time zone (e.g., -04:00:00)
    
    %:::z  numeric time zone with : to necessary precision (e.g., -04, +05:30)
    
    https://bugzilla.gnome.org/show_bug.cgi?id=707151

 glib/gdatetime.c |   99 +++++++++++++++++++++++++++++++++++++++++++++++------
 1 files changed, 87 insertions(+), 12 deletions(-)
---
diff --git a/glib/gdatetime.c b/glib/gdatetime.c
index f3a951c..ccfe574 100644
--- a/glib/gdatetime.c
+++ b/glib/gdatetime.c
@@ -2090,6 +2090,59 @@ g_date_time_to_utc (GDateTime *datetime)
 
 /* Format {{{1 */
 
+static gboolean
+format_z (GString *outstr,
+          gint     offset,
+          guint    colons)
+{
+  gint hours;
+  gint minutes;
+  gint seconds;
+
+  hours = offset / 3600;
+  minutes = ABS (offset) / 60 % 60;
+  seconds = ABS (offset) % 60;
+
+  switch (colons)
+    {
+    case 0:
+      g_string_append_printf (outstr, "%+03d%02d",
+                              hours,
+                              minutes);
+      break;
+
+    case 1:
+      g_string_append_printf (outstr, "%+03d:%02d",
+                              hours,
+                              minutes);
+      break;
+
+    case 2:
+      g_string_append_printf (outstr, "%+03d:%02d:%02d",
+                              hours,
+                              minutes,
+                              seconds);
+      break;
+
+    case 3:
+      g_string_append_printf (outstr, "%+03d", hours);
+
+      if (minutes != 0 || seconds != 0)
+        {
+          g_string_append_printf (outstr, ":%02d", minutes);
+
+          if (seconds != 0)
+            g_string_append_printf (outstr, ":%02d", seconds);
+        }
+      break;
+
+    default:
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 static void
 format_number (GString  *str,
                gboolean  use_alt_digits,
@@ -2185,6 +2238,7 @@ g_date_time_format_locale (GDateTime   *datetime,
                           gboolean     locale_is_utf8)
 {
   guint     len;
+  guint     colons;
   gchar    *tmp;
   gunichar  c;
   gboolean  alt_digits = FALSE;
@@ -2219,6 +2273,7 @@ g_date_time_format_locale (GDateTime   *datetime,
       if (!*format)
        break;
 
+      colons = 0;
       alt_digits = FALSE;
       pad_set = FALSE;
 
@@ -2414,17 +2469,15 @@ g_date_time_format_locale (GDateTime   *datetime,
                         g_date_time_get_year (datetime));
          break;
        case 'z':
-         if (datetime->tz != NULL)
-           {
-             gint64 offset = g_date_time_get_utc_offset (datetime)
-               / USEC_PER_SECOND;
-
-             g_string_append_printf (outstr, "%+03d%02d",
-                                     (int) offset / 3600,
-                                     (int) abs(offset) / 60 % 60);
-           }
-         else
-           g_string_append (outstr, "+0000");
+         {
+           gint64 offset;
+           if (datetime->tz != NULL)
+             offset = g_date_time_get_utc_offset (datetime) / USEC_PER_SECOND;
+           else
+             offset = 0;
+           if (!format_z (outstr, (int) offset, colons))
+             return FALSE;
+         }
          break;
        case 'Z':
          tz = g_date_time_get_timezone_abbreviation (datetime);
@@ -2453,6 +2506,12 @@ g_date_time_format_locale (GDateTime   *datetime,
          pad_set = TRUE;
          pad = "0";
          goto next_mod;
+       case ':':
+         /* Colons are only allowed before 'z' */
+         if (*format && *format != 'z' && *format != ':')
+           return FALSE;
+         colons++;
+         goto next_mod;
        default:
          return FALSE;
        }
@@ -2674,7 +2733,23 @@ g_date_time_format_locale (GDateTime   *datetime,
  *  <varlistentry><term>
  *    <literal>\%z</literal>:
  *   </term><listitem><simpara>
- *    the time-zone as hour offset from UTC
+ *    the time zone as an offset from UTC (+hhmm)
+ *  </simpara></listitem></varlistentry>
+ *  <varlistentry><term>
+ *    <literal>\%:z</literal>:
+ *   </term><listitem><simpara>
+ *    the time zone as an offset from UTC (+hh:mm). This is a gnulib strftime extension. Since: 2.38
+ *  </simpara></listitem></varlistentry>
+ *  <varlistentry><term>
+ *    <literal>\%::z</literal>:
+ *   </term><listitem><simpara>
+ *    the time zone as an offset from UTC (+hh:mm:ss). This is a gnulib strftime extension. Since: 2.38
+ *  </simpara></listitem></varlistentry>
+ *  <varlistentry><term>
+ *    <literal>\%:::z</literal>:
+ *   </term><listitem><simpara>
+ *    the time zone as an offset from UTC, with : to necessary precision
+ *    (e.g., -04, +05:30). This is a gnulib strftime extension. Since: 2.38
  *  </simpara></listitem></varlistentry>
  *  <varlistentry><term>
  *    <literal>\%Z</literal>: