[PATCH v4 2/2] strbuf: change an always NULL/"" strbuf_addftime() param to bool

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change the code for deciding what's to be done about %Z to stop
passing always either a NULL or "" char * to
strbuf_addftime(). Instead pass a boolean int to indicate whether the
strftime() %Z format should be suppressed by converting it to an empty
string, which is what this code is actually doing.

This code grew organically between the changes in 9eafe86d58 ("Merge
branch 'rs/strbuf-addftime-zZ'", 2017-06-22). The intent was to use
this API in the future to pass a custom leave the door open to pass a
custom timezone name to the function (see my [1] and related
messages).

But that's not what this code does now, and this strbuf_addstr() call
always being redundant makes it hard to understand the current
functionality. So simplify this internal API to match its use, we can
always change it in the future if it gets a different use-case.

1. CACBZZX5OQc45fUyDVayE89rkT=+8m5S4efSXCAbCy7Upme5zLA@mail.gmail.com
   (https://public-inbox.org/git/CACBZZX5OQc45fUyDVayE89rkT=+8m5S4efSXCAbCy7Upme5zLA@mail.gmail.com/)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---

On Sat, Jun 24, 2017 at 2:02 PM, Jeff King <peff@peff.net> wrote:
> On Sat, Jun 24, 2017 at 11:36:35AM +0000, Ævar Arnfjörð Bjarmason wrote:
>
>> >>  extern void strbuf_addftime(struct strbuf *sb, const char *fmt,
>> >>                        const struct tm *tm, int tz_offset,
>> >> -                      const char *tz_name);
>> >> +                      const int omit_strftime_tz_name);
>> >
>> > This would need the new name, too (whatever it is).
>>
>> *Nod*. Now the parameter is called suppress_tz_name.
>
> Thanks. That sounds good (and your initial re-ordering patch looks fine,
> too). One minor typo:
>
>> diff --git a/strbuf.h b/strbuf.h
>> index 6708cef0f9..d3e6e65123 100644
>> --- a/strbuf.h
>> +++ b/strbuf.h
>> @@ -343,11 +343,12 @@ extern void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
>>   * `tz_offset` is in decimal hhmm format, e.g. -600 means six hours west
>>   * of Greenwich, and it's used to expand %z internally.  However, tokens
>>   * with modifiers (e.g. %Ez) are passed to `strftime`.
>> - * `tz_name` is used to expand %Z internally unless it's NULL.
>> + * `suppress_tz_name` when set, means let suppress the `strftime` %Z
>> + * format and replace it with an empty string.
>
> I couldn't quite parse "let suppress". I'm not sure if it was supposed
> to be "let's". Probably "means to suppress the strftime..." would be
> more clear. I'd probably have written it more like:
>
>   `suppress_tz_name`, when set, expands %Z internally to the empty
>   string rather than passing it to `strftime`.

Thanks. Docs fixed per your suggestion. I sent a v4 of 1/2 too, but
that's unchanged, just thought it was simpler than having just one
patch have a v4...

 date.c   | 2 +-
 strbuf.c | 5 ++---
 strbuf.h | 5 +++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/date.c b/date.c
index 1fd6d66375..c3e673fd04 100644
--- a/date.c
+++ b/date.c
@@ -256,7 +256,7 @@ const char *show_date(timestamp_t time, int tz, const struct date_mode *mode)
 			tm->tm_hour, tm->tm_min, tm->tm_sec, tz);
 	else if (mode->type == DATE_STRFTIME)
 		strbuf_addftime(&timebuf, mode->strftime_fmt, tm, tz,
-				mode->local ? NULL : "");
+				!mode->local);
 	else
 		strbuf_addf(&timebuf, "%.3s %.3s %d %02d:%02d:%02d %d%c%+05d",
 				weekday_names[tm->tm_wday],
diff --git a/strbuf.c b/strbuf.c
index be3b9e37b1..89e40bb496 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -786,7 +786,7 @@ char *xstrfmt(const char *fmt, ...)
 }
 
 void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm,
-		     int tz_offset, const char *tz_name)
+		     int tz_offset, int suppress_tz_name)
 {
 	struct strbuf munged_fmt = STRBUF_INIT;
 	size_t hint = 128;
@@ -815,8 +815,7 @@ void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm,
 			fmt++;
 			break;
 		case 'Z':
-			if (tz_name) {
-				strbuf_addstr(&munged_fmt, tz_name);
+			if (suppress_tz_name) {
 				fmt++;
 				break;
 			}
diff --git a/strbuf.h b/strbuf.h
index 6708cef0f9..d3e6e65123 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -343,11 +343,12 @@ extern void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
  * `tz_offset` is in decimal hhmm format, e.g. -600 means six hours west
  * of Greenwich, and it's used to expand %z internally.  However, tokens
  * with modifiers (e.g. %Ez) are passed to `strftime`.
- * `tz_name` is used to expand %Z internally unless it's NULL.
+ * `suppress_tz_name` when set, means let suppress the `strftime` %Z
+ * format and replace it with an empty string.
  */
 extern void strbuf_addftime(struct strbuf *sb, const char *fmt,
 			    const struct tm *tm, int tz_offset,
-			    const char *tz_name);
+			    int suppress_tz_name);
 
 /**
  * Read a given size of data from a FILE* pointer to the buffer.
-- 
2.13.1.611.g7e3b11ae1