[PATCH] strftime: support %q to output the quarter of year

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[PATCH] strftime: support %q to output the quarter of year

Pádraig Brady
This is already supported by gnulib.

* manual/time.texi: Document %q outputs quarter 1..4.
* time/strftime_l.c: Implement %q.
---
 manual/time.texi  | 6 ++++++
 time/strftime_l.c | 4 ++++
 2 files changed, 10 insertions(+)

diff --git a/manual/time.texi b/manual/time.texi
index 8a5f94e..f4c5f87 100644
--- a/manual/time.texi
+++ b/manual/time.texi
@@ -1510,6 +1510,12 @@ most locales @samp{AM}/@samp{PM} format is not supported, in such cases
 
 This format is a GNU extension.
 
+@item %q
+Quarter of the year (@samp{1}@dots{}@samp{4}),
+with January starting the first quarter.
+
+This format is a GNU extension.
+
 @item %r
 The complete calendar time using the AM/PM format of the current locale.
 
diff --git a/time/strftime_l.c b/time/strftime_l.c
index 869e0b9..13db490 100644
--- a/time/strftime_l.c
+++ b/time/strftime_l.c
@@ -1108,6 +1108,10 @@ __strftime_internal (s, maxsize, format, tp, tzset_called ut_argument
   goto underlying_strftime;
 #endif
 
+        case L_('q'):           /* GNU extension.  */
+          DO_SIGNED_NUMBER (1, tp->tm_mon < -3, tp->tm_mon / 3 + 1U);
+          break;
+
  case L_('R'):
   subfmt = L_("%H:%M");
   goto subformat;
--
2.5.5

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Re: [PATCH] strftime: support %q to output the quarter of year

Florian Weimer
* Pádraig Brady:

> This is already supported by gnulib.

This needs a test case (at least a test case update).

> +        case L_('q'):           /* GNU extension.  */
> +          DO_SIGNED_NUMBER (1, tp->tm_mon < -3, tp->tm_mon / 3 + 1U);
> +          break;

I don't think we have DO_SIGNED_NUMBER in glibc.
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Re: [PATCH] strftime: support %q to output the quarter of year

Adhemerval Zanella-2


On 03/11/2016 17:58, Florian Weimer wrote:

> * Pádraig Brady:
>
>> This is already supported by gnulib.
>
> This needs a test case (at least a test case update).
>
>> +        case L_('q'):           /* GNU extension.  */
>> +          DO_SIGNED_NUMBER (1, tp->tm_mon < -3, tp->tm_mon / 3 + 1U);
>> +          break;
>
> I don't think we have DO_SIGNED_NUMBER in glibc.
>

Indeed and you need to indicate how/where exactly you have tested
it.
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Re: [PATCH] strftime: support %q to output the quarter of year

Joseph Myers
In reply to this post by Florian Weimer
On Thu, 3 Nov 2016, Florian Weimer wrote:

> * Pádraig Brady:
>
> > This is already supported by gnulib.
>
> This needs a test case (at least a test case update).

And a NEWS entry.

--
Joseph S. Myers
[hidden email]
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Re: [PATCH] strftime: support %q to output the quarter of year

Pádraig Brady
In reply to this post by Pádraig Brady
Updated patch attached.

Tested using:

 sudo alternatives --set ld /usr/bin/ld.bfd
 mkdir build.tmp
 cd build.tmp
 ../configure --quiet --disable-sanity-checks
 make PARALLELMFLAGS=-j$(nproc)
 make -r PARALLELMFLAGS=-j$(nproc) -C $PWD/../time objdir=$(pwd) check
 ./testrun.sh time/tst-strftime && echo ok

Note even though the code is trivial here,
%q is useful as from the shell you need to:
$(( ($(date +%-m)-1)/3+1 ))

thanks,
Pádraig.

glibc-strftime-%q.patch (2K) Download Attachment
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Re: [PATCH] strftime: support %q to output the quarter of year

Paul Eggert
Pádraig Brady wrote:

> +          DO_NUMBER (1, tp->tm_mon / 3 + 1);

I couldn't resist puzzling this one out. We can assume 0 <= tp->tm_mon < 12, so
this should be a tad more efficient:

    DO_NUMBER (1, ((tp->tm_mon * 11) >> 5) + 1);

With gcc 6.2.0 -O2 x86-64, the former uses imull with 6 insns, the latter just
leal with 4 insns. Perhaps GCC should be smart enough to figure this out on its
own, but what would be the fun of that?
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Re: [PATCH] strftime: support %q to output the quarter of year

Rafal Luzynski
In reply to this post by Pádraig Brady
Hi,

Shouldn't strptime() family also support the same?

Regards,

Rafal
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Re: [PATCH] strftime: support %q to output the quarter of year

Szabolcs Nagy-2
In reply to this post by Pádraig Brady
On 03/11/16 19:46, Pádraig Brady wrote:
> This is already supported by gnulib.

why?

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Re: [PATCH] strftime: support %q to output the quarter of year

Pádraig Brady
On 04/11/16 11:41, Szabolcs Nagy wrote:
> On 03/11/16 19:46, Pádraig Brady wrote:
>> This is already supported by gnulib.

> why?

It's a marginal benefit, but as
noted in the cover of my updated patch:

"Note even though the code is trivial here,
%q is useful from the shell as there you need to:
$(( ($(date +%-m)-1)/3+1 ))".

I'll add that to the actual commit.


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Re: [PATCH] strftime: support %q to output the quarter of year

Szabolcs Nagy-2
On 04/11/16 12:00, Pádraig Brady wrote:

> On 04/11/16 11:41, Szabolcs Nagy wrote:
>> On 03/11/16 19:46, Pádraig Brady wrote:
>>> This is already supported by gnulib.
>
>> why?
>
> It's a marginal benefit, but as
> noted in the cover of my updated patch:
>
> "Note even though the code is trivial here,
> %q is useful from the shell as there you need to:
> $(( ($(date +%-m)-1)/3+1 ))".
>
> I'll add that to the actual commit.

this can conflict with future standard, so
there need to be a strong reason for adding
such extensions to portability libraries
such as gnulib or to c runtimes.

how does gnulib plan to deal with the conflict
once posix adds %q with different meaning?

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Re: [PATCH] strftime: support %q to output the quarter of year

Pádraig Brady
On 04/11/16 12:07, Szabolcs Nagy wrote:

> On 04/11/16 12:00, Pádraig Brady wrote:
>> On 04/11/16 11:41, Szabolcs Nagy wrote:
>>> On 03/11/16 19:46, Pádraig Brady wrote:
>>>> This is already supported by gnulib.
>>
>>> why?
>>
>> It's a marginal benefit, but as
>> noted in the cover of my updated patch:
>>
>> "Note even though the code is trivial here,
>> %q is useful from the shell as there you need to:
>> $(( ($(date +%-m)-1)/3+1 ))".
>>
>> I'll add that to the actual commit.
>
> this can conflict with future standard, so
> there need to be a strong reason for adding
> such extensions to portability libraries
> such as gnulib or to c runtimes.
>
> how does gnulib plan to deal with the conflict
> once posix adds %q with different meaning?

Perl's date lib also uses %q for quarter.
So between that and gnulib (and glibc?)
POSIX would be unlikely to choose %q for something else.
In any case I intend to propose it to the POSIX folks.

thanks,
Pádraig

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Re: [PATCH] strftime: support %q to output the quarter of year

Szabolcs Nagy-2
On 04/11/16 12:23, Pádraig Brady wrote:

> On 04/11/16 12:07, Szabolcs Nagy wrote:
>> On 04/11/16 12:00, Pádraig Brady wrote:
>>> On 04/11/16 11:41, Szabolcs Nagy wrote:
>>>> On 03/11/16 19:46, Pádraig Brady wrote:
>>>>> This is already supported by gnulib.
>>>
>>>> why?
>>>
>>> It's a marginal benefit, but as
>>> noted in the cover of my updated patch:
>>>
>>> "Note even though the code is trivial here,
>>> %q is useful from the shell as there you need to:
>>> $(( ($(date +%-m)-1)/3+1 ))".
>>>
>>> I'll add that to the actual commit.
>>
>> this can conflict with future standard, so
>> there need to be a strong reason for adding
>> such extensions to portability libraries
>> such as gnulib or to c runtimes.
>>
>> how does gnulib plan to deal with the conflict
>> once posix adds %q with different meaning?
>
> Perl's date lib also uses %q for quarter.

i don't know what "Perl's date lib" is,
the perl DateTime module does not seem to support %q.
https://metacpan.org/pod/DateTime#strftime-Patterns

> So between that and gnulib (and glibc?)
> POSIX would be unlikely to choose %q for something else.
> In any case I intend to propose it to the POSIX folks.
>
> thanks,
> Pádraig
>

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Re: [PATCH] strftime: support %q to output the quarter of year

Pádraig Brady
On 04/11/16 12:41, Szabolcs Nagy wrote:

> On 04/11/16 12:23, Pádraig Brady wrote:
>> On 04/11/16 12:07, Szabolcs Nagy wrote:
>>> On 04/11/16 12:00, Pádraig Brady wrote:
>>>> On 04/11/16 11:41, Szabolcs Nagy wrote:
>>>>> On 03/11/16 19:46, Pádraig Brady wrote:
>>>>>> This is already supported by gnulib.
>>>>
>>>>> why?
>>>>
>>>> It's a marginal benefit, but as
>>>> noted in the cover of my updated patch:
>>>>
>>>> "Note even though the code is trivial here,
>>>> %q is useful from the shell as there you need to:
>>>> $(( ($(date +%-m)-1)/3+1 ))".
>>>>
>>>> I'll add that to the actual commit.
>>>
>>> this can conflict with future standard, so
>>> there need to be a strong reason for adding
>>> such extensions to portability libraries
>>> such as gnulib or to c runtimes.
>>>
>>> how does gnulib plan to deal with the conflict
>>> once posix adds %q with different meaning?
>>
>> Perl's date lib also uses %q for quarter.
>
> i don't know what "Perl's date lib" is,
> the perl DateTime module does not seem to support %q.
> https://metacpan.org/pod/DateTime#strftime-Patterns

Sorry Perl's Date::Format supports %q
https://metacpan.org/pod/Date::Format#CONVERSION-SPECIFICATION
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Re: [PATCH] strftime: support %q to output the quarter of year

Keld Simonsen-2
In reply to this post by Pádraig Brady
ISO 30112 will poropose %q in the new revision.
I think it is difficult for POSIX then to do something else.

Have you got standardese for the %q spec, which I can use in 30112?

Best regards
keld

On Fri, Nov 04, 2016 at 12:23:28PM +0000, Pádraig Brady wrote:

> On 04/11/16 12:07, Szabolcs Nagy wrote:
> > On 04/11/16 12:00, Pádraig Brady wrote:
> >> On 04/11/16 11:41, Szabolcs Nagy wrote:
> >>> On 03/11/16 19:46, Pádraig Brady wrote:
> >>>> This is already supported by gnulib.
> >>
> >>> why?
> >>
> >> It's a marginal benefit, but as
> >> noted in the cover of my updated patch:
> >>
> >> "Note even though the code is trivial here,
> >> %q is useful from the shell as there you need to:
> >> $(( ($(date +%-m)-1)/3+1 ))".
> >>
> >> I'll add that to the actual commit.
> >
> > this can conflict with future standard, so
> > there need to be a strong reason for adding
> > such extensions to portability libraries
> > such as gnulib or to c runtimes.
> >
> > how does gnulib plan to deal with the conflict
> > once posix adds %q with different meaning?
>
> Perl's date lib also uses %q for quarter.
> So between that and gnulib (and glibc?)
> POSIX would be unlikely to choose %q for something else.
> In any case I intend to propose it to the POSIX folks.
>
> thanks,
> Pádraig
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Re: [PATCH] strftime: support %q to output the quarter of year

Szabolcs Nagy-2
On 04/11/16 13:12, [hidden email] wrote:
> ISO 30112 will poropose %q in the new revision.
> I think it is difficult for POSIX then to do something else.

this should be the other way around: propose the interface
to posix, then add locale specifications later, otherwise
the two standards can diverge.

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[PATCH v3] strftime,strptime: have %q represent the quarter of year

Pádraig Brady
In reply to this post by Rafal Luzynski
On 04/11/16 11:33, Rafal Luzynski wrote:
> Hi,
>
> Shouldn't strptime() family also support the same?

I was debating that, but you're right,
strptime() should support that for consistency.

Updated patch is attached, which also adjusts
to Paul Eggert's optimization.

thanks,
Pádraig

glibc-strptime-%q.patch (5K) Download Attachment
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Re: [PATCH] strftime: support %q to output the quarter of year

Adhemerval Zanella-2
In reply to this post by Szabolcs Nagy-2


On 04/11/2016 12:12, Szabolcs Nagy wrote:
> On 04/11/16 13:12, [hidden email] wrote:
>> ISO 30112 will poropose %q in the new revision.
>> I think it is difficult for POSIX then to do something else.
>
> this should be the other way around: propose the interface
> to posix, then add locale specifications later, otherwise
> the two standards can diverge.

I tend to agree with this rationale.
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Re: [PATCH] strftime: support %q to output the quarter of year

Keld Simonsen-2
In reply to this post by Szabolcs Nagy-2
On Fri, Nov 04, 2016 at 02:12:28PM +0000, Szabolcs Nagy wrote:
> On 04/11/16 13:12, [hidden email] wrote:
> > ISO 30112 will poropose %q in the new revision.
> > I think it is difficult for POSIX then to do something else.
>
> this should be the other way around: propose the interface
> to posix, then add locale specifications later, otherwise
> the two standards can diverge.

Oh, well, 30112 has taken the lead  on many i18n issues, and this is also the agreement with the posix folks.

Best regards
keld