From: Junio C Hamano <gitster@pobox.com>
Date: Sat, 29 Sep 2012 05:35:56 GMT
Subject: Re: [PATCH 2/3] revision: add --grep-reflog to filter commits by reflog messages
Message-ID: <7v4nmhjsqr.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1348893689-20240-1-git-send-email-pclouds@gmail.com>

Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:

> On Sat, Sep 29, 2012 at 12:55 AM, Junio C Hamano <gitster@pobox.com> wrote:
>> For that to happen, the code _must_ know what kind of headers we
>> would support; discarding the existing enum is going in a wrong
>> direction.
>
> Or what kind of manipulation is required for a header. The caller can
> decide if it wants such manipulation or not. Somebody might want to
> grep committer's date, for example.

Yes, if we wanted to filter log outputs to commits authored only on
Thursdays, we would introduce --author-date="<some expression that
yields true only on Thursdays, given the timestmap" option, add
GREP_HEADER_AUTHOR_TIMESTAMP_EXPRESSION=2 to enum grep_header_field,
and add a new element { "author ", 7 } to grep.c::header_field[2]
(the index 2 matches GREP_HEADER_AUTHOR_TIMESTAMP_EXPRESSION), and
implement the evaluator for <some expression that yields true only
on Thursdays, given the timestamp> language in the GREP_PATTERN_HEAD
part of match_one_pattern() and use the p->field to select that
logic.  At that point, we may be better off introducing a helper
function to split the more complex logic for GREP_PATTERN_HEAD out
of the match_one_pattern() function.