Re: [PATCH v2] Teach git diff about Objective-C syntax

From: Brandon Casey <casey@nrlssc.navy.mil>
Date: Oct 1, 2008, 00:52 UTC
Message-ID: <mJtumbyBuR0sRaFjwb6O5_D_ps0fVfz6APTAAjYMixV0MvzP8nEZRw@cipher.nrlssc.navy.mil>
In-Reply-To: <1222818394-11547-1-git-send-email-jon.delStrother@bestbefore.tv>

Jonathan del Strother wrote:

Show 10 quoted lines

> Add support for recognition of Objective-C class & instance methods, C functions, and class implementation/interfaces.
> 
> Signed-off-by: Jonathan del Strother <jon.delStrother@bestbefore.tv>
> ---
> This version is much the same, but rebuilt on top of 1883a0d3b to use the extended regexp stuff, and it doesn't attempt to tidy up other patterns.
> 
> I've been trying to make the objc-method matching line a bit more specific - I think I'm running into a bug (or more likely a misunderstanding) in the matching process.
> Every pattern there uses either .*$ or [^;]*$ to match up to the end of a line.  But in trying to come up with a whitelist of characters to match up to the end of a line, I couldn't do it : there seems to be an invisible character at the end of the line that I can't match.
> That is, a line containing just "FUNCNAME" (terminated by a newline) will be matched by the pattern "^(FUNCNAME.$)" but not "^(FUNCNAME$)".
> Why is this?

I think it is the newline which git is not removing from the string passed to regexec.

See: http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html#tag_09_02

   "...In the regular expression processing described in IEEE Std 1003.1-2001,
    the <newline> is regarded as an ordinary character and both a period and a
    non-matching list can match one."

   "...Those utilities (like grep) that do not allow <newline>s to match are
    responsible for eliminating any <newline> from strings before matching against
    the RE."

Possibly something like:

diff --git a/xdiff-interface.c b/xdiff-interface.c
index 8bab82e..f471c7c 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -191,7 +191,7 @@ struct ff_regs {
 static long ff_regexp(const char *line, long len,
		char *buffer, long buffer_size, void *priv)
 {
-	char *line_buffer = xstrndup(line, len); /* make NUL terminated */
+	char *line_buffer = xstrndup(line, len-1); /* make NUL terminated */
 	struct ff_regs *regs = priv;
 	regmatch_t pmatch[2];
 	int i;