Re* [PATCH v4] userdiff: improve java hunk header regex

From

Junio C Hamano <gitster@pobox.com>

Date

Aug 10, 2021, 22:12 UTC

Message-ID

<xmqq35rhc5la.fsf_-_@gitster.g>

In-Reply-To

<d3484278-8413-0d10-e6cd-59a7ff04564b@kdbg.org>

Johannes Sixt <j6t@kdbg.org> writes:

> I don't see the point in this complicated regex. Please recall that it
> will be applied only to syntactically correct Java text. Therefore, you
> do not have to implement all syntactical corner cases, just be
> sufficiently permissive.

> What is wrong with
>
> 	"^[ \t]*(([A-Za-z_][][?&<>.,A-Za-z_0-9]*[ \t]+)+[A-Za-z_][A-Za-z_0-9]*[
> \t]*\\([^;]*)$",
>
> i.e. take every "token" until an identifier followed by an opening
> parenthesis is found. Can types in Java contain parentheses? That would
> make my suggested simplified regex too permissive, but otherwise it
> would do its job, I would think.

Thanks.

---- >8 -------- >8 -------- >8 -------- >8 -------- >8 --------
Subject: userdiff: comment on the builtin patterns

Text stolen mostly from Johannes Sixt.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 userdiff.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git c/userdiff.c w/userdiff.c
index d9b2ba752f..1a6d27fda6 100644
--- c/userdiff.c
+++ w/userdiff.c
@@ -13,6 +13,16 @@ static int drivers_alloc;
 #define IPATTERN(name, pattern, word_regex)			\
 	{ name, NULL, -1, { pattern, REG_EXTENDED | REG_ICASE }, \
 	  word_regex "|[^[:space:]]|[\xc0-\xff][\x80-\xbf]+" }
+
+/*
+ * Built-in drivers for various languages, sorted by their names
+ * (except that the "default" is left at the end).
+ *
+ * When writing or updating patterns, assume that the contents these
+ * patterns are applied to are syntactically correct.  You do not have
+ * to implement all syntactical corner cases---the patterns have to be
+ * sufficiently permissive.
+ */
 static struct userdiff_driver builtin_drivers[] = {
 IPATTERN("ada",
 	 "!^(.*[ \t])?(is[ \t]+new|renames|is[ \t]+separate)([ \t].*)?$\n"