Re: [PATCH] Improve function dir.c:trim_trailing_spaces()

From: Jeff King <peff@peff.net>
Date: May 29, 2014, 20:13 UTC
Message-ID: <20140529201334.GA17355@sigill.intra.peff.net>
In-Reply-To: <1401320757-9360-1-git-send-email-pasha.bolokhov@gmail.com>

On Wed, May 28, 2014 at 04:45:57PM -0700, Pasha Bolokhov wrote:

> Move backwards from the end of the string (more efficient for
> lines which do not have trailing spaces or have just a couple).

The original code reads the string from left to right. In theory, that means we could get away with not calling strlen() at all, over a right-to-left that must start with a call to strlen().

That being said, I think we already have the length in the calling function, so you could probably avoid the strlen() altogether, which makes a right-to-left function more efficient.

However, I doubt it makes that much of a difference in practice, so unless it's measurable, I would certainly go with the version that is more readable (and correct, of course).

> Slightly more rare occurrences of 'text  \    ' with a backslash
> in between spaces are handled correctly.

Can you add a test for this?

Also, if you are refactoring this function, I think it makes sense to check that:

  "foo\\ "

and

  "foo\\\ "

match "foo\" and "foo\ ", respectively (I think they do with your patch, but it is a tricky case that is not immediately obvious).

-Peff