[PATCH][GSoC] git-compat-util.h:rewrite skip_prefix() as loop

[PATCH][GSoC] git-compat-util.h:rewrite skip_prefix() as loop

[kgeorgiou]

Rewritten git-compat-util.h:skip_prefix() as a loop, so that it doesn't have to
scan through the prefix string twice as a miniproject for GSoC 2014.

(I've just noticed that this miniproject has already been tackled by another 
contributor, if that's a problem I can pick something else.)

Looking forward to any kind of feedback.

- Kyriakos Georgiou

Signed-off-by: kgeorgiou <kyriakos.a.georgiou@gmail.com>
---
 git-compat-util.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/git-compat-util.h b/git-compat-util.h
index 614a5e9..713f37a 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -357,8 +357,11 @@ extern int suffixcmp(const char *str, const char *suffix);
 
 static inline const char *skip_prefix(const char *str, const char *prefix)
 {
-	size_t len = strlen(prefix);
-	return strncmp(str, prefix, len) ? NULL : str + len;
+	while(*prefix && *str == *prefix) {
+		str++;
+		prefix++;
+	}
+	return *prefix ? NULL : str;
 }
 
 #if defined(NO_MMAP) || defined(USE_WIN32_MMAP)
-- 
1.8.3.2

Re: [PATCH][GSoC] git-compat-util.h:rewrite skip_prefix() as loop

[Eric Sunshine]

Thanks for the submission. Minor comments below to give you a taste of
what it's like to contribute to this project...

On Sat, Mar 1, 2014 at 5:42 PM, kgeorgiou <kyriakos.a.georgiou@gmail.com> wrote:
> Subject: git-compat-util.h:rewrite skip_prefix() as loop

Space after colon. You might be able to provide more information in
the short summary of the subject. Perhaps something like this:

    Subject: skip_prefix(): avoid scanning 'prefix' twice

> Rewritten git-compat-util.h:skip_prefix() as a loop, so that it doesn't have to
> scan through the prefix string twice as a miniproject for GSoC 2014.

Good description. In this project, use imperative tone:

    Rewrite skip_prefix() as loop...

> (I've just noticed that this miniproject has already been tackled by another
> contributor, if that's a problem I can pick something else.)

That's okay. The purpose of the miniprojects is for you to get a taste
of what it's like to contribute to this project and to understand what
will be expected of you as a GSoC student; and to give the GSoC
mentors a chance to judge your abilities and observe how you interact
with reviewers.

> Looking forward to any kind of feedback.
>
> - Kyriakos Georgiou

There are two types of information you want to convey to readers. (1)
Patch description, explanation, justification before the "---" line
which is recorded in the permanent project history. (2) Commentary
below the "---" line for readers of the patch but not of interest once
the patch is accepted officially. The "as a miniproject for GSoC" and
all lines following it are just commentary which should go below the
"---" line.

> Signed-off-by: kgeorgiou <kyriakos.a.georgiou@gmail.com>

This project prefers real names, so:

    Signed-off-by: Kyriakos Georgiou <...>

> ---
>  git-compat-util.h | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/git-compat-util.h b/git-compat-util.h
> index 614a5e9..713f37a 100644
> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -357,8 +357,11 @@ extern int suffixcmp(const char *str, const char *suffix);
>
>  static inline const char *skip_prefix(const char *str, const char *prefix)
>  {
> -       size_t len = strlen(prefix);
> -       return strncmp(str, prefix, len) ? NULL : str + len;
> +       while(*prefix && *str == *prefix) {

Style nit: space after 'while'.

> +               str++;
> +               prefix++;
> +       }
> +       return *prefix ? NULL : str;
>  }
>
>  #if defined(NO_MMAP) || defined(USE_WIN32_MMAP)
> --
> 1.8.3.2