Re: [PATCH v5 04/10] grep/icase: avoid kwsset on literal non-ascii strings

[Eric Sunshine <sunshine@sunshineco.com>]

On Thu, Jan 28, 2016 at 6:56 AM, Nguyễn Thái Ngọc Duy <pclouds@gmail.com> wrote:
> When we detect the pattern is just a literal string, we avoid heavy
> regex engine and use fast substring search implemented in kwsset.c.
> But kws uses git-ctype which is locale-independent so it does not know
> how to fold case properly outside ascii range. Let regcomp or pcre
> take care of this case instead. Slower, but accurate.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
> diff --git a/grep.c b/grep.c
> @@ -398,12 +399,16 @@ static int is_fixed(const char *s, size_t len)
>  static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
>  {
> +       int icase_non_ascii;
>         int err;
>
>         p->word_regexp = opt->word_regexp;
>         p->ignore_case = opt->ignore_case;
> +       icase_non_ascii =
> +               (opt->regflags & REG_ICASE || p->ignore_case) &&
> +               has_non_ascii(p->pattern);
>
> -       if (is_fixed(p->pattern, p->patternlen))
> +       if (!icase_non_ascii && is_fixed(p->pattern, p->patternlen))

These double negatives (!non_ascii) here and in patch 5/10 are
difficult to grok. I wonder if a different name, such as
icase_ascii_only would help.

>                 p->fixed = 1;
>         else if (opt->fixed) {
>                 p->fixed = 1;