Re: [PATCH v2 1/5] git-compat-util: add isblank() and isgraph()
- From
René Scharfe <l.s.r@web.de>
- Date
- Feb 26, 2023, 18:45 UTC
- Message-ID
- <36cd059e-c676-2aa2-68d9-41a7b0db57f0@web.de>
- In-Reply-To
- <20230226115021.1681834-2-masahiroy@kernel.org>
Am 26.02.23 um 12:50 schrieb Masahiro Yamada:
Show 10 quoted lines
> git-compat-util.h implements most of is*() macros. > > Add isblank() and isgraph(), which are useful to clean up wildmatch.c > in a consistent way (in this and later commits). > > In the previous submission, I just moved isblank() and isgraph() as > implemented in wildmatch.c. I knew they were not robust against the > pointer increment like isblank(*s++), but I thought it was the same > pattern as isprint(), which has the same issue. Unfortunately, it was > more controversial than I had expected...
Not sure we need that story in the commit message, but it gave me an idea: To go back to the isprint() version from 1c149ab2dd (ctype: support iscntrl, ispunct, isxdigit and isprint, 2012-10-15), which evaluates its argument only once:
#define isprint(x) (sane_istest(x, GIT_ALPHA | GIT_DIGIT | GIT_SPACE | \ GIT_PUNCT | GIT_REGEX_SPECIAL | GIT_GLOB_SPECIAL | \ GIT_PATHSPEC_MAGIC))
But then I realized that it wrongly classifies \t, \r and \n as being printing characters; 567342fc77 (test-ctype: test iscntrl, ispunct, isxdigit and isprint, 2023-02-13) shows it. So it's not so easy, however, ...
> This version implements them as inline functions because we ran out > all bits in the sane_ctype[] table. This is the same pattern as > islower() and isupper().
... if you remove GIT_SPACE from the definition above you get a macro version of isgraph() that uses a single table lookup.
> Once we refactor ctype.c to create more room in sane_ctype[], isblank() > and isgraph() will be able to use sane_istest(). Probably so will > islower() and isupper(). The ctype in Linux kernel (lib/ctype.c) has > the LOWER and UPPER bits separately.
If we're out of bits then isblank() is a good choice to implement without a table lookup, as this class only contains two characters and two comparisons should be quite fast.
Stepping back a bit: Is using the unlocalized is* macros in wildmatch() safe, i.e. do we get the same results as before regardless of locale? Junio's remark in https://lore.kernel.org/git/xmqq3579crsd.fsf@gitster.g/ sounds convincing to me if we don't care about single-byte code pages and require plain ASCII or UTF-8. I think it's a good idea to address that point in the commit message.
And adding tests to t/helper/test-ctype.c would be nice.
Show 82 quoted lines
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>
> Changes in v2:
> - Use inline functions
>
> git-compat-util.h | 14 ++++++++++++++
> wildmatch.c | 14 ++------------
> 2 files changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/git-compat-util.h b/git-compat-util.h
> index 4f0028ce60..b29c238f02 100644
> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -1212,10 +1212,12 @@ extern const unsigned char tolower_trans_tbl[256];
> /* Sane ctype - no locale, and works with signed chars */
> #undef isascii
> #undef isspace
> +#undef isblank
> #undef isdigit
> #undef isalpha
> #undef isalnum
> #undef isprint
> +#undef isgraph
> #undef islower
> #undef isupper
> #undef tolower
> @@ -1236,10 +1238,12 @@ extern const unsigned char sane_ctype[256];
> #define sane_istest(x,mask) ((sane_ctype[(unsigned char)(x)] & (mask)) != 0)
> #define isascii(x) (((x) & ~0x7f) == 0)
> #define isspace(x) sane_istest(x,GIT_SPACE)
> +#define isblank(x) sane_isblank(x)
> #define isdigit(x) sane_istest(x,GIT_DIGIT)
> #define isalpha(x) sane_istest(x,GIT_ALPHA)
> #define isalnum(x) sane_istest(x,GIT_ALPHA | GIT_DIGIT)
> #define isprint(x) ((x) >= 0x20 && (x) <= 0x7e)
> +#define isgraph(x) sane_isgraph(x)
> #define islower(x) sane_iscase(x, 1)
> #define isupper(x) sane_iscase(x, 0)
> #define is_glob_special(x) sane_istest(x,GIT_GLOB_SPECIAL)
> @@ -1270,6 +1274,16 @@ static inline int sane_iscase(int x, int is_lower)
> return (x & 0x20) == 0;
> }
>
> +static inline int sane_isblank(int c)
> +{
> + return c == ' ' || c == '\t';
> +}
> +
> +static inline int sane_isgraph(int c)
> +{
> + return isprint(c) && !isspace(c);
> +}
> +
> /*
> * Like skip_prefix, but compare case-insensitively. Note that the comparison
> * is done via tolower(), so it is strictly ASCII (no multi-byte characters or
> diff --git a/wildmatch.c b/wildmatch.c
> index 7e5a7ea1ea..85c4c7f8a7 100644
> --- a/wildmatch.c
> +++ b/wildmatch.c
> @@ -28,18 +28,8 @@ typedef unsigned char uchar;
> # define ISASCII(c) isascii(c)
> #endif
>
> -#ifdef isblank
> -# define ISBLANK(c) (ISASCII(c) && isblank(c))
> -#else
> -# define ISBLANK(c) ((c) == ' ' || (c) == '\t')
> -#endif
> -
> -#ifdef isgraph
> -# define ISGRAPH(c) (ISASCII(c) && isgraph(c))
> -#else
> -# define ISGRAPH(c) (ISASCII(c) && isprint(c) && !isspace(c))
> -#endif
> -
> +#define ISBLANK(c) (ISASCII(c) && isblank(c))
> +#define ISGRAPH(c) (ISASCII(c) && isgraph(c))
> #define ISPRINT(c) (ISASCII(c) && isprint(c))
> #define ISDIGIT(c) (ISASCII(c) && isdigit(c))
> #define ISALNUM(c) (ISASCII(c) && isalnum(c))