Re: [PATCH v4 3/6] regex.3: Improve REG_STARTEND

[Alejandro Colomar <alx.manpages@gmail.com>]

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On 4/20/23 15:02, наб wrote:
> Explicitly spell out the ranges involved. The original wording always
> confused me, but it's actually very sane.

I like this change.

> 
> Also change the [0]. to -> here to make more obvious the point that
> pmatch is used as a pointer-to-object, not array in this scenario.

Since at the same time [>0] can be meaningful, I prefer using [0],
to note that the first entry is special in the array.  -> looks like
there's no array at all, but rather just one object.

> 
> Remove "this doesn't change R_NOTBOL & R_NEWLINE" ‒ so does it change
> R_NOTEOL? No. That's weird and confusing.
> 
> String largeness doesn't matter, known-lengthness does.

Good.

> 
> Explicitly spell out the influence on returned matches
> (relative to string, not start of range).
> 
> Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>

Cheers,
Alex

> ---
>  man3/regex.3 | 33 ++++++++++++++++++++-------------
>  1 file changed, 20 insertions(+), 13 deletions(-)
> 
> diff --git a/man3/regex.3 b/man3/regex.3
> index b4feaba19..00e7e2c6b 100644
> --- a/man3/regex.3
> +++ b/man3/regex.3
> @@ -131,23 +131,30 @@ compilation flag
>  above).
>  .TP
>  .B REG_STARTEND
> -Use
> -.I pmatch[0]
> -on the input string, starting at byte
> -.I pmatch[0].rm_so
> -and ending before byte
> -.IR pmatch[0].rm_eo .
> +Match
> +.RI [ string " + " pmatch->rm_so ", " string " + " pmatch->rm_eo )
> +instead of
> +.RI [ string ", " string " + \fBstrlen\fP(" string )).
>  This allows matching embedded NUL bytes
>  and avoids a
>  .BR strlen (3)
> -on large strings.
> -It does not use
> +on known-length strings.
> +.I pmatch
> +must point to a valid readable object.
> +If any matches are returned
> +.RB ( REG_NOSUB
> +wasn't passed to
> +.BR regcomp (),
> +the match succeeded, and
>  .I nmatch
> -on input, and does not change
> -.B REG_NOTBOL
> -or
> -.B REG_NEWLINE
> -processing.
> +> 0), they overwrite
> +.I pmatch
> +as usual, and the
> +.B Match offsets
> +remain relative to
> +.IR string
> +(not
> +.IR string " + " pmatch->rm_so ).
>  This flag is a BSD extension, not present in POSIX.
>  .SS Match offsets
>  Unless

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