Re: [RFC v3] scripts: kernel-doc: reduce repeated regex expressions into variables

[Matthew Wilcox <willy@infradead.org>]

On Thu, Apr 29, 2021 at 12:07:29PM +0530, Aditya Srivastava wrote:
> +    my $name = qr{[a-zA-Z0-9_~:]+};
> +    my $prototype_end1 = qr{[^\(]*};
> +    my $prototype_end2 = qr{[^\{]*};
> +    my $prototype_end = qr{\(($prototype_end1|$prototype_end2)\)};

Would this be better written as:

	my $prototype_end = qr{\([^\(\{]*\)}

And now that I look at the whole thing, doesn't this fail to parse
a function declared as:

int f(void (*g)(long));

(that is, f takes a single argument, which is a pointer to a function
which takes a long argument and returns void)

Still, I don't think this was parsed correctly before, so it's not an
argument against this patch, just something to take care of later.

> +    my $type1 = qr{[\w\s]+};
> +    my $type2 = qr{$type1\*+};
> +
> +    if ($define && $prototype =~ m/^()($name)\s+/) {
>          # This is an object-like macro, it has no return type and no parameter
>          # list.
>          # Function-like macros are not allowed to have spaces between
> @@ -1817,23 +1828,9 @@ sub dump_function($$) {
>          $return_type = $1;
>          $declaration_name = $2;
>          $noret = 1;
> -    } elsif ($prototype =~ m/^()([a-zA-Z0-9_~:]+)\s*\(([^\(]*)\)/ ||
> -	$prototype =~ m/^(\w+)\s+([a-zA-Z0-9_~:]+)\s*\(([^\(]*)\)/ ||
> -	$prototype =~ m/^(\w+\s*\*+)\s*([a-zA-Z0-9_~:]+)\s*\(([^\(]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+)\s+([a-zA-Z0-9_~:]+)\s*\(([^\(]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+\s*\*+)\s*([a-zA-Z0-9_~:]+)\s*\(([^\(]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+\s+\w+)\s+([a-zA-Z0-9_~:]+)\s*\(([^\(]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+\s+\w+\s*\*+)\s*([a-zA-Z0-9_~:]+)\s*\(([^\(]*)\)/ ||
> -	$prototype =~ m/^()([a-zA-Z0-9_~:]+)\s*\(([^\{]*)\)/ ||
> -	$prototype =~ m/^(\w+)\s+([a-zA-Z0-9_~:]+)\s*\(([^\{]*)\)/ ||
> -	$prototype =~ m/^(\w+\s*\*+)\s*([a-zA-Z0-9_~:]+)\s*\(([^\{]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+)\s+([a-zA-Z0-9_~:]+)\s*\(([^\{]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+\s*\*+)\s*([a-zA-Z0-9_~:]+)\s*\(([^\{]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+\s+\w+)\s+([a-zA-Z0-9_~:]+)\s*\(([^\{]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+\s+\w+\s*\*+)\s*([a-zA-Z0-9_~:]+)\s*\(([^\{]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+\s+\w+\s+\w+)\s+([a-zA-Z0-9_~:]+)\s*\(([^\{]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+\s+\w+\s+\w+\s*\*+)\s*([a-zA-Z0-9_~:]+)\s*\(([^\{]*)\)/ ||
> -	$prototype =~ m/^(\w+\s+\w+\s*\*+\s*\w+\s*\*+\s*)\s*([a-zA-Z0-9_~:]+)\s*\(([^\{]*)\)/)  {
> +    } elsif ($prototype =~ m/^()($name)\s*$prototype_end/ ||
> +	$prototype =~ m/^($type1)\s+($name)\s*$prototype_end/ ||
> +	$prototype =~ m/^($type2)+\s*($name)\s*$prototype_end/)  {
>  	$return_type = $1;
>  	$declaration_name = $2;
>  	my $args = $3;