Re: [PATCH 8/8] docs: kernel-doc: Don't mangle literal code blocks in comments

Jani Nikula
2018-02-09T09:47:19Z

On Wed, 07 Feb 2018, Jonathan Corbet <corbet@lwn.net> wrote:
> It can be useful to put code snippets into kerneldoc comments; that can be
> done with the "::" operator at the end of a line like this::
>
> if (desperate)
> run_in_circles();
>
> kernel-doc currently fails to understand these literal blocks and applies
> its normal markup to them, which is then treated as literal by sphinx. The
> result is unsightly markup instead of a useful code snippet.
>
> Apply a hack to the output code to recognize literal blocks and avoid
> performing any special markup on them. It's ugly, but that means it fits
> in well with the rest of the script.
>
> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
> ---
> scripts/kernel-doc | 55 +++++++++++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 50 insertions(+), 5 deletions(-)
>
> diff --git a/scripts/kernel-doc b/scripts/kernel-doc
> index c6c9370a1e49..c984f82cb897 100755
> --- a/scripts/kernel-doc
> +++ b/scripts/kernel-doc
> @@ -748,14 +748,59 @@ sub output_blockhead_rst(%) {
> }
> }
>
> -sub output_highlight_rst {
> - my $contents = join "\n",@_;
> - my $line;
> -
> +#
> +# Apply the RST highlights to a sub-block of text.
> +#
> +sub highlight_block($) {
> + # The dohighlight kludge requires the text be called $contents
> + my $contents = shift;
> eval $dohighlight;
> die $@ if $@;
> + return $contents;
> +}
>
> - foreach $line (split "\n", $contents) {
> +sub output_highlight_rst {
> + my $input = join "\n",@_;
> + my $output = "";
> + my $line;
> + my $in_literal = 0;
> + my $litprefix;
> + my $block = "";
> +
> + # The "dohighlight" hack requires that the data be called "$contents"
> + foreach $line (split "\n",$input) {
> + #
> + # If we're in a literal block, see if we should drop out
> + # of it. Otherwise pass the line straight through unmunged.
> + #
> + if ($in_literal) {
> + if (! ($line =~ /$litprefix/ || $line =~ /^\s*$/)) {
> + $in_literal = 0;
> + }
> + else {
> + $output .= $line . "\n";
> + }
> + }
> + #
> + # Not in a literal block (or just dropped out)
> + #
> + if (! $in_literal) {
> + $block .= $line . "\n";
> + if ($line =~ /^[^.].*::$/) {

I think you should also add "code-block:: <language>" to the
regexp. There are only a few uses now, but I think someone's bound to
hit the same problem with those.

Perhaps also extract the regexp to a variable with a self-documenting
name.

Thanks for doing this. Not that I like it, but as you say, it fits right
in the script. I have some ideas on how to do all of the highlights
nicely as post-processing in the Sphinx extension, but we need this now
and not somewhere in the distant future.

BR,
Jani.

> + $in_literal = 1;
> + # Note current indentation - we'll go as long as it's deeper.
> + $line =~ /^(\s*)/;
> + $litprefix = '^' . $1 . ' ';
> + $output .= highlight_block($block);
> + $block = ""
> + }
> + }
> + }
> +
> + if ($block) {
> + $output .= highlight_block($block);
> + }
> + foreach $line (split "\n", $output) {
> print $lineprefix . $line . "\n";
> }
> }

--
Jani Nikula, Intel Open Source Technology Center