trim whitespace in loading LaTeX classes and packages

[dginev]

Minimal example:

\documentclass[
	aps, pra]{revtex4-2}
\begin{document}
Hello world.
\end{document}

This leading \par in the options of \documentclass was the first encountered problem in a recent arXiv report, which turned out to be also related to a greek babel regression, reported in #2429 .

I took the opportunity to sanitize (by trimming whitespace) the options argument to \documentclass, \documentstyle, \usepackage, \RequirePackage, \LoadClass, \PassOptionsToPackage, \PassOptionsToClass, \ExecuteOptions.

This may be removed soon after in a world where we load all of latex.ltx raw, but I realized that only after completing the code changes. So filing the PR in any case, for your consideration.

[brucemiller]

This kinda screams for either a Trimmed type of argument, or at least that the option processing routines would trim their arguments.

[dginev]

Done, thanks. I tried a couple of approaches, then realized the argument handling happens at different stages - some options are Tokens, others are already Boxes (typically a List). So doing the sanitization after the string phase is easier in the short run.

Parameter types could improve too, but OptionalTrimmedSemiverbatim seemed to be a mouthful.

[dginev]

I also found 5 places in 5 bindings which can benefit from sharing this new helper function. I haven't committed them here yet, let me know if you'd like them added (in authblk, cleveref, elsarticle, enumitem and ntheorem).

[brucemiller]

Hmm (again). So actually all(?) of these are cases of keyval or option lists, but at a somewhat special top-level, which may not be quite the same as the usual keyval processing. And a 3rd hmm is that these are commands that call for special treatment anyway, so are likely to always need LaTeXML bindings even if we read latex.ltx. I wonder if some use or adaptation of OptionalKeyVals would be the best long-term approach?

[dginev]

The parameter type name that resonates with me is PackageOptions, since the comma list convention is a top-level latex convention for classes and packages.

With that name we could even avoid the leading Optional, since they are always optional.

I am also wondering if we should be comparing to DirectoryList and CommaList here, rather than KeyVals.