Html toc single build

[ascholerChemeketa]

The ToC is a significant chunk of each HTML page and is mostly the same on every page. This PR precomputes the ToC into a variable and then on each page augments that with the necessary active and contains-active classes.

Reduces xsltproc time by ~15-20% for sample book. For books with lots of smaller pages savings can be 35%+.

Clean diffs on sample book.

[rbeezer]

That is brilliant! Cleaner code, no-change diffs, and a speed-up. (And a nice sequence of commits.)

Will update website shortly, a few more PRs to do. Keep 'em coming!

[oscarlevin]

Uh-oh.... this seems to have broken revealjs builds. I get a lot of:

error: * PTX:BUG:   an element ("frontmatter") does not know its level
error: * PTX:BUG:     asking if a "frontmatter" is a leaf, for a document that is not a "book" nor an "article"

starting at the commit that these were merged.

[ascholerChemeketa]

It looks like it still generates the show correctly, but it does produce those scary-looking messages.

They all come from where the ToC is being built into a variable.

The quick and dirty fix is to add a variable that pretext-revealjs.xsl sets and pretext-html checks while building the ToC. That may be part of the right fix as well - there is no reason that pretext-revealjs.xsl needs the ToC generated. It does feel a little ugly to have the more generic sheet (pretext-html) rely on hints from the most specific sheet, but that may be unavoidable.

It does feel like there is a bigger issue here. Shouldn't we be able to provide the answer to "is-leaf" and "level" for "frontmatter" in a slideshow? If that was fixed the bug reports would go away. That seems like it has implications for #2334

[rbeezer]

Reviewed the PR and the RevealJs stylesheet. Not seeing it.

Shouldn't we be able to provide the answer to "is-leaf" and "level" for "frontmatter" in a slideshow?

Might just be a matter of defining a level for slideshow? And/or slideshow/section.

I'll get back to this in a bit, when I am able.

[rbeezer]

there is no reason that pretext-revealjs.xsl needs the ToC generated

So we override the toc-cache-rtf global variable in the derived worksheet. On it. Push in a minute.

[rbeezer]

Fix in at: 2fb780c

Thanks @oscarlevin for the heads-up and @ascholerChemeketa for the hints.

[oscarlevin]

Can confirm that the most recent commit fixed the issue. Thanks!