Adds a mechanism for per-filename overrides of the chosen language
syntax and configures it for Gerrit's submit rule file.
This also switches the syntax set used to the one from
//third_party/bat_syntaxes, which contains custom additions such as
Prolog support.
Change-Id: I2023dbad5b326305ef2ef0ecf34ef66a3f7575ab
Reviewed-on: https://cl.tvl.fyi/c/depot/+/349
Reviewed-by: riking <rikingcoding@gmail.com>
Reviewed-by: lukegb <lukegb@tvl.fyi>
Cheddar now needs to be passed the --about-filter flag to toggle the
behaviour for rendering Markdown into HTML.
By default Markdown will be highlighted like normal source code (i.e.
cgit source-filtering is the default behaviour).
Implements support for tagging paragraphs that begin with a callout
word (TODO, WARNING, QUESTION, TIP) with an additional `cheddar-*`
class that makes it possible to render these callouts specially.
This is currently not the nicest implementation, but it works.
Since I am going down the path of adding additional Markdown
extensions it makes sense to avoid letting `format_markdown` turn into
a giant beast of a function.
Therefore this commit extracts the logic for rendering code blocks via
syntect and changes the innards of `format_markdown` to instead
provide arbitrary AST value replacements.
Implements fully static (i.e. no JavaScript!) highlighting of code
blocks when rendering Markdown.
This works by walking through the Comrak AST and replacing any code
blocks with pre-rendered HTML blocks.
Syntaxes are chosen based on the "block info", which is the string
users put after the block's opening fence. This can either be
a (case-insensitive) name of a syntax, or alternatively a file
extension associated with the desired syntax.
The theme is set to one that imitates GitHub.
Renders any ".md" file by pushing it through the Comrak rendering
pipeline.
This does not yet implement syntax highlighting of fenced blocks, but
we're getting there.
Generalises the two bits of the program that will be required either
way (extension parsing and syntax loading).
A dependency on Comrak is introduced as I think GitHub-flavoured
Markdown (with all its fancy extensions) is desirable!
This uses Nix to inject the path to the syntax highlighting assets
that ship with the bat source code into the cheddar build at compile
time, where the Rust compiler then inserts it into the binary via
macros.
bat has a lot of custom syntax highlighting definitions that they
collected from all over the place (including for languages like Nix!)
and this makes them accessible to cheddar.
Also if you're reading this, can you just take a moment to appreciate
how incredible it is that Nix just lets us do something like this?!
The first step with this tool will be to use it as a source-filter for
cgit. The second step is to use it as the Markdown renderer by
depending on one of the Markdown libraries, with integration for
rendering code snippets directly.
