Add support for frontmatter

[taniki]

• follow-up of Add support for frontmatter #390
• rebase to catch-up with current HEAD
• copy frontmatter parsing and printing from prettier source code
• ⚠️ it works but doesn't pass the test because of formatting the frontmatter code. Currently digging into that.

Inspiration: https://github.com/LukeHagar/prettier-plugin-openapi/tree/b1a2f010724eb0b29d0e02ed56b3e493b4ec1438/src/prettier-markdown

[taniki]

I have no idea how to put it back

[taniki]

@Shinigami92 I am trying to use https://github.com/inogai/prettier/tree/main/src/language-markdown as a reference but the structure seems a bit different from yours.

[Shinigami92]

@Shinigami92 I am trying to use inogai/prettier@main/src/language-markdown as a reference but the structure seems a bit different from yours.

Yeah, many plugins are fully driven by their own owners like myself. It is fully up to us maintainers how to run our plugins, but we can ship the plugin as officially under the @prettier org / npm-scope as a sign of trust.

[taniki]

frontmatter support in markdown, css, and html seems to be done through support of embeds:

const printer = {
  preprocess,
  print: genericPrint,
  embed,
  massageAstNode: clean,
  hasPrettierIgnore,
  insertPragma,
  getVisitorKeys,
};

export default printer;

but I can't find such mecanism in yours. should insert something like inserting a case in the switch section?

[Shinigami92]

frontmatter support in markdown, css, and html seems to be done through support of embeds:

const printer = {
  preprocess,
  print: genericPrint,
  embed,
  massageAstNode: clean,
  hasPrettierIgnore,
  insertPragma,
  getVisitorKeys,
};

export default printer;

but I can't find such mecanism in yours. should insert something like inserting a case in the switch section?

Yeah... that might be a huge problem, because I implemented plugin-pug when a lot of such things where not available or stable, and then also as pug is a "language" which is very easily written from left to write, top to bottom, it was far more easy to just process the token stream as an array / iterator.

You could have a look how embedded js or css is formatted right now as well as some expressions like embedded vue or angular syntax.
From that you might get a picture of how to achieve similar thing for frontmatter.

[Shinigami92]

issue (blocking): CLI is telling that these files are not TypeScript files, but JavaScript. You need to use TypeScript.

[taniki]

That will be too much for me right now. Thanks for the support.

[taniki]

this should enforce formatting of flow style array and dict but it doesn't and I don't know why.

[taniki]

I am hitting a wall here.

• I have no clue about how to efficiently convert the imported javascript code into typescript.
• the build-in yaml formatter doesn't seem to acknowledge the formatting option enforcing block-style list and dictionaries.
• there are some lint errors beyond my understanding.

All the bricks are in place tho. If someone to take it up from there, it will be great.