fix(mdx-loader): support nested admonitions

[lebalz]

Pre-flight checklist

• I have read the Contributing Guidelines on pull requests.
• If this is a code change: I have written unit tests and/or added dogfooding pages to fully verify the new behavior.
• If this is a new API or substantial change: the PR has an accompanying issue (closes support nested admonitions #8302) and the maintainers have approved on my working plan.

Motivation

See #8302 - support nested admonitions

Test Plan

Test links

• https://deploy-preview-8303--docusaurus-2.netlify.app/docs/markdown-features/admonitions#nested-admonitions
• https://deploy-preview-8303--docusaurus-2.netlify.app/tests/pages/markdownPageTests#admonitions

Related issues/PRs
#8302

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[github-actions]

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[slorber]

Hey

Thanks for the PR

As part of the migration to MDX 2.0 (WIP - #8288) we will likely replace all this code with remark-directive so I'm not sure we are going to merge this PR for now. I'll keep it open but the goal is to get rid of the code. I guess it should be possible to support nested admonitions with the remark plugin.

[Josh-Cena]

I think it's still a valuable fix to get into 2.x? I won't anticipate 3.0 to ship in a few weeks, not to mention its wide adoption.

[slorber]

I think it's still a valuable fix to get into 2.x? I won't anticipate 3.0 to ship in a few weeks, not to mention its wide adoption.

We'll see.

I'd like to see how to implement this in 3.x / MDX 2 before adding such new feature. In case it's complex or impossible to implement in 3.x, I'd rather not introduce a new feature to remove it later, nor to block / delay 3.x because of this new feature.

Let's keep this open and see how we can have it both in 2.x and 3.x

[slorber]

As part of #8288 we want to use the more flexible and generic remark-directive system to provide such features.

The nesting is possible, but works similarly to code blocks by adding more : for parent elements.

Here's a preview:
https://deploy-preview-8288--docusaurus-2.netlify.app/docs/markdown-features/admonitions/#specifying-title

:::::note{title="Your title"}

Some **content** with _Markdown_ `syntax`.

::::note[Your nested Title]

:::note Your very nested Title (does not work yet :s)

Some **content** with _Markdown_ `syntax`.

:::

Some **content** with _Markdown_ `syntax`.

::::

hey

:::::

If we add this feature in v2 I'd rather have the exact same syntax instead of always using :::

That way users do not have to change anything when upgrading and there's no extra breaking change to explain.

Can you update the code to support 4/5+ colons please?

[lebalz]

Thanks for the review and the suggestions. I changed the algorithm which keeps track of the nesting level. Now it handles nested admonitions the way remark-directive does, e.g. with 4/5/+ colons...

[slorber]

LGTM thanks 👍