feat: Expose more AST types from "svelte/compiler"

[xeho91]

So, given that in the Advent of Svelte you have created some new features to Svelte syntax.
Such as <svelte:boundary> and as in {#each} block is no longer needed.

So, I thought it's time to upgrade svelte-ast-print to support printing them too!

Firstly, I noticed that type SvelteBoundary was not a part of ElementLike type. Hence I was getting type error (any) when attempting to walk on it using zimmerframe.

In the meantime, I thought of taking an opportunity to export more types, which I had to manually provide in following places:

• Block
• Directive
• ElementLike
• SvelteNode
• Tag
• TemplateNode

So, I've moved those types inside the AST namespace.
In the meantime I've updaded the codebase where those types are used, with this change - by using AST namespace.

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Tests and linting

• Run the tests with pnpm test and lint the project with pnpm lint

[changeset-bot]

🦋 Changeset detected

Latest commit: 7971acf

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
svelte	Minor

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[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@14601

[Rich-Harris]

preview: https://svelte-dev-git-preview-svelte-14601-svelte.vercel.app/

this is an automated message

[xeho91]

In the meantime, I have a small proposal to add another type:

type AttributeLike = Attribute | SpreadAttribute | Directive;

EDIT. I went ahead and added it.
Commit to revert in case: 4e0d43c

[xeho91]

And also, I have another issue: namespace Css and its types are not exported to the public.

I am not sure which one is the best solution:

1. export to public as separate namespace,
2. or export it inside AST namespace?

EDIT. I went ahead with the 2nd option.
Comit to revert in case: 24a25de

[Rich-Harris]

Thank you! At a high level I think this makes sense. SvelteNode and TemplateNode are somewhat messy though, there are places where they should probably be tightened up (e.g. we should have a type that means 'can be a child of a fragment', i.e. Text | Tag | ElementLike | Block | Comment, that we can use in some of the places where we currently use TemplateNode. Not sure what such a thing should be called). Perhaps we could omit those in the meantime?

I also think we should probably Css to CSS, since we currently capitalise AST.

[xeho91]

I also think we should probably Css to CSS, since we currently capitalise AST.

I agree with this sentiment 👍

I wasn't sure if you meant:

1. only to export namespace Css as CSS: 3b42438
2. or rename it everywhere as AST.CSS: e185e1a
   Note that there's already an existing namespace CSS from TypeScript lib - "dom". Hence why internally named as _CSS, then in codebase used as AST.CSS.

[xeho91]

Thank you! At a high level I think this makes sense. SvelteNode and TemplateNode are somewhat messy though, there are places where they should probably be tightened up (e.g. we should have a type that means 'can be a child of a fragment', i.e. Text | Tag | ElementLike | Block | Comment, that we can use in some of the places where we currently use TemplateNode. Not sure what such a thing should be called). Perhaps we could omit those in the meantime?

Hm... as an developer using those types at higher level... let me demonstrate with a simple reproduction: https://stackblitz.com/edit/stackblitz-starters-evnjpuos?file=index.js

Without SvelteNode, I'm losing DX in terms of typing experience without SvelteNode. Do you have a suggestion of what I could use instead - to still have a nice typing experience?

[Ocean-OS]

I wasn't sure if you meant:

1. only to export namespace Css as CSS: 3b42438
2. or rename it everywhere as AST.CSS: e185e1a
   Note that there's already an existing namespace CSS from TypeScript lib - "dom". Hence why internally named as _CSS, then in codebase used as AST.CSS.

It'd probably be best to rename it as AST.CSS, since it is the CSS AST node types.

[Rich-Harris]

AST.CSS, yeah.

Without SvelteNode, I'm losing DX in terms of typing experience without SvelteNode. Do you have a suggestion of what I could use instead - to still have a nice typing experience?

That's true, it is useful to have a union of all the types you might encounter while walking. I did wonder about dividing things up more neatly so that in addition to AST.CSS there's AST.JS (containing Node from estree plus any TS-specific additions) and AST.Template... but it's all probably overkill. So yeah, maybe it's simpler to keep stuff as-is