Parse provided tag

[sydneypalumbo]

An alternative to #202:

• requires provided tag to be an expression
• parses provided tag to find references / features and determine whether the tag makes the cell async
  • I just mainly took the parts of the CellParser relevant to determining async and created a super basic TagParser, but lmk if I'm misunderstanding the best way to do this 👍
• should only require a minor version bump? this will require a major version change

Like the original PR this also:

• will require a minor adjustment in the compiler so that it doesn't need to add the tag as an additional input
• will require ui / next to handle references / databaseClients with null start and end positions (for nodes in the tag but not cell value)
• adds a few tests

[mbostock]

I like this approach. I think we should expose the parsed AST for the tag too.

[sydneypalumbo]

thanks @mbostock!! 🙏 updated this so that cell.tag is the parsed tag's AST that contains it's own async, generator, references and databaseClients / secrets / fileAttachments properties.

one thing I wasn't totally sure about was whether cell.async should be true if cell.tag.async is true (same for generator)... this currently does not override cell.async if cell.tag.async (and would instead require the caller to check the tag properties the same way it also has to check tag references + features) but let me know if you think it should 👍

[mbostock]

One last thing, let’s use CellTag as the name for these nodes instead of Tag?

[mbostock]

I like the idea of keeping cell.async and cell.tag.async as independent because that doesn’t lose information and makes it easier for us to potentially do smarter things in the future.

[mbostock]

Looks good though one more tiny thing!

When you land would you like me to do the major version bump and publish to npm, or would you like me to pair with you so I can show you how to do it?

[sydneypalumbo]

@mbostock if you have a sec to pair on it this afternoon that'd be great! 🙏