Enhance Typst Language Support

[FlandiaYingman]

Is your feature request related to a problem? Please describe.

The current Typst language support is a regex-based character-by-character text builder. Since Typst allows scripting within math mode and markup mode, it makes it difficult to parse and annotate with only a regex-based parser.

For a large Typst document, it is usual that the program fails to parse at the middle of the document because some markup/code/math transitions are not well-detected, causing an weird and funny output.

Describe the solution you'd like

I think I can write a simple recursive descent parser so that nested markup/code/math transitions are correctly parsed. Since this doesn't involve building an abstract syntax tree, but separating only markup and text, I think it is not difficult to implement one.

Describe alternatives you've considered

I tried to enhance the current regex-based parser for my large document, but failed due to the complexity of markup/code/math transitions.

Additional context

Is such a PR welcome?

[spitzerd]

Sure, such a PR is welcome.