Is there a way to trigger formatter after insert new code by code action?

[jiashengguo]

It would be nice if the inserted code could be formatted instead of manually inserting the indent in the code action.

[msujew]

Hey @jiashengguo,

I would generally recommend to have some sort of infrastructure in place to generate correctly indented code in the first place. There are a few methods in the Formatter such as getExistingIndentationCharacterCount which can be used as inspiration to figure out the required indentation at a specific line. In theory you can also utilize the TextDocument.applyEdits function and then trigger the formatter, but that leads down a rabbit hole, since you will need to create copies of a document, reparse it, apply the formatting, etc., which can quickly become very complicated.

[jiashengguo]

Hi @msujew
Thanks for your suggestion. If I want to call the methods in the Formatter such as getExistingIndentationCharacterCount in CodeActionProvider, how can I get the context: FormattingContext?

[msujew]

You will need to reimplement it, especially since the FormattingContext isn't available, given that this is not a real formatting operation. You'll need to infer whether the user needs tab or whitespace formatting depending on the existing text. I haven't given much thought to this requirement (and the team at Microsoft behind the LSP as well), since I've never encountered code actions which require to add/replace more than a single line or which are depended on indentation.

[jiashengguo]

My case is also inserting a single line, but I want to know whether the current editor uses Tab or Space as an indent. As what FormattingOptions.insertSpaces indicates.

[msujew]

Yeah, you'll need to look at the existing user code. The language client only sends this information to the server when actually performing a formatting operation (one that's been started by the user).