Highlight @example jsdoc body as source code

[mjbvz]

TS and JS Grammar Extension version: 0.0.47 / latest

Code
For a js doc body such as:

/**
 * @example
 * 1 + 1
 */
const a = 1

We mark the body of the @example block specially but do not actually syntax highlight it. I added an injection grammar in VS Code that does this: https://github.com/Microsoft/vscode/blob/master/extensions/typescript-basics/syntaxes/ExampleJsDoc.injection.tmLanguage.json

May be worth including in the core grammar. Let me know if you agree. The injection grammar will not work as is, we're relying on another injection grammar that handles separating the leading stars of the doc block from the documentation content itself

[sheetalkamat]

Isnt this already scoped correctly because of #688

[mjbvz]

This is for highlighting the content 1 + 1 as typescript. Right now, it is just treated as a single token

[sheetalkamat]

@mjbvz I don't think that's as easy as it seems .. I think that need to be handled by editors (by removing starting * on each line). Without that the results will be too unpredictable.

[mjbvz]

We use a while rule to do this, see: https://github.com/Microsoft/vscode/blob/master/extensions/typescript-basics/syntaxes/ExampleJsDoc.injection.tmLanguage.json

It consumes the leading * on each line so that the regular js/ts grammar runs without modification inside the comment

[sheetalkamat]

I still don't understand how multiline example is going to work. Where do you consume leading * wasn't able to figure that out.

[mjbvz]

Looks like the logic that was moved into this file: https://github.com/Microsoft/vscode/blob/master/extensions/typescript-basics/syntaxes/MarkdownDocumentationInjection.tmLanguage.json

The while rule is run on every line until it fails. In this case, it consumes the leading * so that rules inside the while never see it.