propsal: better support for comments in templ files

[a-h]

Currently, HTML comments and Go comments are not well supported. Would be good to have them as an option.

// Support this comment, don't include anything in the HTML.
/* Do not support this syntax for ... reasons */
<!-- Support this syntax and include it in the output -->

[gedw99]

Yeah this would be nice

just means altering the parser to skip it ?

[a-h]

@gedw99 - Yes, but not skip it, add it as a new node type, so that it's retained during reformatting.

I was thinking of basically the same sort of implementation as https://github.com/a-h/templ/blob/main/parser/v2/raw.go (script and style HTML elements) for the multi-line HTML comments, which just looks for the start and end tokens (i.e. if you see <!-- read until -->).

For the // style, there'd be a new node type of comment. The parser would match any line starts with that whitespace followed by //, and then skip until the end of the line.

[tantalic]

@a-h I took a pass at implementing the first part of this proposal in #161 . I would be happy to take feedback on that PR. I would also be interested in helping with the // comment style following this as well.

PS - Thanks for the great project!

[aranw]

I noticed that the parser can't handle HTML in comments for example

<!-- <div> hello world </div> -->

will produce a error such as

parsing error: <div>: expected end tag not present or invalid tag contents: line 20, col 16

[a-h]

Hi @aranw 👋🏻 nice to see you again, hope you're doing well!

Are you using the latest commit? The latest tagged version doesn't have these changes in it yet. I added a new test based on what you were seeing and couldn't reproduce the issue: https://github.com/a-h/templ/actions/runs/6354142654

[aranw]

@a-h 👋🏻 I'm using tagged version v0.2.334

I'll try make a reproducible test in a fork give me a few minutes

[a-h]

I was planning to do a new release, quite a few improvements in since the last tagged release.

[aranw]

@a-h the following example here breaks when I run generate

Edit: I did it like this as I wasn't sure exactly where in the parser code a test for this would make sense. I've not really looked through the source code too much yet. Mostly just been experimenting with converting go templates to templ right now

[a-h]

I'm not convinced you're running the latest (non-tagged) version of the templ binary, since I'm struggling to reproduce that on the latest version.

The integration tests for HTML in comments are also passing:

efd3312

If you want to try the latest version, you can do go install github.com/a-h/templ/cmd/templ@efd33120d9e83e5b9c9c1b06272d5bfcce246436 and it will install that specific commit. Worth also checking which templ to make sure you're running the version you think you're running!

[aranw]

Ah yeah I'm not running the latest version that has definitely fixed the issue!

[a-h]

For Go comments within the template section, I think this might be the place to start... https://github.com/a-h/templ/tree/issue_159_go_comments_before_package Was aiming to solve issue 159, and there's some crossover with this.

@tantalic - have you started on this one yet? Feel free to disregard my thoughts or work on top if you want to pick it up. Just let me know!

[tantalic]

@a-h I have not started anything on go style comments, at least not yet. The next couple of weeks are pretty busy so I don't think I will be jumping in soon on this if anyone else wants to work on it!