# tree-sitter-comment
[Tree-sitter](https://github.com/tree-sitter/tree-sitter) grammar for comment tags like `TODO:`, `FIXME(user):`, etc.
Useful to be embedded inside comments.
Check the playground at <https://stsewd.dev/tree-sitter-comment/>.
## Syntax
Since comment tags aren't a programming language or have a standard,
I have chosen to follow popular conventions for the syntax.
### Comment tags
* Comment tags can contain:
- Upper case ascii letters
- Numbers (can't start with one)
- `-`, `_` (they can't start or end whit these characters)
* Optionally can have an user linked to the tag inside parentheses `()`
* The name must be followed by `:` and a whitespace
### URIs
* http and https links are recognized
If you think there are other popular conventions this syntax doesn't cover,
feel free to open a issue.
## Examples
```
TODO: something needs to be done
TODO(stsewd): something needs to be done by @stsewd
XXX: fix something else.
XXX: extra white spaces.
(NOTE: this works too).
NOTE-BUG (stsewd): tags can be separated by `-`
NOTE_BUG: or by `_`.
This will be recognized as a URI
https://github.com/stsewd/
```
## FAQ
### Can I match a tag that doesn't end in `:`, like `TODO`?
This grammar doesn't provide a specific token for it,
but you can match it with this query:
```scm
("text" @todo
(#eq? @todo "TODO"))
```
### Can I highlight references to issues, PRs, MRs, like `#10` or `!10`?
This grammar doesn't provide a specific token for it,
but you can match it with this query:
```scm
("text" @issue
(#match? @issue "^#[0-9]+$"))
;; NOTE: This matches `!10` and `! 10`.
("text" @symbol . "text" @issue
(#eq? @symbol "!")
(#match? @issue "^[0-9]+$"))
```
## Why C?
Tree-sitter is a [LR parser](https://en.wikipedia.org/wiki/LR_parser) for context-free grammars,
that means it works great for grammars that don't require backtracking,
or to keep a state for whitespaces (like indentation).
For these reasons, parsing _languages_ that need to keep a state or falling back to a general token,
it requires some manual parsing in C.
## Other grammars
- [tree-sitter-rst](https://github.com/stsewd/tree-sitter-rst): reStructuredText grammar.