tree-sitter-comment 0.2.0

# tree-sitter-comment

[![CI](https://github.com/stsewd/tree-sitter-comment/workflows/CI/badge.svg)](https://github.com/stsewd/tree-sitter-comment/actions?query=workflow%3ACI+branch%3Amaster)

[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 with 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]+$"))
```

### I'm using Neovim and don't see all tags highlighted

To avoid false positives, Neovim doesn't highlight all tags,
but a list of specific ones,
see the list at [`queries/comment/highlights.scm`](https://github.com/nvim-treesitter/nvim-treesitter/blob/master/queries/comment/highlights.scm).

If you want your tag highlighted, you can extend the query locally, see `:h treesitter-query`.
Or if you think it's very common, you can suggest it [upstream](https://github.com/nvim-treesitter/nvim-treesitter).

## 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.

## Projects using this grammar

- [nvim-treesitter](https://github.com/nvim-treesitter/nvim-treesitter)
- [helix](https://github.com/helix-editor/helix)
- Yours?

## Other grammars

- [tree-sitter-rst](https://github.com/stsewd/tree-sitter-rst): reStructuredText grammar.