Syntax Highlighting in Escaped String Literals

[jpe90]

Hello,

Is it possible to highlight escaped string literals? Here's how they look currently in neovim w/ TS highlighting enabled:

Vs other editors with highlighted escaped literals:

[tek]

in general, you can use injections to defer to a different grammar, by putting this into $VIMCONFIG/queries/haskell/injections.scm:

(string) @grammar-with-escape-highlights

And I can look into parsing strings directly in the grammar.

[tek]

so, the other grammar would need to be specifically parsing only the string

[jpe90]

Got it working after I realized you didn't mean to literally add @grammar-with-escape-highlights, LOL. Thank you!!

[tek]

oh really, which grammar did you use?

[jpe90]

I just tried a couple at random and went with Rust because it picked up \" and \n without giving me problems in the project I'm working on

[tek]

oh heh. you could create a minimal grammar that only parses strings tho

[jpe90]

I'm not really familiar with treesitter internals (or parsing in general really) to know how to go about that.. would reading https://tree-sitter.github.io/tree-sitter/creating-parsers get me started, or is there other documentation you would also recommend?

[tek]

I did a similar thing for quasiquotes here: https://github.com/tek/vim-bundle-conf/tree/master/tree-sitter/exon

it's bare bones, you'll just have to modify grammar.js, it should be fairly intuitive, using that page you linked.

then you'll have to add it in you vim config in a plugin/foo.vim:

lua <<EOF
local parser_config = require "nvim-treesitter.parsers".get_parser_configs()
parser_config.string_grammar_name = {
  install_info = {
    url = "/path/to/string/grammar/",
    files = {"src/parser.c"}
  }
}
EOF

and you can refer to it in an injection with @string_grammar_name after :TSInstall string_grammar_name

[jpe90]

Thank you, that example was very helpful. I ended up giving it a shot. I set up a minimal grammar named "porcupine" which only parses strings into two nodes, "string_fragment" or "escape_sequence". I inject it into haskell with (string) @porcupine in injections.scm, it installs successfully with :TSInstall porcupine and is applied in the right places when I look at a source file with TSPlayground:

However I can't seem to get the capture groups set up for them. In the minimal grammar, I have a queries/highlights.scm containing:

(string_fragment) @string
(escape_sequence) @escape

and a corresponding "escape" custom capture group set up in my vim config.

But those don't seem to get picked up:

I'm sure I'm missing something on how capture groups work, so I'll try to figure it out, but let me know if anything obvious jumps out that I'm missing.

[tek]

by "in the minimal grammar", do you mean that the highlights file is in the porcupine/queries directory? because that won't get picked up by nvim I think.

[jpe90]

Yeah, I had tried adding those highlights in the haskell queries directory in the fork of nvim-treesitter that my config is hooked up to and treesitter exploded with an error referencing an "invalid node". If I included a porcupine highlight group it got picked up, though. Anyways I should probably find time to figure out how tree-sitter actually works before trying to hack something together :^) my attempt is here

[tek]

well, for nvim, you have to put all the queries and injections into the nvim config. so either your nvim-treesitter fork or your local ~/.config/nvim. and the injection has to be in queries/haskell/injections.scm, while the highlighting for porcupine has to be in queries/porcupine/highlights.scm.

[tek]

@jpe90 can this be closed?

[jpe90]

Sure, thanks for trying to help.

[tek]

@jpe90 oh, were you no able to implement your goal?

[jpe90]

No, I got stuck getting highlights/injections recognized and felt a little out of my depth. I wanted to make more of an effort to understand how they work before I kept bugging for help. I'll give it another shot when I'm feeling brave :^)

[tek]

gotcha, feel free to continue here when you need more input!