C! (cflang) — Zed extension

Syntax highlighting, bracket matching, indentation, folding, and document outline for C! in the Zed editor.

What's here

extension.toml                   Zed manifest — registers the grammar + language
tree-sitter-cflang/grammar.js    the C! grammar, translated from root/specs/ebnf.md
languages/cflang/config.toml     file suffix (.cf), comments (#), brackets, tabs
languages/cflang/*.scm           tree-sitter queries: highlights, brackets,
                                 indents, folds, outline

Zed language support is built entirely on Tree-sitter: every query file runs against a parse tree, so the grammar in tree-sitter-cflang/ is the foundation. There is no separate TextMate/regex grammar.

Install (development)

1. Open Zed → command palette → zed: install dev extension.
2. Pick this directory (usr/zed). Open any .cf file to see it applied.

Zed loads the language config and queries live from this directory, but fetches the grammar from a git commit — see extension.toml:

[grammars.cflang]
repository = "file:///Users/orlowdev/Code/cflang"  # this repo, local — no push
rev = "…"                                            # a commit containing the grammar
path = "usr/zed/tree-sitter-cflang"                     # its subdirectory

file:// means no GitHub push is needed, but git clone only sees committed state, so the grammar must live at a real commit and rev pins it.

Iterating

• Queries / config.toml — edit freely, then zed: reload extensions. No commit needed; Zed reads them live.

• grammar.js — after editing, regenerate, commit, and bump rev:

  cd tree-sitter-cflang
  npx tree-sitter-cli generate      # regenerate src/
  npx tree-sitter-cli parse FILE.cf # sanity-check (look for ERROR nodes)
  cd - && git commit -am "…"        # grammar must be committed for Zed to fetch it
  git rev-parse HEAD                 # put this SHA in extension.toml `rev`

  Then zed: reload extensions.

The grammar parses the entire boot/ corpus with zero error nodes.

Deliberate scope decisions

The grammar serves editor tooling, so a few choices favour resilient highlighting over strict conformance:

• Newlines are insignificant. The language is newline-terminated (one statement per line — see root/code_style/indentation.md), but the compact cf0 test files put several statements on a line. The grammar stays permissive so it highlights both styles without flagging the existing files.
• break / continue carry no label. The EBNF gives them an optional loop label; with insignificant newlines an optional trailing name would swallow the next statement's leading identifier. A break outer still highlights fine.
• Index / type-application overlap (xs[8] vs f[8]) is resolved by the receiver's type in the real language — unknown to a syntax grammar — so the grammar biases toward indexing, the common case.

LSP

Deferred: C! has no language server yet. When one exists, register it under [language_servers.cflang] in extension.toml; nothing else here changes.