Extract Elm language into an extension (#10432)

Release Notes:

- Extracted Elm language support into an extension

Co-authored-by: Marshall <marshall@zed.dev>

Cargo.lock

@@ -5429,7 +5429,6 @@ dependencies = [
  "tree-sitter-cpp",
  "tree-sitter-css",
  "tree-sitter-elixir",
- "tree-sitter-elm",
  "tree-sitter-embedded-template",
  "tree-sitter-glsl",
  "tree-sitter-go",
@@ -10343,15 +10342,6 @@ dependencies = [
  "tree-sitter",
 ]
 
-[[package]]
-name = "tree-sitter-elm"
-version = "5.6.4"
-source = "git+https://github.com/elm-tooling/tree-sitter-elm?rev=692c50c0b961364c40299e73c1306aecb5d20f40#692c50c0b961364c40299e73c1306aecb5d20f40"
-dependencies = [
- "cc",
- "tree-sitter",
-]
-
 [[package]]
 name = "tree-sitter-embedded-template"
 version = "0.20.0"
@@ -12587,6 +12577,13 @@ dependencies = [
  "zed_extension_api 0.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "zed_elm"
+version = "0.0.1"
+dependencies = [
+ "zed_extension_api 0.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "zed_emmet"
 version = "0.0.2"

Cargo.toml

@@ -104,6 +104,7 @@ members = [
     "extensions/clojure",
     "extensions/csharp",
     "extensions/dart",
+    "extensions/elm",
     "extensions/emmet",
     "extensions/erlang",
     "extensions/gleam",
@@ -312,7 +313,6 @@ tree-sitter-c = "0.20.1"
 tree-sitter-cpp = { git = "https://github.com/tree-sitter/tree-sitter-cpp", rev = "f44509141e7e483323d2ec178f2d2e6c0fc041c1" }
 tree-sitter-css = { git = "https://github.com/tree-sitter/tree-sitter-css", rev = "769203d0f9abe1a9a691ac2b9fe4bb4397a73c51" }
 tree-sitter-elixir = { git = "https://github.com/elixir-lang/tree-sitter-elixir", rev = "a2861e88a730287a60c11ea9299c033c7d076e30" }
-tree-sitter-elm = { git = "https://github.com/elm-tooling/tree-sitter-elm", rev = "692c50c0b961364c40299e73c1306aecb5d20f40" }
 tree-sitter-embedded-template = "0.20.0"
 tree-sitter-glsl = { git = "https://github.com/theHamsta/tree-sitter-glsl", rev = "2a56fb7bc8bb03a1892b4741279dd0a8758b7fb3" }
 tree-sitter-go = { git = "https://github.com/tree-sitter/tree-sitter-go", rev = "aeb2f33b366fd78d5789ff104956ce23508b85db" }

crates/extensions_ui/src/extension_suggest.rs

@@ -26,6 +26,7 @@ fn suggested_extensions() -> &'static HashMap<&'static str, Arc<str>> {
             ("dart", "dart"),
             ("dockerfile", "Dockerfile"),
             ("elisp", "el"),
+            ("elm", "elm"),
             ("erlang", "erl"),
             ("erlang", "hrl"),
             ("fish", "fish"),

crates/languages/Cargo.toml

@@ -41,7 +41,6 @@ tree-sitter-c.workspace = true
 tree-sitter-cpp.workspace = true
 tree-sitter-css.workspace = true
 tree-sitter-elixir.workspace = true
-tree-sitter-elm.workspace = true
 tree-sitter-embedded-template.workspace = true
 tree-sitter-glsl.workspace = true
 tree-sitter-go.workspace = true

crates/languages/src/lib.rs

@@ -16,7 +16,6 @@ mod c;
 mod css;
 mod deno;
 mod elixir;
-mod elm;
 mod go;
 mod json;
 mod lua;
@@ -59,7 +58,6 @@ pub fn init(
         ("cpp", tree_sitter_cpp::language()),
         ("css", tree_sitter_css::language()),
         ("elixir", tree_sitter_elixir::language()),
-        ("elm", tree_sitter_elm::language()),
         (
             "embedded_template",
             tree_sitter_embedded_template::language(),
@@ -288,10 +286,6 @@ pub fn init(
         "yaml",
         vec![Arc::new(yaml::YamlLspAdapter::new(node_runtime.clone()))]
     );
-    language!(
-        "elm",
-        vec![Arc::new(elm::ElmLspAdapter::new(node_runtime.clone()))]
-    );
     language!("glsl");
     language!("nix");
     language!("nu", vec![Arc::new(nu::NuLanguageServer {})]);

extensions/elm/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "zed_elm"
+version = "0.0.1"
+edition = "2021"
+publish = false
+license = "Apache-2.0"
+
+[lints]
+workspace = true
+
+[lib]
+path = "src/elm.rs"
+crate-type = ["cdylib"]
+
+[dependencies]
+zed_extension_api = "0.0.6"

extensions/elm/LICENSE-APACHE

@@ -0,0 +1 @@
+../../LICENSE-APACHE

extensions/elm/extension.toml

@@ -0,0 +1,15 @@
+id = "elm"
+name = "Elm"
+description = "Elm support."
+version = "0.0.1"
+schema_version = 1
+authors = ["Quinn Wilton <quinn@quinnwilton.com>", "Andrey Kuzmin <hi@unsoundscapes.com>"]
+repository = "https://github.com/zed-industries/zed"
+
+[language_servers.elm-language-server]
+name = "elm-language-server"
+language = "Elm"
+
+[grammars.elm]
+repository = "https://github.com/elm-tooling/tree-sitter-elm"
+commit = "09dbf221d7491dc8d8839616b27c21b9c025c457"

extensions/elm/languages/elm/config.toml

@@ -10,3 +10,4 @@ brackets = [
     { start = "\"", end = "\"", close = true, newline = false, not_in = ["string"] },
     { start = "'", end = "'", close = true, newline = false, not_in = ["string", "comment"] },
 ]
+tab_size = 2

extensions/elm/src/elm.rs

@@ -0,0 +1,113 @@
+use std::{env, fs};
+use zed::{
+    serde_json::{self, Value},
+    settings::LspSettings,
+};
+use zed_extension_api::{self as zed, Result};
+
+const SERVER_PATH: &str = "node_modules/@elm-tooling/elm-language-server/out/node/index.js";
+const PACKAGE_NAME: &str = "@elm-tooling/elm-language-server";
+
+struct ElmExtension {
+    did_find_server: bool,
+}
+
+impl ElmExtension {
+    fn server_exists(&self) -> bool {
+        fs::metadata(SERVER_PATH).map_or(false, |stat| stat.is_file())
+    }
+
+    fn server_script_path(&mut self, server_id: &zed::LanguageServerId) -> Result<String> {
+        let server_exists = self.server_exists();
+        if self.did_find_server && server_exists {
+            return Ok(SERVER_PATH.to_string());
+        }
+
+        zed::set_language_server_installation_status(
+            &server_id,
+            &zed::LanguageServerInstallationStatus::CheckingForUpdate,
+        );
+        let version = zed::npm_package_latest_version(PACKAGE_NAME)?;
+
+        if !server_exists
+            || zed::npm_package_installed_version(PACKAGE_NAME)?.as_ref() != Some(&version)
+        {
+            zed::set_language_server_installation_status(
+                &server_id,
+                &zed::LanguageServerInstallationStatus::Downloading,
+            );
+            let result = zed::npm_install_package(PACKAGE_NAME, &version);
+            match result {
+                Ok(()) => {
+                    if !self.server_exists() {
+                        Err(format!(
+                            "installed package '{PACKAGE_NAME}' did not contain expected path '{SERVER_PATH}'",
+                        ))?;
+                    }
+                }
+                Err(error) => {
+                    if !self.server_exists() {
+                        Err(error)?;
+                    }
+                }
+            }
+        }
+
+        self.did_find_server = true;
+        Ok(SERVER_PATH.to_string())
+    }
+}
+
+impl zed::Extension for ElmExtension {
+    fn new() -> Self {
+        Self {
+            did_find_server: false,
+        }
+    }
+
+    fn language_server_command(
+        &mut self,
+        server_id: &zed::LanguageServerId,
+        _worktree: &zed::Worktree,
+    ) -> Result<zed::Command> {
+        let server_path = self.server_script_path(server_id)?;
+        Ok(zed::Command {
+            command: zed::node_binary_path()?,
+            args: vec![
+                env::current_dir()
+                    .unwrap()
+                    .join(&server_path)
+                    .to_string_lossy()
+                    .to_string(),
+                "--stdio".to_string(),
+            ],
+            env: Default::default(),
+        })
+    }
+
+    fn language_server_workspace_configuration(
+        &mut self,
+        server_id: &zed::LanguageServerId,
+        worktree: &zed::Worktree,
+    ) -> Result<Option<Value>> {
+        // elm-language-server expects workspace didChangeConfiguration notification
+        // params to be the same as lsp initialization_options
+        let initialization_options = LspSettings::for_worktree(server_id.as_ref(), worktree)?
+            .initialization_options
+            .clone()
+            .unwrap_or_default();
+
+        Ok(Some(match initialization_options.clone().as_object_mut() {
+            Some(op) => {
+                // elm-language-server requests workspace configuration
+                // for the `elmLS` section, so we have to nest
+                // another copy of initialization_options there
+                op.insert("elmLS".into(), initialization_options);
+                serde_json::to_value(op).unwrap_or_default()
+            }
+            None => initialization_options,
+        }))
+    }
+}
+
+zed::register_extension!(ElmExtension);