Extract Elixir extension (#10948)

This PR extracts Elixir support into an extension and removes the
built-in Elixir support from Zed.

As part of this, [Lexical](https://github.com/lexical-lsp/lexical) has
been added as an available language server for Elixir.

Since the Elixir extension provides three different language servers,
you'll need to use the `language_servers` setting to select the one you
want to use:

#### Elixir LS

```json
{
  "languages": {
    "Elixir": {
      "language_servers": [ "elixir-ls", "!next-ls", "!lexical", "..."]
    }
  }
}
```

#### Next LS

```json
{
  "languages": {
    "Elixir": {
      "language_servers": [ "next-ls", "!elixir-ls", "!lexical", "..."]
    }
  }
}
```

#### Lexical

```json
{
  "languages": {
    "Elixir": {
      "language_servers": [ "lexical", "!elixir-ls", "!next-ls", "..."]
    }
  }
}
```

These can either go in your user settings or your project settings.

Release Notes:

- Removed built-in support for Elixir, in favor of making it available
as an extension.

extensions/elixir/Cargo.toml

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

extensions/elixir/LICENSE-APACHE

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

extensions/elixir/extension.toml

@@ -0,0 +1,27 @@
+id = "elixir"
+name = "Elixir"
+description = "Elixir support."
+version = "0.0.1"
+schema_version = 1
+authors = ["Marshall Bowers <elliott.codes@gmail.com>"]
+repository = "https://github.com/zed-industries/zed"
+
+[language_servers.elixir-ls]
+name = "ElixirLS"
+languages = ["Elixir", "HEEX"]
+
+[language_servers.next-ls]
+name = "Next LS"
+languages = ["Elixir", "HEEX"]
+
+[language_servers.lexical]
+name = "Lexical"
+languages = ["Elixir", "HEEX"]
+
+[grammars.elixir]
+repository = "https://github.com/elixir-lang/tree-sitter-elixir"
+commit = "a2861e88a730287a60c11ea9299c033c7d076e30"
+
+[grammars.heex]
+repository = "https://github.com/phoenixframework/tree-sitter-heex"
+commit = "2e1348c3cf2c9323e87c2744796cf3f3868aa82a"

extensions/elixir/languages/elixir/brackets.scm

@@ -0,0 +1,5 @@
+("(" @open ")" @close)
+("[" @open "]" @close)
+("{" @open "}" @close)
+("\"" @open "\"" @close)
+("do" @open "end" @close)

extensions/elixir/languages/elixir/config.toml

@@ -0,0 +1,18 @@
+name = "Elixir"
+grammar = "elixir"
+path_suffixes = ["ex", "exs"]
+line_comments = ["# "]
+autoclose_before = ";:.,=}])>"
+brackets = [
+    { start = "{", end = "}", close = true, newline = true },
+    { start = "[", end = "]", close = true, newline = true },
+    { start = "(", end = ")", close = true, newline = true },
+    { start = "\"", end = "\"", close = true, newline = false, not_in = ["string", "comment"] },
+    { start = "'", end = "'", close = true, newline = false, not_in = ["string", "comment"] },
+]
+tab_size = 2
+scope_opt_in_language_servers = ["tailwindcss-language-server"]
+
+[overrides.string]
+word_characters = ["-"]
+opt_into_language_servers = ["tailwindcss-language-server"]

extensions/elixir/languages/elixir/embedding.scm

@@ -0,0 +1,27 @@
+(
+    (unary_operator
+        operator: "@"
+        operand: (call
+            target: (identifier) @unary
+            (#match? @unary "^(doc)$"))
+        ) @context
+    .
+    (call
+        target: (identifier) @name
+        (arguments
+            [
+            (identifier) @name
+            (call
+                target: (identifier) @name)
+                (binary_operator
+                    left: (call
+                    target: (identifier) @name)
+                    operator: "when")
+            ])
+        (#match? @name "^(def|defp|defdelegate|defguard|defguardp|defmacro|defmacrop|defn|defnp)$")) @item
+        )
+
+    (call
+        target: (identifier) @name
+        (arguments (alias) @name)
+        (#match? @name "^(defmodule|defprotocol)$")) @item

extensions/elixir/languages/elixir/highlights.scm

@@ -0,0 +1,153 @@
+["when" "and" "or" "not" "in" "not in" "fn" "do" "end" "catch" "rescue" "after" "else"] @keyword
+
+(unary_operator
+  operator: "&"
+  operand: (integer) @operator)
+
+(operator_identifier) @operator
+
+(unary_operator
+  operator: _ @operator)
+
+(binary_operator
+  operator: _ @operator)
+
+(dot
+  operator: _ @operator)
+
+(stab_clause
+  operator: _ @operator)
+
+[
+  (boolean)
+  (nil)
+] @constant
+
+[
+  (integer)
+  (float)
+] @number
+
+(alias) @type
+
+(call
+  target: (dot
+    left: (atom) @type))
+
+(char) @constant
+
+(escape_sequence) @string.escape
+
+[
+  (atom)
+  (quoted_atom)
+  (keyword)
+  (quoted_keyword)
+] @string.special.symbol
+
+[
+  (string)
+  (charlist)
+] @string
+
+(sigil
+  (sigil_name) @__name__
+  quoted_start: _ @string
+  quoted_end: _ @string
+  (#match? @__name__ "^[sS]$")) @string
+
+(sigil
+  (sigil_name) @__name__
+  quoted_start: _ @string.regex
+  quoted_end: _ @string.regex
+  (#match? @__name__ "^[rR]$")) @string.regex
+
+(sigil
+  (sigil_name) @__name__
+  quoted_start: _ @string.special
+  quoted_end: _ @string.special) @string.special
+
+(
+  (identifier) @comment.unused
+  (#match? @comment.unused "^_")
+)
+
+(call
+  target: [
+    (identifier) @function
+    (dot
+      right: (identifier) @function)
+  ])
+
+(call
+  target: (identifier) @keyword
+  (arguments
+    [
+      (identifier) @function
+      (binary_operator
+        left: (identifier) @function
+        operator: "when")
+      (binary_operator
+        operator: "|>"
+        right: (identifier))
+    ])
+  (#match? @keyword "^(def|defdelegate|defguard|defguardp|defmacro|defmacrop|defn|defnp|defp)$"))
+
+(binary_operator
+  operator: "|>"
+  right: (identifier) @function)
+
+(call
+  target: (identifier) @keyword
+  (#match? @keyword "^(def|defdelegate|defexception|defguard|defguardp|defimpl|defmacro|defmacrop|defmodule|defn|defnp|defoverridable|defp|defprotocol|defstruct)$"))
+
+(call
+  target: (identifier) @keyword
+  (#match? @keyword "^(alias|case|cond|else|for|if|import|quote|raise|receive|require|reraise|super|throw|try|unless|unquote|unquote_splicing|use|with)$"))
+
+(
+  (identifier) @constant.builtin
+  (#match? @constant.builtin "^(__MODULE__|__DIR__|__ENV__|__CALLER__|__STACKTRACE__)$")
+)
+
+(unary_operator
+  operator: "@" @comment.doc
+  operand: (call
+    target: (identifier) @__attribute__ @comment.doc
+    (arguments
+      [
+        (string)
+        (charlist)
+        (sigil)
+        (boolean)
+      ] @comment.doc))
+  (#match? @__attribute__ "^(moduledoc|typedoc|doc)$"))
+
+(comment) @comment
+
+[
+ "%"
+] @punctuation
+
+[
+ ","
+ ";"
+] @punctuation.delimiter
+
+[
+  "("
+  ")"
+  "["
+  "]"
+  "{"
+  "}"
+  "<<"
+  ">>"
+] @punctuation.bracket
+
+(interpolation "#{" @punctuation.special "}" @punctuation.special) @embedded
+
+((sigil
+  (sigil_name) @_sigil_name
+  (quoted_content) @embedded)
+ (#eq? @_sigil_name "H"))

extensions/elixir/languages/elixir/indents.scm

@@ -0,0 +1,6 @@
+(call) @indent
+
+(_ "[" "]" @end) @indent
+(_ "{" "}" @end) @indent
+(_ "(" ")" @end) @indent
+(_ "do" "end" @end) @indent

extensions/elixir/languages/elixir/injections.scm

@@ -0,0 +1,7 @@
+; Phoenix HTML template
+
+((sigil
+  (sigil_name) @_sigil_name
+  (quoted_content) @content)
+ (#eq? @_sigil_name "H")
+ (#set! language "heex"))

extensions/elixir/languages/elixir/outline.scm

@@ -0,0 +1,46 @@
+(call
+  target: (identifier) @context
+  (arguments (alias) @name)
+  (#match? @context "^(defmodule|defprotocol)$")) @item
+
+(unary_operator
+  operator: "@" @name
+  operand: (call
+  target: (identifier) @context
+    (arguments
+      [
+        (binary_operator
+          left: (identifier) @name)
+        (binary_operator
+          left: (call
+          target: (identifier) @name
+          (arguments
+            "(" @context.extra
+            _* @context.extra
+            ")" @context.extra)))
+      ]
+    )
+)
+(#match? @context "^(callback|type|typep)$")) @item
+
+(call
+  target: (identifier) @context
+  (arguments
+    [
+      (identifier) @name
+      (call
+          target: (identifier) @name
+          (arguments
+              "(" @context.extra
+              _* @context.extra
+              ")" @context.extra))
+      (binary_operator
+        left: (call
+            target: (identifier) @name
+            (arguments
+                "(" @context.extra
+                _* @context.extra
+                ")" @context.extra))
+        operator: "when")
+    ])
+  (#match? @context "^(def|defp|defdelegate|defguard|defguardp|defmacro|defmacrop|defn|defnp)$")) @item

extensions/elixir/languages/elixir/overrides.scm

@@ -0,0 +1,2 @@
+(comment) @comment
+[(string) (charlist)] @string

extensions/elixir/languages/elixir/tasks.json

@@ -0,0 +1,28 @@
+// Taken from https://gist.github.com/josevalim/2e4f60a14ccd52728e3256571259d493#gistcomment-4995881
+[
+  {
+    "label": "mix test",
+    "command": "mix",
+    "args": ["test"]
+  },
+  {
+    "label": "mix test --failed",
+    "command": "mix",
+    "args": ["test", "--failed"]
+  },
+  {
+    "label": "mix test $ZED_SYMBOL",
+    "command": "mix",
+    "args": ["test", "$ZED_SYMBOL"]
+  },
+  {
+    "label": "mix test $ZED_FILE:$ZED_ROW",
+    "command": "mix",
+    "args": ["test", "$ZED_FILE:$ZED_ROW"]
+  },
+  {
+    "label": "Elixir: break line",
+    "command": "iex",
+    "args": ["-S", "mix", "test", "-b", "$ZED_FILE:$ZED_ROW"]
+  }
+]

extensions/elixir/languages/heex/config.toml

@@ -0,0 +1,13 @@
+name = "HEEX"
+grammar = "heex"
+path_suffixes = ["heex"]
+autoclose_before = ">})"
+brackets = [
+    { start = "<", end = ">", close = true, newline = true },
+]
+block_comment = ["<%!-- ", " --%>"]
+scope_opt_in_language_servers = ["tailwindcss-language-server"]
+
+[overrides.string]
+word_characters = ["-"]
+opt_into_language_servers = ["tailwindcss-language-server"]

extensions/elixir/languages/heex/highlights.scm

@@ -0,0 +1,57 @@
+; HEEx delimiters
+[
+  "/>"
+  "<!"
+  "<"
+  "</"
+  "</:"
+  "<:"
+  ">"
+  "{"
+  "}"
+] @punctuation.bracket
+
+[
+  "<%!--"
+  "<%"
+  "<%#"
+  "<%%="
+  "<%="
+  "%>"
+  "--%>"
+  "-->"
+  "<!--"
+] @keyword
+
+; HEEx operators are highlighted as such
+"=" @operator
+
+; HEEx inherits the DOCTYPE tag from HTML
+(doctype) @constant
+
+(comment) @comment
+
+; HEEx tags and slots are highlighted as HTML
+[
+ (tag_name)
+ (slot_name)
+] @tag
+
+; HEEx attributes are highlighted as HTML attributes
+(attribute_name) @attribute
+
+; HEEx special attributes are highlighted as keywords
+(special_attribute_name) @keyword
+
+[
+  (attribute_value)
+  (quoted_attribute_value)
+] @string
+
+; HEEx components are highlighted as Elixir modules and functions
+(component_name
+  [
+    (module) @module
+    (function) @function
+    "." @punctuation.delimiter
+  ])

extensions/elixir/languages/heex/injections.scm

@@ -0,0 +1,13 @@
+(
+  (directive
+    [
+      (partial_expression_value)
+      (expression_value)
+      (ending_expression_value)
+    ] @content)
+  (#set! language "elixir")
+  (#set! combined)
+)
+
+((expression (expression_value) @content)
+ (#set! language "elixir"))

extensions/elixir/languages/heex/overrides.scm

@@ -0,0 +1,4 @@
+[
+  (attribute_value)
+  (quoted_attribute_value)
+] @string

extensions/elixir/src/elixir.rs

@@ -0,0 +1,107 @@
+mod language_servers;
+
+use zed::lsp::{Completion, Symbol};
+use zed::{serde_json, CodeLabel, LanguageServerId};
+use zed_extension_api::{self as zed, Result};
+
+use crate::language_servers::{ElixirLs, Lexical, NextLs};
+
+struct ElixirExtension {
+    elixir_ls: Option<ElixirLs>,
+    next_ls: Option<NextLs>,
+    lexical: Option<Lexical>,
+}
+
+impl zed::Extension for ElixirExtension {
+    fn new() -> Self {
+        Self {
+            elixir_ls: None,
+            next_ls: None,
+            lexical: None,
+        }
+    }
+
+    fn language_server_command(
+        &mut self,
+        language_server_id: &LanguageServerId,
+        worktree: &zed::Worktree,
+    ) -> Result<zed::Command> {
+        match language_server_id.as_ref() {
+            ElixirLs::LANGUAGE_SERVER_ID => {
+                let elixir_ls = self.elixir_ls.get_or_insert_with(|| ElixirLs::new());
+
+                Ok(zed::Command {
+                    command: elixir_ls.language_server_binary_path(language_server_id, worktree)?,
+                    args: vec![],
+                    env: Default::default(),
+                })
+            }
+            NextLs::LANGUAGE_SERVER_ID => {
+                let next_ls = self.next_ls.get_or_insert_with(|| NextLs::new());
+
+                Ok(zed::Command {
+                    command: next_ls.language_server_binary_path(language_server_id, worktree)?,
+                    args: vec!["--stdio".to_string()],
+                    env: Default::default(),
+                })
+            }
+            Lexical::LANGUAGE_SERVER_ID => {
+                let lexical = self.lexical.get_or_insert_with(|| Lexical::new());
+
+                Ok(zed::Command {
+                    command: lexical.language_server_binary_path(language_server_id, worktree)?,
+                    args: vec![],
+                    env: Default::default(),
+                })
+            }
+            language_server_id => Err(format!("unknown language server: {language_server_id}")),
+        }
+    }
+
+    fn label_for_completion(
+        &self,
+        language_server_id: &LanguageServerId,
+        completion: Completion,
+    ) -> Option<CodeLabel> {
+        match language_server_id.as_ref() {
+            ElixirLs::LANGUAGE_SERVER_ID => {
+                self.elixir_ls.as_ref()?.label_for_completion(completion)
+            }
+            NextLs::LANGUAGE_SERVER_ID => self.next_ls.as_ref()?.label_for_completion(completion),
+            Lexical::LANGUAGE_SERVER_ID => self.lexical.as_ref()?.label_for_completion(completion),
+            _ => None,
+        }
+    }
+
+    fn label_for_symbol(
+        &self,
+        language_server_id: &LanguageServerId,
+        symbol: Symbol,
+    ) -> Option<CodeLabel> {
+        match language_server_id.as_ref() {
+            ElixirLs::LANGUAGE_SERVER_ID => self.elixir_ls.as_ref()?.label_for_symbol(symbol),
+            NextLs::LANGUAGE_SERVER_ID => self.next_ls.as_ref()?.label_for_symbol(symbol),
+            Lexical::LANGUAGE_SERVER_ID => self.lexical.as_ref()?.label_for_symbol(symbol),
+            _ => None,
+        }
+    }
+
+    fn language_server_initialization_options(
+        &mut self,
+        language_server_id: &LanguageServerId,
+        _worktree: &zed::Worktree,
+    ) -> Result<Option<serde_json::Value>> {
+        match language_server_id.as_ref() {
+            NextLs::LANGUAGE_SERVER_ID => Ok(Some(serde_json::json!({
+                "experimental": {
+                    "completions": {
+                        "enable": true
+                    }
+                }
+            }))),
+            _ => Ok(None),
+        }
+    }
+}
+
+zed::register_extension!(ElixirExtension);

extensions/elixir/src/language_servers.rs

@@ -0,0 +1,7 @@
+mod elixir_ls;
+mod lexical;
+mod next_ls;
+
+pub use elixir_ls::*;
+pub use lexical::*;
+pub use next_ls::*;

extensions/elixir/src/language_servers/elixir_ls.rs

@@ -0,0 +1,165 @@
+use std::fs;
+
+use zed::lsp::{Completion, CompletionKind, Symbol, SymbolKind};
+use zed::{CodeLabel, CodeLabelSpan, LanguageServerId};
+use zed_extension_api::{self as zed, Result};
+
+pub struct ElixirLs {
+    cached_binary_path: Option<String>,
+}
+
+impl ElixirLs {
+    pub const LANGUAGE_SERVER_ID: &'static str = "elixir-ls";
+
+    pub fn new() -> Self {
+        Self {
+            cached_binary_path: None,
+        }
+    }
+
+    pub fn language_server_binary_path(
+        &mut self,
+        language_server_id: &LanguageServerId,
+        worktree: &zed::Worktree,
+    ) -> Result<String> {
+        if let Some(path) = worktree.which("elixir-ls") {
+            return Ok(path);
+        }
+
+        if let Some(path) = &self.cached_binary_path {
+            if fs::metadata(path).map_or(false, |stat| stat.is_file()) {
+                return Ok(path.clone());
+            }
+        }
+
+        zed::set_language_server_installation_status(
+            &language_server_id,
+            &zed::LanguageServerInstallationStatus::CheckingForUpdate,
+        );
+        let release = zed::latest_github_release(
+            "elixir-lsp/elixir-ls",
+            zed::GithubReleaseOptions {
+                require_assets: true,
+                pre_release: false,
+            },
+        )?;
+
+        let asset_name = format!("elixir-ls-{version}.zip", version = release.version,);
+
+        let asset = release
+            .assets
+            .iter()
+            .find(|asset| asset.name == asset_name)
+            .ok_or_else(|| format!("no asset found matching {:?}", asset_name))?;
+
+        let (platform, _arch) = zed::current_platform();
+        let version_dir = format!("elixir-ls-{}", release.version);
+        let binary_path = format!(
+            "{version_dir}/language_server.{extension}",
+            extension = match platform {
+                zed::Os::Mac | zed::Os::Linux => "sh",
+                zed::Os::Windows => "bat",
+            }
+        );
+
+        if !fs::metadata(&binary_path).map_or(false, |stat| stat.is_file()) {
+            zed::set_language_server_installation_status(
+                &language_server_id,
+                &zed::LanguageServerInstallationStatus::Downloading,
+            );
+
+            zed::download_file(
+                &asset.download_url,
+                &version_dir,
+                zed::DownloadedFileType::Zip,
+            )
+            .map_err(|e| format!("failed to download file: {e}"))?;
+
+            let entries =
+                fs::read_dir(".").map_err(|e| format!("failed to list working directory {e}"))?;
+            for entry in entries {
+                let entry = entry.map_err(|e| format!("failed to load directory entry {e}"))?;
+                if entry.file_name().to_str() != Some(&version_dir) {
+                    fs::remove_dir_all(&entry.path()).ok();
+                }
+            }
+        }
+
+        self.cached_binary_path = Some(binary_path.clone());
+        Ok(binary_path)
+    }
+
+    pub fn label_for_completion(&self, completion: Completion) -> Option<CodeLabel> {
+        match completion.kind? {
+            CompletionKind::Module
+            | CompletionKind::Class
+            | CompletionKind::Interface
+            | CompletionKind::Struct => {
+                let name = completion.label;
+                let defmodule = "defmodule ";
+                let code = format!("{defmodule}{name}");
+
+                Some(CodeLabel {
+                    code,
+                    spans: vec![CodeLabelSpan::code_range(
+                        defmodule.len()..defmodule.len() + name.len(),
+                    )],
+                    filter_range: (0..name.len()).into(),
+                })
+            }
+            CompletionKind::Function | CompletionKind::Constant => {
+                let name = completion.label;
+                let def = "def ";
+                let code = format!("{def}{name}");
+
+                Some(CodeLabel {
+                    code,
+                    spans: vec![CodeLabelSpan::code_range(def.len()..def.len() + name.len())],
+                    filter_range: (0..name.len()).into(),
+                })
+            }
+            CompletionKind::Operator => {
+                let name = completion.label;
+                let def_a = "def a ";
+                let code = format!("{def_a}{name} b");
+
+                Some(CodeLabel {
+                    code,
+                    spans: vec![CodeLabelSpan::code_range(
+                        def_a.len()..def_a.len() + name.len(),
+                    )],
+                    filter_range: (0..name.len()).into(),
+                })
+            }
+            _ => None,
+        }
+    }
+
+    pub fn label_for_symbol(&self, symbol: Symbol) -> Option<CodeLabel> {
+        let name = &symbol.name;
+
+        let (code, filter_range, display_range) = match symbol.kind {
+            SymbolKind::Module | SymbolKind::Class | SymbolKind::Interface | SymbolKind::Struct => {
+                let defmodule = "defmodule ";
+                let code = format!("{defmodule}{name}");
+                let filter_range = 0..name.len();
+                let display_range = defmodule.len()..defmodule.len() + name.len();
+                (code, filter_range, display_range)
+            }
+            SymbolKind::Function | SymbolKind::Constant => {
+                let def = "def ";
+                let code = format!("{def}{name}");
+                let filter_range = 0..name.len();
+                let display_range = def.len()..def.len() + name.len();
+                (code, filter_range, display_range)
+            }
+            _ => return None,
+        };
+
+        Some(CodeLabel {
+            spans: vec![CodeLabelSpan::code_range(display_range)],
+            filter_range: filter_range.into(),
+            code,
+        })
+    }
+}

extensions/elixir/src/language_servers/lexical.rs

@@ -0,0 +1,130 @@
+use std::fs;
+
+use zed::lsp::{Completion, CompletionKind, Symbol};
+use zed::{CodeLabel, CodeLabelSpan, LanguageServerId};
+use zed_extension_api::{self as zed, Result};
+
+pub struct Lexical {
+    cached_binary_path: Option<String>,
+}
+
+impl Lexical {
+    pub const LANGUAGE_SERVER_ID: &'static str = "lexical";
+
+    pub fn new() -> Self {
+        Self {
+            cached_binary_path: None,
+        }
+    }
+
+    pub fn language_server_binary_path(
+        &mut self,
+        language_server_id: &LanguageServerId,
+        _worktree: &zed::Worktree,
+    ) -> Result<String> {
+        if let Some(path) = &self.cached_binary_path {
+            if fs::metadata(path).map_or(false, |stat| stat.is_file()) {
+                return Ok(path.clone());
+            }
+        }
+
+        zed::set_language_server_installation_status(
+            &language_server_id,
+            &zed::LanguageServerInstallationStatus::CheckingForUpdate,
+        );
+        let release = zed::latest_github_release(
+            "lexical-lsp/lexical",
+            zed::GithubReleaseOptions {
+                require_assets: true,
+                pre_release: false,
+            },
+        )?;
+
+        let asset_name = format!("lexical-{version}.zip", version = release.version);
+
+        let asset = release
+            .assets
+            .iter()
+            .find(|asset| asset.name == asset_name)
+            .ok_or_else(|| format!("no asset found matching {:?}", asset_name))?;
+
+        let version_dir = format!("lexical-{}", release.version);
+        let binary_path = format!("{version_dir}/lexical/bin/start_lexical.sh");
+
+        if !fs::metadata(&binary_path).map_or(false, |stat| stat.is_file()) {
+            zed::set_language_server_installation_status(
+                &language_server_id,
+                &zed::LanguageServerInstallationStatus::Downloading,
+            );
+
+            zed::download_file(
+                &asset.download_url,
+                &version_dir,
+                zed::DownloadedFileType::Zip,
+            )
+            .map_err(|e| format!("failed to download file: {e}"))?;
+
+            let entries =
+                fs::read_dir(".").map_err(|e| format!("failed to list working directory {e}"))?;
+            for entry in entries {
+                let entry = entry.map_err(|e| format!("failed to load directory entry {e}"))?;
+                if entry.file_name().to_str() != Some(&version_dir) {
+                    fs::remove_dir_all(&entry.path()).ok();
+                }
+            }
+        }
+
+        self.cached_binary_path = Some(binary_path.clone());
+        Ok(binary_path)
+    }
+
+    pub fn label_for_completion(&self, completion: Completion) -> Option<CodeLabel> {
+        match completion.kind? {
+            CompletionKind::Module
+            | CompletionKind::Class
+            | CompletionKind::Interface
+            | CompletionKind::Struct => {
+                let name = completion.label;
+                let defmodule = "defmodule ";
+                let code = format!("{defmodule}{name}");
+
+                Some(CodeLabel {
+                    code,
+                    spans: vec![CodeLabelSpan::code_range(
+                        defmodule.len()..defmodule.len() + name.len(),
+                    )],
+                    filter_range: (0..name.len()).into(),
+                })
+            }
+            CompletionKind::Function | CompletionKind::Constant => {
+                let name = completion.label;
+                let def = "def ";
+                let code = format!("{def}{name}");
+
+                Some(CodeLabel {
+                    code,
+                    spans: vec![CodeLabelSpan::code_range(def.len()..def.len() + name.len())],
+                    filter_range: (0..name.len()).into(),
+                })
+            }
+            CompletionKind::Operator => {
+                let name = completion.label;
+                let def_a = "def a ";
+                let code = format!("{def_a}{name} b");
+
+                Some(CodeLabel {
+                    code,
+                    spans: vec![CodeLabelSpan::code_range(
+                        def_a.len()..def_a.len() + name.len(),
+                    )],
+                    filter_range: (0..name.len()).into(),
+                })
+            }
+            _ => None,
+        }
+    }
+
+    pub fn label_for_symbol(&self, _symbol: Symbol) -> Option<CodeLabel> {
+        None
+    }
+}

extensions/elixir/src/language_servers/next_ls.rs

@@ -0,0 +1,176 @@
+use std::fs;
+
+use zed::lsp::{Completion, CompletionKind, Symbol, SymbolKind};
+use zed::{CodeLabel, CodeLabelSpan, LanguageServerId};
+use zed_extension_api::{self as zed, Result};
+
+pub struct NextLs {
+    cached_binary_path: Option<String>,
+}
+
+impl NextLs {
+    pub const LANGUAGE_SERVER_ID: &'static str = "next-ls";
+
+    pub fn new() -> Self {
+        Self {
+            cached_binary_path: None,
+        }
+    }
+
+    pub fn language_server_binary_path(
+        &mut self,
+        language_server_id: &LanguageServerId,
+        _worktree: &zed::Worktree,
+    ) -> Result<String> {
+        if let Some(path) = &self.cached_binary_path {
+            if fs::metadata(path).map_or(false, |stat| stat.is_file()) {
+                return Ok(path.clone());
+            }
+        }
+
+        zed::set_language_server_installation_status(
+            &language_server_id,
+            &zed::LanguageServerInstallationStatus::CheckingForUpdate,
+        );
+        let release = zed::latest_github_release(
+            "elixir-tools/next-ls",
+            zed::GithubReleaseOptions {
+                require_assets: true,
+                pre_release: false,
+            },
+        )?;
+
+        let (platform, arch) = zed::current_platform();
+        let asset_name = format!(
+            "next_ls_{os}_{arch}{extension}",
+            os = match platform {
+                zed::Os::Mac => "darwin",
+                zed::Os::Linux => "linux",
+                zed::Os::Windows => "windows",
+            },
+            arch = match arch {
+                zed::Architecture::Aarch64 => "arm64",
+                zed::Architecture::X8664 => "amd64",
+                zed::Architecture::X86 =>
+                    return Err(format!("unsupported architecture: {arch:?}")),
+            },
+            extension = match platform {
+                zed::Os::Mac | zed::Os::Linux => "",
+                zed::Os::Windows => ".exe",
+            }
+        );
+
+        let asset = release
+            .assets
+            .iter()
+            .find(|asset| asset.name == asset_name)
+            .ok_or_else(|| format!("no asset found matching {:?}", asset_name))?;
+
+        let version_dir = format!("next-ls-{}", release.version);
+        fs::create_dir_all(&version_dir).map_err(|e| format!("failed to create directory: {e}"))?;
+
+        let binary_path = format!("{version_dir}/next-ls");
+
+        if !fs::metadata(&binary_path).map_or(false, |stat| stat.is_file()) {
+            zed::set_language_server_installation_status(
+                &language_server_id,
+                &zed::LanguageServerInstallationStatus::Downloading,
+            );
+
+            zed::download_file(
+                &asset.download_url,
+                &binary_path,
+                zed::DownloadedFileType::Uncompressed,
+            )
+            .map_err(|e| format!("failed to download file: {e}"))?;
+
+            zed::make_file_executable(&binary_path)?;
+
+            let entries =
+                fs::read_dir(".").map_err(|e| format!("failed to list working directory {e}"))?;
+            for entry in entries {
+                let entry = entry.map_err(|e| format!("failed to load directory entry {e}"))?;
+                if entry.file_name().to_str() != Some(&version_dir) {
+                    fs::remove_dir_all(&entry.path()).ok();
+                }
+            }
+        }
+
+        self.cached_binary_path = Some(binary_path.clone());
+        Ok(binary_path)
+    }
+
+    pub fn label_for_completion(&self, completion: Completion) -> Option<CodeLabel> {
+        match completion.kind? {
+            CompletionKind::Module
+            | CompletionKind::Class
+            | CompletionKind::Interface
+            | CompletionKind::Struct => {
+                let name = completion.label;
+                let defmodule = "defmodule ";
+                let code = format!("{defmodule}{name}");
+
+                Some(CodeLabel {
+                    code,
+                    spans: vec![CodeLabelSpan::code_range(
+                        defmodule.len()..defmodule.len() + name.len(),
+                    )],
+                    filter_range: (0..name.len()).into(),
+                })
+            }
+            CompletionKind::Function | CompletionKind::Constant => {
+                let name = completion.label;
+                let def = "def ";
+                let code = format!("{def}{name}");
+
+                Some(CodeLabel {
+                    code,
+                    spans: vec![CodeLabelSpan::code_range(def.len()..def.len() + name.len())],
+                    filter_range: (0..name.len()).into(),
+                })
+            }
+            CompletionKind::Operator => {
+                let name = completion.label;
+                let def_a = "def a ";
+                let code = format!("{def_a}{name} b");
+
+                Some(CodeLabel {
+                    code,
+                    spans: vec![CodeLabelSpan::code_range(
+                        def_a.len()..def_a.len() + name.len(),
+                    )],
+                    filter_range: (0..name.len()).into(),
+                })
+            }
+            _ => None,
+        }
+    }
+
+    pub fn label_for_symbol(&self, symbol: Symbol) -> Option<CodeLabel> {
+        let name = &symbol.name;
+
+        let (code, filter_range, display_range) = match symbol.kind {
+            SymbolKind::Module | SymbolKind::Class | SymbolKind::Interface | SymbolKind::Struct => {
+                let defmodule = "defmodule ";
+                let code = format!("{defmodule}{name}");
+                let filter_range = 0..name.len();
+                let display_range = defmodule.len()..defmodule.len() + name.len();
+                (code, filter_range, display_range)
+            }
+            SymbolKind::Function | SymbolKind::Constant => {
+                let def = "def ";
+                let code = format!("{def}{name}");
+                let filter_range = 0..name.len();
+                let display_range = def.len()..def.len() + name.len();
+                (code, filter_range, display_range)
+            }
+            _ => return None,
+        };
+
+        Some(CodeLabel {
+            spans: vec![CodeLabelSpan::code_range(display_range)],
+            filter_range: filter_range.into(),
+            code,
+        })
+    }
+}