erlang: Add Erlang Language Platform support (#14879)

Added support for the [Erlang Language
Platform](https://whatsapp.github.io/erlang-language-platform/) language
server to the Erlang extension.

Release Notes:

- N/A

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

extensions/erlang/extension.toml

@@ -3,13 +3,17 @@ name = "Erlang"
 description = "Erlang support."
 version = "0.0.1"
 schema_version = 1
-authors = ["Dairon M <dairon.medina@gmail.com>"]
+authors = ["Dairon M <dairon.medina@gmail.com>", "Fabian Bergström <fabian@fmbb.se>"]
 repository = "https://github.com/zed-industries/zed"
 
 [language_servers.erlang-ls]
 name = "Erlang Language Server"
 language = "Erlang"
 
+[language_servers.elp]
+name = "Erlang Language Platform"
+language = "Erlang"
+
 [grammars.erlang]
 repository = "https://github.com/WhatsApp/tree-sitter-erlang"
 commit = "57e69513efd831f9cc8207d65d96bad917ca4aa4"

extensions/erlang/src/erlang.rs

@@ -2,15 +2,19 @@ mod language_servers;
 
 use zed_extension_api::{self as zed, Result};
 
-use crate::language_servers::ErlangLs;
+use crate::language_servers::{ErlangLanguagePlatform, ErlangLs};
 
 struct ErlangExtension {
     erlang_ls: Option<ErlangLs>,
+    erlang_language_platform: Option<ErlangLanguagePlatform>,
 }
 
 impl zed::Extension for ErlangExtension {
     fn new() -> Self {
-        Self { erlang_ls: None }
+        Self {
+            erlang_ls: None,
+            erlang_language_platform: None,
+        }
     }
 
     fn language_server_command(
@@ -28,6 +32,12 @@ impl zed::Extension for ErlangExtension {
                     env: Default::default(),
                 })
             }
+            ErlangLanguagePlatform::LANGUAGE_SERVER_ID => {
+                let erlang_language_platform = self
+                    .erlang_language_platform
+                    .get_or_insert_with(|| ErlangLanguagePlatform::new());
+                erlang_language_platform.language_server_command(language_server_id, worktree)
+            }
             language_server_id => Err(format!("unknown language server: {language_server_id}")),
         }
     }

extensions/erlang/src/language_servers.rs

@@ -1,3 +1,5 @@
+mod erlang_language_platform;
 mod erlang_ls;
 
+pub use erlang_language_platform::*;
 pub use erlang_ls::*;

extensions/erlang/src/language_servers/erlang_language_platform.rs

@@ -0,0 +1,33 @@
+use zed_extension_api::{self as zed, LanguageServerId, Result};
+
+pub struct ErlangLanguagePlatform;
+
+impl ErlangLanguagePlatform {
+    pub const LANGUAGE_SERVER_ID: &'static str = "elp";
+
+    pub fn new() -> Self {
+        Self
+    }
+
+    pub fn language_server_command(
+        &mut self,
+        language_server_id: &LanguageServerId,
+        worktree: &zed::Worktree,
+    ) -> Result<zed::Command> {
+        Ok(zed::Command {
+            command: self.language_server_binary_path(language_server_id, worktree)?,
+            args: vec!["server".to_string()],
+            env: Default::default(),
+        })
+    }
+
+    fn language_server_binary_path(
+        &mut self,
+        _language_server_id: &LanguageServerId,
+        worktree: &zed::Worktree,
+    ) -> Result<String> {
+        worktree
+            .which("elp")
+            .ok_or_else(|| "elp must be installed and available on your $PATH".to_string())
+    }
+}