Add support for multi workspace workflow

.vscode/launch.json

@@ -11,6 +11,18 @@
         "--extensionTestsPath=${workspaceFolder}/test/suite/index.js"
       ],
       "outFiles": ["${workspaceFolder}/out/test/**/*.js"]
-    }
+    },
+    {
+			"name": "Run Extension",
+			"type": "extensionHost",
+			"request": "launch",
+			"runtimeExecutable": "${execPath}",
+			"args": [
+				"--extensionDevelopmentPath=${workspaceFolder}"
+			],
+			"outFiles": [
+				"${workspaceFolder}/src/**/*.bs.js"
+			]
+		}
   ]
-}
+}

bsconfig.json

@@ -5,9 +5,6 @@
     "react-jsx": 3
   },
   "sources": [
-    {
-      "dir": "vendor"
-    },
     {
       "subdirs": true,
       "dir": "src"

src/Extension.re

@@ -3,29 +3,33 @@ open LSP;
 
 let createClient = (~id, ~name, ~folder) =>
   Js.Promise.(
-    Server.make(folder)
+    Server.make(folder.Folder.uri.fsPath)
     |> then_(serverOptions => {
-         LanguageClient.make(
-           ~id,
-           ~name,
-           ~serverOptions,
-           ~clientOptions=Client.make(),
+         Ok(
+           LanguageClient.make(
+             ~id,
+             ~name,
+             ~serverOptions,
+             ~clientOptions=Client.make(),
+           ),
          )
          |> resolve
        })
   );
 
-let activate = _context => {
-  Js.Promise.(
-    createClient(
-      ~id="merlin-language-server",
-      ~name="Merlin Language Server",
-      ~folder=Workspace.rootPath,
+let activate = context => {
+  MultiWorkspace.start(
+    ~context, ~commands=[||], ~createClient=(_document, folder) => {
+    Js.Promise.(
+      createClient(
+        ~id="merlin-language-server",
+        ~name="Merlin Language Server",
+        ~folder,
+      )
+      |> catch(e => {
+           let message = Bindings.Error.ofPromiseError(e);
+           Js.Promise.resolve(Error(message));
+         })
     )
-    |> then_((client: LanguageClient.t) => client.start(.) |> resolve)
-    |> catch(e => {
-         let message = Bindings.Error.ofPromiseError(e);
-         Window.showErrorMessage({j|Error: $message|j});
-       })
-  );
+  });
 };

src/LSP.re

@@ -255,3 +255,80 @@ module LanguageClient = {
     t =
     "LanguageClient";
 };
+
+module MultiWorkspace = {
+  module FoldersMap = Belt.HashMap.String;
+  let start = (~context, ~commands, ~createClient): Js.Promise.t(unit) => {
+    let workspaceFolders = FoldersMap.make(~hintSize=1);
+    let startClient = (document: TextDocument.event) => {
+      let uri = document.uri;
+      if (uri.scheme === "file") {
+        let folder = Workspace.getWorkspaceFolder(uri);
+        switch (folder) {
+        | Some(folder)
+            when FoldersMap.has(workspaceFolders, folder.uri.fsPath) =>
+          Js.Promise.resolve()
+        | Some(folder) =>
+          createClient(document, folder)
+          |> Js.Promise.then_(client =>
+               switch (client) {
+               | Ok(client) =>
+                 FoldersMap.set(
+                   workspaceFolders,
+                   Folder.key(folder),
+                   client,
+                 );
+                 client.LanguageClient.start(.) |> Js.Promise.resolve;
+               | Error(message) =>
+                 Window.showErrorMessage({j|Error: $message|j})
+               }
+             )
+        | None => Js.Promise.resolve()
+        };
+      } else {
+        Js.Promise.resolve();
+      };
+    };
+    Workspace.onDidOpenTextDocument(document =>
+      startClient(document) |> ignore
+    );
+    let openTasks =
+      Workspace.textDocuments
+      |> Js.Array.map(startClient)
+      |> Js.Promise.all
+      |> Js.Promise.then_(_ => Js.Promise.resolve());
+    Workspace.onDidChangeWorkspaceFolders(event => {
+      event.removed
+      |> Js.Array.forEach(folder => {
+           switch (FoldersMap.get(workspaceFolders, Folder.key(folder))) {
+           | Some(client) =>
+             FoldersMap.remove(workspaceFolders, Folder.key(folder));
+             client.LanguageClient.stop(.);
+           | None => ()
+           }
+         })
+    });
+
+    commands
+    |> Js.Array.forEach(((cmd, handler)) => {
+         Commands.register(~command=cmd, ~handler)
+       });
+
+    ExtensionContext.(
+      Js.Array.push(
+        {
+          dispose:
+            (.) => {
+              FoldersMap.forEach(workspaceFolders, (_, client) => {
+                client.LanguageClient.stop(.)
+              });
+              FoldersMap.clear(workspaceFolders);
+            },
+        },
+        context.subscriptions,
+      )
+    )
+    |> ignore;
+    openTasks;
+  };
+};

src/bindings/Node.re

@@ -8,7 +8,7 @@ external processEnv: Js.Dict.t(string) = "env";
 module Error = {
   type t;
   [@bs.new] external make: string => t = "Error";
-  let ofPromiseError = [%raw
+  let ofPromiseError: Js.Promise.error => string = [%raw
     error => "return error.message || 'Unknown error'"
   ];
 };