Refactor worksheet support, make it a dynamic feature

- Only enable worksheet features on the client if the server supports
them using the LSP support for dynamic feature registration.
- Replace the global functions and state in worksheet.ts by a
WorksheetProvider class, move some of the global functions specific to
one worksheet into Worksheet

language-server/src/dotty/tools/languageserver/DottyLanguageServer.scala

@@ -153,7 +153,9 @@ class DottyLanguageServer extends LanguageServer
     rootUri = params.getRootUri
     assert(rootUri != null)
 
-    val c = new ServerCapabilities
+    class DottyServerCapabilities(val worksheetRunProvider: Boolean = true) extends lsp4j.ServerCapabilities
+
+    val c = new DottyServerCapabilities
     c.setTextDocumentSync(TextDocumentSyncKind.Full)
     c.setDocumentHighlightProvider(true)
     c.setDocumentSymbolProvider(true)

vscode-dotty/package.json

@@ -43,11 +43,13 @@
     "commands": [
       {
         "command": "worksheet.evaluate",
-        "title": "Run worksheet"
+        "title": "Run worksheet",
+        "category": "Scala"
       },
       {
         "command": "worksheet.cancel",
-        "title": "Cancel worksheet evaluation"
+        "title": "Cancel worksheet evaluation",
+        "category": "Scala"
       }
     ],
     "configurationDefaults": {

vscode-dotty/src/extension.ts

@@ -13,11 +13,12 @@ import { LanguageClient, LanguageClientOptions, RevealOutputChannelOn,
 import { enableOldServerWorkaround } from './compat'
 import { WorksheetPublishOutputNotification } from './protocol'
 import * as worksheet from './worksheet'
+import * as features from './features'
 
+export let client: LanguageClient
 
 let extensionContext: ExtensionContext
 let outputChannel: vscode.OutputChannel
-export let client: LanguageClient
 
 export function activate(context: ExtensionContext) {
   extensionContext = context
@@ -31,18 +32,6 @@ export function activate(context: ExtensionContext) {
   const languageServerDefaultConfigFile = path.join(extensionContext.extensionPath, './out/default-dotty-ide-config')
   const coursierPath = path.join(extensionContext.extensionPath, './out/coursier');
 
-  vscode.workspace.onWillSaveTextDocument(worksheet.prepareWorksheet)
-  vscode.workspace.onDidSaveTextDocument(document => {
-    if (worksheet.isWorksheet(document)) {
-      worksheet.evaluateWorksheet(document)
-    }
-  })
-  vscode.workspace.onDidCloseTextDocument(document => {
-    if (worksheet.isWorksheet(document)) {
-      worksheet.removeWorksheet(document)
-    }
-  })
-
   if (process.env['DLS_DEV_MODE']) {
     const portFile = `${vscode.workspace.rootPath}/.dotty-ide-dev-port`
     fs.readFile(portFile, (err, port) => {
@@ -203,20 +192,12 @@ function run(serverOptions: ServerOptions, isOldServer: boolean) {
   }
 
   client = new LanguageClient("dotty", "Dotty", serverOptions, clientOptions)
+  client.registerFeature(new features.WorksheetExecFeature(client))
+
   if (isOldServer)
     enableOldServerWorkaround(client)
 
-  client.onReady().then(() => {
-    client.onNotification(WorksheetPublishOutputNotification.type, params => {
-      worksheet.handleMessage(params)
-    })
-  })
-
-  vscode.commands.registerCommand(worksheet.worksheetEvaluateKey, () => {
-    worksheet.evaluateWorksheetCommand()
-  })
-
   // Push the disposable to the context's subscriptions so that the
   // client can be deactivated on extension deactivation
-  extensionContext.subscriptions.push(client.start());
+  extensionContext.subscriptions.push(client.start())
 }

vscode-dotty/src/features.ts

@@ -0,0 +1,62 @@
+import * as vscode from 'vscode'
+import {
+  BaseLanguageClient, ClientCapabilities, DynamicFeature, ServerCapabilities,
+  TextDocumentFeature, TextDocumentRegistrationOptions,
+} from 'vscode-languageclient'
+import { generateUuid } from 'vscode-languageclient/lib/utils/uuid'
+import { DocumentSelector } from 'vscode-languageserver-protocol'
+import { Disposable } from 'vscode-jsonrpc'
+
+import { WorksheetExecRequest } from './protocol'
+import { WorksheetProvider } from './worksheet'
+
+// Remove this if
+// https://github.com/Microsoft/vscode-languageserver-node/issues/423 is fixed.
+function ensure<T, K extends keyof T>(target: T, key: K): T[K] {
+  if (target[key] === void 0) {
+    target[key] = {} as any;
+  }
+  return target[key];
+}
+
+export interface WorksheetClientCapabilities {
+  worksheet?: {
+    exec?: {
+      dynamicRegistration?: boolean
+    }
+  }
+}
+
+export interface WorksheetServerCapabilities {
+  /**
+   * The server provides support for running worksheets.
+   */
+  worksheetRunProvider?: boolean
+}
+
+export class WorksheetExecFeature extends TextDocumentFeature<TextDocumentRegistrationOptions> {
+  constructor(client: BaseLanguageClient) {
+    super(client, WorksheetExecRequest.type)
+  }
+
+  public fillClientCapabilities(capabilities: ClientCapabilities & WorksheetClientCapabilities): void {
+    ensure(ensure(capabilities, "worksheet")!, "exec")!.dynamicRegistration = true
+  }
+
+  public initialize(capabilities: ServerCapabilities & WorksheetServerCapabilities, documentSelector: DocumentSelector): void {
+    if (!capabilities.worksheetRunProvider) {
+      return
+    }
+
+    const selector: DocumentSelector = documentSelector || [ { language: 'scala', pattern: '**/*.sc' } ]
+    this.register(this.messages, {
+      id: generateUuid(),
+      registerOptions: { documentSelector: selector }
+    })
+  }
+
+  protected registerLanguageProvider(options: TextDocumentRegistrationOptions): Disposable {
+    let client = this._client
+    return new WorksheetProvider(client, options.documentSelector!)
+  }
+}