[clangd][vscode] Make SemanticHighlightingFeature more self-contained.

[hokein]

Summary

so that we don't have too many usage from the client side (just a single
occurrance for register), this also aligns with how other builtin feature
being implemented in vscode.

[hokein]

wait, there is still an issue.

[hokein]

Update the patch.

[ilya-biryukov]

clang-tools-extra/clangd/clients/clangd-vscode/src/semantic-highlighting.ts

88

Could we subscribe to client.onDidChangeState and dispose() whenever clangd crashes or stops?
This would ensure our initialize <-> dispose calls are properly paired and we will remove the highlightings even if clangd never restarts (I guess that could happen when we crash more than 5 times in a short timespan)

[hokein]

address comments.

[ilya-biryukov]

LGTM, thanks!

clang-tools-extra/clangd/clients/clangd-vscode/src/extension.ts

const clientOptions: vscodelc.LanguageClientOptions = {
         initializationOptions: { clangdFileStatus: true },
         // Do not switch to output window when clangd returns output
         revealOutputChannelOn: vscodelc.RevealOutputChannelOn.Never
     };
 
   const clangdClient = new ClangdLanguageClient('Clang Language Server',
                                                 serverOptions, clientOptions);
   const semanticHighlightingFeature =
-      new semanticHighlighting.SemanticHighlightingFeature();
+      new semanticHighlighting.SemanticHighlightingFeature(clangdClient);
   context.subscriptions.push(
       vscode.Disposable.from(semanticHighlightingFeature));
   clangdClient.registerFeature(semanticHighlightingFeature);
   console.log('Clang Language Server is now active!');
   context.subscriptions.push(clangdClient.start());
   context.subscriptions.push(vscode.commands.registerCommand(
       'clangd-vscode.switchheadersource', async () => {
         const uri =
export function activate(context: vscode.ExtensionContext) {
   context.subscriptions.push(vscode.window.onDidChangeActiveTextEditor(
       () => { status.updateStatus(); }));
   context.subscriptions.push(clangdClient.onDidChangeState(({newState}) => {
     if (newState == vscodelc.State.Running) {
       // clangd starts or restarts after crash.
       clangdClient.onNotification(
           'textDocument/clangd.fileStatus',
           (fileStatus) => { status.onFileUpdated(fileStatus); });
-      clangdClient.onNotification(
-          semanticHighlighting.NotificationType,
-          semanticHighlightingFeature.handleNotification.bind(
-              semanticHighlightingFeature));
     } else if (newState == vscodelc.State.Stopped) {
       // Clear all cached statuses when clangd crashes.
       status.clear();
-      semanticHighlightingFeature.dispose();
     }
   }));
   // An empty place holder for the activate command, otherwise we'll get an
   // "command is not registered" error.
   context.subscriptions.push(vscode.commands.registerCommand(
       'clangd-vscode.activate', async () => {}));
 }

clang-tools-extra/clangd/clients/clangd-vscode/src/semantic-highlighting.ts

export interface SemanticHighlightingLine {
   // The zero-based line position in the text document.
   line: number;
   // All SemanticHighlightingTokens on the line.
   tokens: SemanticHighlightingToken[];
 }
 
 // Language server push notification providing the semantic highlighting
 // information for a text document.
-export const NotificationType =
+const NotificationType =
     new vscodelc.NotificationType<SemanticHighlightingParams, void>(
         'textDocument/semanticHighlighting');
 
 // The feature that should be registered in the vscode lsp for enabling
 // experimental semantic highlighting.
 export class SemanticHighlightingFeature implements vscodelc.StaticFeature {
   // The TextMate scope lookup table. A token with scope index i has the scopes
   // on index i in the lookup table.
   scopeLookupTable: string[][];
   // The object that applies the highlightings clangd sends.
   highlighter: Highlighter;
   // Any disposables that should be cleaned up when clangd crashes.
   private subscriptions: vscode.Disposable[] = [];
+  private clangdClient: vscodelc.BaseLanguageClient;
+
+  constructor(client: vscodelc.BaseLanguageClient) {
+    this.clangdClient = client;
+  }
   fillClientCapabilities(capabilities: vscodelc.ClientCapabilities) {
     // Extend the ClientCapabilities type and add semantic highlighting
     // capability to the object.
     const textDocumentCapabilities: vscodelc.TextDocumentClientCapabilities&
         {semanticHighlightingCapabilities?: {semanticHighlighting : boolean}} =
         capabilities.textDocument;
     textDocumentCapabilities.semanticHighlightingCapabilities = {
       semanticHighlighting : true,
     };
   }
 
   async loadCurrentTheme() {
     const themeRuleMatcher = new ThemeRuleMatcher(
         await loadTheme(vscode.workspace.getConfiguration('workbench')
                             .get<string>('colorTheme')));
     this.highlighter.initialize(themeRuleMatcher);
   }
 
   initialize(capabilities: vscodelc.ServerCapabilities,
              documentSelector: vscodelc.DocumentSelector|undefined) {
+    // Dispose resources everytime we get initialized, e.g. first launch or
+    // recover from clangd crashes.
+    this.dispose();
+    // Register the handler to handle semantic highlighting notification.
+    this.clangdClient.onNotification(NotificationType,
+                                     this.handleNotification.bind(this));
     // The semantic highlighting capability information is in the capabilities
     // object but to access the data we must first extend the ServerCapabilities
     // type.
     const serverCapabilities: vscodelc.ServerCapabilities&
         {semanticHighlighting?: {scopes : string[][]}} = capabilities;
     if (!serverCapabilities.semanticHighlighting)
       return;
     this.scopeLookupTable = serverCapabilities.semanticHighlighting.scopes;