Merge from vscode merge-base (#22780)

* Revert "Revert "Merge from vscode merge-base (#22769)" (#22779)"

This reverts commit 47a1745180.

* Fix notebook download task

* Remove done call from extensions-ci

extensions/css-language-features/server/src/utils/validation.ts

@@ -0,0 +1,108 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { CancellationToken, Connection, Diagnostic, Disposable, DocumentDiagnosticParams, DocumentDiagnosticReport, DocumentDiagnosticReportKind, TextDocuments } from 'vscode-languageserver';
+import { TextDocument } from 'vscode-css-languageservice';
+import { formatError, runSafeAsync } from './runner';
+import { RuntimeEnvironment } from '../cssServer';
+
+export type Validator = (textDocument: TextDocument) => Promise<Diagnostic[]>;
+export type DiagnosticsSupport = {
+	dispose(): void;
+	requestRefresh(): void;
+};
+
+export function registerDiagnosticsPushSupport(documents: TextDocuments<TextDocument>, connection: Connection, runtime: RuntimeEnvironment, validate: Validator): DiagnosticsSupport {
+
+	const pendingValidationRequests: { [uri: string]: Disposable } = {};
+	const validationDelayMs = 500;
+
+	const disposables: Disposable[] = [];
+
+	// The content of a text document has changed. This event is emitted
+	// when the text document first opened or when its content has changed.
+	documents.onDidChangeContent(change => {
+		triggerValidation(change.document);
+	}, undefined, disposables);
+
+	// a document has closed: clear all diagnostics
+	documents.onDidClose(event => {
+		cleanPendingValidation(event.document);
+		connection.sendDiagnostics({ uri: event.document.uri, diagnostics: [] });
+	}, undefined, disposables);
+
+	function cleanPendingValidation(textDocument: TextDocument): void {
+		const request = pendingValidationRequests[textDocument.uri];
+		if (request) {
+			request.dispose();
+			delete pendingValidationRequests[textDocument.uri];
+		}
+	}
+
+	function triggerValidation(textDocument: TextDocument): void {
+		cleanPendingValidation(textDocument);
+		const request = pendingValidationRequests[textDocument.uri] = runtime.timer.setTimeout(async () => {
+			if (request === pendingValidationRequests[textDocument.uri]) {
+				try {
+					const diagnostics = await validate(textDocument);
+					if (request === pendingValidationRequests[textDocument.uri]) {
+						connection.sendDiagnostics({ uri: textDocument.uri, diagnostics });
+					}
+					delete pendingValidationRequests[textDocument.uri];
+				} catch (e) {
+					connection.console.error(formatError(`Error while validating ${textDocument.uri}`, e));
+				}
+			}
+		}, validationDelayMs);
+	}
+
+	return {
+		requestRefresh: () => {
+			documents.all().forEach(triggerValidation);
+		},
+		dispose: () => {
+			disposables.forEach(d => d.dispose());
+			disposables.length = 0;
+			const keys = Object.keys(pendingValidationRequests);
+			for (const key of keys) {
+				pendingValidationRequests[key].dispose();
+				delete pendingValidationRequests[key];
+			}
+		}
+	};
+}
+
+export function registerDiagnosticsPullSupport(documents: TextDocuments<TextDocument>, connection: Connection, runtime: RuntimeEnvironment, validate: Validator): DiagnosticsSupport {
+
+	function newDocumentDiagnosticReport(diagnostics: Diagnostic[]): DocumentDiagnosticReport {
+		return {
+			kind: DocumentDiagnosticReportKind.Full,
+			items: diagnostics
+		};
+	}
+
+	const registration = connection.languages.diagnostics.on(async (params: DocumentDiagnosticParams, token: CancellationToken) => {
+		return runSafeAsync(runtime, async () => {
+			const document = documents.get(params.textDocument.uri);
+			if (document) {
+				return newDocumentDiagnosticReport(await validate(document));
+			}
+			return newDocumentDiagnosticReport([]);
+
+		}, newDocumentDiagnosticReport([]), `Error while computing diagnostics for ${params.textDocument.uri}`, token);
+	});
+
+	function requestRefresh(): void {
+		connection.languages.diagnostics.refresh();
+	}
+
+	return {
+		requestRefresh,
+		dispose: () => {
+			registration.dispose();
+		}
+	};
+
+}