add markdown-language-features to sqlops (#2338)

extensions/markdown-language-features/src/commands/showSource.ts

@@ -0,0 +1,24 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as vscode from 'vscode';
+import { Command } from '../commandManager';
+import { MarkdownPreviewManager } from '../features/previewManager';
+
+export class ShowSourceCommand implements Command {
+	public readonly id = 'markdown.showSource';
+
+	public constructor(
+		private readonly previewManager: MarkdownPreviewManager
+	) { }
+
+	public execute() {
+		if (this.previewManager.activePreviewResource) {
+			return vscode.workspace.openTextDocument(this.previewManager.activePreviewResource)
+				.then(document => vscode.window.showTextDocument(document));
+		}
+		return undefined;
+	}
+}