findDocument API (work in progress)

src/vs/vscode.d.ts

@@ -8050,6 +8050,14 @@ declare module 'vscode' {
 		 */
 		export const textDocuments: TextDocument[];
 
+		/**
+		 * Find a text document known to the system and return it or undefined if there's no such
+		 * a document.
+		 *
+		 * @param uri Identifies the resource to open.
+		 */
+		export function findDocument(uri: Uri): TextDocument | undefined;
+
 		/**
 		 * Opens a document. Will return early if this document is already open. Otherwise
 		 * the document is loaded and the [didOpen](#workspace.onDidOpenTextDocument)-event fires.

src/vs/workbench/api/common/extHost.api.impl.ts

@@ -617,6 +617,10 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 			set textDocuments(value) {
 				throw errors.readonly();
 			},
+			findDocument(uri: vscode.Uri): vscode.TextDocument | undefined {
+				const documentData = extHostDocuments.getDocumentData(uri);
+				return documentData ? documentData.document : undefined;
+			},
 			openTextDocument(uriOrFileNameOrOptions?: vscode.Uri | string | { language?: string; content?: string; }) {
 				let uriPromise: Thenable<URI>;
 

src/vs/workbench/test/common/editor/untitledEditor.test.ts

@@ -308,4 +308,4 @@ suite('Workbench untitled editors', () => {
 		input.dispose();
 		assert.equal(counter, 1);
 	});
-});
+});