Add two alternative language-changing interface functions

src/vs/editor/common/services/languagesRegistry.ts

@@ -211,6 +211,10 @@ export class LanguagesRegistry {
 		return Object.keys(this._nameMap);
 	}
 
+	public isRegisteredModeExact(modeId: string): boolean {
+		return hasOwnProperty.call(this._languages, modeId);
+	}
+
 	public getLanguageName(modeId: string): string {
 		if (!hasOwnProperty.call(this._languages, modeId)) {
 			return null;

src/vs/editor/common/services/modeService.ts

@@ -46,5 +46,6 @@ export interface IModeService {
 	getMode(commaSeparatedMimetypesOrCommaSeparatedIds: string): IMode;
 	getOrCreateMode(commaSeparatedMimetypesOrCommaSeparatedIds: string): TPromise<IMode>;
 	getOrCreateModeByLanguageName(languageName: string): TPromise<IMode>;
+	getOrCreateModeByLanguageId(modeId: string): TPromise<IMode>;
 	getOrCreateModeByFilenameOrFirstLine(filename: string, firstLine?: string): TPromise<IMode>;
 }

src/vs/editor/common/services/modeServiceImpl.ts

@@ -132,6 +132,15 @@ export class ModeServiceImpl implements IModeService {
 		});
 	}
 
+	public getOrCreateModeByLanguageId(modeId: string): TPromise<IMode> {
+		return this._onReady().then(() => {
+			if (!this._registry.isRegisteredModeExact(modeId)) {
+				modeId = 'plaintext';
+			}
+			return this._getOrCreateMode(modeId);
+		});
+	}
+
 	private _getModeIdByLanguageName(languageName: string): string {
 		const modeIds = this._registry.getModeIdsFromLanguageName(languageName);
 

src/vs/vscode.d.ts

@@ -1119,6 +1119,21 @@ declare module 'vscode' {
 		 */
 		edit(callback: (editBuilder: TextEditorEdit) => void, options?: { undoStopBefore: boolean; undoStopAfter: boolean; }): Thenable<boolean>;
 
+		/**
+		 * Change document language by Id
+		 *
+		 * @param languageId new language identifier
+		 */
+		setLanguageById(languageId: string): void;
+
+		/**
+		 * Change document language by Name
+		 *
+		 * @param languageName new language name
+		 */
+		setLanguageByName(languageName: string): void;
+
+
 		/**
 		 * Insert a [snippet](#SnippetString) and put the editor into snippet mode. "Snippet mode"
 		 * means the editor adds placeholders and additional cursors so that the user can complete
@@ -1141,6 +1156,7 @@ declare module 'vscode' {
 		 * @param decorationType A decoration type.
 		 * @param rangesOrOptions Either [ranges](#Range) or more detailed [options](#DecorationOptions).
 		 */
+
 		setDecorations(decorationType: TextEditorDecorationType, rangesOrOptions: Range[] | DecorationOptions[]): void;
 
 		/**
@@ -7375,6 +7391,8 @@ declare module 'vscode' {
 	 */
 	export namespace languages {
 
+		export function setLanguageById(documentUri: Uri, languageId: string): Thenable<void>;
+
 		/**
 		 * Return the identifiers of all known languages.
 		 * @return Promise resolving to an array of identifier strings.

src/vs/workbench/api/electron-browser/mainThreadEditors.ts

@@ -179,14 +179,18 @@ export class MainThreadTextEditors implements MainThreadTextEditorsShape {
 		if (!mainThreadEditor) {
 			return TPromise.wrapError(disposed(`TextEditor(${id})`));
 		}
-		let textModel = mainThreadEditor.getModel();
-		let modelService = this._modelService;
-		let modeService = this._modeService;
-		if (!modelService || !modeService) {
-			return TPromise.wrapError(new Error('modeService is null for some unit tests'));
+		let mode = this._modeService.getOrCreateModeByLanguageId(languageId);
+		this._modelService.setMode(mainThreadEditor.getModel(), mode);
+		return TPromise.as(null);
+	}
+
+	$trySetLanguageByName(id: string, languageName: string): TPromise<void> {
+		let mainThreadEditor = this._documentsAndEditors.getEditor(id);
+		if (!mainThreadEditor) {
+			return TPromise.wrapError(disposed(`TextEditor(${id})`));
 		}
-		let mode = modeService.getOrCreateModeByLanguageName(languageId);
-		modelService.setMode(textModel, mode);
+		let mode = this._modeService.getOrCreateModeByLanguageName(languageName);
+		this._modelService.setMode(mainThreadEditor.getModel(), mode);
 		return TPromise.as(null);
 	}
 

src/vs/workbench/api/electron-browser/mainThreadLanguages.ts

@@ -5,7 +5,9 @@
 'use strict';
 
 import { TPromise } from 'vs/base/common/winjs.base';
+import URI, { UriComponents } from 'vs/base/common/uri';
 import { IModeService } from 'vs/editor/common/services/modeService';
+import { IModelService } from 'vs/editor/common/services/modelService';
 import { MainThreadLanguagesShape, MainContext, IExtHostContext } from '../node/extHost.protocol';
 import { extHostNamedCustomer } from 'vs/workbench/api/electron-browser/extHostCustomers';
 
@@ -13,12 +15,15 @@ import { extHostNamedCustomer } from 'vs/workbench/api/electron-browser/extHostC
 export class MainThreadLanguages implements MainThreadLanguagesShape {
 
 	private _modeService: IModeService;
+	private _modelService: IModelService;
 
 	constructor(
 		extHostContext: IExtHostContext,
-		@IModeService modeService: IModeService
+		@IModeService modeService: IModeService,
+		@IModelService modelService: IModelService
 	) {
 		this._modeService = modeService;
+		this._modelService = modelService;
 	}
 
 	public dispose(): void {
@@ -27,4 +32,15 @@ export class MainThreadLanguages implements MainThreadLanguagesShape {
 	$getLanguages(): TPromise<string[]> {
 		return TPromise.as(this._modeService.getRegisteredModes());
 	}
+
+	$setLanguageById(resource: UriComponents, languageId: string): TPromise<void> {
+		const uri = URI.revive(resource);
+		let model = this._modelService.getModel(uri);
+		if (!model) {
+			return TPromise.wrapError(new Error('Invalid uri'));
+		}
+		let mode = this._modeService.getOrCreateModeByLanguageId(languageId);
+		this._modelService.setMode(model, mode);
+		return TPromise.as(null);
+	}
 }

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

@@ -258,6 +258,9 @@ export function createApiFactory(
 			getLanguages(): TPromise<string[]> {
 				return extHostLanguages.getLanguages();
 			},
+			setLanguageById(documentUri: vscode.Uri, languageId: string): TPromise<void> {
+				return extHostLanguages.setLanguageById(documentUri, languageId);
+			},
 			match(selector: vscode.DocumentSelector, document: vscode.TextDocument): number {
 				return score(typeConverters.LanguageSelector.from(selector), document.uri, document.languageId, true);
 			},

src/vs/workbench/api/node/extHost.protocol.ts

@@ -194,6 +194,7 @@ export interface MainThreadTextEditorsShape extends IDisposable {
 	$tryHideEditor(id: string): TPromise<void>;
 	$trySetOptions(id: string, options: ITextEditorConfigurationUpdate): TPromise<void>;
 	$trySetLanguageById(id: string, languageId: string): TPromise<void>;
+	$trySetLanguageByName(id: string, languageName: string): TPromise<void>;
 	$trySetDecorations(id: string, key: string, ranges: editorCommon.IDecorationOptions[]): TPromise<void>;
 	$trySetDecorationsFast(id: string, key: string, ranges: number[]): TPromise<void>;
 	$tryRevealRange(id: string, range: IRange, revealType: TextEditorRevealType): TPromise<void>;
@@ -288,6 +289,7 @@ export interface MainThreadLanguageFeaturesShape extends IDisposable {
 
 export interface MainThreadLanguagesShape extends IDisposable {
 	$getLanguages(): TPromise<string[]>;
+	$setLanguageById(resource: UriComponents, languageId: string): TPromise<void>;
 }
 
 export interface MainThreadMessageOptions {

src/vs/workbench/api/node/extHostLanguages.ts

@@ -6,6 +6,7 @@
 
 import { TPromise } from 'vs/base/common/winjs.base';
 import { MainContext, MainThreadLanguagesShape, IMainContext } from './extHost.protocol';
+import * as vscode from 'vscode';
 
 export class ExtHostLanguages {
 
@@ -20,4 +21,7 @@ export class ExtHostLanguages {
 	getLanguages(): TPromise<string[]> {
 		return this._proxy.$getLanguages();
 	}
+	setLanguageById(documentUri: vscode.Uri, languageId: string): TPromise<void> {
+		return this._proxy.$setLanguageById(documentUri, languageId);
+	}
 }

src/vs/workbench/api/node/extHostTextEditor.ts

@@ -435,8 +435,12 @@ export class ExtHostTextEditor implements vscode.TextEditor {
 		this._trySetSelection();
 	}
 
-	setLanguageById(language_id: string): void {
-		this._runOnProxy(() => this._proxy.$trySetLanguageById(this._id, language_id));
+	setLanguageById(languageId: string): void {
+		this._runOnProxy(() => this._proxy.$trySetLanguageById(this._id, languageId));
+	}
+
+	setLanguageByName(languageName: string): void {
+		this._runOnProxy(() => this._proxy.$trySetLanguageByName(this._id, languageName));
 	}
 
 	setDecorations(decorationType: vscode.TextEditorDecorationType, ranges: Range[] | vscode.DecorationOptions[]): void {

src/vs/workbench/test/electron-browser/api/extHostTextEditor.test.ts

@@ -61,6 +61,7 @@ suite('ExtHostTextEditorOptions', () => {
 			$tryShowEditor: undefined,
 			$tryHideEditor: undefined,
 			$trySetLanguageById: undefined,
+			$trySetLanguageByName: undefined,
 			$trySetDecorations: undefined,
 			$trySetDecorationsFast: undefined,
 			$tryRevealRange: undefined,