use formatting scanner with languageVariant=JSX for .tsx files

src/services/formatting/formattingScanner.ts

@@ -3,8 +3,14 @@
 
 /* @internal */
 namespace ts.formatting {
-    let scanner = createScanner(ScriptTarget.Latest, /*skipTrivia*/ false);
-
+    const standardScanner = createScanner(ScriptTarget.Latest, /*skipTrivia*/ false, LanguageVariant.Standard);
+    const jsxScanner = createScanner(ScriptTarget.Latest, /*skipTrivia*/ false, LanguageVariant.JSX);
+
+    /**
+     * Scanner that is currently used for formatting
+     */
+    let scanner: Scanner;
+
     export interface FormattingScanner {
         advance(): void;
         isOnToken(): boolean;
@@ -22,6 +28,8 @@ namespace ts.formatting {
     }
 
     export function getFormattingScanner(sourceFile: SourceFile, startPos: number, endPos: number): FormattingScanner {
+        Debug.assert(scanner === undefined);
+        scanner = sourceFile.languageVariant === LanguageVariant.JSX ? jsxScanner : standardScanner;
 
         scanner.setText(sourceFile.text);
         scanner.setTextPos(startPos);
@@ -40,12 +48,17 @@ namespace ts.formatting {
             isOnToken: isOnToken,
             lastTrailingTriviaWasNewLine: () => wasNewLine,
             close: () => {
+                Debug.assert(scanner !== undefined);
+
                 lastTokenInfo = undefined;
                 scanner.setText(undefined);
+                scanner = undefined;
             }
         }
 
         function advance(): void {
+            Debug.assert(scanner !== undefined);
+
             lastTokenInfo = undefined;
             let isStarted = scanner.getStartPos() !== startPos;
 
@@ -138,6 +151,8 @@ namespace ts.formatting {
         }
 
         function readTokenInfo(n: Node): TokenInfo {
+            Debug.assert(scanner !== undefined);
+
             if (!isOnToken()) {
                 // scanner is not on the token (either advance was not called yet or scanner is already past the end position)
                 return {
@@ -245,6 +260,8 @@ namespace ts.formatting {
         }
 
         function isOnToken(): boolean {
+            Debug.assert(scanner !== undefined);
+
             let current = (lastTokenInfo && lastTokenInfo.token.kind) || scanner.getToken();
             let startPos = (lastTokenInfo && lastTokenInfo.token.pos) || scanner.getStartPos();
             return startPos < endPos && current !== SyntaxKind.EndOfFileToken && !isTrivia(current);

tests/cases/fourslash/formatInTsxFiles.ts

@@ -0,0 +1,8 @@
+/// <reference path="fourslash.ts"/>
+
+//@Filename: file.tsx
+////interface I<T1, T2> {
+////    next: I</* */
+////}
+
+format.document();