getFormattingScanner: Ensure scanner is closed, and avoid global variables (#18293)

Author: Andy

src/services/formatting/formatting.ts

@@ -339,17 +339,17 @@ namespace ts.formatting {
     /* @internal */
     export function formatNodeGivenIndentation(node: Node, sourceFileLike: SourceFileLike, languageVariant: LanguageVariant, initialIndentation: number, delta: number,  rulesProvider: RulesProvider): TextChange[] {
         const range = { pos: 0, end: sourceFileLike.text.length };
-        return formatSpanWorker(
+        return getFormattingScanner(sourceFileLike.text, languageVariant, range.pos, range.end, scanner => formatSpanWorker(
             range,
             node,
             initialIndentation,
             delta,
-            getFormattingScanner(sourceFileLike.text, languageVariant, range.pos, range.end),
+            scanner,
             rulesProvider.getFormatOptions(),
             rulesProvider,
             FormattingRequestKind.FormatSelection,
             _ => false, // assume that node does not have any errors
-            sourceFileLike);
+            sourceFileLike));
     }
 
     function formatNodeLines(node: Node, sourceFile: SourceFile, options: FormatCodeSettings, rulesProvider: RulesProvider, requestKind: FormattingRequestKind): TextChange[] {
@@ -372,17 +372,17 @@ namespace ts.formatting {
         requestKind: FormattingRequestKind): TextChange[] {
         // find the smallest node that fully wraps the range and compute the initial indentation for the node
         const enclosingNode = findEnclosingNode(originalRange, sourceFile);
-        return formatSpanWorker(
+        return getFormattingScanner(sourceFile.text, sourceFile.languageVariant, getScanStartPosition(enclosingNode, originalRange, sourceFile), originalRange.end, scanner => formatSpanWorker(
             originalRange,
             enclosingNode,
             SmartIndenter.getIndentationForNode(enclosingNode, originalRange, sourceFile, options),
             getOwnOrInheritedDelta(enclosingNode, options, sourceFile),
-            getFormattingScanner(sourceFile.text, sourceFile.languageVariant, getScanStartPosition(enclosingNode, originalRange, sourceFile), originalRange.end),
+            scanner,
             options,
             rulesProvider,
             requestKind,
             prepareRangeContainsErrorFunction(sourceFile.parseDiagnostics, originalRange),
-            sourceFile);
+            sourceFile));
     }
 
     function formatSpanWorker(originalRange: TextRange,
@@ -427,8 +427,6 @@ namespace ts.formatting {
             }
         }
 
-        formattingScanner.close();
-
         return edits;
 
         // local functions

src/services/formatting/formattingScanner.ts

@@ -6,19 +6,13 @@ namespace ts.formatting {
     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;
         readTokenInfo(n: Node): TokenInfo;
         getCurrentLeadingTrivia(): TextRangeWithKind[];
         lastTrailingTriviaWasNewLine(): boolean;
         skipToEndOf(node: Node): void;
-        close(): void;
     }
 
     const enum ScanAction {
@@ -30,9 +24,8 @@ namespace ts.formatting {
         RescanJsxText,
     }
 
-    export function getFormattingScanner(text: string, languageVariant: LanguageVariant, startPos: number, endPos: number): FormattingScanner {
-        Debug.assert(scanner === undefined, "Scanner should be undefined");
-        scanner = languageVariant === LanguageVariant.JSX ? jsxScanner : standardScanner;
+    export function getFormattingScanner<T>(text: string, languageVariant: LanguageVariant, startPos: number, endPos: number, cb: (scanner: FormattingScanner) => T): T {
+        const scanner = languageVariant === LanguageVariant.JSX ? jsxScanner : standardScanner;
 
         scanner.setText(text);
         scanner.setTextPos(startPos);
@@ -45,21 +38,19 @@ namespace ts.formatting {
         let lastScanAction: ScanAction | undefined;
         let lastTokenInfo: TokenInfo | undefined;
 
-        return {
+        const res = cb({
             advance,
             readTokenInfo,
             isOnToken,
             getCurrentLeadingTrivia: () => leadingTrivia,
             lastTrailingTriviaWasNewLine: () => wasNewLine,
             skipToEndOf,
-            close: () => {
-                Debug.assert(scanner !== undefined);
+        });
 
-                lastTokenInfo = undefined;
-                scanner.setText(undefined);
-                scanner = undefined;
-            }
-        };
+        lastTokenInfo = undefined;
+        scanner.setText(undefined);
+
+        return res;
 
         function advance(): void {
             Debug.assert(scanner !== undefined, "Scanner should be present");