textChanges: Add insertCommentBeforeLine method (#22902)

Author: Andy

src/services/codefixes/disableJsDiagnostics.ts

@@ -27,7 +27,7 @@ namespace ts.codefix {
                     fixId: undefined,
                 }];
 
-            if (isValidLocationToAddComment(sourceFile, span.start)) {
+            if (textChanges.isValidLocationToAddComment(sourceFile, span.start)) {
                 fixes.unshift({
                     description: getLocaleSpecificMessage(Diagnostics.Ignore_this_error_message),
                     changes: textChanges.ChangeTracker.with(context, t => makeChange(t, sourceFile, span.start)),
@@ -41,17 +41,13 @@ namespace ts.codefix {
         getAllCodeActions: context => {
             const seenLines = createMap<true>();
             return codeFixAll(context, errorCodes, (changes, diag) => {
-                if (isValidLocationToAddComment(diag.file!, diag.start!)) {
+                if (textChanges.isValidLocationToAddComment(diag.file!, diag.start!)) {
                     makeChange(changes, diag.file!, diag.start!, seenLines);
                 }
             });
         },
     });
 
-    export function isValidLocationToAddComment(sourceFile: SourceFile, position: number) {
-        return !isInComment(sourceFile, position) && !isInString(sourceFile, position) && !isInTemplateString(sourceFile, position);
-    }
-
     function makeChange(changes: textChanges.ChangeTracker, sourceFile: SourceFile, position: number, seenLines?: Map<true>) {
         const { line: lineNumber } = getLineAndCharacterOfPosition(sourceFile, position);
         // Only need to add `// @ts-ignore` for a line once.

src/services/textChanges.ts

@@ -349,7 +349,7 @@ namespace ts.textChanges {
             // We need to make sure that we are not in the middle of a string literal or a comment.
             // If so, we do not want to separate the node from its comment if we can.
             // Otherwise, add an extra new line immediately before the error span.
-            const insertAtLineStart = codefix.isValidLocationToAddComment(sourceFile, startPosition);
+            const insertAtLineStart = isValidLocationToAddComment(sourceFile, startPosition);
             const token = getTouchingToken(sourceFile, insertAtLineStart ? startPosition : position, /*includeJsDocComment*/ false);
             const text = `${insertAtLineStart ? "" : this.newLineCharacter}${sourceFile.text.slice(lineStartPosition, startPosition)}//${commentText}${this.newLineCharacter}`;
             this.insertText(sourceFile, token.getStart(sourceFile), text);
@@ -879,4 +879,8 @@ namespace ts.textChanges {
             }
         }
     }
+
+    export function isValidLocationToAddComment(sourceFile: SourceFile, position: number) {
+        return !isInComment(sourceFile, position) && !isInString(sourceFile, position) && !isInTemplateString(sourceFile, position);
+    }
 }