iterate only once over lines and exit early if not successful

Author: Janther

src/slang-printers/print-block-comment.ts

@@ -5,6 +5,22 @@ import type { BlockComment } from '../slang-nodes/types.d.ts';
 
 const { hardline, join, literalline } = doc.builders;
 
+function trimmedIndentableLines(lines: string[]): string[] | undefined {
+  // If the comment has multiple lines and every line starts with a star
+  // we can fix the indentation of each line.
+  if (lines.length > 1) {
+    const trimmedLines = [];
+    for (const line of lines) {
+      const trimmedLine = line.trimStart();
+      if (!trimmedLine.startsWith('*')) {
+        return;
+      }
+      trimmedLines.push(trimmedLine);
+    }
+    return trimmedLines;
+  }
+}
+
 function printIndentableBlockComment(lines: string[]): Doc {
   return join(
     hardline,
@@ -15,19 +31,11 @@ function printIndentableBlockComment(lines: string[]): Doc {
 export function printBlockComment(comment: BlockComment): Doc {
   // We remove the initial `/` to check if every line starts with `*`
   const lines = comment.value.slice(1).split('\n');
-  let trimmedLines;
-
-  // Only process lines for possible indentation if the block has multiple
-  // lines
-  if (lines.length > 1) {
-    trimmedLines = lines.map((line) => line.trimStart());
-  }
+  const trimmedLines = trimmedIndentableLines(lines);
 
   return [
     '/',
-    // If the comment has multiple lines and every line starts with a star
-    // we can fix the indentation of each line.
-    trimmedLines?.every((line) => line.startsWith('*'))
+    trimmedLines
       ? printIndentableBlockComment(trimmedLines)
       : join(literalline, lines)
   ];