refactor(formatter): improve handling of type cast node (#14815)

Author: Dunqing

crates/oxc_formatter/src/formatter/comments.rs

@@ -386,6 +386,14 @@ impl<'a> Comments<'a> {
         const TYPE_PATTERN: &[u8] = b"@type";
         const SATISFIES_PATTERN: &[u8] = b"@satisfies";
 
+        /// Checks if a pattern matches at the given position.
+        fn matches_pattern_at(bytes: &[u8], pos: usize, pattern: &[u8]) -> bool {
+            bytes[pos..].starts_with(pattern)
+                && bytes
+                    .get(pos + pattern.len())
+                    .is_some_and(|&byte| byte.is_ascii_whitespace() || byte == b'{')
+        }
+
         if !matches!(comment.content, CommentContent::Jsdoc) {
             return false;
         }
@@ -459,9 +467,3 @@ impl<'a> Comments<'a> {
         self.view_limit = limit;
     }
 }
-
-/// Checks if a pattern matches at the given position.
-fn matches_pattern_at(bytes: &[u8], pos: usize, pattern: &[u8]) -> bool {
-    bytes[pos..].starts_with(pattern)
-        && matches!(bytes.get(pos + pattern.len()), Some(b' ' | b'\t' | b'\n' | b'\r' | b'{'))
-}

crates/oxc_formatter/src/utils/member_chain/mod.rs

@@ -23,6 +23,8 @@ use crate::{
 use oxc_ast::{AstKind, ast::*};
 use oxc_span::{GetSpan, Span};
 
+use super::typecast::is_type_cast_node;
+
 #[derive(Debug)]
 pub struct MemberChain<'a, 'b> {
     root: &'b AstNode<'a, CallExpression<'a>>,
@@ -419,13 +421,7 @@ fn chain_members_iter<'a, 'b>(
 
         let expression = next.take()?;
 
-        if f.comments().get_type_cast_comment_index(expression.span()).is_some()
-            || f.comments()
-                .printed_comments()
-                .last()
-                .is_some_and(|c| f.comments().is_type_cast_comment(c))
-                && f.source_text().next_non_whitespace_byte_is(expression.span().end, b')')
-        {
+        if is_type_cast_node(expression, f).is_some() {
             return ChainMember::Node(expression).into();
         }
 

crates/oxc_formatter/src/utils/typecast.rs

@@ -16,49 +16,42 @@ use crate::{
     },
 };
 
-/// Formats a node with TypeScript type cast comments if present.
-///
-/// This function handles the formatting of JSDoc type cast comments that appear
-/// immediately before parenthesized expressions, creating patterns like:
-/// `(/** @type {string} */ value)` or `(/** @type {number} */ (expression))`
+/// Checks if a node is a type cast node and returns the comments to be printed.
 ///
-/// The function:
-/// 1. Checks if there's a closing parenthesis after the node (indicating a type cast)
-/// 2. Looks for associated type cast comments that precede the node
-/// 3. Wraps the node in parentheses with proper formatting and indentation
-/// 4. Handles both object/array expressions and other expression types differently
+/// This function detects if a node is part of a TypeScript type cast pattern
+/// by checking for JSDoc type cast comments and proper parenthesis structure.
 ///
-/// Returns `Ok(true)` if the node was formatted as a type cast, `Ok(false)` otherwise.
-/// This allows callers to know whether they need to apply their own formatting.
-pub fn format_type_cast_comment_node<'a, T>(
-    node: &(impl Format<'a, T> + GetSpan),
-    is_object_or_array_expression: bool,
-    f: &mut Formatter<'_, 'a>,
-) -> FormatResult<bool> {
+/// Returns:
+/// - `Some(&[])` if the node is a type cast node but no comments need to be printed
+/// - `Some(&[Comment, ...])` if the node is a type cast node with comments to print
+/// - `None` if the node is not a type cast node
+pub fn is_type_cast_node<'a>(node: &impl GetSpan, f: &Formatter<'_, 'a>) -> Option<&'a [Comment]> {
     let comments = f.context().comments();
     let span = node.span();
     let source = f.source_text();
 
+    // Check if there's a closing parenthesis after the node (possibly after comments)
     if !source.next_non_whitespace_byte_is(span.end, b')') {
         let comments_after_node = comments.comments_after(span.end);
         let mut start = span.end;
         // Skip comments after the node to find the next non-whitespace byte whether it's a `)`
         for comment in comments_after_node {
-            if !source.all_bytes_match(start, comment.span.start, |b| b.is_ascii_whitespace()) {
+            if !source.bytes_range(start, comment.span.start).trim_ascii_start().is_empty() {
                 break;
             }
             start = comment.span.end;
         }
         // Still not a `)`, return early because it's not a type cast
         if !source.next_non_whitespace_byte_is(start, b')') {
-            return Ok(false);
+            return None;
         }
     }
 
+    // Check for type cast comment in printed or unprinted comments
     if !comments.is_handled_type_cast_comment()
         && let Some(last_printed_comment) = comments.printed_comments().last()
         && last_printed_comment.span.end <= span.start
-        && f.source_text().next_non_whitespace_byte_is(last_printed_comment.span.end, b'(')
+        && source.next_non_whitespace_byte_is(last_printed_comment.span.end, b'(')
         && f.comments().is_type_cast_comment(last_printed_comment)
     {
         // Get the source text from the end of type cast comment to the node span
@@ -68,10 +61,11 @@ pub fn format_type_cast_comment_node<'a, T>(
         //                         ^^^^
         // Should wrap for `baz` rather than `baz.zoo`
         if has_closed_parentheses(node_source_text) {
-            return Ok(false);
+            None
+        } else {
+            // Type cast node, but comment was already printed
+            Some(&[])
         }
-
-        f.context_mut().comments_mut().mark_as_type_cast_node(node);
     } else if let Some(type_cast_comment_index) = comments.get_type_cast_comment_index(span) {
         let comments = f.context().comments().unprinted_comments();
         let type_cast_comment = &comments[type_cast_comment_index];
@@ -83,19 +77,49 @@ pub fn format_type_cast_comment_node<'a, T>(
         //                         ^^^^
         // Should wrap for `baz` rather than `baz.zoo`
         if has_closed_parentheses(node_source_text) {
-            return Ok(false);
+            None
+        } else {
+            // Type cast node with comments to print
+            Some(&comments[..=type_cast_comment_index])
         }
-
-        let type_cast_comments = &comments[..=type_cast_comment_index];
-
-        write!(f, [FormatLeadingComments::Comments(type_cast_comments)])?;
-        f.context_mut().comments_mut().mark_as_type_cast_node(node);
-        // If the printed cast comment is already handled, return early to avoid infinite recursion.
     } else {
         // No typecast comment
+        None
+    }
+}
+
+/// Formats a node with TypeScript type cast comments if present.
+///
+/// This function handles the formatting of JSDoc type cast comments that appear
+/// immediately before parenthesized expressions, creating patterns like:
+/// `(/** @type {string} */ value)` or `(/** @type {number} */ (expression))`
+///
+/// The function:
+/// 1. Checks if there's a closing parenthesis after the node (indicating a type cast)
+/// 2. Looks for associated type cast comments that precede the node
+/// 3. Wraps the node in parentheses with proper formatting and indentation
+/// 4. Handles both object/array expressions and other expression types differently
+///
+/// Returns `Ok(true)` if the node was formatted as a type cast, `Ok(false)` otherwise.
+/// This allows callers to know whether they need to apply their own formatting.
+pub fn format_type_cast_comment_node<'a, T>(
+    node: &(impl Format<'a, T> + GetSpan),
+    is_object_or_array_expression: bool,
+    f: &mut Formatter<'_, 'a>,
+) -> FormatResult<bool> {
+    // Check if this is a type cast node and get the comments to print
+    let Some(type_cast_comments) = is_type_cast_node(node, f) else {
         return Ok(false);
+    };
+
+    // Print the type cast comments if any
+    if !type_cast_comments.is_empty() {
+        write!(f, [FormatLeadingComments::Comments(type_cast_comments)])?;
     }
 
+    let span = node.span();
+    f.context_mut().comments_mut().mark_as_type_cast_node(node);
+
     // https://github.com/prettier/prettier/blob/7584432401a47a26943dd7a9ca9a8e032ead7285/src/language-js/print/estree.js#L117-L120
     if is_object_or_array_expression && !f.comments().has_comment_before(span.start) {
         write!(f, group(&format_args!("(", &format_once(|f| node.fmt(f)), ")")))?;