perf(parser): cleanup and optimize various parsing functions

[ulrichstark]

• Avoid unnecessary Option wrapping and checks by splitting parse_normal_list function into a breakable and non-breakable variant
• Avoid unnecessary Option wrapping and checks in parse_variable_declaration_for_statement function
• Break up parse_break_or_continue_statement function into function for break and continue
• Remove unnecessary checks in is_using_declaration and use cheaper lexer.peek_token()
• Make parse_variable_declaration take declare: bool instead of &Modifiers avoid constructing empty Modifiers
• some other minor code improvements

I hope these changes are not too much and therefore difficult to review. It's now less code with better performance. I was in the flow of refactoring and couldn't stop :)

Edit:

I don't see the improvements on Codspeed I'm seeing locally when running cargo benchmark --bench parser against main... Feel free to close my PR if there are no verifiable performance improvements. My local output:

[Copilot]

Pull Request Overview

This PR optimizes various parsing functions by reducing unnecessary Option wrapping, eliminating redundant checks, and splitting functions for better performance. The changes focus on streamlining control flow and leveraging more efficient parsing patterns.

• Split parse_normal_list into breakable and non-breakable variants to avoid unnecessary Option handling
• Refactored parse_variable_declaration to accept bool instead of &Modifiers for better performance
• Separated break/continue statement parsing into dedicated functions and optimized various parsing helpers

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/oxc_parser/src/ts/types.rs	Simplified type literal parsing by removing Option wrapper
crates/oxc_parser/src/ts/statement.rs	Updated interface body parsing and variable declaration calls
crates/oxc_parser/src/modifiers.rs	Streamlined modifier construction and early return logic
crates/oxc_parser/src/js/statement.rs	Major refactoring of statement parsing with function splitting and optimization
crates/oxc_parser/src/js/declaration.rs	Simplified variable declaration parameter handling
crates/oxc_parser/src/js/class.rs	Updated class body parsing to use new breakable variant
crates/oxc_parser/src/cursor.rs	Added separate breakable/non-breakable list parsing functions

Comments suppressed due to low confidence (1)

crates/oxc_parser/src/js/statement.rs:1

• This modifier verification logic has been moved here but appears to duplicate the verification that was previously done inside parse_variable_declaration. Consider whether this verification should be consolidated in one location to avoid potential inconsistencies.

use oxc_allocator::{Box, Vec};

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[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #14160 will not alter performance

_{Comparing ulrichstark:cleanup-and-optimize-various-parsing-functions (e3473b6) with main (c0e461f)¹}

Summary

✅ 37 untouched

Footnotes

1. No successful run was found on main (b19f5bc) during the generation of this report, so c0e461f was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[Boshen]

Thank you! Less code, more performant!