Changes in version 4

Overview

Version 4 of Parol introduces significant changes that may affect existing projects and workflows. This document summarizes all updates, breaking changes, and migration hints for users upgrading from previous versions.

Major Changes

1. Switch to scnr2 Scanner Crate

Parol now uses the scnr2 scanner crate for lexical analysis. This change improves performance and maintainability but may require adjustments in custom scanner configurations.

Impact:

• All scanner-related features are now based on scnr2.
• Custom scanner switching logic must be adapted to the new API.

2. Removal of Parser-Based Scanner Switching

Support for parser-based scanner switching has been removed. Scanner switching is now exclusively handled by the scanner itself.

Impact:

• Any grammar or code relying on parser-driven scanner switching must be refactored.
• See migration notes below.

Migration Notes

• Review your grammar files and custom code for any use of parser-based scanner switching and update them to use scanner-based switching.
• Refer to the scnr2 documentation for details on the new scanner API.
• Test your grammars and integrations thoroughly after upgrading.

Further Information

For a complete list of changes, see the Changelog.

If you encounter issues, please consult the Q&A or open an issue on the Parol GitHub repository.