refactor(regular_expression): Improve initizalizing state

[leaysgur]

Fixes #6358

[leaysgur]

• refactor(regular_expression): Improve initizalizing state #15045 👈 (View in Graphite)
• main

---

How to use the Graphite Merge Queue

Add either label to this PR to merge it via the merge queue:

• 0-merge - adds this PR to the back of the merge queue
• hotfix - for urgent hot fixes, skip the queue and merge this PR next

You must have a Graphite account in order to use the merge queue. Sign up using this link.

An organization admin has enabled the Graphite Merge Queue in this repository.

Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.

This stack of pull requests is managed by Graphite. Learn more about stacking.

[Copilot]

Pull Request Overview

This PR refactors the duplicate named capturing group detection in regular expression parsing. The changes replace a complex post-processing approach with a cleaner, more maintainable algorithm that tracks alternative paths during parsing.

• Introduced AlternativeTracker to track nesting depth and alternative branches in real-time
• Replaced SimpleUnit enum and deferred duplicate checking with immediate validation during parsing
• Added NamedGroupInfo struct to store named group metadata including alternative paths

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[codspeed-hq]

CodSpeed Performance Report

Merging #15045 will not alter performance

_{Comparing 10-28-refactor_regular_expression_improve_initizalizing_state (1b59a0c) with main (b27c5b9)}

Summary

✅ 37 untouched

[Boshen]

Merge activity

• Oct 29, 4:11 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Oct 29, 4:11 AM UTC: Boshen added this pull request to the Graphite merge queue.
• Oct 29, 4:17 AM UTC: Merged by the Graphite merge queue.