Use global enum members for parser state lookups

[Kludex]

Use enum.global_enum to export parser state members and access them directly in the parsing loops. Bindings inside TYPE_CHECKING make the exports visible to mypy and Ruff without runtime alias assignments.

The enum classes, values, and member identities are retained. As expected with global_enum, member representations change from forms like <MultipartState.END: 12> to multipart.END.

Performance

Local CPython 3.12.3 on macOS ARM64, 60 interleaved timeit batches with a fresh parser per iteration and a 10% trimmed mean:

Workload	Before	After	Throughput gain
Multipart, two fields	10.52 µs	8.95 µs	17.5%
Multipart, 100 fields	427.30 µs	356.93 µs	19.7%
Querystring, 100 fields	58.81 µs	53.10 µs	10.8%
Multipart, one-byte chunks	277.10 µs	262.13 µs	5.7%
Multipart, 8 MiB upload	630.51 µs	616.01 µs	2.4%
Defnull blocking adapter, 100 fields	643.34 µs	573.60 µs	12.2%

Validation

162 tests pass on Python 3.11 with 100% package coverage, including one test that parser states remain the original enum members. Ruff, mypy, source-distribution, and import-compatibility checks pass; 176,524 multipart and 100,000 querystring differential cases match main in their callbacks, consumed lengths, and errors.

AI Disclaimer

This PR was developed with the assistance of either Claude or Codex. I've reviewed and verified the changes.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-25T07:22:39.121392Z	23773fa	PR opened

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[codspeed]

Merging this PR will improve performance by 13.49%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 2 improved benchmarks
✅ 3 untouched benchmarks
⏩ 5 skipped benchmarks¹

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	test_parse_multipart_large_form	8.3 ms	7.2 ms	+16.25%
⚡	test_parse_querystring_large_form	1.3 ms	1.1 ms	+10.8%

Tip

Curious why performance improved? Comment @codspeedbot explain why performance improved on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing use-global-parser-states (23773fa) with main (1aaac89)}

Footnotes

1. 5 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[cubic-dev-ai]

All reported issues were addressed across 2 files

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