refactor: improve hash implementations for Item, State, and Token#38
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henrylee97
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## Summary - Fix hash semantics for `Item`, `State`, and `Token` to be value-based and class-aware - Replace recursive FIRST/FOLLOW computation with worklist fixed-point algorithms, fixing incorrect results on mutually recursive grammars - Make LR(0) state construction deterministic across repeated `Parser` instantiations - Add English docstrings and SLR(1) algorithm comments throughout the codebase - Expand test coverage with 4 new test modules (safety-net, FIRST/FOLLOW, determinism, hash semantics) ## Changes ### Bug Fixes - Correct hash implementations for `Item`, `State`, `Token` (#38) - Fixed-point FIRST / FOLLOW computation replacing re-entry-guard recursion (#36) ### Improvements - Deterministic LR(0) state construction (#37) ### Documentation - English docstrings and SLR(1) inline algorithm comments (#34) ### Tests - Parser safety-net suite, FIRST/FOLLOW unit tests, determinism tests, hash semantics tests (#35 #36 #37 #38) ### Maintenance - Bumped GitHub Actions: `actions/checkout` 4→6, `actions/setup-python` 5→6, `sambyeol/publish-pytest-action` 2→4, `super-linter/super-linter` 7→8 (#28 #29 #31 #32 #33) ## Test plan - [x] `pytest -q` passes (`29 passed, 2 xfailed`) - [x] `python examples/calc/calc.py examples/calc/data/ex01.calc` prints `2` Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
Item.__hash__: sum-based → tuple-based (hash((self.left, tuple(self.right), self.loc))).Fixes an order-insensitivity bug where
[A, B]and[B, A]in the RHS produced equal hashes.State.__hash__: sum-based → frozenset-based (hash(frozenset(self.items))),consistent with the
frozenset[Item]cache key already used byintern_state(T3).Token.__hash__: now includestype(self)—hash((type(self), self.lineno, self.offset)).The equality contract already incorporates the class via
isinstance(other, self.__class__);the hash now matches. Added one sentence to the docstring to make this explicit.
Existing subclass overrides (
hash(self.value) + super().__hash__()) remain correct.Tests
Added
tests/test_hash_semantics.py(5 tests):test_item_equal_data_hash_equal— independently constructed equal Items are==and share a hashtest_item_different_right_order_hash_different— validates the tuple-based fixtest_state_equal_items_hash_equal— equal item sets produce equal State hashestest_token_hash_includes_class— different subclasses at the same position hash differentlytest_token_same_class_same_position_equal— regression: same class + position → equalResult
29 passed, 2 xfailed— pyright clean, black/isort unchanged.