Fix RecursionError on long elif chains#116
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When a function contains many elif branches (e.g., 160+), mccabe crashes with RecursionError because each elif is represented as a nested ast.If in the orelse of the parent, creating deep recursion through visitIf -> _subgraph -> _subgraph_parse -> dispatch_list. This converts the elif chain processing in _subgraph_parse from recursive to iterative: when the orelse contains a single ast.If node (i.e., an elif), it processes the branch inline in a while loop instead of dispatching recursively. The complexity calculation is unchanged — verified that if/elif/else produces the same complexity number as before. Fixes PyCQA#71 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
Functions with many elif branches (160+) cause
RecursionErrorbecause each elif is represented as a nestedast.Ifin the parent'sorelse, creating deep recursion throughvisitIf→_subgraph→_subgraph_parse→dispatch_list.Root cause
In
_subgraph_parse, whennode.orelsecontains an elif (a singleast.If),dispatch_list(node.orelse)recursively callsvisitIf, which creates another level of recursion for each elif branch.Fix
Convert elif chain processing from recursive to iterative: when
node.orelseis a singleast.If(elif), process it inline in awhileloop instead of dispatching recursively. This handles arbitrarily long elif chains without increasing call stack depth.The complexity calculation is unchanged — verified with existing test suite and manual comparison.
Test plan
test_long_elif_chainregression test (200 elif branches)test_get_module_complexityfailure is unrelated)Fixes #71
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