Fix TypeError in _token_matching when index is None (issue747)#869
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deepakganesh78 wants to merge 1 commit into
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Fix TypeError in _token_matching when index is None (issue747)#869deepakganesh78 wants to merge 1 commit into
deepakganesh78 wants to merge 1 commit into
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`TokenList._token_matching` returned a bare `None` when it was given a
`None` start index, but every caller (`token_matching`, `token_first`,
`token_not_matching`, ...) unpacks or subscripts the result as a
`(idx, token)` tuple. Passing `None` therefore raised
TypeError: 'NoneType' object is not subscriptable
instead of reporting "no match".
Return `(None, None)` in that early-out branch so the contract matches
the normal no-match return value. Adds a regression test.
Fixes andialbrecht#747
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Summary
TokenList._token_matchingreturns a bareNonewhen called with aNonestart index, but all callers (token_matching,token_first,token_not_matching, ...) treat the return value as a(idx, token)tuple. As reported in #747 this makes aNoneindex crash:Root cause
The early-out branch for
start is NonereturnedNoneinstead of the(None, None)tuple the normal no-match path returns, breaking the method's contract with every caller.Fix
Return
(None, None)from that branch so aNoneindex simply reports "no match";token_matchingthen correctly returnsNone.Tests
Added
test_token_matching_none_idx_issue747intests/test_regressions.py. Full suite:Fixes #747