Fix char class normalisation for overlapping class content#1066
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Fix char class normalisation for overlapping class content#1066
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Regression test for #1065: test that a negated char class with overlapping content is generated and matched correctly.
`IntCharSet.sub(s)` expects `s` to be fully contained in `this`. If the contents of the inner char class expression overlap, this assumption is violated and leads to an inconsistent IntCharSet state. Fix this by computing the union of the inner expression first, and then returning the complement. Since the only difference to the CCLASS case is the complement at the end, the two cases can be merged. Fixes #1065
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In a negated character class that has overlapping content, such as
[^\n\s], the normalisation code is violating a precondition ofIntCharSet.sub()and leaves the class content in an inconsistent state. This either triggers an exception at generation time if another set operation interacts with the inconsistent part, or may lead to matching wrong input at runtime if nothing else interacts with the set.This PR fixes the problem by first computing the union of the class content
\n\s, which becomes a single set (joining the overlapping parts) and then computing the complement of that set.IntervalclasssubpreconditionFixes #1065