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Empty/unused groups
===================
>>> import re
>>> import re2
>>> re2.set_fallback_notification(re2.FALLBACK_EXCEPTION)
Unused vs. empty group:
>>> re.search( '(foo)?((.*).)(bar)?', 'a').groups()
(None, 'a', '', None)
>>> re2.search('(foo)?((.*).)(bar)?', 'a').groups()
(None, 'a', '', None)
>>> re.search(r'((.*)?.)', 'a').groups()
('a', '')
>>> re2.search(r'((.*)?.)', 'a').groups()
('a', '')
>>> re.search(r'((.*)+.)', 'a').groups()
('a', '')
>>> re2.search(r'((.*)+.)', 'a').groups()
('a', '')
The following show different behavior for re and re2:
>>> re.search(r'((.*)*.)', 'a').groups()
('a', '')
>>> re2.search(r'((.*)*.)', 'a').groups()
('a', None)
>>> re.search(r'((.*)*.)', 'Hello').groups()
('Hello', '')
>>> re2.search(r'((.*)*.)', 'Hello').groups()
('Hello', 'Hell')
>>> re2.set_fallback_notification(re2.FALLBACK_QUIETLY)
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