local-test-libxml2-delta-01/afc-libxml2/test/regexp/hard

=>((a|b|\p{Nd}){1,2}|aaa|bbbb){1,2}
bab
aaca
aaabbbb
a0b
aa0aaa
b0aaa
=>(\d{1,3}\.){3}\d{1,3}
1.2.3.4
1.22.333.44
1.2.3
1..2.3