1*57718be8SEnji Cooper# back references, ugh 2*57718be8SEnji Coopera\(b\)\2c bC ESUBREG 3*57718be8SEnji Coopera\(b\1\)c bC ESUBREG 4*57718be8SEnji Coopera\(b*\)c\1d b abbcbbd abbcbbd bb 5*57718be8SEnji Coopera\(b*\)c\1d b abbcbd 6*57718be8SEnji Coopera\(b*\)c\1d b abbcbbbd 7*57718be8SEnji Cooper^\(.\)\1 b abc 8*57718be8SEnji Coopera\([bc]\)\1d b abcdabbd abbd b 9*57718be8SEnji Coopera\(\([bc]\)\2\)*d b abbccd abbccd 10*57718be8SEnji Coopera\(\([bc]\)\2\)*d b abbcbd 11*57718be8SEnji Cooper# actually, this next one probably ought to fail, but the spec is unclear 12*57718be8SEnji Coopera\(\(b\)*\2\)*d b abbbd abbbd 13*57718be8SEnji Cooper# here is a case that no NFA implementation does right 14*57718be8SEnji Cooper\(ab*\)[ab]*\1 b ababaaa ababaaa a 15*57718be8SEnji Cooper# check out normal matching in the presence of back refs 16*57718be8SEnji Cooper\(a\)\1bcd b aabcd aabcd 17*57718be8SEnji Cooper\(a\)\1bc*d b aabcd aabcd 18*57718be8SEnji Cooper\(a\)\1bc*d b aabd aabd 19*57718be8SEnji Cooper\(a\)\1bc*d b aabcccd aabcccd 20*57718be8SEnji Cooper\(a\)\1bc*[ce]d b aabcccd aabcccd 21*57718be8SEnji Cooper^\(a\)\1b\(c\)*cd$ b aabcccd aabcccd 22