Question

I wrote a program which can generate regex like this a(b|)c. Actually, it means (abc)|(ac). But is a(b|)c an acceptable regex for any regex engine? Or is there any other alternative to give the same semantic meaning?

Further question: is there any tool can covert it to a “normal” representation? e.g convert a(b|(c|))d to a(b|(c)?)d

Answer 1

ab?c, or ab{0,1}c would make more sense. An a, followed by at most one b, followed by a c.