I'm not having much luck with the alternation code.

I think it'd have problems with 5 or 6 backslashes. What's more, since it matches the backslashes, it'd trim them off the end of the resulting split strings.

I'd better try that out and update...

  DB<9> x @a= split /(?:\\\\X)|(?:(?<!\\)X)/, $escaped_str 
0  ''
1  'a\\X\\\\b'
2  'c'
3  'd'
  DB<10> p $escaped_str 
Xa\X\\bXc\\XdX
[download]

Yes, the c gets striped