It's somewhat confusing that you keep talking of 4 pices of data s,b,c,d, however your sample string contains 4 pieces and your regex is capturing 5 peices?

Also, in your original post, you show this

$hash{'a'}=[something=>'b',another=>'c' ]

which is assigns an array of 4 elements to the hash keyed by a, but the two of the 4 elements are not any of b,c,d(or e?), and two are.

Further, you show the construction of the hash using fat commas (=>) which is usually use for setting up a hash, but in the context of an anonymous array [], means exactly the same (but in a confusing way) as an ordinary comma ','.

I think some clarification is required here.