Thanks all. Though I dont speak Italian at all, I did get your explanation.
I have already decided to ditch the 'use-regex-entirely' approach, and working towards writing a manual parser, that takes the help of a little regex now and then.
Like you said, I am trying to parse an expression with a lot of braces, quotes and other characters. One positive is, this is not free flowing text. These are pre-defined expressions (written by the developer), that are read in from XML files. And I will be trying to handle misbehaving expressions with nested quotes etc in the parser.
Thanks all for your help.