I'm no expert on formal languages, but one thing I do remember from college is that balancing parentheses is something that context-free languages are good at. For example, here's a context-free grammar that matches zero or more left parens followed by the same number of right parens:

S -> ( S ) | ε

To be honest, I don't remember exactly what "context-free" means in a formal sense, but I don't think it's the same as "no context" in the way that you're thinking.

-- Mike

--
just,my${.02}