tag as the pseudo HTML is creating havoc on square brackets.
<code>

Basically I want the most outer [ some chars] or { some chars } but not [] or {}

2 other examples:

1)
a[] = [ this is a test { test2 } ] 
Should only match [ this is a test { test2 } ]

2)
a[] = [ this is a [ test ] { test2 } ]
Should return [ this is a [ test ] { test2 } ]