betweenBrackets method
Gets content between bracket pairs.
Tries parentheses, square brackets, angle brackets, and curly braces in order.
Implementation
String? betweenBrackets() {
if (isEmpty) return null;
String r = between('(', ')');
if (r.isNotEmpty) return r;
r = between('[', ']');
if (r.isNotEmpty) return r;
r = between('<', '>');
if (r.isNotEmpty) return r;
r = between('{', '}');
if (r.isNotEmpty) return r;
return null;
}