apply method
Implementation
@override
Future<String> apply(String content, Map<String, dynamic> context) async {
return content.replaceAllMapped(_strtoupperRegex, (match) {
final expr = match.group(1)!.trim();
try {
final value = _evaluate(expr, context);
return value.toString().toUpperCase();
} catch (_) {
return '';
}
});
}