apply method
Implementation
@override
Future<String> apply(String content, Map<String, dynamic> context) async {
return content.replaceAllMapped(_strlenRegex, (match) {
final expr = match.group(1)!.trim();
try {
final value = _evaluate(expr, context);
return value.toString().length.toString();
} catch (_) {
return '0';
}
});
}