currentMatch method
Implementation
bool currentMatch(exp) {
return (source != null &&
exp is String &&
((RegExp('#\\(.+\\)', multiLine: true).hasMatch(exp) &&
(exp.contains('\$item') || exp.contains('\$index'))) ||
exp == 'item' ||
exp == 'index' ||
exp.startsWith('\$(item') ||
exp.startsWith('\$(index') ||
exp.startsWith('#(\${index') ||
exp.startsWith('#(\${item') ||
exp.startsWith('^(index)') ||
exp.startsWith('^(item)')));
}