final int length = lastToken.endColumn - firstToken.beginColumn + 1;
final BracketOperator bracketOperator = new BracketOperator(_diagnosticFactory, _targetFile, _symbolResolver);
final Diagnostic diagnostic =
bracketOperator.validate(symbolType,
(ValueType)subExprType);
if (diagnostic.getSeverity() != Diagnostic.OK)
{
_reporter.report(diagnostic, offset, length);