private ReadWithCommentResultType HandleUncommonAdvanceResults(ReaderStateMachine.AdvanceResult res, char?lastRead)
{
string c;
if (lastRead.HasValue)
{
c = lastRead.Value.ToString();
}
else
{
c = "<end of data>";
}
return
(res switch
{
ReaderStateMachine.AdvanceResult.Exception_ExpectedEndOfRecord => Throw.InvalidOperationException_Returns <ReadWithCommentResultType>($"Encountered '{c}' when expecting end of record"),
ReaderStateMachine.AdvanceResult.Exception_InvalidState => Throw.InvalidOperationException_Returns <ReadWithCommentResultType>($"Internal state machine is in an invalid state due to a previous error"),
ReaderStateMachine.AdvanceResult.Exception_StartEscapeInValue => Throw.InvalidOperationException_Returns <ReadWithCommentResultType>($"Encountered '{c}', starting an escaped value, when already in a value"),
ReaderStateMachine.AdvanceResult.Exception_UnexpectedCharacterInEscapeSequence => Throw.InvalidOperationException_Returns <ReadWithCommentResultType>($"Encountered '{c}' in an escape sequence, which is invalid"),
ReaderStateMachine.AdvanceResult.Exception_ExpectedEndOfRecordOrValue => Throw.InvalidOperationException_Returns <ReadWithCommentResultType>($"Encountered '{c}' when expecting the end of a record or value"),
ReaderStateMachine.AdvanceResult.Exception_UnexpectedEnd => Throw.InvalidOperationException_Returns <ReadWithCommentResultType>($"Data ended unexpectedly"),
// this is CRAZY unlikely, but indicates that the TransitionMatrix used was incorrect
ReaderStateMachine.AdvanceResult.Exception_UnexpectedLineEnding => Throw.ImpossibleException_Returns <ReadWithCommentResultType, T>($"Unexpected {nameof(Cesil.ReadRowEnding)} value encountered", Configuration),
// likewise, CRAZY unlikely
ReaderStateMachine.AdvanceResult.Exception_UnexpectedState => Throw.ImpossibleException_Returns <ReadWithCommentResultType, T>($"Unexpected state value entered", Configuration),
_ => Throw.ImpossibleException_Returns <ReadWithCommentResultType, T>($"Unexpected {nameof(ReaderStateMachine.AdvanceResult)}: {res}", Configuration),
});
internal static void StateTransition_ChangeState(ReaderStateMachine.State from, char c, ReaderStateMachine.State to, ReaderStateMachine.AdvanceResult res, [CallerMemberName] string?caller = null)
{
caller = SetCaller(caller);
Debug.WriteLine($"{caller}: {from} + {c} => {to} & {res}");
}
