/// <summary>
/// Read a single line from intake. In case of X12, the line means segment (so, CR/LF is not (necessarily) a delimiter).
/// </summary>
/// <returns>A tuple consisting of the line sequence number (1-based), source number (1-based) and the line read from intake; or null as EOD mark</returns>
internal Tuple <int, int, ExternalLine> GetLineFromIntake()
{
// linePlus is a Tuple<ExternalLine,int>: Item1 = line, Item2 = source number
// End-of-data indicators: * non-null linePlus.Item1 means data
// * null linePlus.Item1 means end-of-data for a single source (only if asynchronous)
// * null linePlus means end-of-data for all sources
Tuple <ExternalLine, int> linePlus;
do //note that this loop is for consistency with async intake from files where tuple with end-of-data mark denotes end of each source (but not the entire intake)
{ // (even though in case of synchronous intake, tuples with null contents should not be received from LineFeeder or IntakeSupplier).
//IOW, this loop should always execute a single iteration.
linePlus = _intakeFromReader ? _intakeReader.GetNextLine() : _config.IntakeSupplier(_globalCache);
Debug.Assert(linePlus == null || linePlus.Item1 != null);
}while (linePlus != null && linePlus.Item1 == null); // ignore tuples with null lines (end-of-data marks for individual sources)
if (linePlus == null)
{
return(null); // EOD mark
}
var lineCnt = Interlocked.Increment(ref _lineCnt); // adjustment for header row(s) may be needed
return(Tuple.Create(lineCnt, linePlus.Item2, linePlus.Item1));
}
