/// <summary>
/// Iterate through all remaining rows in the next N result sets, mapping all rows to objects
/// of the given type. Useful only if the next N result sets all represent the same type
/// of object
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="results"></param>
/// <param name="numResultSets">The number of result sets to consume</param>
/// <param name="setup"></param>
/// <returns></returns>
public static IEnumerable <T> AsEnumerableNextSeveral <T>(this IDataResultsBase results, int numResultSets, Action <IMapCompilerSettings> setup = null)
{
Argument.NotNull(results, nameof(results));
if (numResultSets <= 0)
{
yield break;
}
var values = results.AsEnumerable <T>(setup);
var currentSet = results.CurrentSet;
foreach (var value in values)
{
if (currentSet != results.CurrentSet)
{
throw DataReaderException.EnumeratorBroken();
}
yield return(value);
}
numResultSets--;
while (numResultSets > 0)
{
// Make sure we're still where we think we are
if (currentSet != results.CurrentSet)
{
throw DataReaderException.EnumeratorBroken();
}
// Move to the next result set
var hasMore = results.TryAdvanceToNextResultSet();
if (!hasMore)
{
yield break;
}
numResultSets--;
// Make sure the next set is what we expect (no preemption)
var nextSet = results.CurrentSet;
if (nextSet != currentSet + 1)
{
throw DataReaderException.EnumeratorBroken();
}
currentSet = nextSet;
// Enumerate, checking before each value to make sure we are still on the correct
// result set
var nextValues = results.AsEnumerable <T>(setup);
foreach (var value in nextValues)
{
if (currentSet != results.CurrentSet)
{
throw DataReaderException.EnumeratorBroken();
}
yield return(value);
}
}
}
public IEnumerator <T> GetEnumerator()
{
var attempt = Interlocked.Increment(ref _readAttempts);
if (attempt > 1)
{
throw DataReaderException.ResultSetReadMoreThanOnce();
}
if ((_context != null && _context.IsCompleted) || _reader.Reader.IsClosed)
{
throw DataReaderException.ReaderClosed();
}
return(new ResultSetEnumerator(_results, _reader, _context, _map, _currentSet));
}
public IAsyncEnumerator <T> GetAsyncEnumerator(CancellationToken cancellationToken = new CancellationToken())
{
var attempt = Interlocked.Increment(ref _readAttempts);
if (attempt > 1)
{
throw DataReaderException.ResultSetReadMoreThanOnce();
}
if (_context?.IsCompleted == true || _reader.Reader.IsClosed)
{
throw DataReaderException.ReaderClosed();
}
return(new ResultSetEnumerator(_results, _reader, _context, _map, _currentSet));
}
