private static bool TryParseFile(IChannel ch, TextLoader.Arguments args, IMultiStreamSource source, bool skipStrictValidation, out ColumnSplitResult result)
{
result = default(ColumnSplitResult);
try
{
// No need to provide information from unsuccessful loader, so we create temporary environment and get information from it in case of success
using (var loaderEnv = new ConsoleEnvironment(0, true))
{
var messages = new ConcurrentBag <ChannelMessage>();
loaderEnv.AddListener <ChannelMessage>(
(src, msg) =>
{
messages.Add(msg);
});
var idv = TextLoader.ReadFile(loaderEnv, args, source).Take(1000);
var columnCounts = new List <int>();
int columnIndex;
bool found = idv.Schema.TryGetColumnIndex("C", out columnIndex);
ch.Assert(found);
using (var cursor = idv.GetRowCursor(x => x == columnIndex))
{
var getter = cursor.GetGetter <VBuffer <ReadOnlyMemory <char> > >(columnIndex);
VBuffer <ReadOnlyMemory <char> > line = default;
while (cursor.MoveNext())
{
getter(ref line);
columnCounts.Add(line.Length);
}
}
Contracts.Check(columnCounts.Count > 0);
var mostCommon = columnCounts.GroupBy(x => x).OrderByDescending(x => x.Count()).First();
if (!skipStrictValidation && mostCommon.Count() < UniformColumnCountThreshold * columnCounts.Count)
{
return(false);
}
// If user explicitly specified separator we're allowing "single" column case;
// Otherwise user will see message informing that we were not able to detect any columns.
if (!skipStrictValidation && mostCommon.Key <= 1)
{
return(false);
}
result = new ColumnSplitResult(true, args.Separator, args.AllowQuoting, args.AllowSparse, mostCommon.Key);
ch.Trace("Discovered {0} columns using separator '{1}'", mostCommon.Key, args.Separator);
foreach (var msg in messages)
{
ch.Send(msg);
}
return(true);
}
}
catch (Exception ex)
{
if (!ex.IsMarked())
{
throw;
}
// For known exceptions, we just continue to the next separator candidate.
}
return(false);
}