protected override bool TryParse(string str)
{
Contracts.AssertNonEmpty(str);
// We accept N:T:S where N is the new column name, T is the new type,
// and S is source column names.
string extra;
if (!base.TryParse(str, out extra))
{
return(false);
}
if (extra == null)
{
return(true);
}
DataKind kind;
if (!TypeParsingUtils.TryParseDataKind(extra, out kind, out KeyRange))
{
return(false);
}
ResultType = kind == default(DataKind) ? default(DataKind?) : kind;
return(true);
}
public static bool TryParse(string str, out Column column)
{
column = null;
if (string.IsNullOrEmpty(str))
{
return(false);
}
if (!ColumnParsingUtils.TryParse(str, out string name, out string sourceStr, out string kindStr))
{
return(false);
}
DataKind?kind = null;
if (kindStr != null && TypeParsingUtils.TryParseDataKind(kindStr, out DataKind parsedKind, out KeyRange range))
{
kind = parsedKind;
}
if (!int.TryParse(sourceStr, out int source))
{
return(false);
}
column = new Column()
{
Name = name,
Source = source,
Type = kind
};
return(true);
}
private static bool TryCreateEx(IExceptionContext ectx, ColInfo info, DataKind kind, KeyRange range, out PrimitiveType itemType, out ColInfoEx ex)
{
ectx.AssertValue(info);
ectx.Assert(Enum.IsDefined(typeof(DataKind), kind));
ex = null;
var typeSrc = info.TypeSrc;
if (range != null)
{
itemType = TypeParsingUtils.ConstructKeyType(kind, range);
if (!typeSrc.ItemType.IsKey && !typeSrc.ItemType.IsText)
{
return(false);
}
}
else if (!typeSrc.ItemType.IsKey)
{
itemType = PrimitiveType.FromKind(kind);
}
else if (!KeyType.IsValidDataKind(kind))
{
itemType = PrimitiveType.FromKind(kind);
return(false);
}
else
{
var key = typeSrc.ItemType.AsKey;
ectx.Assert(KeyType.IsValidDataKind(key.RawKind));
int count = key.Count;
// Technically, it's an error for the counts not to match, but we'll let the Conversions
// code return false below. There's a possibility we'll change the standard conversions to
// map out of bounds values to zero, in which case, this is the right thing to do.
ulong max = kind.ToMaxInt();
if ((ulong)count > max)
{
count = (int)max;
}
itemType = new KeyType(kind, key.Min, count, key.Contiguous);
}
// Ensure that the conversion is legal. We don't actually cache the delegate here. It will get
// re-fetched by the utils code when needed.
bool identity;
Delegate del;
if (!Conversions.Instance.TryGetStandardConversion(typeSrc.ItemType, itemType, out del, out identity))
{
return(false);
}
ColumnType typeDst = itemType;
if (typeSrc.IsVector)
{
typeDst = new VectorType(itemType, typeSrc.AsVector);
}
// An output column is transposable iff the input column was transposable.
VectorType slotType = null;
if (info.SlotTypeSrc != null)
{
slotType = new VectorType(itemType, info.SlotTypeSrc);
}
ex = new ColInfoEx(kind, range != null, typeDst, slotType);
return(true);
}