// Parses a type specification, returns true and sets 'type' on success.
public static bool TryParse(DTypeSpecLexer lexer, out DType type)
{
Contracts.AssertValue(lexer);
Contracts.Assert(_typeEncodings.Length == _types.Length);
Contracts.Assert(_typeEncodings.ToCharArray().Zip(_types, (c, t) => DType.MapKindToStr(t.Kind) == c.ToString()).All(x => x));
string token;
if (!lexer.TryNextToken(out token) || token.Length != 1)
{
type = DType.Invalid;
return(false);
}
// Older documents may use an "a" type, which for legacy reasons is a duplicate of "o" type.
if (token == DType.MapKindToStr(DKind.LegacyBlob))
{
token = DType.MapKindToStr(DKind.Blob);
}
// Note that control types "v" or "E" are parsed to Error, since the type spec language is not a mechanism for serializing/deserializing controls.
if (token == DType.MapKindToStr(DKind.Control) || token == DType.MapKindToStr(DKind.DataEntity))
{
type = DType.Error;
return(true);
}
int typeIdx = _typeEncodings.IndexOf(token);
if (typeIdx < 0)
{
type = DType.Invalid;
return(false);
}
Contracts.AssertIndex(typeIdx, _types.Length);
DType result = _types[typeIdx];
if (result == DType.ObjNull)
{
// For null value
type = result;
return(true);
}
if (!result.IsAggregate)
{
if (result.IsEnum)
{
DType enumSupertype;
ValueTree valueMap;
if (!TryParse(lexer, out enumSupertype) ||
(!enumSupertype.IsPrimitive && !enumSupertype.IsUnknown) ||
!TryParseValueMap(lexer, out valueMap))
{
type = DType.Invalid;
return(false);
}
// For enums
type = new DType(enumSupertype.Kind, valueMap);
return(true);
}
// For non-enums, non-aggregates
type = result;
return(true);
}
Contracts.Assert(result.IsRecord || result.IsTable);
TypeTree typeMap;
if (!TryParseTypeMap(lexer, out typeMap))
{
type = DType.Invalid;
return(false);
}
type = new DType(result.Kind, typeMap);
return(true);
}