private Feature ReadAttribute()
{
string attributeName = ReadToken(endOfLine: false);
string typeString = ReadToken(endOfLine: false, quoting: false);
FeatureType attributeType;
if (string.Equals(typeString, "integer", StringComparison.OrdinalIgnoreCase))
{
attributeType = FeatureType.Integer;
ReadToken(endOfLine: true);
}
else if (string.Equals(typeString, "numeric", StringComparison.OrdinalIgnoreCase) ||
string.Equals(typeString, "real", StringComparison.OrdinalIgnoreCase))
{
attributeType = FeatureType.Numeric;
ReadToken(endOfLine: true);
}
else if (string.Equals(typeString, "string", StringComparison.OrdinalIgnoreCase))
{
attributeType = FeatureType.String;
ReadToken(endOfLine: true);
}
else if (string.Equals(typeString, "date", StringComparison.OrdinalIgnoreCase))
{
string dateFormat = ReadToken();
if (dateFormat == null)
{
attributeType = FeatureType.Date();
}
else
{
attributeType = FeatureType.Date(dateFormat);
ReadToken(endOfLine: true);
}
}
else if (typeString == "{")
{
List <string> nominalValues = new List <string>();
while (true)
{
string value = ReadToken(out bool quoted, endOfLine: false);
if (!quoted && value == "}")
{
break;
}
else if (!quoted && value == ",")
{
continue;
}
else
{
nominalValues.Add(value);
}
}
attributeType = FeatureType.Nominal(nominalValues);
ReadToken(endOfLine: true);
}
else if (string.Equals(typeString, "relational", StringComparison.OrdinalIgnoreCase))
{
ReadToken(endOfLine: true);
List <Feature> childAttributes = new List <Feature>();
while (true)
{
string token = ReadToken(skipEndOfLine: true, endOfLine: false, quoting: false);
if (string.Equals(token, "@attribute", StringComparison.OrdinalIgnoreCase))
{
Feature attribute = ReadAttribute();
childAttributes.Add(attribute);
}
else if (string.Equals(token, "@end", StringComparison.OrdinalIgnoreCase))
{
ReadToken(expectedToken: attributeName, endOfLine: false);
ReadToken(endOfLine: true);
break;
}
else
{
throw new InvalidDataException($"Unexpected token \"{token}\". Expected \"@attribute\" or \"@end\".");
}
}
attributeType = FeatureType.Relational(childAttributes);
}
else
{
throw new InvalidDataException($"Unexpected token \"{typeString}\". Expected attribute type.");
}
return(new Feature(attributeName, attributeType));
}