// reads a STON address path segment
private IStonPathSegment ReadPathSegment(StonTokenReader reader)
{
int pathOpen = reader.ExpectAndSkip(StonChartype.PathSegmentBegin);
if (pathOpen == '.')
{
// ancestor access segment
if (reader.TryAndSkip(StonChartype.AncestorAccess))
{
int ancestorOrder = 1;
while (reader.TryAndSkip(StonChartype.AncestorAccess))
{
++ancestorOrder;
}
return(ElementFactory.CreateAncestorPathSegment(ancestorOrder));
}
// named member access segment
else
{
return(ElementFactory.CreateMemberPathSegment(ReadBindingName(reader)));
}
}
else
{
// collection element access segment
if (reader.TryAndSkip(StonChartype.PathSegmentCollection))
{
int currentPosition = reader.Position;
int currentLine = reader.Line;
int currentColumn = reader.Column;
if (reader.Peek().HasChartype(StonChartype.Sign))
{
if (reader.Peek() == '-')
{
throw new StonParsingException(currentPosition, currentLine, currentColumn, "Collection element index cannot be negative.");
}
reader.ReadAndSkip();
if (!reader.Peek().HasChartype(StonChartype.Digit))
{
throw reader.MakeUnexpectedCharacterException(StonChartype.Digit);
}
}
IStonEntity elementIndex;
// number or binary integer index
if (reader.Peek().HasChartype(StonChartype.ZeroDigit))
{
reader.ReadAndSkip();
if (reader.Peek().HasChartype(StonChartype.BaseIdentifier))
{
elementIndex = ElementFactory.CreateSimpleEntity(ElementFactory.CreateSimpleValue(StonDataType.Binary, reader.ReadBinaryContent(false)));
}
else
{
elementIndex = ElementFactory.CreateSimpleEntity(ElementFactory.CreateSimpleValue(StonDataType.Number, reader.ReadNumberContent(false)));
}
}
// number integer index
else if (reader.Peek().HasChartype(StonChartype.NonZeroDigit))
{
elementIndex = ElementFactory.CreateSimpleEntity(ElementFactory.CreateSimpleValue(StonDataType.Number, reader.ReadNumberContent(false)));
}
// resolved reference index
else if (reader.Peek().HasChartype(StonChartype.AddressBegin))
{
elementIndex = ElementFactory.CreateReferenceEntity(ReadAddress(reader));
}
else
{
throw reader.MakeUnexpectedCharacterException(StonChartype.Digit | StonChartype.AddressBegin | StonChartype.Sign);
}
reader.ExpectAndSkip(StonChartype.IndexClose);
return(ElementFactory.CreateCollectionElementPathSegment(elementIndex));
}
// index member access segment
else
{
IEnumerable <IStonEntity> indexParameters = ReadSequence(reader, ReadAddressEntity, StonChartype.IndexClose);
return(ElementFactory.CreateMemberPathSegment(ElementFactory.CreateBindingIndex(indexParameters)));
}
}
}
