API to read source position

[re-xyr]

As title. ANTLR allows to read the source interval (start offset, end offset, start row, end row, start col, end col) of any node. Trifecta has DeltaParsing. I did not find such an API here and I think this is a crucial feature for any further error reporting after parsing.

[johnynek]

There is Parser.index which gives the current offset, which can be used to get the range: get index, parse, get the index. If you want line and column numbers see LocationMap which can convert offsets into rows and columns.

[re-xyr]

I see. Do we want to provide Carets and Spans like Trifecta? If so maybe I can make a pr.

[johnynek]

Yeah, that could be nice, especially if we can do it without breaking compatibility.