Allow to specify start line number

[dnicolodi]

I've looked everywhere but I haven't found a way to specify the starting line number when scanning the input text. It is possible to specify a filename but not a start line number. Being able to do specify the start line number is handy when parsing text embedded into a larger document. If there is agreement that this is a desirable feature, I can work to implement it.

[apalala]

The way to do what you want is to skip to a token that marks the start of the text of interest.

Another way to do it is to write a function that knows about line numbers and extracts the text of interest for the parser.

[dnicolodi]

I think I did a poor job explaining the issue. I would like to add an offset to the line number reported by parseinfo. I already pass to the parse() method only the portion of input that the parser should consider, I just would like the parseifo to reflect the fact that it is not located at the beginning of the file. The parse() method has a filename argument used to populate the filename filed in the parseifo. I would like a lineno argument that specifies an offset to be added to the line number reported by parseifo. This would be similar to the yyset_lineno() of flex.

[apalala]

Now I understand.

This is very doable, though there are subtleties to be considered.

Let's see a pull request? If it's simple and nothing breaks, I'd be OK with it.