Parsing, form, meaning, context, morphology? (John)

It's a third conditional; it refers to a hypothetical action that did not ocurr.

"If you had invited me I would have come". It means that if I had got an invitation I would have come, but I didn't come because I didn't receive an invitation. Maybe if I had received a formal invitation a letter, a readable fax then I would have come. Since the details are not clear, there is no point in speculating further.