how the location implementation work?

I have seen the “Clang” CFE Internals Manual ,the part of The SourceLocation and SourceManager classes ,but i sitll cann`t understand the way of sourcelocation implementation.
can anyone tell me ,the details of the programe run?

Hi, it is probably best to read the source code, it is well commented and there is not that much code involved. If you have a specific question, I'm happy to try to help.