Which function or code is for calculating the highlighting parts of the left and right lines?

[roadfar]

As lines 5, 6, 13, and 23 show in the following figure show, which function or code is for calculating the highlighting parts (i.e., the string start index and end index) of the left and right lines?

[dandavison]

Hi @roadfar, I'm not sure I understand the question exactly. You're asking about delta implementation, right? Have you looked at https://github.com/dandavison/delta/blob/main/ARCHITECTURE.md?