Iterates over the diff calling file_cb, binary_cb, hunk_cb and line_cb.
The DiffFile mode always be 0, path will be null and when a blob is null the oid will be 0.
If diff_options is null then the defaults specified in
DiffOptions are used.
| old_blob |
a Blob to diff from. |
| old_as_path |
treat |
| new_blob |
a Blob to diff to. |
| new_as_path |
treat |
| diff_options |
a DiffOptions, or null. |
| file_cb | |
| binary_cb | |
| hunk_cb | |
| line_cb | |
| user_data |
callback user data. |