xdiff generated hunks for the differences (ex. questionmarks in the
@@ -?,? +?,? @@ part from diff --git output). However, bdiff generates
matched hunks instead.
This patch adds a XDL_EMIT_BDIFFHUNK flag used by the output function
xdl_call_hunk_func. Once set, xdiff will generate bdiff-like hunks
instead. That makes it easier to use xdiff as a drop-in replacement of bdiff.
Note that since bdiff('', '') returns [(0, 0, 0, 0)], the shortcut path
if (xscr) is removed. I have checked functions called with xscr argument
(xdl_mark_ignorable, xdl_call_hunk_func, xdl_emit_diff,
xdl_free_script) work just fine with xscr = NULL.