Re: your mail

On Tue, 21 Nov 2006, Johannes Schindelin wrote:

[PATCH] xdiff: add xdl_merge()

This new function implements the functionality of RCS merge, but
in-memory. It returns < 0 on error, otherwise the number of conflicts.

Finding the conflicting lines can be a very expensive task. You can
control the eagerness of this algorithm:

- a level value of 0 means that all overlapping changes are treated
  as conflicts,
- a value of 1 means that if the overlapping changes are identical,
  it is not treated as a conflict.
- If you set level to 2, overlapping changes will be analyzed, so that
  almost identical changes will not result in huge conflicts. Rather,
  only the conflicting lines will be shown inside conflict markers.

With each increasing level, the algorithm gets slower, but more accurate.
Note that the code for level 2 depends on the simple definition of
mmfile_t specific to git, and therefore it will be harder to port that
to LibXDiff.

Johannes, at the moment I'm chased by a huge storm of never ending emails, 
so I won't be able to follow up this one soon. A smart 3-way merge is in 
my plans for LibXDiff though.
There is quite some nice code around, that does pretty smart tricks and 
goes down to resolve sub-hunk non-trivial conflicts. You may want to take 
a look at that code too.



- Davide