731     def merge3(self, fl, fn, my, other, transaction, link):

   732         """perform a 3-way merge and append the result"""

   733         

   734         def temp(prefix, node):

   735             pre = "%s~%s." % (os.path.basename(fn), prefix)

   736             (fd, name) = tempfile.mkstemp("", pre)

   737             f = os.fdopen(fd, "w")

   738             f.write(fl.revision(node))

   739             f.close()

   740             return name

   741 

   742         base = fl.ancestor(my, other)

   743         self.ui.note("resolving %s\n" % fn)

   744         self.ui.debug("local %s remote %s ancestor %s\n" %

   745                               (short(my), short(other), short(base)))

   746 

   747         if my == base: 

   748             text = fl.revision(other)

   749         else:

   750             a = temp("local", my)

   751             b = temp("remote", other)

   752             c = temp("parent", base)

   753 

   754             cmd = os.environ["HGMERGE"]

   755             self.ui.debug("invoking merge with %s\n" % cmd)

   756             r = os.system("%s %s %s %s" % (cmd, a, b, c))

   757             if r:

   758                 raise "Merge failed!"

   759 

   760             text = open(a).read()

   761             os.unlink(a)

   762             os.unlink(b)

   763             os.unlink(c)

   764             

   765         return fl.addrevision(text, transaction, link, my, other)

   766