--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/filemerge.py	Sun Feb 03 19:29:05 2008 -0600
@@ -0,0 +1,65 @@
+# filemerge.py - file-level merge handling for Mercurial
+#
+# Copyright 2006, 2007, 2008 Matt Mackall <mpm@selenic.com>
+#
+# This software may be used and distributed according to the terms
+# of the GNU General Public License, incorporated herein by reference.
+
+from node import *
+from i18n import _
+import util, os, tempfile, context
+
+def filemerge(repo, fw, fd, fo, wctx, mctx):
+    """perform a 3-way merge in the working directory
+
+    fw = original filename in the working directory
+    fd = destination filename in the working directory
+    fo = filename in other parent
+    wctx, mctx = working and merge changecontexts
+    """
+
+    def temp(prefix, ctx):
+        pre = "%s~%s." % (os.path.basename(ctx.path()), prefix)
+        (fd, name) = tempfile.mkstemp(prefix=pre)
+        data = repo.wwritedata(ctx.path(), ctx.data())
+        f = os.fdopen(fd, "wb")
+        f.write(data)
+        f.close()
+        return name
+
+    fcm = wctx.filectx(fw)
+    fcmdata = wctx.filectx(fd).data()
+    fco = mctx.filectx(fo)
+
+    if not fco.cmp(fcmdata): # files identical?
+        return None
+
+    fca = fcm.ancestor(fco)
+    if not fca:
+        fca = repo.filectx(fw, fileid=nullrev)
+    a = repo.wjoin(fd)
+    b = temp("base", fca)
+    c = temp("other", fco)
+
+    if fw != fo:
+        repo.ui.status(_("merging %s and %s\n") % (fw, fo))
+    else:
+        repo.ui.status(_("merging %s\n") % fw)
+
+    repo.ui.debug(_("my %s other %s ancestor %s\n") % (fcm, fco, fca))
+
+    cmd = (os.environ.get("HGMERGE") or repo.ui.config("ui", "merge")
+           or "hgmerge")
+    r = util.system('%s "%s" "%s" "%s"' % (cmd, a, b, c), cwd=repo.root,
+                    environ={'HG_FILE': fd,
+                             'HG_MY_NODE': str(wctx.parents()[0]),
+                             'HG_OTHER_NODE': str(mctx),
+                             'HG_MY_ISLINK': fcm.islink(),
+                             'HG_OTHER_ISLINK': fco.islink(),
+                             'HG_BASE_ISLINK': fca.islink(),})
+    if r:
+        repo.ui.warn(_("merging %s failed!\n") % fd)
+
+    os.unlink(b)
+    os.unlink(c)
+    return r