--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/copies.py	Sat Mar 15 10:02:31 2008 -0500
@@ -0,0 +1,193 @@
+# copies.py - copy detection for Mercurial
+#
+# Copyright 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 nullid, nullrev
+from i18n import _
+import util, ancestor
+
+def _nonoverlap(d1, d2, d3):
+    "Return list of elements in d1 not in d2 or d3"
+    l = [d for d in d1 if d not in d3 and d not in d2]
+    l.sort()
+    return l
+
+def _dirname(f):
+    s = f.rfind("/")
+    if s == -1:
+        return ""
+    return f[:s]
+
+def _dirs(files):
+    d = {}
+    for f in files:
+        f = _dirname(f)
+        while f not in d:
+            d[f] = True
+            f = _dirname(f)
+    return d
+
+def _findoldnames(fctx, limit):
+    "find files that path was copied from, back to linkrev limit"
+    old = {}
+    seen = {}
+    orig = fctx.path()
+    visit = [fctx]
+    while visit:
+        fc = visit.pop()
+        s = str(fc)
+        if s in seen:
+            continue
+        seen[s] = 1
+        if fc.path() != orig and fc.path() not in old:
+            old[fc.path()] = 1
+        if fc.rev() < limit and fc.rev() is not None:
+            continue
+        visit += fc.parents()
+
+    old = old.keys()
+    old.sort()
+    return old
+
+def copies(repo, c1, c2, ca):
+    """
+    Find moves and copies between context c1 and c2
+    """
+    # avoid silly behavior for update from empty dir
+    if not c1 or not c2 or not ca:
+        return {}, {}
+
+    rev1, rev2 = c1.rev(), c2.rev()
+    if rev1 is None: # c1 is a workingctx
+        rev1 = c1.parents()[0].rev()
+    if rev2 is None: # c2 is a workingctx
+        rev2 = c2.parents()[0].rev()
+    pr = repo.changelog.parentrevs
+    def parents(rev):
+        return [p for p in pr(rev) if p != nullrev]
+    limit = min(ancestor.symmetricdifference(rev1, rev2, parents))
+    m1 = c1.manifest()
+    m2 = c2.manifest()
+    ma = ca.manifest()
+
+    def makectx(f, n):
+        if len(n) != 20: # in a working context?
+            if c1.rev() is None:
+                return c1.filectx(f)
+            return c2.filectx(f)
+        return repo.filectx(f, fileid=n)
+    ctx = util.cachefunc(makectx)
+
+    copy = {}
+    fullcopy = {}
+    diverge = {}
+
+    def checkcopies(f, m1, m2):
+        '''check possible copies of f from m1 to m2'''
+        c1 = ctx(f, m1[f])
+        for of in _findoldnames(c1, limit):
+            fullcopy[f] = of # remember for dir rename detection
+            if of in m2: # original file not in other manifest?
+                # if the original file is unchanged on the other branch,
+                # no merge needed
+                if m2[of] != ma.get(of):
+                    c2 = ctx(of, m2[of])
+                    ca = c1.ancestor(c2)
+                    # related and named changed on only one side?
+                    if ca and ca.path() == f or ca.path() == c2.path():
+                        if c1 != ca or c2 != ca: # merge needed?
+                            copy[f] = of
+            elif of in ma:
+                diverge.setdefault(of, []).append(f)
+
+    if not repo.ui.configbool("merge", "followcopies", True):
+        return {}, {}
+
+    repo.ui.debug(_("  searching for copies back to rev %d\n") % limit)
+
+    u1 = _nonoverlap(m1, m2, ma)
+    u2 = _nonoverlap(m2, m1, ma)
+
+    if u1:
+        repo.ui.debug(_("  unmatched files in local:\n   %s\n")
+                      % "\n   ".join(u1))
+    if u2:
+        repo.ui.debug(_("  unmatched files in other:\n   %s\n")
+                      % "\n   ".join(u2))
+
+    for f in u1:
+        checkcopies(f, m1, m2)
+    for f in u2:
+        checkcopies(f, m2, m1)
+
+    diverge2 = {}
+    for of, fl in diverge.items():
+        if len(fl) == 1:
+            del diverge[of] # not actually divergent
+        else:
+            diverge2.update(dict.fromkeys(fl)) # reverse map for below
+
+    if fullcopy:
+        repo.ui.debug(_("  all copies found (* = to merge, ! = divergent):\n"))
+        for f in fullcopy:
+            note = ""
+            if f in copy: note += "*"
+            if f in diverge2: note += "!"
+            repo.ui.debug(_("   %s -> %s %s\n") % (f, fullcopy[f], note))
+    del diverge2
+
+    if not fullcopy or not repo.ui.configbool("merge", "followdirs", True):
+        return copy, diverge
+
+    repo.ui.debug(_("  checking for directory renames\n"))
+
+    # generate a directory move map
+    d1, d2 = _dirs(m1), _dirs(m2)
+    invalid = {}
+    dirmove = {}
+
+    # examine each file copy for a potential directory move, which is
+    # when all the files in a directory are moved to a new directory
+    for dst, src in fullcopy.items():
+        dsrc, ddst = _dirname(src), _dirname(dst)
+        if dsrc in invalid:
+            # already seen to be uninteresting
+            continue
+        elif dsrc in d1 and ddst in d1:
+            # directory wasn't entirely moved locally
+            invalid[dsrc] = True
+        elif dsrc in d2 and ddst in d2:
+            # directory wasn't entirely moved remotely
+            invalid[dsrc] = True
+        elif dsrc in dirmove and dirmove[dsrc] != ddst:
+            # files from the same directory moved to two different places
+            invalid[dsrc] = True
+        else:
+            # looks good so far
+            dirmove[dsrc + "/"] = ddst + "/"
+
+    for i in invalid:
+        if i in dirmove:
+            del dirmove[i]
+    del d1, d2, invalid
+
+    if not dirmove:
+        return copy, diverge
+
+    for d in dirmove:
+        repo.ui.debug(_("  dir %s -> %s\n") % (d, dirmove[d]))
+
+    # check unaccounted nonoverlapping files against directory moves
+    for f in u1 + u2:
+        if f not in fullcopy:
+            for d in dirmove:
+                if f.startswith(d):
+                    # new file added in a directory that was moved, move it
+                    copy[f] = dirmove[d] + f[len(d):]
+                    repo.ui.debug(_("  file %s -> %s\n") % (f, copy[f]))
+                    break
+
+    return copy, diverge