[StGit PATCH 04/14] Add utility function for reordering patches

["Karl Hasselström" <kha@treskal.com>]

Signed-off-by: Karl Hasselström <kha@treskal.com>

---

 stgit/lib/transaction.py |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)


diff --git a/stgit/lib/transaction.py b/stgit/lib/transaction.py
index 4c4da1a..16f5a4b 100644
--- a/stgit/lib/transaction.py
+++ b/stgit/lib/transaction.py
@@ -1,6 +1,8 @@
 """The L{StackTransaction} class makes it possible to make complex
 updates to an StGit stack in a safe and convenient way."""
 
+import itertools as it
+
 from stgit import exception, utils
 from stgit.utils import any, all
 from stgit.out import *
@@ -274,3 +276,15 @@ class StackTransaction(object):
             self.__allow_conflicts = lambda trans: True
 
             self.__halt('Merge conflict')
+
+    def reorder_patches(self, applied, unapplied, iw = None):
+        """Push and pop patches to attain the given ordering."""
+        common = len(list(it.takewhile(lambda (a, b): a == b,
+                                       zip(self.applied, applied))))
+        to_pop = set(self.applied[common:])
+        self.pop_patches(lambda pn: pn in to_pop)
+        for pn in applied[common:]:
+            self.push_patch(pn, iw)
+        assert self.applied == applied
+        assert set(self.unapplied) == set(unapplied)
+        self.unapplied = unapplied