Rev 2252: Slightly smarter tag merge in http://sourcefrog.net/bzr/tags

[Martin Pool]

At http://sourcefrog.net/bzr/tags

------------------------------------------------------------
revno: 2252
revision-id: mbp at sourcefrog.net-20070222050352-98ohnhisvcc71ela
parent: mbp at sourcefrog.net-20070222045206-zxhd8xxpepbuw8uj
committer: Martin Pool <mbp at sourcefrog.net>
branch nick: tags
timestamp: Thu 2007-02-22 16:03:52 +1100
message:
  Slightly smarter tag merge
modified:
  BRANCH.TODO                    BRANCH.TODO-20060103052123-79ac4969351c03a9
  bzrlib/tag.py                  tag.py-20070212110532-91cw79inah2cfozx-1
  bzrlib/tests/branch_implementations/test_tags.py test_tags.py-20070212110545-w2s799hm2jlbsmg5-1
=== modified file 'BRANCH.TODO'
--- a/BRANCH.TODO	2007-02-22 04:39:08 +0000
+++ b/BRANCH.TODO	2007-02-22 05:03:52 +0000
@@ -60,6 +60,7 @@
  - copy only selected tags
  - refuse to add tags if the tag is already present, but allow it to 
    be forced
+ - maybe rename merge_to to merge_from (and invert the code)?
 
 
 Later

=== modified file 'bzrlib/tag.py'
--- a/bzrlib/tag.py	2007-02-22 04:39:08 +0000
+++ b/bzrlib/tag.py	2007-02-22 05:03:52 +0000
@@ -153,14 +153,17 @@
             return r
         except ValueError, e:
             raise ValueError("failed to deserialize tag dictionary %r: %s"
-                    % (tag_content, e))
+                % (tag_content, e))
 
-    def merge_to(self, to_tags, just_warn=False):
+    def merge_to(self, to_tags):
         """Copy tags between repositories if necessary and possible.
         
         This method has common command-line behaviour about handling 
         error cases.
 
+        All new definitions are copied across, except that tags that already
+        exist keep their existing definitions.
+
         :param to_tags: Branch to receive these tags
         :param just_warn: If the destination doesn't support tags and the 
             source does have tags, just give a warning.  Otherwise, raise
@@ -171,17 +174,26 @@
         if not self.supports_tags():
             # obviously nothing to copy
             return
-        td = self.get_tag_dict()
-        if not td:
+        source_dict = self.get_tag_dict()
+        if not source_dict:
             # no tags in the source, and we don't want to clobber anything
             # that's in the destination
             return
         to_tags.branch.lock_write()
         try:
-            to_tags._set_tag_dict(td)
+            dest_dict = to_tags.get_tag_dict()
+            result = self._reconcile_tags(source_dict, dest_dict)
+            if result != dest_dict:
+                to_tags._set_tag_dict(result)
         finally:
             to_tags.branch.unlock()
 
+    def _reconcile_tags(self, source_dict, dest_dict):
+        """Return the result of a two-way merge of tags"""
+        result = dict(source_dict)
+        result.update(dest_dict)
+        return result
+
 
 def _merge_tags_if_possible(from_branch, to_branch):
     from_branch.tags.merge_to(to_branch.tags)

=== modified file 'bzrlib/tests/branch_implementations/test_tags.py'
--- a/bzrlib/tests/branch_implementations/test_tags.py	2007-02-22 04:52:06 +0000
+++ b/bzrlib/tests/branch_implementations/test_tags.py	2007-02-22 05:03:52 +0000
@@ -86,6 +86,11 @@
         b1.tags.set_tag('tagname', 'revid')
         b1.tags.merge_to(b2.tags)
         self.assertEquals(b2.tags.lookup_tag('tagname'), 'revid')
+        # if a tag is in the destination and not in the source, it is not
+        # removed when we merge them
+        b2.tags.set_tag('in-destination', 'revid')
+        b1.tags.merge_to(b2.tags)
+        self.assertEquals(b2.tags.lookup_tag('in-destination'), 'revid')
 
     def test_unicode_tag(self):
         b1 = self.make_branch('b')