Refactor: moved flatten function to utils

Previously, the keystone.common.authorization module contained the function
"flatten", which would transform a dictionary (possibly nested) into a
single level dictionary. Given that the "flattening" of a dictionary is
a more general concept, not related to authorization, I thought it would
be more intuitive to have it in the keystone.common.utils module.

Change-Id: Ic1f6fa70634ade41e392ee7c5cd8adac913fd0b8

keystone/common/authorization.py

@@ -16,8 +16,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import collections
-
 from keystone.contrib import federation
 from keystone import exception
 from keystone.openstack.common.gettextutils import _
@@ -43,23 +41,6 @@ It is a dictionary with the following attributes:
 LOG = log.getLogger(__name__)
 
 
-def flatten(d, parent_key=''):
-    """Flatten a nested dictionary
-
-    Converts a dictionary with nested values to a single level flat
-    dictionary, with dotted notation for each key.
-
-    """
-    items = []
-    for k, v in d.items():
-        new_key = parent_key + '.' + k if parent_key else k
-        if isinstance(v, collections.MutableMapping):
-            items.extend(flatten(v, new_key).items())
-        else:
-            items.append((new_key, v))
-    return dict(items)
-
-
 def is_v3_token(token):
     # V3 token data are encapsulated into "token" key while
     # V2 token data are encapsulated into "access" key.

keystone/common/controller.py

@@ -147,7 +147,7 @@ def protected(callback=None):
                 policy_dict.update(kwargs)
                 self.policy_api.enforce(creds,
                                         action,
-                                        authorization.flatten(policy_dict))
+                                        utils.flatten_dict(policy_dict))
                 LOG.debug(_('RBAC: Authorization granted'))
             return f(self, context, *args, **kwargs)
         return inner
@@ -188,7 +188,7 @@ def filterprotected(*filters):
 
                 self.policy_api.enforce(creds,
                                         action,
-                                        authorization.flatten(target))
+                                        utils.flatten_dict(target))
 
                 LOG.debug(_('RBAC: Authorization granted'))
             else:
@@ -452,7 +452,7 @@ class V3Controller(wsgi.Application):
                 attr = filter['name']
                 value = filter['value']
                 refs = [r for r in refs if _attr_match(
-                    authorization.flatten(r).get(attr), value)]
+                    utils.flatten_dict(r).get(attr), value)]
             else:
                 # It might be an inexact filter
                 refs = [r for r in refs if _inexact_attr_match(
@@ -612,7 +612,7 @@ class V3Controller(wsgi.Application):
             policy_dict.update(prep_info['input_attr'])
             self.policy_api.enforce(creds,
                                     action,
-                                    authorization.flatten(policy_dict))
+                                    utils.flatten_dict(policy_dict))
             LOG.debug(_('RBAC: Authorization granted'))
 
     @classmethod

keystone/common/utils.py

@@ -17,6 +17,7 @@
 #    under the License.
 
 import calendar
+import collections
 import grp
 import hashlib
 import json
@@ -40,6 +41,23 @@ CONF = config.CONF
 LOG = log.getLogger(__name__)
 
 
+def flatten_dict(d, parent_key=''):
+    """Flatten a nested dictionary
+
+    Converts a dictionary with nested values to a single level flat
+    dictionary, with dotted notation for each key.
+
+    """
+    items = []
+    for k, v in d.items():
+        new_key = parent_key + '.' + k if parent_key else k
+        if isinstance(v, collections.MutableMapping):
+            items.extend(flatten_dict(v, new_key).items())
+        else:
+            items.append((new_key, v))
+    return dict(items)
+
+
 def read_cached_file(filename, cache_info, reload_func=None):
     """Read from a file if it has been modified.