[IMP] api: make the implementation of field protection more robust

1 files changed, 44 insertions, 2 deletions

diff --git a/odoo/tools/misc.py b/odoo/tools/misc.py
index ac3a56b3825..a9b66117f03 100644
--- a/odoo/tools/misc.py
+++ b/odoo/tools/misc.py
@@ -25,8 +25,7 @@ import types
 import unicodedata
 import werkzeug.utils
 import zipfile
-
-from collections import defaultdict, Iterable, Mapping, MutableSet, OrderedDict
+from collections import defaultdict, Iterable, Mapping, MutableMapping, MutableSet, OrderedDict
 from itertools import islice, groupby, repeat
 from lxml import etree
 
@@ -998,6 +997,49 @@ class Collector(Mapping):
     def __len__(self):
         return len(self._map)
 
+
+@pycompat.implements_to_string
+class StackMap(MutableMapping):
+    """ A stack of mappings behaving as a single mapping, and used to implement
+        nested scopes. The lookups search the stack from top to bottom, and
+        returns the first value found. Mutable operations modify the topmost
+        mapping only.
+    """
+    __slots__ = ['_maps']
+
+    def __init__(self, m=None):
+        self._maps = [] if m is None else [m]
+
+    def __getitem__(self, key):
+        for mapping in reversed(self._maps):
+            try:
+                return mapping[key]
+            except KeyError:
+                pass
+        raise KeyError(key)
+
+    def __setitem__(self, key, val):
+        self._maps[-1][key] = val
+
+    def __delitem__(self, key):
+        del self._maps[-1][key]
+
+    def __iter__(self):
+        return iter({key for mapping in self._maps for key in mapping})
+
+    def __len__(self):
+        return sum(1 for key in self)
+
+    def __str__(self):
+        return u"<StackMap %s>" % self._maps
+
+    def pushmap(self, m=None):
+        self._maps.append({} if m is None else m)
+
+    def popmap(self):
+        return self._maps.pop()
+
+
 class OrderedSet(MutableSet):
     """ A set collection that remembers the elements first insertion order. """
     __slots__ = ['_map']