1 files changed, 58 insertions, 0 deletions
diff --git a/macaroonbakery/checkers/_auth_context.py b/macaroonbakery/checkers/_auth_context.py
new file mode 100644
index 0000000..dceb015
--- /dev/null
+++ b/macaroonbakery/checkers/_auth_context.py
@@ -0,0 +1,58 @@
+# Copyright 2017 Canonical Ltd.
+# Licensed under the LGPLv3, see LICENCE file for details.
+import collections
+
+
+class AuthContext(collections.Mapping):
+    ''' Holds a set of keys and values relevant to authorization.
+
+    It is passed as an argument to authorization checkers, so that the checkers
+    can access information about the context of the authorization request.
+    It is immutable - values can only be added by copying the whole thing.
+    '''
+    def __init__(self, somedict=None):
+        if somedict is None:
+            somedict = {}
+        self._dict = dict(somedict)
+        self._hash = None
+
+    def with_value(self, key, val):
+        ''' Return a copy of the AuthContext object with the given key and
+        value added.
+        '''
+        new_dict = dict(self._dict)
+        new_dict[key] = val
+        return AuthContext(new_dict)
+
+    def __getitem__(self, key):
+        return self._dict[key]
+
+    def __len__(self):
+        return len(self._dict)
+
+    def __iter__(self):
+        return iter(self._dict)
+
+    def __hash__(self):
+        if self._hash is None:
+            self._hash = hash(frozenset(self._dict.items()))
+        return self._hash
+
+    def __eq__(self, other):
+        return self._dict == other._dict
+
+
+class ContextKey(object):
+    '''Provides a unique key suitable for use as a key into AuthContext.'''
+
+    def __init__(self, name):
+        '''Creates a context key using the given name. The name is
+     only for informational purposes.
+     '''
+        self._name = name
+
+    def __str__(self):
+        return '%s#%#x' % (self._name, id(self))
+
+    def __repr__(self):
+        return 'context_key(%r, %#x)' % (self._name, id(self))