Add a CLIArgs Singleton class that will hold the parse cli arguments

lib/ansible/module_utils/common/collections.py

@@ -1,4 +1,5 @@
-# Copyright (c), Sviatoslav Sydorenko <ssydoren@redhat.com> 2018
+# Copyright: (c) 2018, Sviatoslav Sydorenko <ssydoren@redhat.com>
+# Copyright: (c) 2018, Ansible Project
 # Simplified BSD License (see licenses/simplified_bsd.txt or https://opensource.org/licenses/BSD-2-Clause)
 """Collection of low-level utility functions."""
 
@@ -7,7 +8,52 @@ __metaclass__ = type
 
 
 from ansible.module_utils.six import binary_type, text_type
-from ansible.module_utils.common._collections_compat import Sequence
+from ansible.module_utils.common._collections_compat import Hashable, Mapping, Sequence
+
+
+class ImmutableDict(Hashable, Mapping):
+    """Dictionary that cannot be updated"""
+    def __init__(self, *args, **kwargs):
+        self._store = dict(*args, **kwargs)
+
+    def __getitem__(self, key):
+        return self._store[key]
+
+    def __iter__(self):
+        return self._store.__iter__()
+
+    def __len__(self):
+        return self._store.__len__()
+
+    def __hash__(self):
+        return hash(frozenset(self.items()))
+
+    def __repr__(self):
+        return 'ImmutableDict({0})'.format(repr(self._store))
+
+    def union(self, overriding_mapping):
+        """
+        Create an ImmutableDict as a combination of the original and overriding_mapping
+
+        :arg overriding_mapping: A Mapping of replacement and additional items
+        :return: A copy of the ImmutableDict with key-value pairs from the overriding_mapping added
+
+        If any of the keys in overriding_mapping are already present in the original ImmutableDict,
+        the overriding_mapping item replaces the one in the original ImmutableDict.
+        """
+        return ImmutableDict(self._store, **overriding_mapping)
+
+    def difference(self, subtractive_iterable):
+        """
+        Create an ImmutableDict as a combination of the original minus keys in subtractive_iterable
+
+        :arg subtractive_iterable: Any iterable containing keys that should not be present in the
+            new ImmutableDict
+        :return: A copy of the ImmutableDict with keys from the subtractive_iterable removed
+        """
+        remove_keys = frozenset(subtractive_iterable)
+        keys = (k for k in self._store.keys() if k not in remove_keys)
+        return ImmutableDict((k, self._store[k]) for k in keys)
 
 
 def is_string(seq):