1 # -------------------------------------------------------------------------
2 # Copyright (c) 2015-2017 AT&T Intellectual Property
4 # Licensed under the Apache License, Version 2.0 (the "License");
5 # you may not use this file except in compliance with the License.
6 # You may obtain a copy of the License at
8 # http://www.apache.org/licenses/LICENSE-2.0
10 # Unless required by applicable law or agreed to in writing, software
11 # distributed under the License is distributed on an "AS IS" BASIS,
12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 # See the License for the specific language governing permissions and
14 # limitations under the License.
16 # -------------------------------------------------------------------------
24 """A dot-dict mixin to be able to access a dictionary via dot notation
25 source: https://stackoverflow.com/questions/2352181/how-to-use-a-dot-to-access-members-of-dictionary
27 __getattr__ = dict.get
28 __setattr__ = dict.__setitem__
29 __delattr__ = dict.__delitem__
32 class MetaSingleton(type):
33 """Singleton class (2nd Chapter) from Learning Python Design Patterns - 2nd ed.
34 Chetan Giridhar, Packt Publ. 2016"""
37 def __call__(cls, *args, **kwargs):
38 if cls not in cls._instances:
39 cls._instances[cls] = super(MetaSingleton, cls).__call__(*args, **kwargs)
40 return cls._instances[cls]
43 def namedtuple_with_defaults(typename, field_names, default_values=()):
44 """A namedtuple with default values -- Stack overflow recipe from Mark Lodato
45 http://stackoverflow.com/questions/11351032/named-tuple-and-optional-keyword-arguments
46 :param typename: Name for the class (same as for namedtuple)
47 :param field_names: Field names (same as for namedtuple)
48 :param default_values: Can be specified as a dictionary or as a list
49 :return: New namedtuple object
51 T = collections.namedtuple(typename, field_names)
52 T.__new__.__defaults__ = (None,) * len(T._fields)
53 if isinstance(default_values, collections.Mapping):
54 prototype = T(**default_values)
56 prototype = T(*default_values)
57 T.__new__.__defaults__ = tuple(prototype)
61 def dot_notation(dict_like, dot_spec):
62 """Return the value corresponding to the dot_spec from a dict_like object
63 :param dict_like: dictionary, JSON, etc.
64 :param dot_spec: a dot notation (e.g. a1.b1.c1.d1 => a1["b1"]["c1"]["d1"])
65 :return: the value referenced by the dot_spec
67 attrs = dot_spec.split(".") # we split the path
68 parent = dict_like.get(attrs[0])
69 children = ".".join(attrs[1:])
70 if not (parent and children): # if no children or no parent, bail out
72 if isinstance(parent, list): # here, we apply remaining path spec to all children
73 return [dot_notation(j, children) for j in parent]
74 elif isinstance(parent, dict):
75 return dot_notation(parent, children)
82 Flatten a complex nested list of nested lists into a flat list (DFS).
83 For example, [ [1, 2], [[[2,3,4], [2,3,4]], [3,4,5, 'hello']]]
84 will produce [1, 2, 2, 3, 4, 2, 3, 4, 3, 4, 5, 'hello']
86 return list(itertools.chain(*[list_flatten(j) if isinstance(j, list) else [j] for j in l]))
89 def inverted_dict(keys: list, key_val_dict: dict) -> dict:
91 Get val -> [keys] mapping for the given keys using key_val_dict
92 :param keys: the keys we are interested in (a list)
93 :param key_val_dict: the key -> val mapping
94 :return: inverted dictionary of val -> [keys] (for the subset dict of given keys)
97 all_tuples = ((k, key_val_dict[k] if k in key_val_dict else 'no-parent-' + k) for k in keys)
98 for k, v in all_tuples:
103 # making sure to remove duplicate keys
104 res = dict((v, list(set(k_list))) for v, k_list in res.items())