Source Code for Module wsgiwapi.overlaydict

 1  # Copyright (c) 2009 Richard Boulton 
 2  # 
 3  # Permission is hereby granted, free of charge, to any person obtaining a copy 
 4  # of this software and associated documentation files (the "Software"), to deal 
 5  # in the Software without restriction, including without limitation the rights 
 6  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
 7  # copies of the Software, and to permit persons to whom the Software is 
 8  # furnished to do so, subject to the following conditions: 
 9  # 
10  # The above copyright notice and this permission notice shall be included in 
11  # all copies or substantial portions of the Software. 
12  # 
13  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
14  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
15  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
16  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
17  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
18  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 
19  # SOFTWARE. 
20  r"""Overlay one dict on top of another. 
21   
22  """ 
23  __docformat__ = "restructuredtext en" 
24   
25  import UserDict 
26   
27 -class _Unused(object): 
28      """Sentinel class used for initial value of lastkey. 
29   
30      """ 
31      pass 
32   
33 -class OverlayDict(UserDict.DictMixin): 
34      """A dictionary which behaves as if one dict is layered on top of another. 
35   
36      """ 
37 -    def __init__(self, dict1, dict2): 
38          self.dict1 = dict1 
39          self.dict2 = dict2 
40   
41 -    def __contains__(self, key): 
42          if key in self.dict1: 
43              return True 
44          return key in self.dict2 
45   
46 -    def __getitem__(self, key): 
47          try: 
48              items = self.dict1[key] 
49              try: 
50                  items2 = self.dict2[key] 
51                  return items + items2 
52              except KeyError: 
53                  return items 
54          except KeyError: 
55              return self.dict2[key] 
56   
57 -    def __iter__(self): 
58          keys = self.dict1.keys() 
59          keys.extend(self.dict2.keys()) 
60          keys.sort() 
61          lastkey = _Unused 
62          for key in keys: 
63              if key != lastkey: 
64                  yield key 
65                  lastkey = key 
66   
67 -    def keys(self): 
68          return list(iter(self)) 
69   
70  # vim: set fileencoding=utf-8 : 
71