Source Code for Module flumotion.common.enum

  1  # -*- Mode: Python; test-case-name: flumotion.test.test_enum -*- 
  2  # vi:si:et:sw=4:sts=4:ts=4 
  3  # 
  4  # Flumotion - a streaming media server 
  5  # Copyright (C) 2004,2005,2006,2007 Fluendo, S.L. (www.fluendo.com). 
  6  # All rights reserved. 
  7   
  8  # This file may be distributed and/or modified under the terms of 
  9  # the GNU General Public License version 2 as published by 
 10  # the Free Software Foundation. 
 11  # This file is distributed without any warranty; without even the implied 
 12  # warranty of merchantability or fitness for a particular purpose. 
 13  # See "LICENSE.GPL" in the source distribution for more information. 
 14   
 15  # Licensees having purchased or holding a valid Flumotion Advanced 
 16  # Streaming Server license may use this file in accordance with the 
 17  # Flumotion Advanced Streaming Server Commercial License Agreement. 
 18  # See "LICENSE.Flumotion" in the source distribution for more information. 
 19   
 20  # Headers in this file shall remain intact. 
 21   
 22  """ 
 23  Enum class implementation 
 24  """ 
 25   
 26  from twisted.python.reflect import qual 
 27  from twisted.spread import jelly 
 28   
 29  _enumClassRegistry = {} 
 30   
 31 -class EnumMetaClass(type): 
 32      # pychecker likes this attribute to be there since we use it in this class 
 33      __enums__ = {} 
 34   
 35 -    def __len__(self): 
 36          return len(self.__enums__) 
 37   
 38 -    def __getitem__(self, value): 
 39          try: 
 40              return self.__enums__[value] 
 41          except KeyError: 
 42              raise StopIteration 
 43   
 44 -    def __setitem__(self, value, enum): 
 45          self.__enums__[value] = enum 
 46          setattr(self, enum.name, enum) 
 47   
 48   
 49 -class Enum(object, jelly.Jellyable): 
 50   
 51      __metaclass__ = EnumMetaClass 
 52 -    def __init__(self, value, name, nick=None): 
 53          self.value = value 
 54          self.name = name 
 55   
 56          if nick == None: 
 57              nick = name 
 58   
 59          self.nick = nick 
 60          self._enumClassName = self.__class__.__name__ 
 61   
 62 -    def __repr__(self): 
 63          return '<enum %s of type %s>' % (self.name, 
 64                                           self.__class__.__name__) 
 65   
 66 -    def get(klass, value): 
 67          return klass.__enums__[value] 
 68      get = classmethod(get) 
 69   
 70 -    def set(klass, value, item): 
 71          klass[value] = item 
 72      set = classmethod(set) 
 73   
 74 -    def jellyFor(self, jellier): 
 75          sxp = jellier.prepare(self) 
 76          sxp.extend([ 
 77              qual(Enum), 
 78              self._enumClassName, 
 79              self.value, self.name, self.nick]) 
 80          return jellier.preserve(self, sxp) 
 81   
 82   
 83 -class EnumClass(object): 
 84 -    def __new__(klass, type_name, names=(), nicks=(), **extras): 
 85          if nicks: 
 86              if len(names) != len(nicks): 
 87                  raise TypeError("nicks must have the same length as names") 
 88          else: 
 89              nicks = names 
 90   
 91          for extra in extras.values(): 
 92              if not isinstance(extra, tuple): 
 93                  raise TypeError('extra must be a tuple, not %s' % type(extra)) 
 94   
 95              if len(extra) != len(names): 
 96                  raise TypeError("extra items must have a length of %d" % 
 97                                  len(names)) 
 98   
 99          # we reset __enums__ to {} otherwise it retains the other registered 
100          # ones 
101          etype = EnumMetaClass(type_name, (Enum,), {'__enums__': {}}) 
102          for value, name in enumerate(names): 
103              enum = etype(value, name, nicks[value]) 
104              for extra_key, extra_values in extras.items(): 
105                  assert not hasattr(enum, extra_key) 
106                  setattr(enum, extra_key, extra_values[value]) 
107              etype[value] = enum 
108   
109          _enumClassRegistry[type_name] = etype 
110          return etype 
111   
112   
113  # Enum unjellyer should not be a new style class, 
114  # otherwise Twsited 2.0.1 will not recognise it. 
115 -class EnumUnjellyer(jelly.Unjellyable): 
116   
117 -    def unjellyFor(self, unjellier, jellyList): 
118          enumClassName, value, name, nick = jellyList[1:] 
119          enumClass = _enumClassRegistry.get(enumClassName, None) 
120          if enumClass: 
121              # Retrieve the enum singleton 
122              enum = enumClass.get(value) 
123              assert enum.name == name, "Inconsistent Enum Name" 
124          else: 
125              # Create a generic Enum container 
126              enum = Enum(value, name, nick) 
127              enum._enumClassName = enumClassName 
128          return enum 
129   
130   
131  jelly.setUnjellyableForClass(qual(Enum), EnumUnjellyer) 
132