1 | # -*- test-case-name: wokkel.test.test_compat -*- |
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2 | # |
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3 | # Copyright (c) Twisted Matrix Laboratories. |
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4 | # See LICENSE for details. |
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5 | |
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6 | """ |
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7 | Compatibility module to provide backwards compatibility with Twisted features. |
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8 | """ |
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9 | |
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10 | __all__ = ['BootstrapMixin', 'XmlStreamServerFactory', 'IQ', |
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11 | 'NamedConstant', 'ValueConstant', 'Names', 'Values'] |
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12 | |
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13 | from itertools import count |
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14 | |
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15 | from twisted.internet import protocol |
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16 | from twisted.words.protocols.jabber import xmlstream |
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17 | |
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18 | class BootstrapMixin(object): |
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19 | """ |
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20 | XmlStream factory mixin to install bootstrap event observers. |
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21 | |
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22 | This mixin is for factories providing |
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23 | L{IProtocolFactory<twisted.internet.interfaces.IProtocolFactory>} to make |
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24 | sure bootstrap event observers are set up on protocols, before incoming |
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25 | data is processed. Such protocols typically derive from |
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26 | L{utility.EventDispatcher}, like L{XmlStream}. |
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27 | |
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28 | You can set up bootstrap event observers using C{addBootstrap}. The |
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29 | C{event} and C{fn} parameters correspond with the C{event} and |
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30 | C{observerfn} arguments to L{utility.EventDispatcher.addObserver}. |
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31 | |
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32 | @since: 8.2. |
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33 | @ivar bootstraps: The list of registered bootstrap event observers. |
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34 | @type bootstrap: C{list} |
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35 | """ |
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36 | |
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37 | def __init__(self): |
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38 | self.bootstraps = [] |
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39 | |
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40 | |
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41 | def installBootstraps(self, dispatcher): |
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42 | """ |
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43 | Install registered bootstrap observers. |
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44 | |
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45 | @param dispatcher: Event dispatcher to add the observers to. |
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46 | @type dispatcher: L{utility.EventDispatcher} |
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47 | """ |
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48 | for event, fn in self.bootstraps: |
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49 | dispatcher.addObserver(event, fn) |
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50 | |
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51 | |
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52 | def addBootstrap(self, event, fn): |
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53 | """ |
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54 | Add a bootstrap event handler. |
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55 | |
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56 | @param event: The event to register an observer for. |
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57 | @type event: C{str} or L{xpath.XPathQuery} |
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58 | @param fn: The observer callable to be registered. |
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59 | """ |
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60 | self.bootstraps.append((event, fn)) |
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61 | |
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62 | |
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63 | def removeBootstrap(self, event, fn): |
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64 | """ |
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65 | Remove a bootstrap event handler. |
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66 | |
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67 | @param event: The event the observer is registered for. |
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68 | @type event: C{str} or L{xpath.XPathQuery} |
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69 | @param fn: The registered observer callable. |
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70 | """ |
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71 | self.bootstraps.remove((event, fn)) |
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72 | |
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73 | |
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74 | |
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75 | class XmlStreamServerFactory(BootstrapMixin, |
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76 | protocol.ServerFactory): |
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77 | """ |
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78 | Factory for Jabber XmlStream objects as a server. |
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79 | |
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80 | @since: 8.2. |
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81 | @ivar authenticatorFactory: Factory callable that takes no arguments, to |
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82 | create a fresh authenticator to be associated |
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83 | with the XmlStream. |
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84 | """ |
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85 | |
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86 | protocol = xmlstream.XmlStream |
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87 | |
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88 | def __init__(self, authenticatorFactory): |
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89 | BootstrapMixin.__init__(self) |
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90 | self.authenticatorFactory = authenticatorFactory |
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91 | |
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92 | |
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93 | def buildProtocol(self, addr): |
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94 | """ |
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95 | Create an instance of XmlStream. |
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96 | |
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97 | A new authenticator instance will be created and passed to the new |
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98 | XmlStream. Registered bootstrap event observers are installed as well. |
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99 | """ |
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100 | authenticator = self.authenticatorFactory() |
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101 | xs = self.protocol(authenticator) |
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102 | xs.factory = self |
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103 | self.installBootstraps(xs) |
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104 | return xs |
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105 | |
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106 | |
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107 | |
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108 | class IQ(xmlstream.IQ): |
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109 | def __init__(self, *args, **kwargs): |
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110 | # Make sure we have a reactor parameter |
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111 | try: |
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112 | reactor = kwargs['reactor'] |
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113 | except KeyError: |
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114 | from twisted.internet import reactor |
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115 | kwargs['reactor'] = reactor |
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116 | |
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117 | # Check if IQ's init accepts the reactor parameter |
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118 | try: |
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119 | xmlstream.IQ.__init__(self, *args, **kwargs) |
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120 | except TypeError: |
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121 | # Guess not. Remove the reactor parameter and try again. |
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122 | del kwargs['reactor'] |
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123 | xmlstream.IQ.__init__(self, *args, **kwargs) |
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124 | |
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125 | # Patch the XmlStream instance so that it has a _callLater |
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126 | self._xmlstream._callLater = reactor.callLater |
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127 | |
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128 | |
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129 | |
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130 | _unspecified = object() |
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131 | _constantOrder = count().next |
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132 | |
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133 | |
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134 | class _Constant(object): |
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135 | """ |
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136 | @ivar _index: A C{int} allocated from a shared counter in order to keep |
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137 | track of the order in which L{_Constant}s are instantiated. |
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138 | |
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139 | @ivar name: A C{str} giving the name of this constant; only set once the |
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140 | constant is initialized by L{_ConstantsContainer}. |
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141 | |
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142 | @ivar _container: The L{_ConstantsContainer} subclass this constant belongs |
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143 | to; only set once the constant is initialized by that subclass. |
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144 | """ |
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145 | def __init__(self): |
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146 | self._index = _constantOrder() |
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147 | |
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148 | |
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149 | def __get__(self, oself, cls): |
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150 | """ |
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151 | Ensure this constant has been initialized before returning it. |
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152 | """ |
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153 | cls._initializeEnumerants() |
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154 | return self |
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155 | |
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156 | |
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157 | def __repr__(self): |
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158 | """ |
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159 | Return text identifying both which constant this is and which collection |
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160 | it belongs to. |
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161 | """ |
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162 | return "<%s=%s>" % (self._container.__name__, self.name) |
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163 | |
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164 | |
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165 | def _realize(self, container, name, value): |
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166 | """ |
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167 | Complete the initialization of this L{_Constant}. |
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168 | |
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169 | @param container: The L{_ConstantsContainer} subclass this constant is |
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170 | part of. |
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171 | |
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172 | @param name: The name of this constant in its container. |
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173 | |
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174 | @param value: The value of this constant; not used, as named constants |
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175 | have no value apart from their identity. |
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176 | """ |
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177 | self._container = container |
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178 | self.name = name |
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179 | |
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180 | |
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181 | |
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182 | class _EnumerantsInitializer(object): |
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183 | """ |
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184 | L{_EnumerantsInitializer} is a descriptor used to initialize a cache of |
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185 | objects representing named constants for a particular L{_ConstantsContainer} |
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186 | subclass. |
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187 | """ |
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188 | def __get__(self, oself, cls): |
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189 | """ |
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190 | Trigger the initialization of the enumerants cache on C{cls} and then |
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191 | return it. |
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192 | """ |
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193 | cls._initializeEnumerants() |
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194 | return cls._enumerants |
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195 | |
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196 | |
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197 | |
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198 | class _ConstantsContainer(object): |
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199 | """ |
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200 | L{_ConstantsContainer} is a class with attributes used as symbolic |
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201 | constants. It is up to subclasses to specify what kind of constants are |
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202 | allowed. |
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203 | |
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204 | @cvar _constantType: Specified by a L{_ConstantsContainer} subclass to |
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205 | specify the type of constants allowed by that subclass. |
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206 | |
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207 | @cvar _enumerantsInitialized: A C{bool} tracking whether C{_enumerants} has |
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208 | been initialized yet or not. |
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209 | |
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210 | @cvar _enumerants: A C{dict} mapping the names of constants (eg |
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211 | L{NamedConstant} instances) found in the class definition to those |
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212 | instances. This is initialized via the L{_EnumerantsInitializer} |
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213 | descriptor the first time it is accessed. |
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214 | """ |
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215 | _constantType = None |
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216 | |
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217 | _enumerantsInitialized = False |
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218 | _enumerants = _EnumerantsInitializer() |
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219 | |
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220 | def __new__(cls): |
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221 | """ |
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222 | Classes representing constants containers are not intended to be |
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223 | instantiated. |
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224 | |
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225 | The class object itself is used directly. |
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226 | """ |
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227 | raise TypeError("%s may not be instantiated." % (cls.__name__,)) |
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228 | |
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229 | |
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230 | def _initializeEnumerants(cls): |
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231 | """ |
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232 | Find all of the L{NamedConstant} instances in the definition of C{cls}, |
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233 | initialize them with constant values, and build a mapping from their |
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234 | names to them to attach to C{cls}. |
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235 | """ |
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236 | if not cls._enumerantsInitialized: |
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237 | constants = [] |
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238 | for (name, descriptor) in cls.__dict__.iteritems(): |
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239 | if isinstance(descriptor, cls._constantType): |
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240 | constants.append((descriptor._index, name, descriptor)) |
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241 | enumerants = {} |
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242 | for (index, enumerant, descriptor) in constants: |
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243 | value = cls._constantFactory(enumerant) |
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244 | descriptor._realize(cls, enumerant, value) |
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245 | enumerants[enumerant] = descriptor |
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246 | # Replace the _enumerants descriptor with the result so future |
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247 | # access will go directly to the values. The _enumerantsInitialized |
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248 | # flag is still necessary because NamedConstant.__get__ may also |
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249 | # call this method. |
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250 | cls._enumerants = enumerants |
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251 | cls._enumerantsInitialized = True |
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252 | _initializeEnumerants = classmethod(_initializeEnumerants) |
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253 | |
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254 | |
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255 | def _constantFactory(cls, name): |
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256 | """ |
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257 | Construct the value for a new constant to add to this container. |
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258 | |
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259 | @param name: The name of the constant to create. |
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260 | |
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261 | @return: L{NamedConstant} instances have no value apart from identity, |
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262 | so return a meaningless dummy value. |
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263 | """ |
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264 | return _unspecified |
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265 | _constantFactory = classmethod(_constantFactory) |
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266 | |
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267 | |
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268 | def lookupByName(cls, name): |
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269 | """ |
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270 | Retrieve a constant by its name or raise a C{ValueError} if there is no |
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271 | constant associated with that name. |
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272 | |
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273 | @param name: A C{str} giving the name of one of the constants defined by |
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274 | C{cls}. |
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275 | |
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276 | @raise ValueError: If C{name} is not the name of one of the constants |
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277 | defined by C{cls}. |
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278 | |
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279 | @return: The L{NamedConstant} associated with C{name}. |
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280 | """ |
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281 | if name in cls._enumerants: |
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282 | return getattr(cls, name) |
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283 | raise ValueError(name) |
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284 | lookupByName = classmethod(lookupByName) |
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285 | |
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286 | |
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287 | def iterconstants(cls): |
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288 | """ |
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289 | Iteration over a L{Names} subclass results in all of the constants it |
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290 | contains. |
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291 | |
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292 | @return: an iterator the elements of which are the L{NamedConstant} |
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293 | instances defined in the body of this L{Names} subclass. |
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294 | """ |
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295 | constants = cls._enumerants.values() |
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296 | constants.sort(key=lambda descriptor: descriptor._index) |
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297 | return iter(constants) |
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298 | iterconstants = classmethod(iterconstants) |
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299 | |
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300 | |
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301 | |
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302 | class NamedConstant(_Constant): |
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303 | """ |
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304 | L{NamedConstant} defines an attribute to be a named constant within a |
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305 | collection defined by a L{Names} subclass. |
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306 | |
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307 | L{NamedConstant} is only for use in the definition of L{Names} |
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308 | subclasses. Do not instantiate L{NamedConstant} elsewhere and do not |
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309 | subclass it. |
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310 | """ |
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311 | |
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312 | |
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313 | |
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314 | class Names(_ConstantsContainer): |
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315 | """ |
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316 | A L{Names} subclass contains constants which differ only in their names and |
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317 | identities. |
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318 | """ |
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319 | _constantType = NamedConstant |
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320 | |
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321 | |
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322 | |
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323 | class ValueConstant(_Constant): |
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324 | """ |
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325 | L{ValueConstant} defines an attribute to be a named constant within a |
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326 | collection defined by a L{Values} subclass. |
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327 | |
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328 | L{ValueConstant} is only for use in the definition of L{Values} subclasses. |
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329 | Do not instantiate L{ValueConstant} elsewhere and do not subclass it. |
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330 | """ |
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331 | def __init__(self, value): |
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332 | _Constant.__init__(self) |
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333 | self.value = value |
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334 | |
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335 | |
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336 | |
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337 | class Values(_ConstantsContainer): |
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338 | """ |
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339 | A L{Values} subclass contains constants which are associated with arbitrary |
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340 | values. |
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341 | """ |
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342 | _constantType = ValueConstant |
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343 | |
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344 | def lookupByValue(cls, value): |
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345 | """ |
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346 | Retrieve a constant by its value or raise a C{ValueError} if there is no |
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347 | constant associated with that value. |
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348 | |
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349 | @param value: The value of one of the constants defined by C{cls}. |
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350 | |
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351 | @raise ValueError: If C{value} is not the value of one of the constants |
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352 | defined by C{cls}. |
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353 | |
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354 | @return: The L{ValueConstant} associated with C{value}. |
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355 | """ |
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356 | for constant in cls.iterconstants(): |
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357 | if constant.value == value: |
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358 | return constant |
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359 | raise ValueError(value) |
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360 | lookupByValue = classmethod(lookupByValue) |
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