lib/yaml/representer.py

   1
   2 __all__ = ['BaseRepresenter', 'SafeRepresenter', 'Representer',
   3     'RepresenterError']
   4
   5 from error import *
   6 from nodes import *
   7
   8 import datetime
   9
  10 try:
  11     set
  12 except NameError:
  13     from sets import Set as set
  14
  15 import sys, copy_reg, types
  16
  17 class RepresenterError(YAMLError):
  18     pass
  19
  20 class BaseRepresenter(object):
  21
  22     yaml_representers = {}
  23     yaml_multi_representers = {}
  24
  25     def __init__(self, default_style=None, default_flow_style=None):
  26         self.default_style = default_style
  27         self.default_flow_style = default_flow_style
  28         self.represented_objects = {}
  29         self.object_keeper = []
  30         self.alias_key = None
  31
  32     def represent(self, data):
  33         node = self.represent_data(data)
  34         self.serialize(node)
  35         self.represented_objects = {}
  36         self.object_keeper = []
  37         self.alias_key = None
  38
  39     def get_classobj_bases(self, cls):
  40         bases = [cls]
  41         for base in cls.__bases__:
  42             bases.extend(self.get_classobj_bases(base))
  43         return bases
  44
  45     def represent_data(self, data):
  46         if self.ignore_aliases(data):
  47             self.alias_key = None
  48         else:
  49             self.alias_key = id(data)
  50         if self.alias_key is not None:
  51             if self.alias_key in self.represented_objects:
  52                 node = self.represented_objects[self.alias_key]
  53                 #if node is None:
  54                 #    raise RepresenterError("recursive objects are not allowed: %r" % data)
  55                 return node
  56             #self.represented_objects[alias_key] = None
  57             self.object_keeper.append(data)
  58         data_types = type(data).__mro__
  59         if type(data) is types.InstanceType:
  60             data_types = self.get_classobj_bases(data.__class__)+list(data_types)
  61         if data_types[0] in self.yaml_representers:
  62             node = self.yaml_representers[data_types[0]](self, data)
  63         else:
  64             for data_type in data_types:
  65                 if data_type in self.yaml_multi_representers:
  66                     node = self.yaml_multi_representers[data_type](self, data)
  67                     break
  68             else:
  69                 if None in self.yaml_multi_representers:
  70                     node = self.yaml_multi_representers[None](self, data)
  71                 elif None in self.yaml_representers:
  72                     node = self.yaml_representers[None](self, data)
  73                 else:
  74                     node = ScalarNode(None, unicode(data))
  75         #if alias_key is not None:
  76         #    self.represented_objects[alias_key] = node
  77         return node
  78
  79     def add_representer(cls, data_type, representer):
  80         if not 'yaml_representers' in cls.__dict__:
  81             cls.yaml_representers = cls.yaml_representers.copy()
  82         cls.yaml_representers[data_type] = representer
  83     add_representer = classmethod(add_representer)
  84
  85     def add_multi_representer(cls, data_type, representer):
  86         if not 'yaml_multi_representers' in cls.__dict__:
  87             cls.yaml_multi_representers = cls.yaml_multi_representers.copy()
  88         cls.yaml_multi_representers[data_type] = representer
  89     add_multi_representer = classmethod(add_multi_representer)
  90
  91     def represent_scalar(self, tag, value, style=None):
  92         if style is None:
  93             style = self.default_style
  94         node = ScalarNode(tag, value, style=style)
  95         if self.alias_key is not None:
  96             self.represented_objects[self.alias_key] = node
  97         return node
  98
  99     def represent_sequence(self, tag, sequence, flow_style=None):
 100         value = []
 101         node = SequenceNode(tag, value, flow_style=flow_style)
 102         if self.alias_key is not None:
 103             self.represented_objects[self.alias_key] = node
 104         best_style = True
 105         for item in sequence:
 106             node_item = self.represent_data(item)
 107             if not (isinstance(node_item, ScalarNode) and not node_item.style):
 108                 best_style = False
 109             value.append(node_item)
 110         if flow_style is None:
 111             if self.default_flow_style is not None:
 112                 node.flow_style = self.default_flow_style
 113             else:
 114                 node.flow_style = best_style
 115         return node
 116
 117     def represent_mapping(self, tag, mapping, flow_style=None):
 118         value = []
 119         node = MappingNode(tag, value, flow_style=flow_style)
 120         if self.alias_key is not None:
 121             self.represented_objects[self.alias_key] = node
 122         best_style = True
 123         if hasattr(mapping, 'items'):
 124             mapping = mapping.items()
 125             mapping.sort()
 126         for item_key, item_value in mapping:
 127             node_key = self.represent_data(item_key)
 128             node_value = self.represent_data(item_value)
 129             if not (isinstance(node_key, ScalarNode) and not node_key.style):
 130                 best_style = False
 131             if not (isinstance(node_value, ScalarNode) and not node_value.style):
 132                 best_style = False
 133             value.append((node_key, node_value))
 134         if flow_style is None:
 135             if self.default_flow_style is not None:
 136                 node.flow_style = self.default_flow_style
 137             else:
 138                 node.flow_style = best_style
 139         return node
 140
 141     def ignore_aliases(self, data):
 142         return False
 143
 144 class SafeRepresenter(BaseRepresenter):
 145
 146     def ignore_aliases(self, data):
 147         if data in [None, ()]:
 148             return True
 149         if isinstance(data, (str, unicode, bool, int, float)):
 150             return True
 151
 152     def represent_none(self, data):
 153         return self.represent_scalar(u'tag:yaml.org,2002:null',
 154                 u'null')
 155
 156     def represent_str(self, data):
 157         tag = None
 158         style = None
 159         try:
 160             data = unicode(data, 'ascii')
 161             tag = u'tag:yaml.org,2002:str'
 162         except UnicodeDecodeError:
 163             try:
 164                 data = unicode(data, 'utf-8')
 165                 tag = u'tag:yaml.org,2002:str'
 166             except UnicodeDecodeError:
 167                 data = data.encode('base64')
 168                 tag = u'tag:yaml.org,2002:binary'
 169                 style = '|'
 170         return self.represent_scalar(tag, data, style=style)
 171
 172     def represent_unicode(self, data):
 173         return self.represent_scalar(u'tag:yaml.org,2002:str', data)
 174
 175     def represent_bool(self, data):
 176         if data:
 177             value = u'true'
 178         else:
 179             value = u'false'
 180         return self.represent_scalar(u'tag:yaml.org,2002:bool', value)
 181
 182     def represent_int(self, data):
 183         return self.represent_scalar(u'tag:yaml.org,2002:int', unicode(data))
 184
 185     def represent_long(self, data):
 186         return self.represent_scalar(u'tag:yaml.org,2002:int', unicode(data))
 187
 188     inf_value = 1e300
 189     while repr(inf_value) != repr(inf_value*inf_value):
 190         inf_value *= inf_value
 191
 192     def represent_float(self, data):
 193         if data != data or (data == 0.0 and data == 1.0):
 194             value = u'.nan'
 195         elif data == self.inf_value:
 196             value = u'.inf'
 197         elif data == -self.inf_value:
 198             value = u'-.inf'
 199         else:
 200             value = unicode(repr(data)).lower()
 201             # Note that in some cases `repr(data)` represents a float number
 202             # without the decimal parts.  For instance:
 203             #   >>> repr(1e17)
 204             #   '1e17'
 205             # Unfortunately, this is not a valid float representation according
 206             # to the definition of the `!!float` tag.  We fix this by adding
 207             # '.0' before the 'e' symbol.
 208             if u'.' not in value and u'e' in value:
 209                 value = value.replace(u'e', u'.0e', 1)
 210         return self.represent_scalar(u'tag:yaml.org,2002:float', value)
 211
 212     def represent_list(self, data):
 213         #pairs = (len(data) > 0 and isinstance(data, list))
 214         #if pairs:
 215         #    for item in data:
 216         #        if not isinstance(item, tuple) or len(item) != 2:
 217         #            pairs = False
 218         #            break
 219         #if not pairs:
 220             return self.represent_sequence(u'tag:yaml.org,2002:seq', data)
 221         #value = []
 222         #for item_key, item_value in data:
 223         #    value.append(self.represent_mapping(u'tag:yaml.org,2002:map',
 224         #        [(item_key, item_value)]))
 225         #return SequenceNode(u'tag:yaml.org,2002:pairs', value)
 226
 227     def represent_dict(self, data):
 228         return self.represent_mapping(u'tag:yaml.org,2002:map', data)
 229
 230     def represent_set(self, data):
 231         value = {}
 232         for key in data:
 233             value[key] = None
 234         return self.represent_mapping(u'tag:yaml.org,2002:set', value)
 235
 236     def represent_date(self, data):
 237         value = unicode(data.isoformat())
 238         return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
 239
 240     def represent_datetime(self, data):
 241         value = unicode(data.isoformat(' '))
 242         return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
 243
 244     def represent_yaml_object(self, tag, data, cls, flow_style=None):
 245         if hasattr(data, '__getstate__'):
 246             state = data.__getstate__()
 247         else:
 248             state = data.__dict__.copy()
 249         return self.represent_mapping(tag, state, flow_style=flow_style)
 250
 251     def represent_undefined(self, data):
 252         raise RepresenterError("cannot represent an object: %s" % data)
 253
 254 SafeRepresenter.add_representer(type(None),
 255         SafeRepresenter.represent_none)
 256
 257 SafeRepresenter.add_representer(str,
 258         SafeRepresenter.represent_str)
 259
 260 SafeRepresenter.add_representer(unicode,
 261         SafeRepresenter.represent_unicode)
 262
 263 SafeRepresenter.add_representer(bool,
 264         SafeRepresenter.represent_bool)
 265
 266 SafeRepresenter.add_representer(int,
 267         SafeRepresenter.represent_int)
 268
 269 SafeRepresenter.add_representer(long,
 270         SafeRepresenter.represent_long)
 271
 272 SafeRepresenter.add_representer(float,
 273         SafeRepresenter.represent_float)
 274
 275 SafeRepresenter.add_representer(list,
 276         SafeRepresenter.represent_list)
 277
 278 SafeRepresenter.add_representer(tuple,
 279         SafeRepresenter.represent_list)
 280
 281 SafeRepresenter.add_representer(dict,
 282         SafeRepresenter.represent_dict)
 283
 284 SafeRepresenter.add_representer(set,
 285         SafeRepresenter.represent_set)
 286
 287 SafeRepresenter.add_representer(datetime.date,
 288         SafeRepresenter.represent_date)
 289 SafeRepresenter.add_representer(datetime.datetime,
 290         SafeRepresenter.represent_datetime)
 291
 292 SafeRepresenter.add_representer(None,
 293         SafeRepresenter.represent_undefined)
 294
 295 class Representer(SafeRepresenter):
 296
 297     def represent_str(self, data):
 298         tag = None
 299         style = None
 300         try:
 301             data = unicode(data, 'ascii')
 302             tag = u'tag:yaml.org,2002:str'
 303         except UnicodeDecodeError:
 304             try:
 305                 data = unicode(data, 'utf-8')
 306                 tag = u'tag:yaml.org,2002:python/str'
 307             except UnicodeDecodeError:
 308                 data = data.encode('base64')
 309                 tag = u'tag:yaml.org,2002:binary'
 310                 style = '|'
 311         return self.represent_scalar(tag, data, style=style)
 312
 313     def represent_unicode(self, data):
 314         tag = None
 315         try:
 316             data.encode('ascii')
 317             tag = u'tag:yaml.org,2002:python/unicode'
 318         except UnicodeEncodeError:
 319             tag = u'tag:yaml.org,2002:str'
 320         return self.represent_scalar(tag, data)
 321
 322     def represent_long(self, data):
 323         tag = u'tag:yaml.org,2002:int'
 324         if int(data) is not data:
 325             tag = u'tag:yaml.org,2002:python/long'
 326         return self.represent_scalar(tag, unicode(data))
 327
 328     def represent_complex(self, data):
 329         if data.imag == 0.0:
 330             data = u'%r' % data.real
 331         elif data.real == 0.0:
 332             data = u'%rj' % data.imag
 333         elif data.imag > 0:
 334             data = u'%r+%rj' % (data.real, data.imag)
 335         else:
 336             data = u'%r%rj' % (data.real, data.imag)
 337         return self.represent_scalar(u'tag:yaml.org,2002:python/complex', data)
 338
 339     def represent_tuple(self, data):
 340         return self.represent_sequence(u'tag:yaml.org,2002:python/tuple', data)
 341
 342     def represent_name(self, data):
 343         name = u'%s.%s' % (data.__module__, data.__name__)
 344         return self.represent_scalar(u'tag:yaml.org,2002:python/name:'+name, u'')
 345
 346     def represent_module(self, data):
 347         return self.represent_scalar(
 348                 u'tag:yaml.org,2002:python/module:'+data.__name__, u'')
 349
 350     def represent_instance(self, data):
 351         # For instances of classic classes, we use __getinitargs__ and
 352         # __getstate__ to serialize the data.
 353
 354         # If data.__getinitargs__ exists, the object must be reconstructed by
 355         # calling cls(**args), where args is a tuple returned by
 356         # __getinitargs__. Otherwise, the cls.__init__ method should never be
 357         # called and the class instance is created by instantiating a trivial
 358         # class and assigning to the instance's __class__ variable.
 359
 360         # If data.__getstate__ exists, it returns the state of the object.
 361         # Otherwise, the state of the object is data.__dict__.
 362
 363         # We produce either a !!python/object or !!python/object/new node.
 364         # If data.__getinitargs__ does not exist and state is a dictionary, we
 365         # produce a !!python/object node . Otherwise we produce a
 366         # !!python/object/new node.
 367
 368         cls = data.__class__
 369         class_name = u'%s.%s' % (cls.__module__, cls.__name__)
 370         args = None
 371         state = None
 372         if hasattr(data, '__getinitargs__'):
 373             args = list(data.__getinitargs__())
 374         if hasattr(data, '__getstate__'):
 375             state = data.__getstate__()
 376         else:
 377             state = data.__dict__
 378         if args is None and isinstance(state, dict):
 379             return self.represent_mapping(
 380                     u'tag:yaml.org,2002:python/object:'+class_name, state)
 381         if isinstance(state, dict) and not state:
 382             return self.represent_sequence(
 383                     u'tag:yaml.org,2002:python/object/new:'+class_name, args)
 384         value = {}
 385         if args:
 386             value['args'] = args
 387         value['state'] = state
 388         return self.represent_mapping(
 389                 u'tag:yaml.org,2002:python/object/new:'+class_name, value)
 390
 391     def represent_object(self, data):
 392         # We use __reduce__ API to save the data. data.__reduce__ returns
 393         # a tuple of length 2-5:
 394         #   (function, args, state, listitems, dictitems)
 395
 396         # For reconstructing, we calls function(*args), then set its state,
 397         # listitems, and dictitems if they are not None.
 398
 399         # A special case is when function.__name__ == '__newobj__'. In this
 400         # case we create the object with args[0].__new__(*args).
 401
 402         # Another special case is when __reduce__ returns a string - we don't
 403         # support it.
 404
 405         # We produce a !!python/object, !!python/object/new or
 406         # !!python/object/apply node.
 407
 408         cls = type(data)
 409         if cls in copy_reg.dispatch_table:
 410             reduce = copy_reg.dispatch_table[cls](data)
 411         elif hasattr(data, '__reduce_ex__'):
 412             reduce = data.__reduce_ex__(2)
 413         elif hasattr(data, '__reduce__'):
 414             reduce = data.__reduce__()
 415         else:
 416             raise RepresenterError("cannot represent object: %r" % data)
 417         reduce = (list(reduce)+[None]*5)[:5]
 418         function, args, state, listitems, dictitems = reduce
 419         args = list(args)
 420         if state is None:
 421             state = {}
 422         if listitems is not None:
 423             listitems = list(listitems)
 424         if dictitems is not None:
 425             dictitems = dict(dictitems)
 426         if function.__name__ == '__newobj__':
 427             function = args[0]
 428             args = args[1:]
 429             tag = u'tag:yaml.org,2002:python/object/new:'
 430             newobj = True
 431         else:
 432             tag = u'tag:yaml.org,2002:python/object/apply:'
 433             newobj = False
 434         function_name = u'%s.%s' % (function.__module__, function.__name__)
 435         if not args and not listitems and not dictitems \
 436                 and isinstance(state, dict) and newobj:
 437             return self.represent_mapping(
 438                     u'tag:yaml.org,2002:python/object:'+function_name, state)
 439         if not listitems and not dictitems  \
 440                 and isinstance(state, dict) and not state:
 441             return self.represent_sequence(tag+function_name, args)
 442         value = {}
 443         if args:
 444             value['args'] = args
 445         if state or not isinstance(state, dict):
 446             value['state'] = state
 447         if listitems:
 448             value['listitems'] = listitems
 449         if dictitems:
 450             value['dictitems'] = dictitems
 451         return self.represent_mapping(tag+function_name, value)
 452
 453 Representer.add_representer(str,
 454         Representer.represent_str)
 455
 456 Representer.add_representer(unicode,
 457         Representer.represent_unicode)
 458
 459 Representer.add_representer(long,
 460         Representer.represent_long)
 461
 462 Representer.add_representer(complex,
 463         Representer.represent_complex)
 464
 465 Representer.add_representer(tuple,
 466         Representer.represent_tuple)
 467
 468 Representer.add_representer(type,
 469         Representer.represent_name)
 470
 471 Representer.add_representer(types.ClassType,
 472         Representer.represent_name)
 473
 474 Representer.add_representer(types.FunctionType,
 475         Representer.represent_name)
 476
 477 Representer.add_representer(types.BuiltinFunctionType,
 478         Representer.represent_name)
 479
 480 Representer.add_representer(types.ModuleType,
 481         Representer.represent_module)
 482
 483 Representer.add_multi_representer(types.InstanceType,
 484         Representer.represent_instance)
 485
 486 Representer.add_multi_representer(object,
 487         Representer.represent_object)
 488