lib/yaml/representer.py

   1
   2 __all__ = ['BaseRepresenter', 'SafeRepresenter', 'Representer',
   3     'RepresenterError']
   4
   5 from error import *
   6 from nodes import *
   7
   8 try:
   9     import datetime
  10     datetime_available = True
  11 except ImportError:
  12     datetime_available = False
  13
  14 try:
  15     set
  16 except NameError:
  17     from sets import Set as set
  18
  19 import sys, copy_reg
  20
  21 class RepresenterError(YAMLError):
  22     pass
  23
  24 class BaseRepresenter:
  25
  26     yaml_representers = {}
  27     yaml_multi_representers = {}
  28
  29     def __init__(self):
  30         self.represented_objects = {}
  31
  32     def represent(self, data):
  33         node = self.represent_data(data)
  34         self.serialize(node)
  35         self.represented_objects = {}
  36
  37     class C: pass
  38     c = C()
  39     def f(): pass
  40     classobj_type = type(C)
  41     instance_type = type(c)
  42     function_type = type(f)
  43     builtin_function_type = type(abs)
  44     module_type = type(sys)
  45     del C, c, f
  46
  47     def get_classobj_bases(self, cls):
  48         bases = [cls]
  49         for base in cls.__bases__:
  50             bases.extend(self.get_classobj_bases(base))
  51         return bases
  52
  53     def represent_data(self, data):
  54         if self.ignore_aliases(data):
  55             alias_key = None
  56         else:
  57             alias_key = id(data)
  58         if alias_key is not None:
  59             if alias_key in self.represented_objects:
  60                 node = self.represented_objects[alias_key]
  61                 if node is None:
  62                     raise RepresenterError("recursive objects are not allowed: %r" % data)
  63                 return node
  64             self.represented_objects[alias_key] = None
  65         data_types = type(data).__mro__
  66         if type(data) is self.instance_type:
  67             data_types = self.get_classobj_bases(data.__class__)+list(data_types)
  68         if data_types[0] in self.yaml_representers:
  69             node = self.yaml_representers[data_types[0]](self, data)
  70         else:
  71             for data_type in data_types:
  72                 if data_type in self.yaml_multi_representers:
  73                     node = self.yaml_multi_representers[data_type](self, data)
  74                     break
  75             else:
  76                 if None in self.yaml_multi_representers:
  77                     node = self.yaml_multi_representers[None](self, data)
  78                 elif None in self.yaml_representers:
  79                     node = self.yaml_representers[None](self, data)
  80                 else:
  81                     node = ScalarNode(None, unicode(data))
  82         if alias_key is not None:
  83             self.represented_objects[alias_key] = node
  84         return node
  85
  86     def add_representer(cls, data_type, representer):
  87         if not 'yaml_representers' in cls.__dict__:
  88             cls.yaml_representers = cls.yaml_representers.copy()
  89         cls.yaml_representers[data_type] = representer
  90     add_representer = classmethod(add_representer)
  91
  92     def add_multi_representer(cls, data_type, representer):
  93         if not 'yaml_multi_representers' in cls.__dict__:
  94             cls.yaml_multi_representers = cls.yaml_multi_representers.copy()
  95         cls.yaml_multi_representers[data_type] = representer
  96     add_multi_representer = classmethod(add_multi_representer)
  97
  98     def represent_scalar(self, tag, value, style=None):
  99         return ScalarNode(tag, value, style=style)
 100
 101     def represent_sequence(self, tag, sequence, flow_style=None):
 102         best_style = True
 103         value = []
 104         for item in sequence:
 105             node_item = self.represent_data(item)
 106             if not (isinstance(node_item, ScalarNode) and not node_item.style):
 107                 best_style = False
 108             value.append(self.represent_data(item))
 109         if flow_style is None:
 110             flow_style = best_style
 111         return SequenceNode(tag, value, flow_style=flow_style)
 112
 113     def represent_mapping(self, tag, mapping, flow_style=None):
 114         best_style = True
 115         if hasattr(mapping, 'keys'):
 116             value = {}
 117             for item_key in mapping.keys():
 118                 item_value = mapping[item_key]
 119                 node_key = self.represent_data(item_key)
 120                 node_value = self.represent_data(item_value)
 121                 if not (isinstance(node_key, ScalarNode) and not node_key.style):
 122                     best_style = False
 123                 if not (isinstance(node_value, ScalarNode) and not node_value.style):
 124                     best_style = False
 125                 value[node_key] = node_value
 126         else:
 127             value = []
 128             for item_key, item_value in mapping:
 129                 node_key = self.represent_data(item_key)
 130                 node_value = self.represent_data(item_value)
 131                 if not (isinstance(node_key, ScalarNode) and not node_key.style):
 132                     best_style = False
 133                 if not (isinstance(node_value, ScalarNode) and not node_value.style):
 134                     best_style = False
 135                 value.append((node_key, node_value))
 136         if flow_style is None:
 137             flow_style = best_style
 138         return MappingNode(tag, value, flow_style=flow_style)
 139
 140     def ignore_aliases(self, data):
 141         return False
 142
 143 class SafeRepresenter(BaseRepresenter):
 144
 145     def ignore_aliases(self, data):
 146         if data in [None, ()]:
 147             return True
 148         if isinstance(data, (str, unicode, bool, int, float)):
 149             return True
 150
 151     def represent_none(self, data):
 152         return self.represent_scalar(u'tag:yaml.org,2002:null',
 153                 u'null')
 154
 155     def represent_str(self, data):
 156         tag = None
 157         style = None
 158         try:
 159             data = unicode(data, 'ascii')
 160             tag = u'tag:yaml.org,2002:str'
 161         except UnicodeDecodeError:
 162             try:
 163                 data = unicode(data, 'utf-8')
 164                 tag = u'tag:yaml.org,2002:str'
 165             except UnicodeDecodeError:
 166                 data = data.encode('base64')
 167                 tag = u'tag:yaml.org,2002:binary'
 168                 style = '|'
 169         return self.represent_scalar(tag, data, style=style)
 170
 171     def represent_unicode(self, data):
 172         return self.represent_scalar(u'tag:yaml.org,2002:str', data)
 173
 174     def represent_bool(self, data):
 175         if data:
 176             value = u'true'
 177         else:
 178             value = u'false'
 179         return self.represent_scalar(u'tag:yaml.org,2002:bool', value)
 180
 181     def represent_int(self, data):
 182         return self.represent_scalar(u'tag:yaml.org,2002:int', unicode(data))
 183
 184     def represent_long(self, data):
 185         return self.represent_scalar(u'tag:yaml.org,2002:int', unicode(data))
 186
 187     inf_value = 1e300000
 188     nan_value = inf_value/inf_value
 189
 190     def represent_float(self, data):
 191         if data == self.inf_value:
 192             value = u'.inf'
 193         elif data == -self.inf_value:
 194             value = u'-.inf'
 195         elif data == self.nan_value or data != data:
 196             value = u'.nan'
 197         else:
 198             value = unicode(repr(data))
 199         return self.represent_scalar(u'tag:yaml.org,2002:float', value)
 200
 201     def represent_list(self, data):
 202         pairs = (len(data) > 0 and isinstance(data, list))
 203         if pairs:
 204             for item in data:
 205                 if not isinstance(item, tuple) or len(item) != 2:
 206                     pairs = False
 207                     break
 208         if not pairs:
 209             return self.represent_sequence(u'tag:yaml.org,2002:seq', data)
 210         value = []
 211         for item_key, item_value in data:
 212             value.append(self.represent_mapping(u'tag:yaml.org,2002:map',
 213                 [(item_key, item_value)]))
 214         return SequenceNode(u'tag:yaml.org,2002:pairs', value)
 215
 216     def represent_dict(self, data):
 217         return self.represent_mapping(u'tag:yaml.org,2002:map', data)
 218
 219     def represent_set(self, data):
 220         value = {}
 221         for key in data:
 222             value[key] = None
 223         return self.represent_mapping(u'tag:yaml.org,2002:set', value)
 224
 225     def represent_date(self, data):
 226         value = u'%04d-%02d-%02d' % (data.year, data.month, data.day)
 227         return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
 228
 229     def represent_datetime(self, data):
 230         value = u'%04d-%02d-%02d %02d:%02d:%02d' \
 231                 % (data.year, data.month, data.day,
 232                     data.hour, data.minute, data.second)
 233         if data.microsecond:
 234             value += u'.' + unicode(data.microsecond/1000000.0).split(u'.')[1]
 235         if data.utcoffset():
 236             value += unicode(data.utcoffset())
 237         return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
 238
 239     def represent_yaml_object(self, tag, data, cls, flow_style=None):
 240         if hasattr(data, '__getstate__'):
 241             state = data.__getstate__()
 242         else:
 243             state = data.__dict__.copy()
 244         if isinstance(state, dict):
 245             state = state.items()
 246             state.sort()
 247         return self.represent_mapping(tag, state, flow_style=flow_style)
 248
 249     def represent_undefined(self, data):
 250         raise RepresenterError("cannot represent an object: %s" % data)
 251
 252 SafeRepresenter.add_representer(type(None),
 253         SafeRepresenter.represent_none)
 254
 255 SafeRepresenter.add_representer(str,
 256         SafeRepresenter.represent_str)
 257
 258 SafeRepresenter.add_representer(unicode,
 259         SafeRepresenter.represent_unicode)
 260
 261 SafeRepresenter.add_representer(bool,
 262         SafeRepresenter.represent_bool)
 263
 264 SafeRepresenter.add_representer(int,
 265         SafeRepresenter.represent_int)
 266
 267 SafeRepresenter.add_representer(long,
 268         SafeRepresenter.represent_long)
 269
 270 SafeRepresenter.add_representer(float,
 271         SafeRepresenter.represent_float)
 272
 273 SafeRepresenter.add_representer(list,
 274         SafeRepresenter.represent_list)
 275
 276 SafeRepresenter.add_representer(tuple,
 277         SafeRepresenter.represent_list)
 278
 279 SafeRepresenter.add_representer(dict,
 280         SafeRepresenter.represent_dict)
 281
 282 SafeRepresenter.add_representer(set,
 283         SafeRepresenter.represent_set)
 284
 285 if datetime_available:
 286     SafeRepresenter.add_representer(datetime.date,
 287             SafeRepresenter.represent_date)
 288     SafeRepresenter.add_representer(datetime.datetime,
 289             SafeRepresenter.represent_datetime)
 290
 291 SafeRepresenter.add_representer(None,
 292         SafeRepresenter.represent_undefined)
 293
 294 class Representer(SafeRepresenter):
 295
 296     def represent_str(self, data):
 297         tag = None
 298         style = None
 299         try:
 300             data = unicode(data, 'ascii')
 301             tag = u'tag:yaml.org,2002:str'
 302         except UnicodeDecodeError:
 303             try:
 304                 data = unicode(data, 'utf-8')
 305                 tag = u'tag:yaml.org,2002:python/str'
 306             except UnicodeDecodeError:
 307                 data = data.encode('base64')
 308                 tag = u'tag:yaml.org,2002:binary'
 309                 style = '|'
 310         return self.represent_scalar(tag, data, style=style)
 311
 312     def represent_unicode(self, data):
 313         tag = None
 314         try:
 315             data.encode('ascii')
 316             tag = u'tag:yaml.org,2002:python/unicode'
 317         except UnicodeEncodeError:
 318             tag = u'tag:yaml.org,2002:str'
 319         return self.represent_scalar(tag, data)
 320
 321     def represent_long(self, data):
 322         tag = u'tag:yaml.org,2002:int'
 323         if int(data) is not data:
 324             tag = u'tag:yaml.org,2002:python/long'
 325         return self.represent_scalar(tag, unicode(data))
 326
 327     def represent_complex(self, data):
 328         if data.imag == 0.0:
 329             data = u'%r' % data.real
 330         elif data.real == 0.0:
 331             data = u'%rj' % data.imag
 332         elif data.imag > 0:
 333             data = u'%r+%rj' % (data.real, data.imag)
 334         else:
 335             data = u'%r%rj' % (data.real, data.imag)
 336         return self.represent_scalar(u'tag:yaml.org,2002:python/complex', data)
 337
 338     def represent_tuple(self, data):
 339         return self.represent_sequence(u'tag:yaml.org,2002:python/tuple', data)
 340
 341     def represent_name(self, data):
 342         name = u'%s.%s' % (data.__module__, data.__name__)
 343         return self.represent_scalar(u'tag:yaml.org,2002:python/name:'+name, u'')
 344
 345     def represent_module(self, data):
 346         return self.represent_scalar(
 347                 u'tag:yaml.org,2002:python/module:'+data.__name__, u'')
 348
 349     def represent_instance(self, data):
 350         # For instances of classic classes, we use __getinitargs__ and
 351         # __getstate__ to serialize the data.
 352
 353         # If data.__getinitargs__ exists, the object must be reconstructed by
 354         # calling cls(**args), where args is a tuple returned by
 355         # __getinitargs__. Otherwise, the cls.__init__ method should never be
 356         # called and the class instance is created by instantiating a trivial
 357         # class and assigning to the instance's __class__ variable.
 358
 359         # If data.__getstate__ exists, it returns the state of the object.
 360         # Otherwise, the state of the object is data.__dict__.
 361
 362         # We produce either a !!python/object or !!python/object/new node.
 363         # If data.__getinitargs__ does not exist and state is a dictionary, we
 364         # produce a !!python/object node . Otherwise we produce a
 365         # !!python/object/new node.
 366
 367         cls = data.__class__
 368         class_name = u'%s.%s' % (cls.__module__, cls.__name__)
 369         args = None
 370         state = None
 371         if hasattr(data, '__getinitargs__'):
 372             args = list(data.__getinitargs__())
 373         if hasattr(data, '__getstate__'):
 374             state = data.__getstate__()
 375         else:
 376             state = data.__dict__
 377         if args is None and isinstance(state, dict):
 378             state = state.items()
 379             state.sort()
 380             return self.represent_mapping(
 381                     u'tag:yaml.org,2002:python/object:'+class_name, state)
 382         if isinstance(state, dict) and not state:
 383             return self.represent_sequence(
 384                     u'tag:yaml.org,2002:python/object/new:'+class_name, args)
 385         value = {}
 386         if args:
 387             value['args'] = args
 388         value['state'] = state
 389         return self.represent_mapping(
 390                 u'tag:yaml.org,2002:python/object/new:'+class_name, value)
 391
 392     def represent_object(self, data):
 393         # We use __reduce__ API to save the data. data.__reduce__ returns
 394         # a tuple of length 2-5:
 395         #   (function, args, state, listitems, dictitems)
 396
 397         # For reconstructing, we calls function(*args), then set its state,
 398         # listitems, and dictitems if they are not None.
 399
 400         # A special case is when function.__name__ == '__newobj__'. In this
 401         # case we create the object with args[0].__new__(*args).
 402
 403         # Another special case is when __reduce__ returns a string - we don't
 404         # support it.
 405
 406         # We produce a !!python/object, !!python/object/new or
 407         # !!python/object/apply node.
 408
 409         cls = type(data)
 410         if cls in copy_reg.dispatch_table:
 411             reduce = copy_reg.dispatch_table[cls]
 412         elif hasattr(data, '__reduce_ex__'):
 413             reduce = data.__reduce_ex__(2)
 414         elif hasattr(data, '__reduce__'):
 415             reduce = data.__reduce__()
 416         else:
 417             raise RepresenterError("cannot represent object: %r" % data)
 418         reduce = (list(reduce)+[None]*5)[:5]
 419         function, args, state, listitems, dictitems = reduce
 420         args = list(args)
 421         if state is None:
 422             state = {}
 423         if listitems is not None:
 424             listitems = list(listitems)
 425         if dictitems is not None:
 426             dictitems = dict(dictitems)
 427         if function.__name__ == '__newobj__':
 428             function = args[0]
 429             args = args[1:]
 430             tag = u'tag:yaml.org,2002:python/object/new:'
 431             newobj = True
 432         else:
 433             tag = u'tag:yaml.org,2002:python/object/apply:'
 434             newobj = False
 435         function_name = u'%s.%s' % (function.__module__, function.__name__)
 436         if not args and not listitems and not dictitems \
 437                 and isinstance(state, dict) and newobj:
 438             state = state.items()
 439             state.sort()
 440             return self.represent_mapping(
 441                     u'tag:yaml.org,2002:python/object:'+function_name, state)
 442         if not listitems and not dictitems  \
 443                 and isinstance(state, dict) and not state:
 444             return self.represent_sequence(tag+function_name, args)
 445         value = {}
 446         if args:
 447             value['args'] = args
 448         if state or not isinstance(state, dict):
 449             value['state'] = state
 450         if listitems:
 451             value['listitems'] = listitems
 452         if dictitems:
 453             value['dictitems'] = dictitems
 454         return self.represent_mapping(tag+function_name, value)
 455
 456 Representer.add_representer(str,
 457         Representer.represent_str)
 458
 459 Representer.add_representer(unicode,
 460         Representer.represent_unicode)
 461
 462 Representer.add_representer(long,
 463         Representer.represent_long)
 464
 465 Representer.add_representer(complex,
 466         Representer.represent_complex)
 467
 468 Representer.add_representer(tuple,
 469         Representer.represent_tuple)
 470
 471 Representer.add_representer(type,
 472         Representer.represent_name)
 473
 474 Representer.add_representer(Representer.classobj_type,
 475         Representer.represent_name)
 476
 477 Representer.add_representer(Representer.function_type,
 478         Representer.represent_name)
 479
 480 Representer.add_representer(Representer.builtin_function_type,
 481         Representer.represent_name)
 482
 483 Representer.add_representer(Representer.module_type,
 484         Representer.represent_module)
 485
 486 Representer.add_multi_representer(Representer.instance_type,
 487         Representer.represent_instance)
 488
 489 Representer.add_multi_representer(object,
 490         Representer.represent_object)
 491