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