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, default_style=None, default_flow_style=None):
  30         self.default_style = default_style
  31         self.default_flow_style = default_flow_style
  32         self.represented_objects = {}
  33
  34     def represent(self, data):
  35         node = self.represent_data(data)
  36         self.serialize(node)
  37         self.represented_objects = {}
  38
  39     class C: pass
  40     c = C()
  41     def f(): pass
  42     classobj_type = type(C)
  43     instance_type = type(c)
  44     function_type = type(f)
  45     builtin_function_type = type(abs)
  46     module_type = type(sys)
  47     del C, c, f
  48
  49     def get_classobj_bases(self, cls):
  50         bases = [cls]
  51         for base in cls.__bases__:
  52             bases.extend(self.get_classobj_bases(base))
  53         return bases
  54
  55     def represent_data(self, data):
  56         if self.ignore_aliases(data):
  57             alias_key = None
  58         else:
  59             alias_key = id(data)
  60         if alias_key is not None:
  61             if alias_key in self.represented_objects:
  62                 node = self.represented_objects[alias_key]
  63                 if node is None:
  64                     raise RepresenterError("recursive objects are not allowed: %r" % data)
  65                 return node
  66             self.represented_objects[alias_key] = None
  67         data_types = type(data).__mro__
  68         if type(data) is self.instance_type:
  69             data_types = self.get_classobj_bases(data.__class__)+list(data_types)
  70         if data_types[0] in self.yaml_representers:
  71             node = self.yaml_representers[data_types[0]](self, data)
  72         else:
  73             for data_type in data_types:
  74                 if data_type in self.yaml_multi_representers:
  75                     node = self.yaml_multi_representers[data_type](self, data)
  76                     break
  77             else:
  78                 if None in self.yaml_multi_representers:
  79                     node = self.yaml_multi_representers[None](self, data)
  80                 elif None in self.yaml_representers:
  81                     node = self.yaml_representers[None](self, data)
  82                 else:
  83                     node = ScalarNode(None, unicode(data))
  84         if alias_key is not None:
  85             self.represented_objects[alias_key] = node
  86         return node
  87
  88     def add_representer(cls, data_type, representer):
  89         if not 'yaml_representers' in cls.__dict__:
  90             cls.yaml_representers = cls.yaml_representers.copy()
  91         cls.yaml_representers[data_type] = representer
  92     add_representer = classmethod(add_representer)
  93
  94     def add_multi_representer(cls, data_type, representer):
  95         if not 'yaml_multi_representers' in cls.__dict__:
  96             cls.yaml_multi_representers = cls.yaml_multi_representers.copy()
  97         cls.yaml_multi_representers[data_type] = representer
  98     add_multi_representer = classmethod(add_multi_representer)
  99
 100     def represent_scalar(self, tag, value, style=None):
 101         if style is None:
 102             style = self.default_style
 103         return ScalarNode(tag, value, style=style)
 104
 105     def represent_sequence(self, tag, sequence, flow_style=None):
 106         best_style = True
 107         value = []
 108         for item in sequence:
 109             node_item = self.represent_data(item)
 110             if not (isinstance(node_item, ScalarNode) and not node_item.style):
 111                 best_style = False
 112             value.append(self.represent_data(item))
 113         if flow_style is None:
 114             flow_style = self.default_flow_style
 115         if flow_style is None:
 116             flow_style = best_style
 117         return SequenceNode(tag, value, flow_style=flow_style)
 118
 119     def represent_mapping(self, tag, mapping, flow_style=None):
 120         best_style = True
 121         if hasattr(mapping, 'keys'):
 122             value = {}
 123             for item_key in mapping.keys():
 124                 item_value = mapping[item_key]
 125                 node_key = self.represent_data(item_key)
 126                 node_value = self.represent_data(item_value)
 127                 if not (isinstance(node_key, ScalarNode) and not node_key.style):
 128                     best_style = False
 129                 if not (isinstance(node_value, ScalarNode) and not node_value.style):
 130                     best_style = False
 131                 value[node_key] = node_value
 132         else:
 133             value = []
 134             for item_key, item_value in mapping:
 135                 node_key = self.represent_data(item_key)
 136                 node_value = self.represent_data(item_value)
 137                 if not (isinstance(node_key, ScalarNode) and not node_key.style):
 138                     best_style = False
 139                 if not (isinstance(node_value, ScalarNode) and not node_value.style):
 140                     best_style = False
 141                 value.append((node_key, node_value))
 142         if flow_style is None:
 143             flow_style = self.default_flow_style
 144         if flow_style is None:
 145             flow_style = best_style
 146         return MappingNode(tag, value, flow_style=flow_style)
 147
 148     def ignore_aliases(self, data):
 149         return False
 150
 151 class SafeRepresenter(BaseRepresenter):
 152
 153     def ignore_aliases(self, data):
 154         if data in [None, ()]:
 155             return True
 156         if isinstance(data, (str, unicode, bool, int, float)):
 157             return True
 158
 159     def represent_none(self, data):
 160         return self.represent_scalar(u'tag:yaml.org,2002:null',
 161                 u'null')
 162
 163     def represent_str(self, data):
 164         tag = None
 165         style = None
 166         try:
 167             data = unicode(data, 'ascii')
 168             tag = u'tag:yaml.org,2002:str'
 169         except UnicodeDecodeError:
 170             try:
 171                 data = unicode(data, 'utf-8')
 172                 tag = u'tag:yaml.org,2002:str'
 173             except UnicodeDecodeError:
 174                 data = data.encode('base64')
 175                 tag = u'tag:yaml.org,2002:binary'
 176                 style = '|'
 177         return self.represent_scalar(tag, data, style=style)
 178
 179     def represent_unicode(self, data):
 180         return self.represent_scalar(u'tag:yaml.org,2002:str', data)
 181
 182     def represent_bool(self, data):
 183         if data:
 184             value = u'true'
 185         else:
 186             value = u'false'
 187         return self.represent_scalar(u'tag:yaml.org,2002:bool', value)
 188
 189     def represent_int(self, data):
 190         return self.represent_scalar(u'tag:yaml.org,2002:int', unicode(data))
 191
 192     def represent_long(self, data):
 193         return self.represent_scalar(u'tag:yaml.org,2002:int', unicode(data))
 194
 195     inf_value = 1e300
 196     while repr(inf_value) != repr(inf_value*inf_value):
 197         inf_value *= inf_value
 198
 199     def represent_float(self, data):
 200         if data != data or (data == 0.0 and data == 1.0):
 201             value = u'.nan'
 202         elif data == self.inf_value:
 203             value = u'.inf'
 204         elif data == -self.inf_value:
 205             value = u'-.inf'
 206         else:
 207             value = unicode(repr(data))
 208         return self.represent_scalar(u'tag:yaml.org,2002:float', value)
 209
 210     def represent_list(self, data):
 211         pairs = (len(data) > 0 and isinstance(data, list))
 212         if pairs:
 213             for item in data:
 214                 if not isinstance(item, tuple) or len(item) != 2:
 215                     pairs = False
 216                     break
 217         if not pairs:
 218             return self.represent_sequence(u'tag:yaml.org,2002:seq', data)
 219         value = []
 220         for item_key, item_value in data:
 221             value.append(self.represent_mapping(u'tag:yaml.org,2002:map',
 222                 [(item_key, item_value)]))
 223         return SequenceNode(u'tag:yaml.org,2002:pairs', value)
 224
 225     def represent_dict(self, data):
 226         return self.represent_mapping(u'tag:yaml.org,2002:map', data)
 227
 228     def represent_set(self, data):
 229         value = {}
 230         for key in data:
 231             value[key] = None
 232         return self.represent_mapping(u'tag:yaml.org,2002:set', value)
 233
 234     def represent_date(self, data):
 235         value = u'%04d-%02d-%02d' % (data.year, data.month, data.day)
 236         return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
 237
 238     def represent_datetime(self, data):
 239         value = u'%04d-%02d-%02d %02d:%02d:%02d' \
 240                 % (data.year, data.month, data.day,
 241                     data.hour, data.minute, data.second)
 242         if data.microsecond:
 243             value += u'.' + unicode(data.microsecond/1000000.0).split(u'.')[1]
 244         if data.utcoffset():
 245             value += unicode(data.utcoffset())
 246         return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
 247
 248     def represent_yaml_object(self, tag, data, cls, flow_style=None):
 249         if hasattr(data, '__getstate__'):
 250             state = data.__getstate__()
 251         else:
 252             state = data.__dict__.copy()
 253         if isinstance(state, dict):
 254             state = state.items()
 255             state.sort()
 256         return self.represent_mapping(tag, state, flow_style=flow_style)
 257
 258     def represent_undefined(self, data):
 259         raise RepresenterError("cannot represent an object: %s" % data)
 260
 261 SafeRepresenter.add_representer(type(None),
 262         SafeRepresenter.represent_none)
 263
 264 SafeRepresenter.add_representer(str,
 265         SafeRepresenter.represent_str)
 266
 267 SafeRepresenter.add_representer(unicode,
 268         SafeRepresenter.represent_unicode)
 269
 270 SafeRepresenter.add_representer(bool,
 271         SafeRepresenter.represent_bool)
 272
 273 SafeRepresenter.add_representer(int,
 274         SafeRepresenter.represent_int)
 275
 276 SafeRepresenter.add_representer(long,
 277         SafeRepresenter.represent_long)
 278
 279 SafeRepresenter.add_representer(float,
 280         SafeRepresenter.represent_float)
 281
 282 SafeRepresenter.add_representer(list,
 283         SafeRepresenter.represent_list)
 284
 285 SafeRepresenter.add_representer(tuple,
 286         SafeRepresenter.represent_list)
 287
 288 SafeRepresenter.add_representer(dict,
 289         SafeRepresenter.represent_dict)
 290
 291 SafeRepresenter.add_representer(set,
 292         SafeRepresenter.represent_set)
 293
 294 if datetime_available:
 295     SafeRepresenter.add_representer(datetime.date,
 296             SafeRepresenter.represent_date)
 297     SafeRepresenter.add_representer(datetime.datetime,
 298             SafeRepresenter.represent_datetime)
 299
 300 SafeRepresenter.add_representer(None,
 301         SafeRepresenter.represent_undefined)
 302
 303 class Representer(SafeRepresenter):
 304
 305     def represent_str(self, data):
 306         tag = None
 307         style = None
 308         try:
 309             data = unicode(data, 'ascii')
 310             tag = u'tag:yaml.org,2002:str'
 311         except UnicodeDecodeError:
 312             try:
 313                 data = unicode(data, 'utf-8')
 314                 tag = u'tag:yaml.org,2002:python/str'
 315             except UnicodeDecodeError:
 316                 data = data.encode('base64')
 317                 tag = u'tag:yaml.org,2002:binary'
 318                 style = '|'
 319         return self.represent_scalar(tag, data, style=style)
 320
 321     def represent_unicode(self, data):
 322         tag = None
 323         try:
 324             data.encode('ascii')
 325             tag = u'tag:yaml.org,2002:python/unicode'
 326         except UnicodeEncodeError:
 327             tag = u'tag:yaml.org,2002:str'
 328         return self.represent_scalar(tag, data)
 329
 330     def represent_long(self, data):
 331         tag = u'tag:yaml.org,2002:int'
 332         if int(data) is not data:
 333             tag = u'tag:yaml.org,2002:python/long'
 334         return self.represent_scalar(tag, unicode(data))
 335
 336     def represent_complex(self, data):
 337         if data.imag == 0.0:
 338             data = u'%r' % data.real
 339         elif data.real == 0.0:
 340             data = u'%rj' % data.imag
 341         elif data.imag > 0:
 342             data = u'%r+%rj' % (data.real, data.imag)
 343         else:
 344             data = u'%r%rj' % (data.real, data.imag)
 345         return self.represent_scalar(u'tag:yaml.org,2002:python/complex', data)
 346
 347     def represent_tuple(self, data):
 348         return self.represent_sequence(u'tag:yaml.org,2002:python/tuple', data)
 349
 350     def represent_name(self, data):
 351         name = u'%s.%s' % (data.__module__, data.__name__)
 352         return self.represent_scalar(u'tag:yaml.org,2002:python/name:'+name, u'')
 353
 354     def represent_module(self, data):
 355         return self.represent_scalar(
 356                 u'tag:yaml.org,2002:python/module:'+data.__name__, u'')
 357
 358     def represent_instance(self, data):
 359         # For instances of classic classes, we use __getinitargs__ and
 360         # __getstate__ to serialize the data.
 361
 362         # If data.__getinitargs__ exists, the object must be reconstructed by
 363         # calling cls(**args), where args is a tuple returned by
 364         # __getinitargs__. Otherwise, the cls.__init__ method should never be
 365         # called and the class instance is created by instantiating a trivial
 366         # class and assigning to the instance's __class__ variable.
 367
 368         # If data.__getstate__ exists, it returns the state of the object.
 369         # Otherwise, the state of the object is data.__dict__.
 370
 371         # We produce either a !!python/object or !!python/object/new node.
 372         # If data.__getinitargs__ does not exist and state is a dictionary, we
 373         # produce a !!python/object node . Otherwise we produce a
 374         # !!python/object/new node.
 375
 376         cls = data.__class__
 377         class_name = u'%s.%s' % (cls.__module__, cls.__name__)
 378         args = None
 379         state = None
 380         if hasattr(data, '__getinitargs__'):
 381             args = list(data.__getinitargs__())
 382         if hasattr(data, '__getstate__'):
 383             state = data.__getstate__()
 384         else:
 385             state = data.__dict__
 386         if args is None and isinstance(state, dict):
 387             state = state.items()
 388             state.sort()
 389             return self.represent_mapping(
 390                     u'tag:yaml.org,2002:python/object:'+class_name, state)
 391         if isinstance(state, dict) and not state:
 392             return self.represent_sequence(
 393                     u'tag:yaml.org,2002:python/object/new:'+class_name, args)
 394         value = {}
 395         if args:
 396             value['args'] = args
 397         value['state'] = state
 398         return self.represent_mapping(
 399                 u'tag:yaml.org,2002:python/object/new:'+class_name, value)
 400
 401     def represent_object(self, data):
 402         # We use __reduce__ API to save the data. data.__reduce__ returns
 403         # a tuple of length 2-5:
 404         #   (function, args, state, listitems, dictitems)
 405
 406         # For reconstructing, we calls function(*args), then set its state,
 407         # listitems, and dictitems if they are not None.
 408
 409         # A special case is when function.__name__ == '__newobj__'. In this
 410         # case we create the object with args[0].__new__(*args).
 411
 412         # Another special case is when __reduce__ returns a string - we don't
 413         # support it.
 414
 415         # We produce a !!python/object, !!python/object/new or
 416         # !!python/object/apply node.
 417
 418         cls = type(data)
 419         if cls in copy_reg.dispatch_table:
 420             reduce = copy_reg.dispatch_table[cls](data)
 421         elif hasattr(data, '__reduce_ex__'):
 422             reduce = data.__reduce_ex__(2)
 423         elif hasattr(data, '__reduce__'):
 424             reduce = data.__reduce__()
 425         else:
 426             raise RepresenterError("cannot represent object: %r" % data)
 427         reduce = (list(reduce)+[None]*5)[:5]
 428         function, args, state, listitems, dictitems = reduce
 429         args = list(args)
 430         if state is None:
 431             state = {}
 432         if listitems is not None:
 433             listitems = list(listitems)
 434         if dictitems is not None:
 435             dictitems = dict(dictitems)
 436         if function.__name__ == '__newobj__':
 437             function = args[0]
 438             args = args[1:]
 439             tag = u'tag:yaml.org,2002:python/object/new:'
 440             newobj = True
 441         else:
 442             tag = u'tag:yaml.org,2002:python/object/apply:'
 443             newobj = False
 444         function_name = u'%s.%s' % (function.__module__, function.__name__)
 445         if not args and not listitems and not dictitems \
 446                 and isinstance(state, dict) and newobj:
 447             state = state.items()
 448             state.sort()
 449             return self.represent_mapping(
 450                     u'tag:yaml.org,2002:python/object:'+function_name, state)
 451         if not listitems and not dictitems  \
 452                 and isinstance(state, dict) and not state:
 453             return self.represent_sequence(tag+function_name, args)
 454         value = {}
 455         if args:
 456             value['args'] = args
 457         if state or not isinstance(state, dict):
 458             value['state'] = state
 459         if listitems:
 460             value['listitems'] = listitems
 461         if dictitems:
 462             value['dictitems'] = dictitems
 463         return self.represent_mapping(tag+function_name, value)
 464
 465 Representer.add_representer(str,
 466         Representer.represent_str)
 467
 468 Representer.add_representer(unicode,
 469         Representer.represent_unicode)
 470
 471 Representer.add_representer(long,
 472         Representer.represent_long)
 473
 474 Representer.add_representer(complex,
 475         Representer.represent_complex)
 476
 477 Representer.add_representer(tuple,
 478         Representer.represent_tuple)
 479
 480 Representer.add_representer(type,
 481         Representer.represent_name)
 482
 483 Representer.add_representer(Representer.classobj_type,
 484         Representer.represent_name)
 485
 486 Representer.add_representer(Representer.function_type,
 487         Representer.represent_name)
 488
 489 Representer.add_representer(Representer.builtin_function_type,
 490         Representer.represent_name)
 491
 492 Representer.add_representer(Representer.module_type,
 493         Representer.represent_module)
 494
 495 Representer.add_multi_representer(Representer.instance_type,
 496         Representer.represent_instance)
 497
 498 Representer.add_multi_representer(object,
 499         Representer.represent_object)
 500