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     repr_pos_inf = repr(1e300000)
 188     repr_neg_inf = repr(-1e300000)
 189     repr_nan = repr(1e300000/1e300000)
 190
 191     def represent_float(self, data):
 192         repr_data = repr(data)
 193         if repr_data == self.repr_pos_inf:
 194             value = u'.inf'
 195         elif repr_data == self.repr_neg_inf:
 196             value = u'-.inf'
 197         elif repr_data == self.repr_nan:
 198             value = u'.nan'
 199         else:
 200             value = unicode(repr_data)
 201         return self.represent_scalar(u'tag:yaml.org,2002:float', value)
 202
 203     def represent_list(self, data):
 204         pairs = (len(data) > 0 and isinstance(data, list))
 205         if pairs:
 206             for item in data:
 207                 if not isinstance(item, tuple) or len(item) != 2:
 208                     pairs = False
 209                     break
 210         if not pairs:
 211             return self.represent_sequence(u'tag:yaml.org,2002:seq', data)
 212         value = []
 213         for item_key, item_value in data:
 214             value.append(self.represent_mapping(u'tag:yaml.org,2002:map',
 215                 [(item_key, item_value)]))
 216         return SequenceNode(u'tag:yaml.org,2002:pairs', value)
 217
 218     def represent_dict(self, data):
 219         return self.represent_mapping(u'tag:yaml.org,2002:map', data)
 220
 221     def represent_set(self, data):
 222         value = {}
 223         for key in data:
 224             value[key] = None
 225         return self.represent_mapping(u'tag:yaml.org,2002:set', value)
 226
 227     def represent_date(self, data):
 228         value = u'%04d-%02d-%02d' % (data.year, data.month, data.day)
 229         return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
 230
 231     def represent_datetime(self, data):
 232         value = u'%04d-%02d-%02d %02d:%02d:%02d' \
 233                 % (data.year, data.month, data.day,
 234                     data.hour, data.minute, data.second)
 235         if data.microsecond:
 236             value += u'.' + unicode(data.microsecond/1000000.0).split(u'.')[1]
 237         if data.utcoffset():
 238             value += unicode(data.utcoffset())
 239         return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
 240
 241     def represent_yaml_object(self, tag, data, cls, flow_style=None):
 242         if hasattr(data, '__getstate__'):
 243             state = data.__getstate__()
 244         else:
 245             state = data.__dict__.copy()
 246         if isinstance(state, dict):
 247             state = state.items()
 248             state.sort()
 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 if datetime_available:
 288     SafeRepresenter.add_representer(datetime.date,
 289             SafeRepresenter.represent_date)
 290     SafeRepresenter.add_representer(datetime.datetime,
 291             SafeRepresenter.represent_datetime)
 292
 293 SafeRepresenter.add_representer(None,
 294         SafeRepresenter.represent_undefined)
 295
 296 class Representer(SafeRepresenter):
 297
 298     def represent_str(self, data):
 299         tag = None
 300         style = None
 301         try:
 302             data = unicode(data, 'ascii')
 303             tag = u'tag:yaml.org,2002:str'
 304         except UnicodeDecodeError:
 305             try:
 306                 data = unicode(data, 'utf-8')
 307                 tag = u'tag:yaml.org,2002:python/str'
 308             except UnicodeDecodeError:
 309                 data = data.encode('base64')
 310                 tag = u'tag:yaml.org,2002:binary'
 311                 style = '|'
 312         return self.represent_scalar(tag, data, style=style)
 313
 314     def represent_unicode(self, data):
 315         tag = None
 316         try:
 317             data.encode('ascii')
 318             tag = u'tag:yaml.org,2002:python/unicode'
 319         except UnicodeEncodeError:
 320             tag = u'tag:yaml.org,2002:str'
 321         return self.represent_scalar(tag, data)
 322
 323     def represent_long(self, data):
 324         tag = u'tag:yaml.org,2002:int'
 325         if int(data) is not data:
 326             tag = u'tag:yaml.org,2002:python/long'
 327         return self.represent_scalar(tag, unicode(data))
 328
 329     def represent_complex(self, data):
 330         if data.imag == 0.0:
 331             data = u'%r' % data.real
 332         elif data.real == 0.0:
 333             data = u'%rj' % data.imag
 334         elif data.imag > 0:
 335             data = u'%r+%rj' % (data.real, data.imag)
 336         else:
 337             data = u'%r%rj' % (data.real, data.imag)
 338         return self.represent_scalar(u'tag:yaml.org,2002:python/complex', data)
 339
 340     def represent_tuple(self, data):
 341         return self.represent_sequence(u'tag:yaml.org,2002:python/tuple', data)
 342
 343     def represent_name(self, data):
 344         name = u'%s.%s' % (data.__module__, data.__name__)
 345         return self.represent_scalar(u'tag:yaml.org,2002:python/name:'+name, u'')
 346
 347     def represent_module(self, data):
 348         return self.represent_scalar(
 349                 u'tag:yaml.org,2002:python/module:'+data.__name__, u'')
 350
 351     def represent_instance(self, data):
 352         # For instances of classic classes, we use __getinitargs__ and
 353         # __getstate__ to serialize the data.
 354
 355         # If data.__getinitargs__ exists, the object must be reconstructed by
 356         # calling cls(**args), where args is a tuple returned by
 357         # __getinitargs__. Otherwise, the cls.__init__ method should never be
 358         # called and the class instance is created by instantiating a trivial
 359         # class and assigning to the instance's __class__ variable.
 360
 361         # If data.__getstate__ exists, it returns the state of the object.
 362         # Otherwise, the state of the object is data.__dict__.
 363
 364         # We produce either a !!python/object or !!python/object/new node.
 365         # If data.__getinitargs__ does not exist and state is a dictionary, we
 366         # produce a !!python/object node . Otherwise we produce a
 367         # !!python/object/new node.
 368
 369         cls = data.__class__
 370         class_name = u'%s.%s' % (cls.__module__, cls.__name__)
 371         args = None
 372         state = None
 373         if hasattr(data, '__getinitargs__'):
 374             args = list(data.__getinitargs__())
 375         if hasattr(data, '__getstate__'):
 376             state = data.__getstate__()
 377         else:
 378             state = data.__dict__
 379         if args is None and isinstance(state, dict):
 380             state = state.items()
 381             state.sort()
 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]
 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             state = state.items()
 441             state.sort()
 442             return self.represent_mapping(
 443                     u'tag:yaml.org,2002:python/object:'+function_name, state)
 444         if not listitems and not dictitems  \
 445                 and isinstance(state, dict) and not state:
 446             return self.represent_sequence(tag+function_name, args)
 447         value = {}
 448         if args:
 449             value['args'] = args
 450         if state or not isinstance(state, dict):
 451             value['state'] = state
 452         if listitems:
 453             value['listitems'] = listitems
 454         if dictitems:
 455             value['dictitems'] = dictitems
 456         return self.represent_mapping(tag+function_name, value)
 457
 458 Representer.add_representer(str,
 459         Representer.represent_str)
 460
 461 Representer.add_representer(unicode,
 462         Representer.represent_unicode)
 463
 464 Representer.add_representer(long,
 465         Representer.represent_long)
 466
 467 Representer.add_representer(complex,
 468         Representer.represent_complex)
 469
 470 Representer.add_representer(tuple,
 471         Representer.represent_tuple)
 472
 473 Representer.add_representer(type,
 474         Representer.represent_name)
 475
 476 Representer.add_representer(Representer.classobj_type,
 477         Representer.represent_name)
 478
 479 Representer.add_representer(Representer.function_type,
 480         Representer.represent_name)
 481
 482 Representer.add_representer(Representer.builtin_function_type,
 483         Representer.represent_name)
 484
 485 Representer.add_representer(Representer.module_type,
 486         Representer.represent_module)
 487
 488 Representer.add_multi_representer(Representer.instance_type,
 489         Representer.represent_instance)
 490
 491 Representer.add_multi_representer(object,
 492         Representer.represent_object)
 493