lib/yaml/constructor.py

   1
   2 __all__ = ['BaseConstructor', 'SafeConstructor', 'Constructor',
   3     'ConstructorError']
   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 binascii, re, sys
  16
  17 class ConstructorError(MarkedYAMLError):
  18     pass
  19
  20 class BaseConstructor(object):
  21
  22     yaml_constructors = {}
  23     yaml_multi_constructors = {}
  24
  25     def __init__(self):
  26         self.constructed_objects = {}
  27         self.recursive_objects = {}
  28         self.state_generators = []
  29         self.deep_construct = False
  30
  31     def check_data(self):
  32         # If there are more documents available?
  33         return self.check_node()
  34
  35     def get_data(self):
  36         # Construct and return the next document.
  37         if self.check_node():
  38             return self.construct_document(self.get_node())
  39
  40     def g(): yield None
  41     generator_type = type(g())
  42     del g
  43
  44     def construct_document(self, node):
  45         data = self.construct_object(node)
  46         while self.state_generators:
  47             state_generators = self.state_generators
  48             self.state_generators = []
  49             for generator in state_generators:
  50                 for dummy in generator:
  51                     pass
  52         self.constructed_objects = {}
  53         self.recursive_objects = {}
  54         self.deep_construct = False
  55         return data
  56
  57     def construct_object(self, node, deep=False):
  58         if deep:
  59             old_deep = self.deep_construct
  60             self.deep_construct = True
  61         if node in self.constructed_objects:
  62             return self.constructed_objects[node]
  63         if node in self.recursive_objects:
  64             raise ConstructorError(None, None,
  65                     "found unconstructable recursive node", node.start_mark)
  66         self.recursive_objects[node] = None
  67         constructor = None
  68         state_constructor = None
  69         tag_suffix = None
  70         if node.tag in self.yaml_constructors:
  71             constructor = self.yaml_constructors[node.tag]
  72         else:
  73             for tag_prefix in self.yaml_multi_constructors:
  74                 if node.tag.startswith(tag_prefix):
  75                     tag_suffix = node.tag[len(tag_prefix):]
  76                     constructor = self.yaml_multi_constructors[tag_prefix]
  77                     break
  78             else:
  79                 if None in self.yaml_multi_constructors:
  80                     tag_suffix = node.tag
  81                     constructor = self.yaml_multi_constructors[None]
  82                 elif None in self.yaml_constructors:
  83                     constructor = self.yaml_constructors[None]
  84                 elif isinstance(node, ScalarNode):
  85                     constructor = self.__class__.construct_scalar
  86                 elif isinstance(node, SequenceNode):
  87                     constructor = self.__class__.construct_sequence
  88                 elif isinstance(node, MappingNode):
  89                     constructor = self.__class__.construct_mapping
  90         if tag_suffix is None:
  91             data = constructor(self, node)
  92         else:
  93             data = constructor(self, tag_suffix, node)
  94         if isinstance(data, self.generator_type):
  95             generator = data
  96             data = generator.next()
  97             if self.deep_construct:
  98                 for dummy in generator:
  99                     pass
 100             else:
 101                 self.state_generators.append(generator)
 102         self.constructed_objects[node] = data
 103         del self.recursive_objects[node]
 104         if deep:
 105             self.deep_construct = old_deep
 106         return data
 107
 108     def construct_scalar(self, node):
 109         if not isinstance(node, ScalarNode):
 110             raise ConstructorError(None, None,
 111                     "expected a scalar node, but found %s" % node.id,
 112                     node.start_mark)
 113         return node.value
 114
 115     def construct_sequence(self, node, deep=False):
 116         if not isinstance(node, SequenceNode):
 117             raise ConstructorError(None, None,
 118                     "expected a sequence node, but found %s" % node.id,
 119                     node.start_mark)
 120         return [self.construct_object(child, deep=deep)
 121                 for child in node.value]
 122
 123     def construct_mapping(self, node, deep=False):
 124         if not isinstance(node, MappingNode):
 125             raise ConstructorError(None, None,
 126                     "expected a mapping node, but found %s" % node.id,
 127                     node.start_mark)
 128         mapping = {}
 129         for key_node, value_node in node.value:
 130             key = self.construct_object(key_node, deep=deep)
 131             try:
 132                 hash(key)
 133             except TypeError, exc:
 134                 raise ConstructorError("while constructing a mapping", node.start_mark,
 135                         "found unacceptable key (%s)" % exc, key_node.start_mark)
 136             value = self.construct_object(value_node, deep=deep)
 137             mapping[key] = value
 138         return mapping
 139
 140     def construct_pairs(self, node, deep=False):
 141         if not isinstance(node, MappingNode):
 142             raise ConstructorError(None, None,
 143                     "expected a mapping node, but found %s" % node.id,
 144                     node.start_mark)
 145         pairs = []
 146         for key_node, value_node in node.value:
 147             key = self.construct_object(key_node, deep=deep)
 148             value = self.construct_object(value_node, deep=deep)
 149             pairs.append((key, value))
 150         return pairs
 151
 152     def add_constructor(cls, tag, constructor):
 153         if not 'yaml_constructors' in cls.__dict__:
 154             cls.yaml_constructors = cls.yaml_constructors.copy()
 155         cls.yaml_constructors[tag] = constructor
 156     add_constructor = classmethod(add_constructor)
 157
 158     def add_multi_constructor(cls, tag_prefix, multi_constructor):
 159         if not 'yaml_multi_constructors' in cls.__dict__:
 160             cls.yaml_multi_constructors = cls.yaml_multi_constructors.copy()
 161         cls.yaml_multi_constructors[tag_prefix] = multi_constructor
 162     add_multi_constructor = classmethod(add_multi_constructor)
 163
 164 class SafeConstructor(BaseConstructor):
 165
 166     def construct_scalar(self, node):
 167         if isinstance(node, MappingNode):
 168             for key_node, value_node in node.value:
 169                 if key_node.tag == u'tag:yaml.org,2002:value':
 170                     return self.construct_scalar(value_node)
 171         return BaseConstructor.construct_scalar(self, node)
 172
 173     def flatten_mapping(self, node):
 174         merge = []
 175         index = 0
 176         while index < len(node.value):
 177             key_node, value_node = node.value[index]
 178             if key_node.tag == u'tag:yaml.org,2002:merge':
 179                 del node.value[index]
 180                 if isinstance(value_node, MappingNode):
 181                     self.flatten_mapping(value_node)
 182                     merge.extend(value_node.value)
 183                 elif isinstance(value_node, SequenceNode):
 184                     submerge = []
 185                     for subnode in value_node.value:
 186                         if not isinstance(subnode, MappingNode):
 187                             raise ConstructorError("while constructing a mapping",
 188                                     node.start_mark,
 189                                     "expected a mapping for merging, but found %s"
 190                                     % subnode.id, subnode.start_mark)
 191                         self.flatten_mapping(subnode)
 192                         submerge.append(subnode.value)
 193                     submerge.reverse()
 194                     for value in submerge:
 195                         merge.extend(value)
 196                 else:
 197                     raise ConstructorError("while constructing a mapping", node.start_mark,
 198                             "expected a mapping or list of mappings for merging, but found %s"
 199                             % value_node.id, value_node.start_mark)
 200             elif key_node.tag == u'tag:yaml.org,2002:value':
 201                 key_node.tag = u'tag:yaml.org,2002:str'
 202                 index += 1
 203             else:
 204                 index += 1
 205         if merge:
 206             node.value = merge + node.value
 207
 208     def construct_mapping(self, node, deep=False):
 209         if isinstance(node, MappingNode):
 210             self.flatten_mapping(node)
 211         return BaseConstructor.construct_mapping(self, node, deep=deep)
 212
 213     def construct_yaml_null(self, node):
 214         self.construct_scalar(node)
 215         return None
 216
 217     bool_values = {
 218         u'yes':     True,
 219         u'no':      False,
 220         u'true':    True,
 221         u'false':   False,
 222         u'on':      True,
 223         u'off':     False,
 224     }
 225
 226     def construct_yaml_bool(self, node):
 227         value = self.construct_scalar(node)
 228         return self.bool_values[value.lower()]
 229
 230     def construct_yaml_int(self, node):
 231         value = str(self.construct_scalar(node))
 232         value = value.replace('_', '')
 233         sign = +1
 234         if value[0] == '-':
 235             sign = -1
 236         if value[0] in '+-':
 237             value = value[1:]
 238         if value == '0':
 239             return 0
 240         elif value.startswith('0b'):
 241             return sign*int(value[2:], 2)
 242         elif value.startswith('0x'):
 243             return sign*int(value[2:], 16)
 244         elif value[0] == '0':
 245             return sign*int(value, 8)
 246         elif ':' in value:
 247             digits = [int(part) for part in value.split(':')]
 248             digits.reverse()
 249             base = 1
 250             value = 0
 251             for digit in digits:
 252                 value += digit*base
 253                 base *= 60
 254             return sign*value
 255         else:
 256             return sign*int(value)
 257
 258     inf_value = 1e300
 259     while inf_value != inf_value*inf_value:
 260         inf_value *= inf_value
 261     nan_value = -inf_value/inf_value   # Trying to make a quiet NaN (like C99).
 262
 263     def construct_yaml_float(self, node):
 264         value = str(self.construct_scalar(node))
 265         value = value.replace('_', '').lower()
 266         sign = +1
 267         if value[0] == '-':
 268             sign = -1
 269         if value[0] in '+-':
 270             value = value[1:]
 271         if value == '.inf':
 272             return sign*self.inf_value
 273         elif value == '.nan':
 274             return self.nan_value
 275         elif ':' in value:
 276             digits = [float(part) for part in value.split(':')]
 277             digits.reverse()
 278             base = 1
 279             value = 0.0
 280             for digit in digits:
 281                 value += digit*base
 282                 base *= 60
 283             return sign*value
 284         else:
 285             return sign*float(value)
 286
 287     def construct_yaml_binary(self, node):
 288         value = self.construct_scalar(node)
 289         try:
 290             return str(value).decode('base64')
 291         except (binascii.Error, UnicodeEncodeError), exc:
 292             raise ConstructorError(None, None,
 293                     "failed to decode base64 data: %s" % exc, node.start_mark)
 294
 295     timestamp_regexp = re.compile(
 296             ur'''^(?P<year>[0-9][0-9][0-9][0-9])
 297                 -(?P<month>[0-9][0-9]?)
 298                 -(?P<day>[0-9][0-9]?)
 299                 (?:(?:[Tt]|[ \t]+)
 300                 (?P<hour>[0-9][0-9]?)
 301                 :(?P<minute>[0-9][0-9])
 302                 :(?P<second>[0-9][0-9])
 303                 (?:\.(?P<fraction>[0-9]*))?
 304                 (?:[ \t]*(?P<tz>Z|(?P<tz_sign>[-+])(?P<tz_hour>[0-9][0-9]?)
 305                 (?::(?P<tz_minute>[0-9][0-9]))?))?)?$''', re.X)
 306
 307     def construct_yaml_timestamp(self, node):
 308         value = self.construct_scalar(node)
 309         match = self.timestamp_regexp.match(node.value)
 310         values = match.groupdict()
 311         year = int(values['year'])
 312         month = int(values['month'])
 313         day = int(values['day'])
 314         if not values['hour']:
 315             return datetime.date(year, month, day)
 316         hour = int(values['hour'])
 317         minute = int(values['minute'])
 318         second = int(values['second'])
 319         fraction = 0
 320         if values['fraction']:
 321             fraction = int(values['fraction'][:6].ljust(6, '0'))
 322         delta = None
 323         if values['tz_sign']:
 324             tz_hour = int(values['tz_hour'])
 325             tz_minute = int(values['tz_minute'] or 0)
 326             delta = datetime.timedelta(hours=tz_hour, minutes=tz_minute)
 327             if values['tz_sign'] == '-':
 328                 delta = -delta
 329         data = datetime.datetime(year, month, day, hour, minute, second, fraction)
 330         if delta:
 331             data -= delta
 332         return data
 333
 334     def construct_yaml_omap(self, node):
 335         # Note: we do not check for duplicate keys, because it's too
 336         # CPU-expensive.
 337         omap = []
 338         yield omap
 339         if not isinstance(node, SequenceNode):
 340             raise ConstructorError("while constructing an ordered map", node.start_mark,
 341                     "expected a sequence, but found %s" % node.id, node.start_mark)
 342         for subnode in node.value:
 343             if not isinstance(subnode, MappingNode):
 344                 raise ConstructorError("while constructing an ordered map", node.start_mark,
 345                         "expected a mapping of length 1, but found %s" % subnode.id,
 346                         subnode.start_mark)
 347             if len(subnode.value) != 1:
 348                 raise ConstructorError("while constructing an ordered map", node.start_mark,
 349                         "expected a single mapping item, but found %d items" % len(subnode.value),
 350                         subnode.start_mark)
 351             key_node, value_node = subnode.value[0]
 352             key = self.construct_object(key_node)
 353             value = self.construct_object(value_node)
 354             omap.append((key, value))
 355
 356     def construct_yaml_pairs(self, node):
 357         # Note: the same code as `construct_yaml_omap`.
 358         pairs = []
 359         yield pairs
 360         if not isinstance(node, SequenceNode):
 361             raise ConstructorError("while constructing pairs", node.start_mark,
 362                     "expected a sequence, but found %s" % node.id, node.start_mark)
 363         for subnode in node.value:
 364             if not isinstance(subnode, MappingNode):
 365                 raise ConstructorError("while constructing pairs", node.start_mark,
 366                         "expected a mapping of length 1, but found %s" % subnode.id,
 367                         subnode.start_mark)
 368             if len(subnode.value) != 1:
 369                 raise ConstructorError("while constructing pairs", node.start_mark,
 370                         "expected a single mapping item, but found %d items" % len(subnode.value),
 371                         subnode.start_mark)
 372             key_node, value_node = subnode.value[0]
 373             key = self.construct_object(key_node)
 374             value = self.construct_object(value_node)
 375             pairs.append((key, value))
 376
 377     def construct_yaml_set(self, node):
 378         data = set()
 379         yield data
 380         value = self.construct_mapping(node)
 381         data.update(value)
 382
 383     def construct_yaml_str(self, node):
 384         value = self.construct_scalar(node)
 385         try:
 386             return str(value)
 387         except UnicodeEncodeError:
 388             return value
 389
 390     def construct_yaml_seq(self, node):
 391         data = []
 392         yield data
 393         data.extend(self.construct_sequence(node))
 394
 395     def construct_yaml_map(self, node):
 396         data = {}
 397         yield data
 398         value = self.construct_mapping(node)
 399         data.update(value)
 400
 401     def construct_yaml_object(self, node, cls):
 402         data = cls.__new__(cls)
 403         yield data
 404         if hasattr(data, '__setstate__'):
 405             state = self.construct_mapping(node, deep=True)
 406             data.__setstate__(state)
 407         else:
 408             state = self.construct_mapping(node)
 409             data.__dict__.update(state)
 410
 411     def construct_undefined(self, node):
 412         raise ConstructorError(None, None,
 413                 "could not determine a constructor for the tag %r" % node.tag.encode('utf-8'),
 414                 node.start_mark)
 415
 416 SafeConstructor.add_constructor(
 417         u'tag:yaml.org,2002:null',
 418         SafeConstructor.construct_yaml_null)
 419
 420 SafeConstructor.add_constructor(
 421         u'tag:yaml.org,2002:bool',
 422         SafeConstructor.construct_yaml_bool)
 423
 424 SafeConstructor.add_constructor(
 425         u'tag:yaml.org,2002:int',
 426         SafeConstructor.construct_yaml_int)
 427
 428 SafeConstructor.add_constructor(
 429         u'tag:yaml.org,2002:float',
 430         SafeConstructor.construct_yaml_float)
 431
 432 SafeConstructor.add_constructor(
 433         u'tag:yaml.org,2002:binary',
 434         SafeConstructor.construct_yaml_binary)
 435
 436 SafeConstructor.add_constructor(
 437         u'tag:yaml.org,2002:timestamp',
 438         SafeConstructor.construct_yaml_timestamp)
 439
 440 SafeConstructor.add_constructor(
 441         u'tag:yaml.org,2002:omap',
 442         SafeConstructor.construct_yaml_omap)
 443
 444 SafeConstructor.add_constructor(
 445         u'tag:yaml.org,2002:pairs',
 446         SafeConstructor.construct_yaml_pairs)
 447
 448 SafeConstructor.add_constructor(
 449         u'tag:yaml.org,2002:set',
 450         SafeConstructor.construct_yaml_set)
 451
 452 SafeConstructor.add_constructor(
 453         u'tag:yaml.org,2002:str',
 454         SafeConstructor.construct_yaml_str)
 455
 456 SafeConstructor.add_constructor(
 457         u'tag:yaml.org,2002:seq',
 458         SafeConstructor.construct_yaml_seq)
 459
 460 SafeConstructor.add_constructor(
 461         u'tag:yaml.org,2002:map',
 462         SafeConstructor.construct_yaml_map)
 463
 464 SafeConstructor.add_constructor(None,
 465         SafeConstructor.construct_undefined)
 466
 467 class Constructor(SafeConstructor):
 468
 469     def construct_python_str(self, node):
 470         return self.construct_scalar(node).encode('utf-8')
 471
 472     def construct_python_unicode(self, node):
 473         return self.construct_scalar(node)
 474
 475     def construct_python_long(self, node):
 476         return long(self.construct_yaml_int(node))
 477
 478     def construct_python_complex(self, node):
 479        return complex(self.construct_scalar(node))
 480
 481     def construct_python_tuple(self, node):
 482         return tuple(self.construct_sequence(node))
 483
 484     def find_python_module(self, name, mark):
 485         if not name:
 486             raise ConstructorError("while constructing a Python module", mark,
 487                     "expected non-empty name appended to the tag", mark)
 488         try:
 489             __import__(name)
 490         except ImportError, exc:
 491             raise ConstructorError("while constructing a Python module", mark,
 492                     "cannot find module %r (%s)" % (name.encode('utf-8'), exc), mark)
 493         return sys.modules[name]
 494
 495     def find_python_name(self, name, mark):
 496         if not name:
 497             raise ConstructorError("while constructing a Python object", mark,
 498                     "expected non-empty name appended to the tag", mark)
 499         if u'.' in name:
 500             # Python 2.4 only
 501             #module_name, object_name = name.rsplit('.', 1)
 502             items = name.split('.')
 503             object_name = items.pop()
 504             module_name = '.'.join(items)
 505         else:
 506             module_name = '__builtin__'
 507             object_name = name
 508         try:
 509             __import__(module_name)
 510         except ImportError, exc:
 511             raise ConstructorError("while constructing a Python object", mark,
 512                     "cannot find module %r (%s)" % (module_name.encode('utf-8'), exc), mark)
 513         module = sys.modules[module_name]
 514         if not hasattr(module, object_name):
 515             raise ConstructorError("while constructing a Python object", mark,
 516                     "cannot find %r in the module %r" % (object_name.encode('utf-8'),
 517                         module.__name__), mark)
 518         return getattr(module, object_name)
 519
 520     def construct_python_name(self, suffix, node):
 521         value = self.construct_scalar(node)
 522         if value:
 523             raise ConstructorError("while constructing a Python name", node.start_mark,
 524                     "expected the empty value, but found %r" % value.encode('utf-8'),
 525                     node.start_mark)
 526         return self.find_python_name(suffix, node.start_mark)
 527
 528     def construct_python_module(self, suffix, node):
 529         value = self.construct_scalar(node)
 530         if value:
 531             raise ConstructorError("while constructing a Python module", node.start_mark,
 532                     "expected the empty value, but found %r" % value.encode('utf-8'),
 533                     node.start_mark)
 534         return self.find_python_module(suffix, node.start_mark)
 535
 536     class classobj: pass
 537
 538     def make_python_instance(self, suffix, node,
 539             args=None, kwds=None, newobj=False):
 540         if not args:
 541             args = []
 542         if not kwds:
 543             kwds = {}
 544         cls = self.find_python_name(suffix, node.start_mark)
 545         if newobj and isinstance(cls, type(self.classobj))  \
 546                 and not args and not kwds:
 547             instance = self.classobj()
 548             instance.__class__ = cls
 549             return instance
 550         elif newobj and isinstance(cls, type):
 551             return cls.__new__(cls, *args, **kwds)
 552         else:
 553             return cls(*args, **kwds)
 554
 555     def set_python_instance_state(self, instance, state):
 556         if hasattr(instance, '__setstate__'):
 557             instance.__setstate__(state)
 558         else:
 559             slotstate = {}
 560             if isinstance(state, tuple) and len(state) == 2:
 561                 state, slotstate = state
 562             if hasattr(instance, '__dict__'):
 563                 instance.__dict__.update(state)
 564             elif state:
 565                 slotstate.update(state)
 566             for key, value in slotstate.items():
 567                 setattr(object, key, value)
 568
 569     def construct_python_object(self, suffix, node):
 570         # Format:
 571         #   !!python/object:module.name { ... state ... }
 572         instance = self.make_python_instance(suffix, node, newobj=True)
 573         yield instance
 574         deep = hasattr(instance, '__setstate__')
 575         state = self.construct_mapping(node, deep=deep)
 576         self.set_python_instance_state(instance, state)
 577
 578     def construct_python_object_apply(self, suffix, node, newobj=False):
 579         # Format:
 580         #   !!python/object/apply       # (or !!python/object/new)
 581         #   args: [ ... arguments ... ]
 582         #   kwds: { ... keywords ... }
 583         #   state: ... state ...
 584         #   listitems: [ ... listitems ... ]
 585         #   dictitems: { ... dictitems ... }
 586         # or short format:
 587         #   !!python/object/apply [ ... arguments ... ]
 588         # The difference between !!python/object/apply and !!python/object/new
 589         # is how an object is created, check make_python_instance for details.
 590         if isinstance(node, SequenceNode):
 591             args = self.construct_sequence(node, deep=True)
 592             kwds = {}
 593             state = {}
 594             listitems = []
 595             dictitems = {}
 596         else:
 597             value = self.construct_mapping(node, deep=True)
 598             args = value.get('args', [])
 599             kwds = value.get('kwds', {})
 600             state = value.get('state', {})
 601             listitems = value.get('listitems', [])
 602             dictitems = value.get('dictitems', {})
 603         instance = self.make_python_instance(suffix, node, args, kwds, newobj)
 604         if state:
 605             self.set_python_instance_state(instance, state)
 606         if listitems:
 607             instance.extend(listitems)
 608         if dictitems:
 609             for key in dictitems:
 610                 instance[key] = dictitems[key]
 611         return instance
 612
 613     def construct_python_object_new(self, suffix, node):
 614         return self.construct_python_object_apply(suffix, node, newobj=True)
 615
 616 Constructor.add_constructor(
 617     u'tag:yaml.org,2002:python/none',
 618     Constructor.construct_yaml_null)
 619
 620 Constructor.add_constructor(
 621     u'tag:yaml.org,2002:python/bool',
 622     Constructor.construct_yaml_bool)
 623
 624 Constructor.add_constructor(
 625     u'tag:yaml.org,2002:python/str',
 626     Constructor.construct_python_str)
 627
 628 Constructor.add_constructor(
 629     u'tag:yaml.org,2002:python/unicode',
 630     Constructor.construct_python_unicode)
 631
 632 Constructor.add_constructor(
 633     u'tag:yaml.org,2002:python/int',
 634     Constructor.construct_yaml_int)
 635
 636 Constructor.add_constructor(
 637     u'tag:yaml.org,2002:python/long',
 638     Constructor.construct_python_long)
 639
 640 Constructor.add_constructor(
 641     u'tag:yaml.org,2002:python/float',
 642     Constructor.construct_yaml_float)
 643
 644 Constructor.add_constructor(
 645     u'tag:yaml.org,2002:python/complex',
 646     Constructor.construct_python_complex)
 647
 648 Constructor.add_constructor(
 649     u'tag:yaml.org,2002:python/list',
 650     Constructor.construct_yaml_seq)
 651
 652 Constructor.add_constructor(
 653     u'tag:yaml.org,2002:python/tuple',
 654     Constructor.construct_python_tuple)
 655
 656 Constructor.add_constructor(
 657     u'tag:yaml.org,2002:python/dict',
 658     Constructor.construct_yaml_map)
 659
 660 Constructor.add_multi_constructor(
 661     u'tag:yaml.org,2002:python/name:',
 662     Constructor.construct_python_name)
 663
 664 Constructor.add_multi_constructor(
 665     u'tag:yaml.org,2002:python/module:',
 666     Constructor.construct_python_module)
 667
 668 Constructor.add_multi_constructor(
 669     u'tag:yaml.org,2002:python/object:',
 670     Constructor.construct_python_object)
 671
 672 Constructor.add_multi_constructor(
 673     u'tag:yaml.org,2002:python/object/apply:',
 674     Constructor.construct_python_object_apply)
 675
 676 Constructor.add_multi_constructor(
 677     u'tag:yaml.org,2002:python/object/new:',
 678     Constructor.construct_python_object_new)
 679