text: 
  __all__ = ['BaseRepresenter', 'SafeRepresenter', 'Representer',
      'RepresenterError']
  
  from error import *
  from nodes import *
  
  import base64
  import datetime
  
  import sys, copy_reg, types
  
  class RepresenterError(YAMLError):
      pass
  
  class BaseRepresenter(object):
  
      yaml_representers = {}
      yaml_multi_representers = {}
  
      def __init__(self, default_style=None, default_flow_style=None):
          self.default_style = default_style
          self.default_flow_style = default_flow_style
          self.represented_objects = {}
          self.object_keeper = []
          self.alias_key = None
  
      def represent(self, data):
          node = self.represent_data(data)
          self.serialize(node)
          self.represented_objects = {}
          self.object_keeper = []
          self.alias_key = None
  
      def get_classobj_bases(self, cls):
          bases = [cls]
          for base in cls.__bases__:
              bases.extend(self.get_classobj_bases(base))
          return bases
  
      def represent_data(self, data):
          if self.ignore_aliases(data):
              self.alias_key = None
          else:
              self.alias_key = id(data)
          if self.alias_key is not None:
              if self.alias_key in self.represented_objects:
                  node = self.represented_objects[self.alias_key]
                  #if node is None:
                  #    raise RepresenterError("recursive objects are not allowed: %r" % data)
                  return node
              #self.represented_objects[alias_key] = None
              self.object_keeper.append(data)
          data_types = type(data).__mro__
          if type(data) is types.InstanceType:
              data_types = self.get_classobj_bases(data.__class__)+list(data_types)
          for dt in data_types:
              rep = self.yaml_representers.get(dt)
              if rep:
                  return rep(self, data)
          for data_type in data_types:
              if data_type in self.yaml_multi_representers:
                  node = self.yaml_multi_representers[data_type](self, data)
                  break
          else:
              if None in self.yaml_multi_representers:
                  node = self.yaml_multi_representers[None](self, data)
              elif None in self.yaml_representers:
                  node = self.yaml_representers[None](self, data)
              else:
                  node = ScalarNode(None, unicode(data))
          #if alias_key is not None:
          #    self.represented_objects[alias_key] = node
          return node
  
      def add_representer(cls, data_type, representer):
          if not 'yaml_representers' in cls.__dict__:
              cls.yaml_representers = cls.yaml_representers.copy()
          cls.yaml_representers[data_type] = representer
      add_representer = classmethod(add_representer)
  
      def add_multi_representer(cls, data_type, representer):
          if not 'yaml_multi_representers' in cls.__dict__:
              cls.yaml_multi_representers = cls.yaml_multi_representers.copy()
          cls.yaml_multi_representers[data_type] = representer
      add_multi_representer = classmethod(add_multi_representer)
  
      def represent_scalar(self, tag, value, style=None):
          if style is None:
              style = self.default_style
          node = ScalarNode(tag, value, style=style)
          if self.alias_key is not None:
              self.represented_objects[self.alias_key] = node
          return node
  
      def represent_sequence(self, tag, sequence, flow_style=None):
          value = []
          node = SequenceNode(tag, value, flow_style=flow_style)
          if self.alias_key is not None:
              self.represented_objects[self.alias_key] = node
          best_style = True
          for item in sequence:
              node_item = self.represent_data(item)
              if not (isinstance(node_item, ScalarNode) and not node_item.style):
                  best_style = False
              value.append(node_item)
          if flow_style is None:
              if self.default_flow_style is not None:
                  node.flow_style = self.default_flow_style
              else:
                  node.flow_style = best_style
          return node
  
      def represent_mapping(self, tag, mapping, flow_style=None):
          value = []
          node = MappingNode(tag, value, flow_style=flow_style)
          if self.alias_key is not None:
              self.represented_objects[self.alias_key] = node
          best_style = True
          if hasattr(mapping, 'items'):
              mapping = mapping.items()
              mapping.sort()
          for item_key, item_value in mapping:
              node_key = self.represent_data(item_key)
              node_value = self.represent_data(item_value)
              if not (isinstance(node_key, ScalarNode) and not node_key.style):
                  best_style = False
              if not (isinstance(node_value, ScalarNode) and not node_value.style):
                  best_style = False
              value.append((node_key, node_value))
          if flow_style is None:
              if self.default_flow_style is not None:
                  node.flow_style = self.default_flow_style
              else:
                  node.flow_style = best_style
          return node
  
      def ignore_aliases(self, data):
          return False
  
  class SafeRepresenter(BaseRepresenter):
  
      def ignore_aliases(self, data):
          if data in [None, ()]:
              return True
          if isinstance(data, (str, unicode, bool, int, float)):
              return True
  
      def represent_none(self, data):
          return self.represent_scalar(u'tag:yaml.org,2002:null',
                  u'null')
  
      def represent_str(self, data):
          tag = None
          style = None
          try:
              data = unicode(data, 'ascii')
              tag = u'tag:yaml.org,2002:str'
          except UnicodeDecodeError:
              try:
                  data = unicode(data, 'utf-8')
                  tag = u'tag:yaml.org,2002:str'
              except UnicodeDecodeError:
                  data = data.encode('base64')
                  tag = u'tag:yaml.org,2002:binary'
                  style = '|'
          return self.represent_scalar(tag, data, style=style)
  
      def represent_bytearray(self, data):
          return self.represent_scalar(
              u'tag:yaml.org,2002:binary', base64.encodestring(data), style='|')
  
      def represent_unicode(self, data):
          return self.represent_scalar(u'tag:yaml.org,2002:str', data)
  
      def represent_bool(self, data):
          if data:
              value = u'true'
          else:
              value = u'false'
          return self.represent_scalar(u'tag:yaml.org,2002:bool', value)
  
      def represent_int(self, data):
          return self.represent_scalar(u'tag:yaml.org,2002:int', unicode(data))
  
      def represent_long(self, data):
          return self.represent_scalar(u'tag:yaml.org,2002:int', unicode(data))
  
      inf_value = 1e300
      while repr(inf_value) != repr(inf_value*inf_value):
          inf_value *= inf_value
  
      def represent_float(self, data):
          if data != data or (data == 0.0 and data == 1.0):
              value = u'.nan'
          elif data == self.inf_value:
              value = u'.inf'
          elif data == -self.inf_value:
              value = u'-.inf'
          else:
              value = unicode(repr(data)).lower()
              # Note that in some cases `repr(data)` represents a float number
              # without the decimal parts.  For instance:
              #   >>> repr(1e17)
              #   '1e17'
              # Unfortunately, this is not a valid float representation according
              # to the definition of the `!!float` tag.  We fix this by adding
              # '.0' before the 'e' symbol.
              if u'.' not in value and u'e' in value:
                  value = value.replace(u'e', u'.0e', 1)
          return self.represent_scalar(u'tag:yaml.org,2002:float', value)
  
      def represent_list(self, data):
          #pairs = (len(data) > 0 and isinstance(data, list))
          #if pairs:
          #    for item in data:
          #        if not isinstance(item, tuple) or len(item) != 2:
          #            pairs = False
          #            break
          #if not pairs:
              return self.represent_sequence(u'tag:yaml.org,2002:seq', data)
          #value = []
          #for item_key, item_value in data:
          #    value.append(self.represent_mapping(u'tag:yaml.org,2002:map',
          #        [(item_key, item_value)]))
          #return SequenceNode(u'tag:yaml.org,2002:pairs', value)
  
      def represent_dict(self, data):
          return self.represent_mapping(u'tag:yaml.org,2002:map', data)
  
      def represent_set(self, data):
          value = {}
          for key in data:
              value[key] = None
          return self.represent_mapping(u'tag:yaml.org,2002:set', value)
  
      def represent_date(self, data):
          value = unicode(data.isoformat())
          return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
  
      def represent_datetime(self, data):
          value = unicode(data.isoformat(' '))
          return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
  
      def represent_yaml_object(self, tag, data, cls, flow_style=None):
          if hasattr(data, '__getstate__'):
              state = data.__getstate__()
          else:
              state = data.__dict__.copy()
          return self.represent_mapping(tag, state, flow_style=flow_style)
  
      def represent_undefined(self, data):
          raise RepresenterError("cannot represent an object: %s" % data)
  
  SafeRepresenter.add_representer(type(None),
          SafeRepresenter.represent_none)
  
  SafeRepresenter.add_representer(str,
          SafeRepresenter.represent_str)
  
  SafeRepresenter.add_representer(bytearray,
          SafeRepresenter.represent_bytearray)
  
  SafeRepresenter.add_representer(unicode,
          SafeRepresenter.represent_unicode)
  
  SafeRepresenter.add_representer(bool,
          SafeRepresenter.represent_bool)
  
  SafeRepresenter.add_representer(int,
          SafeRepresenter.represent_int)
  
  SafeRepresenter.add_representer(long,
          SafeRepresenter.represent_long)
  
  SafeRepresenter.add_representer(float,
          SafeRepresenter.represent_float)
  
  SafeRepresenter.add_representer(list,
          SafeRepresenter.represent_list)
  
  SafeRepresenter.add_representer(tuple,
          SafeRepresenter.represent_list)
  
  SafeRepresenter.add_representer(dict,
          SafeRepresenter.represent_dict)
  
  SafeRepresenter.add_representer(set,
          SafeRepresenter.represent_set)
  
  SafeRepresenter.add_representer(datetime.date,
          SafeRepresenter.represent_date)
  
  SafeRepresenter.add_representer(datetime.datetime,
          SafeRepresenter.represent_datetime)
  
  SafeRepresenter.add_representer(None,
          SafeRepresenter.represent_undefined)
  
  class Representer(SafeRepresenter):
  
      def represent_str(self, data):
          tag = None
          style = None
          try:
              data = unicode(data, 'ascii')
              tag = u'tag:yaml.org,2002:str'
          except UnicodeDecodeError:
              try:
                  data = unicode(data, 'utf-8')
                  tag = u'tag:yaml.org,2002:python/str'
              except UnicodeDecodeError:
                  data = data.encode('base64')
                  tag = u'tag:yaml.org,2002:binary'
                  style = '|'
          return self.represent_scalar(tag, data, style=style)
  
      def represent_unicode(self, data):
          tag = None
          try:
              data.encode('ascii')
              tag = u'tag:yaml.org,2002:python/unicode'
          except UnicodeEncodeError:
              tag = u'tag:yaml.org,2002:str'
          return self.represent_scalar(tag, data)
  
      def represent_long(self, data):
          tag = u'tag:yaml.org,2002:int'
          if int(data) is not data:
              tag = u'tag:yaml.org,2002:python/long'
          return self.represent_scalar(tag, unicode(data))
  
      def represent_complex(self, data):
          if data.imag == 0.0:
              data = u'%r' % data.real
          elif data.real == 0.0:
              data = u'%rj' % data.imag
          elif data.imag > 0:
              data = u'%r+%rj' % (data.real, data.imag)
          else:
              data = u'%r%rj' % (data.real, data.imag)
          return self.represent_scalar(u'tag:yaml.org,2002:python/complex', data)
  
      def represent_tuple(self, data):
          return self.represent_sequence(u'tag:yaml.org,2002:python/tuple', data)
  
      def represent_name(self, data):
          name = u'%s.%s' % (data.__module__, data.__name__)
          return self.represent_scalar(u'tag:yaml.org,2002:python/name:'+name, u'')
  
      def represent_module(self, data):
          return self.represent_scalar(
                  u'tag:yaml.org,2002:python/module:'+data.__name__, u'')
  
      def represent_instance(self, data):
          # For instances of classic classes, we use __getinitargs__ and
          # __getstate__ to serialize the data.
  
          # If data.__getinitargs__ exists, the object must be reconstructed by
          # calling cls(**args), where args is a tuple returned by
          # __getinitargs__. Otherwise, the cls.__init__ method should never be
          # called and the class instance is created by instantiating a trivial
          # class and assigning to the instance's __class__ variable.
  
          # If data.__getstate__ exists, it returns the state of the object.
          # Otherwise, the state of the object is data.__dict__.
  
          # We produce either a !!python/object or !!python/object/new node.
          # If data.__getinitargs__ does not exist and state is a dictionary, we
          # produce a !!python/object node . Otherwise we produce a
          # !!python/object/new node.
  
          cls = data.__class__
          class_name = u'%s.%s' % (cls.__module__, cls.__name__)
          args = None
          state = None
          if hasattr(data, '__getinitargs__'):
              args = list(data.__getinitargs__())
          if hasattr(data, '__getstate__'):
              state = data.__getstate__()
          else:
              state = data.__dict__
          if args is None and isinstance(state, dict):
              return self.represent_mapping(
                      u'tag:yaml.org,2002:python/object:'+class_name, state)
          if isinstance(state, dict) and not state:
              return self.represent_sequence(
                      u'tag:yaml.org,2002:python/object/new:'+class_name, args)
          value = {}
          if args:
              value['args'] = args
          value['state'] = state
          return self.represent_mapping(
                  u'tag:yaml.org,2002:python/object/new:'+class_name, value)
  
      def represent_object(self, data):
          # We use __reduce__ API to save the data. data.__reduce__ returns
          # a tuple of length 2-5:
          #   (function, args, state, listitems, dictitems)
  
          # For reconstructing, we calls function(*args), then set its state,
          # listitems, and dictitems if they are not None.
  
          # A special case is when function.__name__ == '__newobj__'. In this
          # case we create the object with args[0].__new__(*args).
  
          # Another special case is when __reduce__ returns a string - we don't
          # support it.
  
          # We produce a !!python/object, !!python/object/new or
          # !!python/object/apply node.
  
          cls = type(data)
          if cls in copy_reg.dispatch_table:
              reduce = copy_reg.dispatch_table[cls](data)
          elif hasattr(data, '__reduce_ex__'):
              reduce = data.__reduce_ex__(2)
          elif hasattr(data, '__reduce__'):
              reduce = data.__reduce__()
          else:
              raise RepresenterError("cannot represent object: %r" % data)
          reduce = (list(reduce)+[None]*5)[:5]
          function, args, state, listitems, dictitems = reduce
          args = list(args)
          if state is None:
              state = {}
          if listitems is not None:
              listitems = list(listitems)
          if dictitems is not None:
              dictitems = dict(dictitems)
          if function.__name__ == '__newobj__':
              function = args[0]
              args = args[1:]
              tag = u'tag:yaml.org,2002:python/object/new:'
              newobj = True
          else:
              tag = u'tag:yaml.org,2002:python/object/apply:'
              newobj = False
          function_name = u'%s.%s' % (function.__module__, function.__name__)
          if not args and not listitems and not dictitems \
                  and isinstance(state, dict) and newobj:
              return self.represent_mapping(
                      u'tag:yaml.org,2002:python/object:'+function_name, state)
          if not listitems and not dictitems  \
                  and isinstance(state, dict) and not state:
              return self.represent_sequence(tag+function_name, args)
          value = {}
          if args:
              value['args'] = args
          if state or not isinstance(state, dict):
              value['state'] = state
          if listitems:
              value['listitems'] = listitems
          if dictitems:
              value['dictitems'] = dictitems
          return self.represent_mapping(tag+function_name, value)
  
  Representer.add_representer(str,
          Representer.represent_str)
  
  Representer.add_representer(unicode,
          Representer.represent_unicode)
  
  Representer.add_representer(long,
          Representer.represent_long)
  
  Representer.add_representer(complex,
          Representer.represent_complex)
  
  Representer.add_representer(tuple,
          Representer.represent_tuple)
  
  Representer.add_representer(type,
          Representer.represent_name)
  
  Representer.add_representer(types.ClassType,
          Representer.represent_name)
  
  Representer.add_representer(types.FunctionType,
          Representer.represent_name)
  
  Representer.add_representer(types.BuiltinFunctionType,
          Representer.represent_name)
  
  Representer.add_representer(types.ModuleType,
          Representer.represent_module)
  
  Representer.add_multi_representer(types.InstanceType,
          Representer.represent_instance)
  
  Representer.add_multi_representer(object,
          Representer.represent_object)
  
  