def __init__(self, stream):
     Reader.__init__(self, stream)
     Scanner.__init__(self)
     Parser.__init__(self)
     Composer.__init__(self)
     SafeConstructor.__init__(self)
     Resolver.__init__(self)

    def __init__(self, stream):
        Reader.__init__(self, stream)
        Scanner12.__init__(self)
        Parser.__init__(self)
        Composer.__init__(self)

# PKM2014 - uses SafeConstructor instead of Constructor. This should make no
# difference, because "Is it YAML?" only gets as far as the composition stage,
# but - well: it reduces the risk of something bad happening.

#        Constructor.__init__(self)
        SafeConstructor.__init__(self)
        Resolver.__init__(self)

    def __init__(self):
        self.add_multi_constructor("!vol/", self.__class__.vol_constructor)
        self.add_multi_constructor("!type/", self.__class__.type_constructor)
        self.add_constructor(
            "!include", self.__class__.include_file_constructor)
        self.add_constructor(
            "!include_merge", self.__class__.include_merge_constructor)
        self.add_constructor(
            "!include_dir_file_mapped",
            self.__class__.include_dir_file_mapped_constructor)
        self.add_constructor("!env_var", self.__class__.env_var_constructor)
        self.add_constructor("!path", self.__class__.path_constructor)

        SafeConstructor.__init__(self)

    def construct_yaml_map(self, node):
        """
        Return a node class representing a line-marked dictionary.

        """
        obj, = SafeConstructor.construct_yaml_map(self, node)
        return DictNode(obj, node.start_mark, node.end_mark)

    def construct_yaml_seq(self, node):
        """
        Return a node class representing a line-marked sequence.

        """
        obj, = SafeConstructor.construct_yaml_seq(self, node)
        return ListNode(obj, node.start_mark, node.end_mark)

    def construct_yaml_str(self, node):
        """
        Return a node class representing a line-marked string.

        """
        obj = SafeConstructor.construct_scalar(self, node)
        assert da.util.is_string(obj)
        return StringNode(obj, node.start_mark, node.end_mark)

 def construct_yaml_str(self, node):
     obj = SafeConstructor.construct_yaml_str(self, node)
     try:
         obj = str(obj)
     except UnicodeEncodeError:
         raise DSLParsingInputTypeException(
             ERROR_INVALID_CHARS,
             'illegal characters in line: {0}, column: {1}. '
             'Only valid ascii chars are supported.'.format(
                 node.start_mark.line, node.start_mark.column))
     return self._holder(obj, node)

 def construct_mapping(self, node, deep=False):
     if not isinstance(node, yaml.nodes.MappingNode):
         raise ConstructorError(
             None, None,
             "expected a mapping node, but found %s" % node.id,
             node.start_mark)
     keys = set([])
     for key_node, value_node in node.value:
         key = self.construct_object(key_node, deep=deep)
         if key in keys:
             raise ConstructorError(
                 "while constructing a mapping", node.start_mark,
                 "found duplicate key (%s)" % key, key_node.start_mark)
         keys.add(key)
     return SafeConstructor.construct_mapping(self, node, deep)

 def construct_yaml_float(self, node):
     obj = SafeConstructor.construct_scalar(self, node)
     return float_node(obj, node.start_mark, node.end_mark)

 def construct_yaml_bool(self, node):
     obj = SafeConstructor.construct_yaml_bool(self, node)
     return int_node(obj, node.start_mark, node.end_mark)

 def construct_yaml_str(self, node):
     obj = SafeConstructor.construct_scalar(self, node)
     assert isinstance(obj, unicode)
     return unicode_node(obj, node.start_mark, node.end_mark)

 def construct_yaml_seq(self, node):
     obj, = SafeConstructor.construct_yaml_seq(self, node)
     return list_node(obj, node.start_mark, node.end_mark)

 def construct_yaml_map(self, node):
     obj, = SafeConstructor.construct_yaml_map(self, node)
     return self._holder(obj, node)

 def construct_yaml_timestamp(self, node):
     obj = SafeConstructor.construct_yaml_timestamp(self, node)
     return self._holder(obj, node)

 def construct_yaml_binary(self, node):
     obj = SafeConstructor.construct_yaml_binary(self, node)
     return self._holder(obj, node)

 def __init__(self, filename):
     SafeConstructor.__init__(self)
     self.filename = filename

        value = self.construct_object(value_node, deep=deep)
        mapping[key] = value
    
    return mapping

BaseConstructor.construct_mapping = construct_ordered_mapping


def construct_yaml_map_with_ordered_dict(self, node):
    data = OrderedDict()
    yield data
    value = self.construct_mapping(node)
    data.update(value)

for t in [u'tag:yaml.org,2002:map', u'tag:yaml.org,2002:omap']:
    SafeConstructor.add_constructor( t, construct_yaml_map_with_ordered_dict )
    Constructor.add_constructor( t, construct_yaml_map_with_ordered_dict )
    yaml.add_constructor( t, construct_yaml_map_with_ordered_dict )


def represent_ordered_mapping(self, tag, mapping, flow_style=None):
    value = []
    node = yaml.MappingNode(tag, value, flow_style=flow_style)
    best_style = True
    
    if self.alias_key is not None:
        self.represented_objects[self.alias_key] = node
    
    if hasattr(mapping, 'items'):
        mapping = list(mapping.items())
    

    def parse(self, content, **kwargs):
        """ Parses the given YAML content to create stringset and template

        Steps are:
            1. Load yaml content using our custom loader TxYamlLoader that
               in addition to the value for each key notes the `start` and
               `end` index of each node in the file and some metadata.
            2. Flattens the output of the loader to be a list of the form:
               ```
               [{
                   'key': 'string_key1',
                   'value': 'string1',
                   'end': <end_index_of_node>,
                   'start': <start_index_value>,
                   'style': '|, >, ...'
                },
                ...
               ]
               ```
            3. Iterates over the flattened list and for each entry creates an
               OpenString object, appends it to stringset and replace its value
               with the template_replacement in the template.
            4. Returns the (template, stringset) tuple.
        """
        template = []
        stringset = []
        # The first argument of the add_constructor method is the tag you want
        # to handle. If you provide None as an argument, all the unknown tags
        # will be handled by the constructor specified in the second argument.
        # We need this in order parse all unknown custom-tagged values as
        # strings.
        SafeConstructor.add_constructor(None,
                                        SafeConstructor.construct_yaml_str)
        yaml_data = self._load_yaml(content, loader=TxYamlLoader)
        yaml_data = self._get_yaml_data_to_parse(yaml_data)
        # Helper to store the processed data while parsing the file
        self._parsed_data = []
        self._parse_yaml_data(yaml_data, '', '')
        self._parsed_data = sorted(self._parsed_data,
                                   key=lambda node: node.get('start'))

        end = 0
        order = 0
        for node in self._parsed_data:
            start = node.get('start')
            end_ = node.get('end')
            key = node.get('key')
            tag = node.get('tag')
            value = node.get('value')
            style = node.get('style')
            if not value:
                continue
            if isinstance(value, dict) and not all(six.itervalues(value)):
                continue
            string_object = OpenString(
                key, value, context=tag or '', flags=style, order=order,
            )
            stringset.append(string_object)
            order += 1
            template.append(u"{}{}".format(content[end:start],
                                           string_object.template_replacement))
            comment = self._find_comment(content, end, start)
            string_object.developer_comment = comment
            end = end_

        template.append(content[end:])
        template = u''.join(template)
        return template, stringset