- main problem in moving stuff from yaml/py to yaml was that

  parser.py clashes with built-in parser module (CPython, C-module)
  which is inlucded from pkg_resources/__init__.py
- no C compile yet

1 files changed, 808 insertions, 0 deletions

diff --git a/representer.py b/representer.py
new file mode 100644
index 0000000..63c0d0d
--- /dev/null
+++ b/representer.py
@@ -0,0 +1,808 @@
+from __future__ import absolute_import
+from __future__ import print_function
+
+__all__ = ['BaseRepresenter', 'SafeRepresenter', 'Representer',
+           'RepresenterError', 'RoundTripRepresenter']
+
+from .error import *
+from .nodes import *
+from .compat import text_type, binary_type, to_unicode, PY2, PY3, \
+    ordereddict, nprint
+from .scalarstring import *
+
+import datetime
+import sys
+import types
+if PY3:
+    import copyreg
+    import base64
+else:
+    import copy_reg as copyreg
+
+
+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
+
+    if PY2:
+        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 PY2:
+            # if type(data) is types.InstanceType:
+            if isinstance(data, types.InstanceType):
+                data_types = self.get_classobj_bases(data.__class__) + \
+                    list(data_types)
+        if data_types[0] in self.yaml_representers:
+            node = self.yaml_representers[data_types[0]](self, data)
+        else:
+            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, text_type(data))
+        # if alias_key is not None:
+        #     self.represented_objects[alias_key] = node
+        return node
+
+    def represent_key(self, data):
+        """
+        David Fraser: Extract a method to represent keys in mappings, so that
+        a subclass can choose not to quote them (for example)
+        used in repesent_mapping
+        https://bitbucket.org/davidfraser/pyyaml/commits/d81df6eb95f20cac4a79eed95ae553b5c6f77b8c
+        """
+        return self.represent_data(data)
+
+    @classmethod
+    def add_representer(cls, data_type, representer):
+        if 'yaml_representers' not in cls.__dict__:
+            cls.yaml_representers = cls.yaml_representers.copy()
+        cls.yaml_representers[data_type] = representer
+
+    @classmethod
+    def add_multi_representer(cls, data_type, representer):
+        if 'yaml_multi_representers' not in cls.__dict__:
+            cls.yaml_multi_representers = cls.yaml_multi_representers.copy()
+        cls.yaml_multi_representers[data_type] = 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_omap(self, tag, omap, 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_key in omap:
+            item_val = omap[item_key]
+            node_item = self.represent_data({item_key: item_val})
+            # 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 = list(mapping.items())
+            try:
+                mapping = sorted(mapping)
+            except TypeError:
+                pass
+        for item_key, item_value in mapping:
+            node_key = self.represent_key(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, (binary_type, text_type, bool, int, float)):
+            return True
+
+    def represent_none(self, data):
+        return self.represent_scalar(u'tag:yaml.org,2002:null',
+                                     u'null')
+
+    if PY3:
+        def represent_str(self, data):
+            return self.represent_scalar(u'tag:yaml.org,2002:str', data)
+
+        def represent_binary(self, data):
+            if hasattr(base64, 'encodebytes'):
+                data = base64.encodebytes(data).decode('ascii')
+            else:
+                data = base64.encodestring(data).decode('ascii')
+            return self.represent_scalar(u'tag:yaml.org,2002:binary', data,
+                                         style='|')
+    else:
+        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_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', text_type(data))
+
+    if PY2:
+        def represent_long(self, data):
+            return self.represent_scalar(u'tag:yaml.org,2002:int',
+                                         text_type(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 = to_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_ordereddict(self, data):
+        return self.represent_omap(u'tag:yaml.org,2002:omap', 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 = to_unicode(data.isoformat())
+        return self.represent_scalar(u'tag:yaml.org,2002:timestamp', value)
+
+    def represent_datetime(self, data):
+        value = to_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)
+
+if PY2:
+    SafeRepresenter.add_representer(unicode,
+                                    SafeRepresenter.represent_unicode)
+else:
+    SafeRepresenter.add_representer(bytes,
+                                    SafeRepresenter.represent_binary)
+
+SafeRepresenter.add_representer(bool,
+                                SafeRepresenter.represent_bool)
+
+SafeRepresenter.add_representer(int,
+                                SafeRepresenter.represent_int)
+
+if PY2:
+    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(ordereddict,
+                                SafeRepresenter.represent_ordereddict)
+
+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):
+    if PY2:
+        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, to_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'')
+
+    if PY2:
+        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 copyreg.dispatch_table:
+            reduce = copyreg.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)
+
+if PY2:
+    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)
+
+if PY2:
+    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)
+
+if PY2:
+    Representer.add_multi_representer(types.InstanceType,
+                                      Representer.represent_instance)
+
+Representer.add_multi_representer(object,
+                                  Representer.represent_object)
+
+
+from .comments import CommentedMap, CommentedOrderedMap, CommentedSeq, \
+    CommentedSet, comment_attrib, merge_attrib
+
+
+class RoundTripRepresenter(SafeRepresenter):
+    # need to add type here and write out the .comment
+    # in serializer and emitter
+
+    def __init__(self, default_style=None, default_flow_style=None):
+        if default_flow_style is None:
+            default_flow_style = False
+        SafeRepresenter.__init__(self, default_style=default_style,
+                                 default_flow_style=default_flow_style)
+
+    def represent_none(self, data):
+        return self.represent_scalar(u'tag:yaml.org,2002:null',
+                                     u'')
+
+    def represent_preserved_scalarstring(self, data):
+        tag = None
+        style = '|'
+        if PY2 and not isinstance(data, unicode):
+            data = unicode(data, 'ascii')
+        tag = u'tag:yaml.org,2002:str'
+        return self.represent_scalar(tag, data, style=style)
+
+    def represent_sequence(self, tag, sequence, flow_style=None):
+        value = []
+        # if the flow_style is None, the flow style tacked on to the object
+        # explicitly will be taken. If that is None as well the default flow
+        # style rules
+        try:
+            flow_style = sequence.fa.flow_style(flow_style)
+        except AttributeError:
+            flow_style = flow_style
+        try:
+            anchor = sequence.yaml_anchor()
+        except AttributeError:
+            anchor = None
+        node = SequenceNode(tag, value, flow_style=flow_style, anchor=anchor)
+        if self.alias_key is not None:
+            self.represented_objects[self.alias_key] = node
+        best_style = True
+        try:
+            comment = getattr(sequence, comment_attrib)
+            item_comments = comment.items
+            node.comment = comment.comment
+            try:
+                node.comment.append(comment.end)
+            except AttributeError:
+                pass
+        except AttributeError:
+            item_comments = {}
+        for idx, item in enumerate(sequence):
+            node_item = self.represent_data(item)
+            node_item.comment = item_comments.get(idx)
+            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 = []
+        try:
+            flow_style = mapping.fa.flow_style(flow_style)
+        except AttributeError:
+            flow_style = flow_style
+        try:
+            anchor = mapping.yaml_anchor()
+        except AttributeError:
+            anchor = None
+        node = MappingNode(tag, value, flow_style=flow_style, anchor=anchor)
+        if self.alias_key is not None:
+            self.represented_objects[self.alias_key] = node
+        best_style = True
+        # no sorting! !!
+        try:
+            comment = getattr(mapping, comment_attrib)
+            node.comment = comment.comment
+            item_comments = comment.items
+            try:
+                node.comment.append(comment.end)
+            except AttributeError:
+                pass
+        except AttributeError:
+            item_comments = {}
+        for item_key, item_value in mapping.items():
+            node_key = self.represent_key(item_key)
+            node_value = self.represent_data(item_value)
+            item_comment = item_comments.get(item_key)
+            if item_comment:
+                assert getattr(node_key, 'comment', None) is None
+                node_key.comment = item_comment[:2]
+                nvc = getattr(node_value, 'comment', None)
+                if nvc is not None:  # end comment already there
+                    nvc[0] = item_comment[2]
+                    nvc[1] = item_comment[3]
+                else:
+                    node_value.comment = item_comment[2:]
+            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
+        merge_list = [m[1] for m in getattr(mapping, merge_attrib, [])]
+        if merge_list:
+            # because of the call to represent_data here, the anchors
+            # are marked as being used and thereby created
+            if len(merge_list) == 1:
+                arg = self.represent_data(merge_list[0])
+            else:
+                arg = self.represent_data(merge_list)
+                arg.flow_style = True
+            value.insert(0,
+                         (ScalarNode(u'tag:yaml.org,2002:merge', '<<'), arg))
+        return node
+
+    def represent_omap(self, tag, omap, flow_style=None):
+        value = []
+        try:
+            flow_style = omap.fa.flow_style(flow_style)
+        except AttributeError:
+            flow_style = flow_style
+        try:
+            anchor = omap.yaml_anchor()
+        except AttributeError:
+            anchor = None
+        node = SequenceNode(tag, value, flow_style=flow_style, anchor=anchor)
+        if self.alias_key is not None:
+            self.represented_objects[self.alias_key] = node
+        best_style = True
+        try:
+            comment = getattr(omap, comment_attrib)
+            node.comment = comment.comment
+            item_comments = comment.items
+            try:
+                node.comment.append(comment.end)
+            except AttributeError:
+                pass
+        except AttributeError:
+            item_comments = {}
+        for item_key in omap:
+            item_val = omap[item_key]
+            node_item = self.represent_data({item_key: item_val})
+            # node item has two scalars in value: node_key and node_value
+            item_comment = item_comments.get(item_key)
+            if item_comment:
+                if item_comment[1]:
+                    node_item.comment = [None, item_comment[1]]
+                assert getattr(node_item.value[0][0], 'comment', None) is None
+                node_item.value[0][0].comment = [item_comment[0], None]
+                nvc = getattr(node_item.value[0][1], 'comment', None)
+                if nvc is not None:  # end comment already there
+                    nvc[0] = item_comment[2]
+                    nvc[1] = item_comment[3]
+                else:
+                    node_item.value[0][1].comment = item_comment[2:]
+            # 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_set(self, setting):
+        flow_style = False
+        tag = u'tag:yaml.org,2002:set'
+        # return self.represent_mapping(tag, value)
+        value = []
+        flow_style = setting.fa.flow_style(flow_style)
+        try:
+            anchor = setting.yaml_anchor()
+        except AttributeError:
+            anchor = None
+        node = MappingNode(tag, value, flow_style=flow_style, anchor=anchor)
+        if self.alias_key is not None:
+            self.represented_objects[self.alias_key] = node
+        best_style = True
+        # no sorting! !!
+        try:
+            comment = getattr(setting, comment_attrib)
+            node.comment = comment.comment
+            item_comments = comment.items
+            try:
+                node.comment.append(comment.end)
+            except AttributeError:
+                pass
+        except AttributeError:
+            item_comments = {}
+        for item_key in setting.odict:
+            node_key = self.represent_key(item_key)
+            node_value = self.represent_data(None)
+            item_comment = item_comments.get(item_key)
+            if item_comment:
+                assert getattr(node_key, 'comment', None) is None
+                node_key.comment = item_comment[:2]
+            node_key.style = node_value.style = "?"
+            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))
+        return node
+
+
+RoundTripRepresenter.add_representer(type(None),
+                                     RoundTripRepresenter.represent_none)
+
+RoundTripRepresenter.add_representer(
+    PreservedScalarString,
+    RoundTripRepresenter.represent_preserved_scalarstring)
+
+RoundTripRepresenter.add_representer(CommentedSeq,
+                                     RoundTripRepresenter.represent_list)
+
+RoundTripRepresenter.add_representer(CommentedMap,
+                                     RoundTripRepresenter.represent_dict)
+
+RoundTripRepresenter.add_representer(
+    CommentedOrderedMap,
+    RoundTripRepresenter.represent_ordereddict)
+
+RoundTripRepresenter.add_representer(CommentedSet,
+                                     RoundTripRepresenter.represent_set)