diff env/lib/python3.9/site-packages/ruamel/yaml/constructor.py @ 0:4f3585e2f14b draft default tip

"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.9/site-packages/ruamel/yaml/constructor.py	Mon Mar 22 18:12:50 2021 +0000
@@ -0,0 +1,1805 @@
+# coding: utf-8
+
+from __future__ import print_function, absolute_import, division
+
+import datetime
+import base64
+import binascii
+import re
+import sys
+import types
+import warnings
+
+# fmt: off
+from ruamel.yaml.error import (MarkedYAMLError, MarkedYAMLFutureWarning,
+                               MantissaNoDotYAML1_1Warning)
+from ruamel.yaml.nodes import *                               # NOQA
+from ruamel.yaml.nodes import (SequenceNode, MappingNode, ScalarNode)
+from ruamel.yaml.compat import (utf8, builtins_module, to_str, PY2, PY3,  # NOQA
+                                text_type, nprint, nprintf, version_tnf)
+from ruamel.yaml.compat import ordereddict, Hashable, MutableSequence  # type: ignore
+from ruamel.yaml.compat import MutableMapping  # type: ignore
+
+from ruamel.yaml.comments import *                               # NOQA
+from ruamel.yaml.comments import (CommentedMap, CommentedOrderedMap, CommentedSet,
+                                  CommentedKeySeq, CommentedSeq, TaggedScalar,
+                                  CommentedKeyMap)
+from ruamel.yaml.scalarstring import (SingleQuotedScalarString, DoubleQuotedScalarString,
+                                      LiteralScalarString, FoldedScalarString,
+                                      PlainScalarString, ScalarString,)
+from ruamel.yaml.scalarint import ScalarInt, BinaryInt, OctalInt, HexInt, HexCapsInt
+from ruamel.yaml.scalarfloat import ScalarFloat
+from ruamel.yaml.scalarbool import ScalarBoolean
+from ruamel.yaml.timestamp import TimeStamp
+from ruamel.yaml.util import RegExp
+
+if False:  # MYPY
+    from typing import Any, Dict, List, Set, Generator, Union, Optional  # NOQA
+
+
+__all__ = ['BaseConstructor', 'SafeConstructor', 'Constructor',
+           'ConstructorError', 'RoundTripConstructor']
+# fmt: on
+
+
+class ConstructorError(MarkedYAMLError):
+    pass
+
+
+class DuplicateKeyFutureWarning(MarkedYAMLFutureWarning):
+    pass
+
+
+class DuplicateKeyError(MarkedYAMLFutureWarning):
+    pass
+
+
+class BaseConstructor(object):
+
+    yaml_constructors = {}  # type: Dict[Any, Any]
+    yaml_multi_constructors = {}  # type: Dict[Any, Any]
+
+    def __init__(self, preserve_quotes=None, loader=None):
+        # type: (Optional[bool], Any) -> None
+        self.loader = loader
+        if self.loader is not None and getattr(self.loader, '_constructor', None) is None:
+            self.loader._constructor = self
+        self.loader = loader
+        self.yaml_base_dict_type = dict
+        self.yaml_base_list_type = list
+        self.constructed_objects = {}  # type: Dict[Any, Any]
+        self.recursive_objects = {}  # type: Dict[Any, Any]
+        self.state_generators = []  # type: List[Any]
+        self.deep_construct = False
+        self._preserve_quotes = preserve_quotes
+        self.allow_duplicate_keys = version_tnf((0, 15, 1), (0, 16))
+
+    @property
+    def composer(self):
+        # type: () -> Any
+        if hasattr(self.loader, 'typ'):
+            return self.loader.composer
+        try:
+            return self.loader._composer
+        except AttributeError:
+            sys.stdout.write('slt {}\n'.format(type(self)))
+            sys.stdout.write('slc {}\n'.format(self.loader._composer))
+            sys.stdout.write('{}\n'.format(dir(self)))
+            raise
+
+    @property
+    def resolver(self):
+        # type: () -> Any
+        if hasattr(self.loader, 'typ'):
+            return self.loader.resolver
+        return self.loader._resolver
+
+    def check_data(self):
+        # type: () -> Any
+        # If there are more documents available?
+        return self.composer.check_node()
+
+    def get_data(self):
+        # type: () -> Any
+        # Construct and return the next document.
+        if self.composer.check_node():
+            return self.construct_document(self.composer.get_node())
+
+    def get_single_data(self):
+        # type: () -> Any
+        # Ensure that the stream contains a single document and construct it.
+        node = self.composer.get_single_node()
+        if node is not None:
+            return self.construct_document(node)
+        return None
+
+    def construct_document(self, node):
+        # type: (Any) -> Any
+        data = self.construct_object(node)
+        while bool(self.state_generators):
+            state_generators = self.state_generators
+            self.state_generators = []
+            for generator in state_generators:
+                for _dummy in generator:
+                    pass
+        self.constructed_objects = {}
+        self.recursive_objects = {}
+        self.deep_construct = False
+        return data
+
+    def construct_object(self, node, deep=False):
+        # type: (Any, bool) -> Any
+        """deep is True when creating an object/mapping recursively,
+        in that case want the underlying elements available during construction
+        """
+        if node in self.constructed_objects:
+            return self.constructed_objects[node]
+        if deep:
+            old_deep = self.deep_construct
+            self.deep_construct = True
+        if node in self.recursive_objects:
+            return self.recursive_objects[node]
+            # raise ConstructorError(
+            #     None, None, 'found unconstructable recursive node', node.start_mark
+            # )
+        self.recursive_objects[node] = None
+        data = self.construct_non_recursive_object(node)
+
+        self.constructed_objects[node] = data
+        del self.recursive_objects[node]
+        if deep:
+            self.deep_construct = old_deep
+        return data
+
+    def construct_non_recursive_object(self, node, tag=None):
+        # type: (Any, Optional[str]) -> Any
+        constructor = None  # type: Any
+        tag_suffix = None
+        if tag is None:
+            tag = node.tag
+        if tag in self.yaml_constructors:
+            constructor = self.yaml_constructors[tag]
+        else:
+            for tag_prefix in self.yaml_multi_constructors:
+                if tag.startswith(tag_prefix):
+                    tag_suffix = tag[len(tag_prefix) :]
+                    constructor = self.yaml_multi_constructors[tag_prefix]
+                    break
+            else:
+                if None in self.yaml_multi_constructors:
+                    tag_suffix = tag
+                    constructor = self.yaml_multi_constructors[None]
+                elif None in self.yaml_constructors:
+                    constructor = self.yaml_constructors[None]
+                elif isinstance(node, ScalarNode):
+                    constructor = self.__class__.construct_scalar
+                elif isinstance(node, SequenceNode):
+                    constructor = self.__class__.construct_sequence
+                elif isinstance(node, MappingNode):
+                    constructor = self.__class__.construct_mapping
+        if tag_suffix is None:
+            data = constructor(self, node)
+        else:
+            data = constructor(self, tag_suffix, node)
+        if isinstance(data, types.GeneratorType):
+            generator = data
+            data = next(generator)
+            if self.deep_construct:
+                for _dummy in generator:
+                    pass
+            else:
+                self.state_generators.append(generator)
+        return data
+
+    def construct_scalar(self, node):
+        # type: (Any) -> Any
+        if not isinstance(node, ScalarNode):
+            raise ConstructorError(
+                None, None, 'expected a scalar node, but found %s' % node.id, node.start_mark
+            )
+        return node.value
+
+    def construct_sequence(self, node, deep=False):
+        # type: (Any, bool) -> Any
+        """deep is True when creating an object/mapping recursively,
+        in that case want the underlying elements available during construction
+        """
+        if not isinstance(node, SequenceNode):
+            raise ConstructorError(
+                None, None, 'expected a sequence node, but found %s' % node.id, node.start_mark
+            )
+        return [self.construct_object(child, deep=deep) for child in node.value]
+
+    def construct_mapping(self, node, deep=False):
+        # type: (Any, bool) -> Any
+        """deep is True when creating an object/mapping recursively,
+        in that case want the underlying elements available during construction
+        """
+        if not isinstance(node, MappingNode):
+            raise ConstructorError(
+                None, None, 'expected a mapping node, but found %s' % node.id, node.start_mark
+            )
+        total_mapping = self.yaml_base_dict_type()
+        if getattr(node, 'merge', None) is not None:
+            todo = [(node.merge, False), (node.value, False)]
+        else:
+            todo = [(node.value, True)]
+        for values, check in todo:
+            mapping = self.yaml_base_dict_type()  # type: Dict[Any, Any]
+            for key_node, value_node in values:
+                # keys can be list -> deep
+                key = self.construct_object(key_node, deep=True)
+                # lists are not hashable, but tuples are
+                if not isinstance(key, Hashable):
+                    if isinstance(key, list):
+                        key = tuple(key)
+                if PY2:
+                    try:
+                        hash(key)
+                    except TypeError as exc:
+                        raise ConstructorError(
+                            'while constructing a mapping',
+                            node.start_mark,
+                            'found unacceptable key (%s)' % exc,
+                            key_node.start_mark,
+                        )
+                else:
+                    if not isinstance(key, Hashable):
+                        raise ConstructorError(
+                            'while constructing a mapping',
+                            node.start_mark,
+                            'found unhashable key',
+                            key_node.start_mark,
+                        )
+
+                value = self.construct_object(value_node, deep=deep)
+                if check:
+                    if self.check_mapping_key(node, key_node, mapping, key, value):
+                        mapping[key] = value
+                else:
+                    mapping[key] = value
+            total_mapping.update(mapping)
+        return total_mapping
+
+    def check_mapping_key(self, node, key_node, mapping, key, value):
+        # type: (Any, Any, Any, Any, Any) -> bool
+        """return True if key is unique"""
+        if key in mapping:
+            if not self.allow_duplicate_keys:
+                mk = mapping.get(key)
+                if PY2:
+                    if isinstance(key, unicode):
+                        key = key.encode('utf-8')
+                    if isinstance(value, unicode):
+                        value = value.encode('utf-8')
+                    if isinstance(mk, unicode):
+                        mk = mk.encode('utf-8')
+                args = [
+                    'while constructing a mapping',
+                    node.start_mark,
+                    'found duplicate key "{}" with value "{}" '
+                    '(original value: "{}")'.format(key, value, mk),
+                    key_node.start_mark,
+                    """
+                    To suppress this check see:
+                        http://yaml.readthedocs.io/en/latest/api.html#duplicate-keys
+                    """,
+                    """\
+                    Duplicate keys will become an error in future releases, and are errors
+                    by default when using the new API.
+                    """,
+                ]
+                if self.allow_duplicate_keys is None:
+                    warnings.warn(DuplicateKeyFutureWarning(*args))
+                else:
+                    raise DuplicateKeyError(*args)
+            return False
+        return True
+
+    def check_set_key(self, node, key_node, setting, key):
+        # type: (Any, Any, Any, Any, Any) -> None
+        if key in setting:
+            if not self.allow_duplicate_keys:
+                if PY2:
+                    if isinstance(key, unicode):
+                        key = key.encode('utf-8')
+                args = [
+                    'while constructing a set',
+                    node.start_mark,
+                    'found duplicate key "{}"'.format(key),
+                    key_node.start_mark,
+                    """
+                    To suppress this check see:
+                        http://yaml.readthedocs.io/en/latest/api.html#duplicate-keys
+                    """,
+                    """\
+                    Duplicate keys will become an error in future releases, and are errors
+                    by default when using the new API.
+                    """,
+                ]
+                if self.allow_duplicate_keys is None:
+                    warnings.warn(DuplicateKeyFutureWarning(*args))
+                else:
+                    raise DuplicateKeyError(*args)
+
+    def construct_pairs(self, node, deep=False):
+        # type: (Any, bool) -> Any
+        if not isinstance(node, MappingNode):
+            raise ConstructorError(
+                None, None, 'expected a mapping node, but found %s' % node.id, node.start_mark
+            )
+        pairs = []
+        for key_node, value_node in node.value:
+            key = self.construct_object(key_node, deep=deep)
+            value = self.construct_object(value_node, deep=deep)
+            pairs.append((key, value))
+        return pairs
+
+    @classmethod
+    def add_constructor(cls, tag, constructor):
+        # type: (Any, Any) -> None
+        if 'yaml_constructors' not in cls.__dict__:
+            cls.yaml_constructors = cls.yaml_constructors.copy()
+        cls.yaml_constructors[tag] = constructor
+
+    @classmethod
+    def add_multi_constructor(cls, tag_prefix, multi_constructor):
+        # type: (Any, Any) -> None
+        if 'yaml_multi_constructors' not in cls.__dict__:
+            cls.yaml_multi_constructors = cls.yaml_multi_constructors.copy()
+        cls.yaml_multi_constructors[tag_prefix] = multi_constructor
+
+
+class SafeConstructor(BaseConstructor):
+    def construct_scalar(self, node):
+        # type: (Any) -> Any
+        if isinstance(node, MappingNode):
+            for key_node, value_node in node.value:
+                if key_node.tag == u'tag:yaml.org,2002:value':
+                    return self.construct_scalar(value_node)
+        return BaseConstructor.construct_scalar(self, node)
+
+    def flatten_mapping(self, node):
+        # type: (Any) -> Any
+        """
+        This implements the merge key feature http://yaml.org/type/merge.html
+        by inserting keys from the merge dict/list of dicts if not yet
+        available in this node
+        """
+        merge = []  # type: List[Any]
+        index = 0
+        while index < len(node.value):
+            key_node, value_node = node.value[index]
+            if key_node.tag == u'tag:yaml.org,2002:merge':
+                if merge:  # double << key
+                    if self.allow_duplicate_keys:
+                        del node.value[index]
+                        index += 1
+                        continue
+                    args = [
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'found duplicate key "{}"'.format(key_node.value),
+                        key_node.start_mark,
+                        """
+                        To suppress this check see:
+                           http://yaml.readthedocs.io/en/latest/api.html#duplicate-keys
+                        """,
+                        """\
+                        Duplicate keys will become an error in future releases, and are errors
+                        by default when using the new API.
+                        """,
+                    ]
+                    if self.allow_duplicate_keys is None:
+                        warnings.warn(DuplicateKeyFutureWarning(*args))
+                    else:
+                        raise DuplicateKeyError(*args)
+                del node.value[index]
+                if isinstance(value_node, MappingNode):
+                    self.flatten_mapping(value_node)
+                    merge.extend(value_node.value)
+                elif isinstance(value_node, SequenceNode):
+                    submerge = []
+                    for subnode in value_node.value:
+                        if not isinstance(subnode, MappingNode):
+                            raise ConstructorError(
+                                'while constructing a mapping',
+                                node.start_mark,
+                                'expected a mapping for merging, but found %s' % subnode.id,
+                                subnode.start_mark,
+                            )
+                        self.flatten_mapping(subnode)
+                        submerge.append(subnode.value)
+                    submerge.reverse()
+                    for value in submerge:
+                        merge.extend(value)
+                else:
+                    raise ConstructorError(
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'expected a mapping or list of mappings for merging, '
+                        'but found %s' % value_node.id,
+                        value_node.start_mark,
+                    )
+            elif key_node.tag == u'tag:yaml.org,2002:value':
+                key_node.tag = u'tag:yaml.org,2002:str'
+                index += 1
+            else:
+                index += 1
+        if bool(merge):
+            node.merge = merge  # separate merge keys to be able to update without duplicate
+            node.value = merge + node.value
+
+    def construct_mapping(self, node, deep=False):
+        # type: (Any, bool) -> Any
+        """deep is True when creating an object/mapping recursively,
+        in that case want the underlying elements available during construction
+        """
+        if isinstance(node, MappingNode):
+            self.flatten_mapping(node)
+        return BaseConstructor.construct_mapping(self, node, deep=deep)
+
+    def construct_yaml_null(self, node):
+        # type: (Any) -> Any
+        self.construct_scalar(node)
+        return None
+
+    # YAML 1.2 spec doesn't mention yes/no etc any more, 1.1 does
+    bool_values = {
+        u'yes': True,
+        u'no': False,
+        u'y': True,
+        u'n': False,
+        u'true': True,
+        u'false': False,
+        u'on': True,
+        u'off': False,
+    }
+
+    def construct_yaml_bool(self, node):
+        # type: (Any) -> bool
+        value = self.construct_scalar(node)
+        return self.bool_values[value.lower()]
+
+    def construct_yaml_int(self, node):
+        # type: (Any) -> int
+        value_s = to_str(self.construct_scalar(node))
+        value_s = value_s.replace('_', "")
+        sign = +1
+        if value_s[0] == '-':
+            sign = -1
+        if value_s[0] in '+-':
+            value_s = value_s[1:]
+        if value_s == '0':
+            return 0
+        elif value_s.startswith('0b'):
+            return sign * int(value_s[2:], 2)
+        elif value_s.startswith('0x'):
+            return sign * int(value_s[2:], 16)
+        elif value_s.startswith('0o'):
+            return sign * int(value_s[2:], 8)
+        elif self.resolver.processing_version == (1, 1) and value_s[0] == '0':
+            return sign * int(value_s, 8)
+        elif self.resolver.processing_version == (1, 1) and ':' in value_s:
+            digits = [int(part) for part in value_s.split(':')]
+            digits.reverse()
+            base = 1
+            value = 0
+            for digit in digits:
+                value += digit * base
+                base *= 60
+            return sign * value
+        else:
+            return sign * int(value_s)
+
+    inf_value = 1e300
+    while inf_value != inf_value * inf_value:
+        inf_value *= inf_value
+    nan_value = -inf_value / inf_value  # Trying to make a quiet NaN (like C99).
+
+    def construct_yaml_float(self, node):
+        # type: (Any) -> float
+        value_so = to_str(self.construct_scalar(node))
+        value_s = value_so.replace('_', "").lower()
+        sign = +1
+        if value_s[0] == '-':
+            sign = -1
+        if value_s[0] in '+-':
+            value_s = value_s[1:]
+        if value_s == '.inf':
+            return sign * self.inf_value
+        elif value_s == '.nan':
+            return self.nan_value
+        elif self.resolver.processing_version != (1, 2) and ':' in value_s:
+            digits = [float(part) for part in value_s.split(':')]
+            digits.reverse()
+            base = 1
+            value = 0.0
+            for digit in digits:
+                value += digit * base
+                base *= 60
+            return sign * value
+        else:
+            if self.resolver.processing_version != (1, 2) and 'e' in value_s:
+                # value_s is lower case independent of input
+                mantissa, exponent = value_s.split('e')
+                if '.' not in mantissa:
+                    warnings.warn(MantissaNoDotYAML1_1Warning(node, value_so))
+            return sign * float(value_s)
+
+    if PY3:
+
+        def construct_yaml_binary(self, node):
+            # type: (Any) -> Any
+            try:
+                value = self.construct_scalar(node).encode('ascii')
+            except UnicodeEncodeError as exc:
+                raise ConstructorError(
+                    None,
+                    None,
+                    'failed to convert base64 data into ascii: %s' % exc,
+                    node.start_mark,
+                )
+            try:
+                if hasattr(base64, 'decodebytes'):
+                    return base64.decodebytes(value)
+                else:
+                    return base64.decodestring(value)
+            except binascii.Error as exc:
+                raise ConstructorError(
+                    None, None, 'failed to decode base64 data: %s' % exc, node.start_mark
+                )
+
+    else:
+
+        def construct_yaml_binary(self, node):
+            # type: (Any) -> Any
+            value = self.construct_scalar(node)
+            try:
+                return to_str(value).decode('base64')
+            except (binascii.Error, UnicodeEncodeError) as exc:
+                raise ConstructorError(
+                    None, None, 'failed to decode base64 data: %s' % exc, node.start_mark
+                )
+
+    timestamp_regexp = RegExp(
+        u"""^(?P<year>[0-9][0-9][0-9][0-9])
+          -(?P<month>[0-9][0-9]?)
+          -(?P<day>[0-9][0-9]?)
+          (?:((?P<t>[Tt])|[ \\t]+)   # explictly not retaining extra spaces
+          (?P<hour>[0-9][0-9]?)
+          :(?P<minute>[0-9][0-9])
+          :(?P<second>[0-9][0-9])
+          (?:\\.(?P<fraction>[0-9]*))?
+          (?:[ \\t]*(?P<tz>Z|(?P<tz_sign>[-+])(?P<tz_hour>[0-9][0-9]?)
+          (?::(?P<tz_minute>[0-9][0-9]))?))?)?$""",
+        re.X,
+    )
+
+    def construct_yaml_timestamp(self, node, values=None):
+        # type: (Any, Any) -> Any
+        if values is None:
+            try:
+                match = self.timestamp_regexp.match(node.value)
+            except TypeError:
+                match = None
+            if match is None:
+                raise ConstructorError(
+                    None,
+                    None,
+                    'failed to construct timestamp from "{}"'.format(node.value),
+                    node.start_mark,
+                )
+            values = match.groupdict()
+        year = int(values['year'])
+        month = int(values['month'])
+        day = int(values['day'])
+        if not values['hour']:
+            return datetime.date(year, month, day)
+        hour = int(values['hour'])
+        minute = int(values['minute'])
+        second = int(values['second'])
+        fraction = 0
+        if values['fraction']:
+            fraction_s = values['fraction'][:6]
+            while len(fraction_s) < 6:
+                fraction_s += '0'
+            fraction = int(fraction_s)
+            if len(values['fraction']) > 6 and int(values['fraction'][6]) > 4:
+                fraction += 1
+        delta = None
+        if values['tz_sign']:
+            tz_hour = int(values['tz_hour'])
+            minutes = values['tz_minute']
+            tz_minute = int(minutes) if minutes else 0
+            delta = datetime.timedelta(hours=tz_hour, minutes=tz_minute)
+            if values['tz_sign'] == '-':
+                delta = -delta
+        # should do something else instead (or hook this up to the preceding if statement
+        # in reverse
+        #  if delta is None:
+        #      return datetime.datetime(year, month, day, hour, minute, second, fraction)
+        #  return datetime.datetime(year, month, day, hour, minute, second, fraction,
+        #                           datetime.timezone.utc)
+        # the above is not good enough though, should provide tzinfo. In Python3 that is easily
+        # doable drop that kind of support for Python2 as it has not native tzinfo
+        data = datetime.datetime(year, month, day, hour, minute, second, fraction)
+        if delta:
+            data -= delta
+        return data
+
+    def construct_yaml_omap(self, node):
+        # type: (Any) -> Any
+        # Note: we do now check for duplicate keys
+        omap = ordereddict()
+        yield omap
+        if not isinstance(node, SequenceNode):
+            raise ConstructorError(
+                'while constructing an ordered map',
+                node.start_mark,
+                'expected a sequence, but found %s' % node.id,
+                node.start_mark,
+            )
+        for subnode in node.value:
+            if not isinstance(subnode, MappingNode):
+                raise ConstructorError(
+                    'while constructing an ordered map',
+                    node.start_mark,
+                    'expected a mapping of length 1, but found %s' % subnode.id,
+                    subnode.start_mark,
+                )
+            if len(subnode.value) != 1:
+                raise ConstructorError(
+                    'while constructing an ordered map',
+                    node.start_mark,
+                    'expected a single mapping item, but found %d items' % len(subnode.value),
+                    subnode.start_mark,
+                )
+            key_node, value_node = subnode.value[0]
+            key = self.construct_object(key_node)
+            assert key not in omap
+            value = self.construct_object(value_node)
+            omap[key] = value
+
+    def construct_yaml_pairs(self, node):
+        # type: (Any) -> Any
+        # Note: the same code as `construct_yaml_omap`.
+        pairs = []  # type: List[Any]
+        yield pairs
+        if not isinstance(node, SequenceNode):
+            raise ConstructorError(
+                'while constructing pairs',
+                node.start_mark,
+                'expected a sequence, but found %s' % node.id,
+                node.start_mark,
+            )
+        for subnode in node.value:
+            if not isinstance(subnode, MappingNode):
+                raise ConstructorError(
+                    'while constructing pairs',
+                    node.start_mark,
+                    'expected a mapping of length 1, but found %s' % subnode.id,
+                    subnode.start_mark,
+                )
+            if len(subnode.value) != 1:
+                raise ConstructorError(
+                    'while constructing pairs',
+                    node.start_mark,
+                    'expected a single mapping item, but found %d items' % len(subnode.value),
+                    subnode.start_mark,
+                )
+            key_node, value_node = subnode.value[0]
+            key = self.construct_object(key_node)
+            value = self.construct_object(value_node)
+            pairs.append((key, value))
+
+    def construct_yaml_set(self, node):
+        # type: (Any) -> Any
+        data = set()  # type: Set[Any]
+        yield data
+        value = self.construct_mapping(node)
+        data.update(value)
+
+    def construct_yaml_str(self, node):
+        # type: (Any) -> Any
+        value = self.construct_scalar(node)
+        if PY3:
+            return value
+        try:
+            return value.encode('ascii')
+        except UnicodeEncodeError:
+            return value
+
+    def construct_yaml_seq(self, node):
+        # type: (Any) -> Any
+        data = self.yaml_base_list_type()  # type: List[Any]
+        yield data
+        data.extend(self.construct_sequence(node))
+
+    def construct_yaml_map(self, node):
+        # type: (Any) -> Any
+        data = self.yaml_base_dict_type()  # type: Dict[Any, Any]
+        yield data
+        value = self.construct_mapping(node)
+        data.update(value)
+
+    def construct_yaml_object(self, node, cls):
+        # type: (Any, Any) -> Any
+        data = cls.__new__(cls)
+        yield data
+        if hasattr(data, '__setstate__'):
+            state = self.construct_mapping(node, deep=True)
+            data.__setstate__(state)
+        else:
+            state = self.construct_mapping(node)
+            data.__dict__.update(state)
+
+    def construct_undefined(self, node):
+        # type: (Any) -> None
+        raise ConstructorError(
+            None,
+            None,
+            'could not determine a constructor for the tag %r' % utf8(node.tag),
+            node.start_mark,
+        )
+
+
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:null', SafeConstructor.construct_yaml_null)
+
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:bool', SafeConstructor.construct_yaml_bool)
+
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:int', SafeConstructor.construct_yaml_int)
+
+SafeConstructor.add_constructor(
+    u'tag:yaml.org,2002:float', SafeConstructor.construct_yaml_float
+)
+
+SafeConstructor.add_constructor(
+    u'tag:yaml.org,2002:binary', SafeConstructor.construct_yaml_binary
+)
+
+SafeConstructor.add_constructor(
+    u'tag:yaml.org,2002:timestamp', SafeConstructor.construct_yaml_timestamp
+)
+
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:omap', SafeConstructor.construct_yaml_omap)
+
+SafeConstructor.add_constructor(
+    u'tag:yaml.org,2002:pairs', SafeConstructor.construct_yaml_pairs
+)
+
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:set', SafeConstructor.construct_yaml_set)
+
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:str', SafeConstructor.construct_yaml_str)
+
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:seq', SafeConstructor.construct_yaml_seq)
+
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:map', SafeConstructor.construct_yaml_map)
+
+SafeConstructor.add_constructor(None, SafeConstructor.construct_undefined)
+
+if PY2:
+
+    class classobj:
+        pass
+
+
+class Constructor(SafeConstructor):
+    def construct_python_str(self, node):
+        # type: (Any) -> Any
+        return utf8(self.construct_scalar(node))
+
+    def construct_python_unicode(self, node):
+        # type: (Any) -> Any
+        return self.construct_scalar(node)
+
+    if PY3:
+
+        def construct_python_bytes(self, node):
+            # type: (Any) -> Any
+            try:
+                value = self.construct_scalar(node).encode('ascii')
+            except UnicodeEncodeError as exc:
+                raise ConstructorError(
+                    None,
+                    None,
+                    'failed to convert base64 data into ascii: %s' % exc,
+                    node.start_mark,
+                )
+            try:
+                if hasattr(base64, 'decodebytes'):
+                    return base64.decodebytes(value)
+                else:
+                    return base64.decodestring(value)
+            except binascii.Error as exc:
+                raise ConstructorError(
+                    None, None, 'failed to decode base64 data: %s' % exc, node.start_mark
+                )
+
+    def construct_python_long(self, node):
+        # type: (Any) -> int
+        val = self.construct_yaml_int(node)
+        if PY3:
+            return val
+        return int(val)
+
+    def construct_python_complex(self, node):
+        # type: (Any) -> Any
+        return complex(self.construct_scalar(node))
+
+    def construct_python_tuple(self, node):
+        # type: (Any) -> Any
+        return tuple(self.construct_sequence(node))
+
+    def find_python_module(self, name, mark):
+        # type: (Any, Any) -> Any
+        if not name:
+            raise ConstructorError(
+                'while constructing a Python module',
+                mark,
+                'expected non-empty name appended to the tag',
+                mark,
+            )
+        try:
+            __import__(name)
+        except ImportError as exc:
+            raise ConstructorError(
+                'while constructing a Python module',
+                mark,
+                'cannot find module %r (%s)' % (utf8(name), exc),
+                mark,
+            )
+        return sys.modules[name]
+
+    def find_python_name(self, name, mark):
+        # type: (Any, Any) -> Any
+        if not name:
+            raise ConstructorError(
+                'while constructing a Python object',
+                mark,
+                'expected non-empty name appended to the tag',
+                mark,
+            )
+        if u'.' in name:
+            lname = name.split('.')
+            lmodule_name = lname
+            lobject_name = []  # type: List[Any]
+            while len(lmodule_name) > 1:
+                lobject_name.insert(0, lmodule_name.pop())
+                module_name = '.'.join(lmodule_name)
+                try:
+                    __import__(module_name)
+                    # object_name = '.'.join(object_name)
+                    break
+                except ImportError:
+                    continue
+        else:
+            module_name = builtins_module
+            lobject_name = [name]
+        try:
+            __import__(module_name)
+        except ImportError as exc:
+            raise ConstructorError(
+                'while constructing a Python object',
+                mark,
+                'cannot find module %r (%s)' % (utf8(module_name), exc),
+                mark,
+            )
+        module = sys.modules[module_name]
+        object_name = '.'.join(lobject_name)
+        obj = module
+        while lobject_name:
+            if not hasattr(obj, lobject_name[0]):
+
+                raise ConstructorError(
+                    'while constructing a Python object',
+                    mark,
+                    'cannot find %r in the module %r' % (utf8(object_name), module.__name__),
+                    mark,
+                )
+            obj = getattr(obj, lobject_name.pop(0))
+        return obj
+
+    def construct_python_name(self, suffix, node):
+        # type: (Any, Any) -> Any
+        value = self.construct_scalar(node)
+        if value:
+            raise ConstructorError(
+                'while constructing a Python name',
+                node.start_mark,
+                'expected the empty value, but found %r' % utf8(value),
+                node.start_mark,
+            )
+        return self.find_python_name(suffix, node.start_mark)
+
+    def construct_python_module(self, suffix, node):
+        # type: (Any, Any) -> Any
+        value = self.construct_scalar(node)
+        if value:
+            raise ConstructorError(
+                'while constructing a Python module',
+                node.start_mark,
+                'expected the empty value, but found %r' % utf8(value),
+                node.start_mark,
+            )
+        return self.find_python_module(suffix, node.start_mark)
+
+    def make_python_instance(self, suffix, node, args=None, kwds=None, newobj=False):
+        # type: (Any, Any, Any, Any, bool) -> Any
+        if not args:
+            args = []
+        if not kwds:
+            kwds = {}
+        cls = self.find_python_name(suffix, node.start_mark)
+        if PY3:
+            if newobj and isinstance(cls, type):
+                return cls.__new__(cls, *args, **kwds)
+            else:
+                return cls(*args, **kwds)
+        else:
+            if newobj and isinstance(cls, type(classobj)) and not args and not kwds:
+                instance = classobj()
+                instance.__class__ = cls
+                return instance
+            elif newobj and isinstance(cls, type):
+                return cls.__new__(cls, *args, **kwds)
+            else:
+                return cls(*args, **kwds)
+
+    def set_python_instance_state(self, instance, state):
+        # type: (Any, Any) -> None
+        if hasattr(instance, '__setstate__'):
+            instance.__setstate__(state)
+        else:
+            slotstate = {}  # type: Dict[Any, Any]
+            if isinstance(state, tuple) and len(state) == 2:
+                state, slotstate = state
+            if hasattr(instance, '__dict__'):
+                instance.__dict__.update(state)
+            elif state:
+                slotstate.update(state)
+            for key, value in slotstate.items():
+                setattr(object, key, value)
+
+    def construct_python_object(self, suffix, node):
+        # type: (Any, Any) -> Any
+        # Format:
+        #   !!python/object:module.name { ... state ... }
+        instance = self.make_python_instance(suffix, node, newobj=True)
+        self.recursive_objects[node] = instance
+        yield instance
+        deep = hasattr(instance, '__setstate__')
+        state = self.construct_mapping(node, deep=deep)
+        self.set_python_instance_state(instance, state)
+
+    def construct_python_object_apply(self, suffix, node, newobj=False):
+        # type: (Any, Any, bool) -> Any
+        # Format:
+        #   !!python/object/apply       # (or !!python/object/new)
+        #   args: [ ... arguments ... ]
+        #   kwds: { ... keywords ... }
+        #   state: ... state ...
+        #   listitems: [ ... listitems ... ]
+        #   dictitems: { ... dictitems ... }
+        # or short format:
+        #   !!python/object/apply [ ... arguments ... ]
+        # The difference between !!python/object/apply and !!python/object/new
+        # is how an object is created, check make_python_instance for details.
+        if isinstance(node, SequenceNode):
+            args = self.construct_sequence(node, deep=True)
+            kwds = {}  # type: Dict[Any, Any]
+            state = {}  # type: Dict[Any, Any]
+            listitems = []  # type: List[Any]
+            dictitems = {}  # type: Dict[Any, Any]
+        else:
+            value = self.construct_mapping(node, deep=True)
+            args = value.get('args', [])
+            kwds = value.get('kwds', {})
+            state = value.get('state', {})
+            listitems = value.get('listitems', [])
+            dictitems = value.get('dictitems', {})
+        instance = self.make_python_instance(suffix, node, args, kwds, newobj)
+        if bool(state):
+            self.set_python_instance_state(instance, state)
+        if bool(listitems):
+            instance.extend(listitems)
+        if bool(dictitems):
+            for key in dictitems:
+                instance[key] = dictitems[key]
+        return instance
+
+    def construct_python_object_new(self, suffix, node):
+        # type: (Any, Any) -> Any
+        return self.construct_python_object_apply(suffix, node, newobj=True)
+
+
+Constructor.add_constructor(u'tag:yaml.org,2002:python/none', Constructor.construct_yaml_null)
+
+Constructor.add_constructor(u'tag:yaml.org,2002:python/bool', Constructor.construct_yaml_bool)
+
+Constructor.add_constructor(u'tag:yaml.org,2002:python/str', Constructor.construct_python_str)
+
+Constructor.add_constructor(
+    u'tag:yaml.org,2002:python/unicode', Constructor.construct_python_unicode
+)
+
+if PY3:
+    Constructor.add_constructor(
+        u'tag:yaml.org,2002:python/bytes', Constructor.construct_python_bytes
+    )
+
+Constructor.add_constructor(u'tag:yaml.org,2002:python/int', Constructor.construct_yaml_int)
+
+Constructor.add_constructor(
+    u'tag:yaml.org,2002:python/long', Constructor.construct_python_long
+)
+
+Constructor.add_constructor(
+    u'tag:yaml.org,2002:python/float', Constructor.construct_yaml_float
+)
+
+Constructor.add_constructor(
+    u'tag:yaml.org,2002:python/complex', Constructor.construct_python_complex
+)
+
+Constructor.add_constructor(u'tag:yaml.org,2002:python/list', Constructor.construct_yaml_seq)
+
+Constructor.add_constructor(
+    u'tag:yaml.org,2002:python/tuple', Constructor.construct_python_tuple
+)
+
+Constructor.add_constructor(u'tag:yaml.org,2002:python/dict', Constructor.construct_yaml_map)
+
+Constructor.add_multi_constructor(
+    u'tag:yaml.org,2002:python/name:', Constructor.construct_python_name
+)
+
+Constructor.add_multi_constructor(
+    u'tag:yaml.org,2002:python/module:', Constructor.construct_python_module
+)
+
+Constructor.add_multi_constructor(
+    u'tag:yaml.org,2002:python/object:', Constructor.construct_python_object
+)
+
+Constructor.add_multi_constructor(
+    u'tag:yaml.org,2002:python/object/apply:', Constructor.construct_python_object_apply
+)
+
+Constructor.add_multi_constructor(
+    u'tag:yaml.org,2002:python/object/new:', Constructor.construct_python_object_new
+)
+
+
+class RoundTripConstructor(SafeConstructor):
+    """need to store the comments on the node itself,
+    as well as on the items
+    """
+
+    def construct_scalar(self, node):
+        # type: (Any) -> Any
+        if not isinstance(node, ScalarNode):
+            raise ConstructorError(
+                None, None, 'expected a scalar node, but found %s' % node.id, node.start_mark
+            )
+
+        if node.style == '|' and isinstance(node.value, text_type):
+            lss = LiteralScalarString(node.value, anchor=node.anchor)
+            if node.comment and node.comment[1]:
+                lss.comment = node.comment[1][0]  # type: ignore
+            return lss
+        if node.style == '>' and isinstance(node.value, text_type):
+            fold_positions = []  # type: List[int]
+            idx = -1
+            while True:
+                idx = node.value.find('\a', idx + 1)
+                if idx < 0:
+                    break
+                fold_positions.append(idx - len(fold_positions))
+            fss = FoldedScalarString(node.value.replace('\a', ''), anchor=node.anchor)
+            if node.comment and node.comment[1]:
+                fss.comment = node.comment[1][0]  # type: ignore
+            if fold_positions:
+                fss.fold_pos = fold_positions  # type: ignore
+            return fss
+        elif bool(self._preserve_quotes) and isinstance(node.value, text_type):
+            if node.style == "'":
+                return SingleQuotedScalarString(node.value, anchor=node.anchor)
+            if node.style == '"':
+                return DoubleQuotedScalarString(node.value, anchor=node.anchor)
+        if node.anchor:
+            return PlainScalarString(node.value, anchor=node.anchor)
+        return node.value
+
+    def construct_yaml_int(self, node):
+        # type: (Any) -> Any
+        width = None  # type: Any
+        value_su = to_str(self.construct_scalar(node))
+        try:
+            sx = value_su.rstrip('_')
+            underscore = [len(sx) - sx.rindex('_') - 1, False, False]  # type: Any
+        except ValueError:
+            underscore = None
+        except IndexError:
+            underscore = None
+        value_s = value_su.replace('_', "")
+        sign = +1
+        if value_s[0] == '-':
+            sign = -1
+        if value_s[0] in '+-':
+            value_s = value_s[1:]
+        if value_s == '0':
+            return 0
+        elif value_s.startswith('0b'):
+            if self.resolver.processing_version > (1, 1) and value_s[2] == '0':
+                width = len(value_s[2:])
+            if underscore is not None:
+                underscore[1] = value_su[2] == '_'
+                underscore[2] = len(value_su[2:]) > 1 and value_su[-1] == '_'
+            return BinaryInt(
+                sign * int(value_s[2:], 2),
+                width=width,
+                underscore=underscore,
+                anchor=node.anchor,
+            )
+        elif value_s.startswith('0x'):
+            # default to lower-case if no a-fA-F in string
+            if self.resolver.processing_version > (1, 1) and value_s[2] == '0':
+                width = len(value_s[2:])
+            hex_fun = HexInt  # type: Any
+            for ch in value_s[2:]:
+                if ch in 'ABCDEF':  # first non-digit is capital
+                    hex_fun = HexCapsInt
+                    break
+                if ch in 'abcdef':
+                    break
+            if underscore is not None:
+                underscore[1] = value_su[2] == '_'
+                underscore[2] = len(value_su[2:]) > 1 and value_su[-1] == '_'
+            return hex_fun(
+                sign * int(value_s[2:], 16),
+                width=width,
+                underscore=underscore,
+                anchor=node.anchor,
+            )
+        elif value_s.startswith('0o'):
+            if self.resolver.processing_version > (1, 1) and value_s[2] == '0':
+                width = len(value_s[2:])
+            if underscore is not None:
+                underscore[1] = value_su[2] == '_'
+                underscore[2] = len(value_su[2:]) > 1 and value_su[-1] == '_'
+            return OctalInt(
+                sign * int(value_s[2:], 8),
+                width=width,
+                underscore=underscore,
+                anchor=node.anchor,
+            )
+        elif self.resolver.processing_version != (1, 2) and value_s[0] == '0':
+            return sign * int(value_s, 8)
+        elif self.resolver.processing_version != (1, 2) and ':' in value_s:
+            digits = [int(part) for part in value_s.split(':')]
+            digits.reverse()
+            base = 1
+            value = 0
+            for digit in digits:
+                value += digit * base
+                base *= 60
+            return sign * value
+        elif self.resolver.processing_version > (1, 1) and value_s[0] == '0':
+            # not an octal, an integer with leading zero(s)
+            if underscore is not None:
+                # cannot have a leading underscore
+                underscore[2] = len(value_su) > 1 and value_su[-1] == '_'
+            return ScalarInt(sign * int(value_s), width=len(value_s), underscore=underscore)
+        elif underscore:
+            # cannot have a leading underscore
+            underscore[2] = len(value_su) > 1 and value_su[-1] == '_'
+            return ScalarInt(
+                sign * int(value_s), width=None, underscore=underscore, anchor=node.anchor
+            )
+        elif node.anchor:
+            return ScalarInt(sign * int(value_s), width=None, anchor=node.anchor)
+        else:
+            return sign * int(value_s)
+
+    def construct_yaml_float(self, node):
+        # type: (Any) -> Any
+        def leading_zeros(v):
+            # type: (Any) -> int
+            lead0 = 0
+            idx = 0
+            while idx < len(v) and v[idx] in '0.':
+                if v[idx] == '0':
+                    lead0 += 1
+                idx += 1
+            return lead0
+
+        # underscore = None
+        m_sign = False  # type: Any
+        value_so = to_str(self.construct_scalar(node))
+        value_s = value_so.replace('_', "").lower()
+        sign = +1
+        if value_s[0] == '-':
+            sign = -1
+        if value_s[0] in '+-':
+            m_sign = value_s[0]
+            value_s = value_s[1:]
+        if value_s == '.inf':
+            return sign * self.inf_value
+        if value_s == '.nan':
+            return self.nan_value
+        if self.resolver.processing_version != (1, 2) and ':' in value_s:
+            digits = [float(part) for part in value_s.split(':')]
+            digits.reverse()
+            base = 1
+            value = 0.0
+            for digit in digits:
+                value += digit * base
+                base *= 60
+            return sign * value
+        if 'e' in value_s:
+            try:
+                mantissa, exponent = value_so.split('e')
+                exp = 'e'
+            except ValueError:
+                mantissa, exponent = value_so.split('E')
+                exp = 'E'
+            if self.resolver.processing_version != (1, 2):
+                # value_s is lower case independent of input
+                if '.' not in mantissa:
+                    warnings.warn(MantissaNoDotYAML1_1Warning(node, value_so))
+            lead0 = leading_zeros(mantissa)
+            width = len(mantissa)
+            prec = mantissa.find('.')
+            if m_sign:
+                width -= 1
+            e_width = len(exponent)
+            e_sign = exponent[0] in '+-'
+            # nprint('sf', width, prec, m_sign, exp, e_width, e_sign)
+            return ScalarFloat(
+                sign * float(value_s),
+                width=width,
+                prec=prec,
+                m_sign=m_sign,
+                m_lead0=lead0,
+                exp=exp,
+                e_width=e_width,
+                e_sign=e_sign,
+                anchor=node.anchor,
+            )
+        width = len(value_so)
+        prec = value_so.index('.')  # you can use index, this would not be float without dot
+        lead0 = leading_zeros(value_so)
+        return ScalarFloat(
+            sign * float(value_s),
+            width=width,
+            prec=prec,
+            m_sign=m_sign,
+            m_lead0=lead0,
+            anchor=node.anchor,
+        )
+
+    def construct_yaml_str(self, node):
+        # type: (Any) -> Any
+        value = self.construct_scalar(node)
+        if isinstance(value, ScalarString):
+            return value
+        if PY3:
+            return value
+        try:
+            return value.encode('ascii')
+        except AttributeError:
+            # in case you replace the node dynamically e.g. with a dict
+            return value
+        except UnicodeEncodeError:
+            return value
+
+    def construct_rt_sequence(self, node, seqtyp, deep=False):
+        # type: (Any, Any, bool) -> Any
+        if not isinstance(node, SequenceNode):
+            raise ConstructorError(
+                None, None, 'expected a sequence node, but found %s' % node.id, node.start_mark
+            )
+        ret_val = []
+        if node.comment:
+            seqtyp._yaml_add_comment(node.comment[:2])
+            if len(node.comment) > 2:
+                seqtyp.yaml_end_comment_extend(node.comment[2], clear=True)
+        if node.anchor:
+            from ruamel.yaml.serializer import templated_id
+
+            if not templated_id(node.anchor):
+                seqtyp.yaml_set_anchor(node.anchor)
+        for idx, child in enumerate(node.value):
+            ret_val.append(self.construct_object(child, deep=deep))
+            if child.comment:
+                seqtyp._yaml_add_comment(child.comment, key=idx)
+            seqtyp._yaml_set_idx_line_col(
+                idx, [child.start_mark.line, child.start_mark.column]
+            )
+        return ret_val
+
+    def flatten_mapping(self, node):
+        # type: (Any) -> Any
+        """
+        This implements the merge key feature http://yaml.org/type/merge.html
+        by inserting keys from the merge dict/list of dicts if not yet
+        available in this node
+        """
+
+        def constructed(value_node):
+            # type: (Any) -> Any
+            # If the contents of a merge are defined within the
+            # merge marker, then they won't have been constructed
+            # yet. But if they were already constructed, we need to use
+            # the existing object.
+            if value_node in self.constructed_objects:
+                value = self.constructed_objects[value_node]
+            else:
+                value = self.construct_object(value_node, deep=False)
+            return value
+
+        # merge = []
+        merge_map_list = []  # type: List[Any]
+        index = 0
+        while index < len(node.value):
+            key_node, value_node = node.value[index]
+            if key_node.tag == u'tag:yaml.org,2002:merge':
+                if merge_map_list:  # double << key
+                    if self.allow_duplicate_keys:
+                        del node.value[index]
+                        index += 1
+                        continue
+                    args = [
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'found duplicate key "{}"'.format(key_node.value),
+                        key_node.start_mark,
+                        """
+                        To suppress this check see:
+                           http://yaml.readthedocs.io/en/latest/api.html#duplicate-keys
+                        """,
+                        """\
+                        Duplicate keys will become an error in future releases, and are errors
+                        by default when using the new API.
+                        """,
+                    ]
+                    if self.allow_duplicate_keys is None:
+                        warnings.warn(DuplicateKeyFutureWarning(*args))
+                    else:
+                        raise DuplicateKeyError(*args)
+                del node.value[index]
+                if isinstance(value_node, MappingNode):
+                    merge_map_list.append((index, constructed(value_node)))
+                    # self.flatten_mapping(value_node)
+                    # merge.extend(value_node.value)
+                elif isinstance(value_node, SequenceNode):
+                    # submerge = []
+                    for subnode in value_node.value:
+                        if not isinstance(subnode, MappingNode):
+                            raise ConstructorError(
+                                'while constructing a mapping',
+                                node.start_mark,
+                                'expected a mapping for merging, but found %s' % subnode.id,
+                                subnode.start_mark,
+                            )
+                        merge_map_list.append((index, constructed(subnode)))
+                    #     self.flatten_mapping(subnode)
+                    #     submerge.append(subnode.value)
+                    # submerge.reverse()
+                    # for value in submerge:
+                    #     merge.extend(value)
+                else:
+                    raise ConstructorError(
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'expected a mapping or list of mappings for merging, '
+                        'but found %s' % value_node.id,
+                        value_node.start_mark,
+                    )
+            elif key_node.tag == u'tag:yaml.org,2002:value':
+                key_node.tag = u'tag:yaml.org,2002:str'
+                index += 1
+            else:
+                index += 1
+        return merge_map_list
+        # if merge:
+        #     node.value = merge + node.value
+
+    def _sentinel(self):
+        # type: () -> None
+        pass
+
+    def construct_mapping(self, node, maptyp, deep=False):  # type: ignore
+        # type: (Any, Any, bool) -> Any
+        if not isinstance(node, MappingNode):
+            raise ConstructorError(
+                None, None, 'expected a mapping node, but found %s' % node.id, node.start_mark
+            )
+        merge_map = self.flatten_mapping(node)
+        # mapping = {}
+        if node.comment:
+            maptyp._yaml_add_comment(node.comment[:2])
+            if len(node.comment) > 2:
+                maptyp.yaml_end_comment_extend(node.comment[2], clear=True)
+        if node.anchor:
+            from ruamel.yaml.serializer import templated_id
+
+            if not templated_id(node.anchor):
+                maptyp.yaml_set_anchor(node.anchor)
+        last_key, last_value = None, self._sentinel
+        for key_node, value_node in node.value:
+            # keys can be list -> deep
+            key = self.construct_object(key_node, deep=True)
+            # lists are not hashable, but tuples are
+            if not isinstance(key, Hashable):
+                if isinstance(key, MutableSequence):
+                    key_s = CommentedKeySeq(key)
+                    if key_node.flow_style is True:
+                        key_s.fa.set_flow_style()
+                    elif key_node.flow_style is False:
+                        key_s.fa.set_block_style()
+                    key = key_s
+                elif isinstance(key, MutableMapping):
+                    key_m = CommentedKeyMap(key)
+                    if key_node.flow_style is True:
+                        key_m.fa.set_flow_style()
+                    elif key_node.flow_style is False:
+                        key_m.fa.set_block_style()
+                    key = key_m
+            if PY2:
+                try:
+                    hash(key)
+                except TypeError as exc:
+                    raise ConstructorError(
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'found unacceptable key (%s)' % exc,
+                        key_node.start_mark,
+                    )
+            else:
+                if not isinstance(key, Hashable):
+                    raise ConstructorError(
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'found unhashable key',
+                        key_node.start_mark,
+                    )
+            value = self.construct_object(value_node, deep=deep)
+            if self.check_mapping_key(node, key_node, maptyp, key, value):
+
+                if key_node.comment and len(key_node.comment) > 4 and key_node.comment[4]:
+                    if last_value is None:
+                        key_node.comment[0] = key_node.comment.pop(4)
+                        maptyp._yaml_add_comment(key_node.comment, value=last_key)
+                    else:
+                        key_node.comment[2] = key_node.comment.pop(4)
+                        maptyp._yaml_add_comment(key_node.comment, key=key)
+                    key_node.comment = None
+                if key_node.comment:
+                    maptyp._yaml_add_comment(key_node.comment, key=key)
+                if value_node.comment:
+                    maptyp._yaml_add_comment(value_node.comment, value=key)
+                maptyp._yaml_set_kv_line_col(
+                    key,
+                    [
+                        key_node.start_mark.line,
+                        key_node.start_mark.column,
+                        value_node.start_mark.line,
+                        value_node.start_mark.column,
+                    ],
+                )
+                maptyp[key] = value
+                last_key, last_value = key, value  # could use indexing
+        # do this last, or <<: before a key will prevent insertion in instances
+        # of collections.OrderedDict (as they have no __contains__
+        if merge_map:
+            maptyp.add_yaml_merge(merge_map)
+
+    def construct_setting(self, node, typ, deep=False):
+        # type: (Any, Any, bool) -> Any
+        if not isinstance(node, MappingNode):
+            raise ConstructorError(
+                None, None, 'expected a mapping node, but found %s' % node.id, node.start_mark
+            )
+        if node.comment:
+            typ._yaml_add_comment(node.comment[:2])
+            if len(node.comment) > 2:
+                typ.yaml_end_comment_extend(node.comment[2], clear=True)
+        if node.anchor:
+            from ruamel.yaml.serializer import templated_id
+
+            if not templated_id(node.anchor):
+                typ.yaml_set_anchor(node.anchor)
+        for key_node, value_node in node.value:
+            # keys can be list -> deep
+            key = self.construct_object(key_node, deep=True)
+            # lists are not hashable, but tuples are
+            if not isinstance(key, Hashable):
+                if isinstance(key, list):
+                    key = tuple(key)
+            if PY2:
+                try:
+                    hash(key)
+                except TypeError as exc:
+                    raise ConstructorError(
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'found unacceptable key (%s)' % exc,
+                        key_node.start_mark,
+                    )
+            else:
+                if not isinstance(key, Hashable):
+                    raise ConstructorError(
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'found unhashable key',
+                        key_node.start_mark,
+                    )
+            # construct but should be null
+            value = self.construct_object(value_node, deep=deep)  # NOQA
+            self.check_set_key(node, key_node, typ, key)
+            if key_node.comment:
+                typ._yaml_add_comment(key_node.comment, key=key)
+            if value_node.comment:
+                typ._yaml_add_comment(value_node.comment, value=key)
+            typ.add(key)
+
+    def construct_yaml_seq(self, node):
+        # type: (Any) -> Any
+        data = CommentedSeq()
+        data._yaml_set_line_col(node.start_mark.line, node.start_mark.column)
+        if node.comment:
+            data._yaml_add_comment(node.comment)
+        yield data
+        data.extend(self.construct_rt_sequence(node, data))
+        self.set_collection_style(data, node)
+
+    def construct_yaml_map(self, node):
+        # type: (Any) -> Any
+        data = CommentedMap()
+        data._yaml_set_line_col(node.start_mark.line, node.start_mark.column)
+        yield data
+        self.construct_mapping(node, data, deep=True)
+        self.set_collection_style(data, node)
+
+    def set_collection_style(self, data, node):
+        # type: (Any, Any) -> None
+        if len(data) == 0:
+            return
+        if node.flow_style is True:
+            data.fa.set_flow_style()
+        elif node.flow_style is False:
+            data.fa.set_block_style()
+
+    def construct_yaml_object(self, node, cls):
+        # type: (Any, Any) -> Any
+        data = cls.__new__(cls)
+        yield data
+        if hasattr(data, '__setstate__'):
+            state = SafeConstructor.construct_mapping(self, node, deep=True)
+            data.__setstate__(state)
+        else:
+            state = SafeConstructor.construct_mapping(self, node)
+            data.__dict__.update(state)
+
+    def construct_yaml_omap(self, node):
+        # type: (Any) -> Any
+        # Note: we do now check for duplicate keys
+        omap = CommentedOrderedMap()
+        omap._yaml_set_line_col(node.start_mark.line, node.start_mark.column)
+        if node.flow_style is True:
+            omap.fa.set_flow_style()
+        elif node.flow_style is False:
+            omap.fa.set_block_style()
+        yield omap
+        if node.comment:
+            omap._yaml_add_comment(node.comment[:2])
+            if len(node.comment) > 2:
+                omap.yaml_end_comment_extend(node.comment[2], clear=True)
+        if not isinstance(node, SequenceNode):
+            raise ConstructorError(
+                'while constructing an ordered map',
+                node.start_mark,
+                'expected a sequence, but found %s' % node.id,
+                node.start_mark,
+            )
+        for subnode in node.value:
+            if not isinstance(subnode, MappingNode):
+                raise ConstructorError(
+                    'while constructing an ordered map',
+                    node.start_mark,
+                    'expected a mapping of length 1, but found %s' % subnode.id,
+                    subnode.start_mark,
+                )
+            if len(subnode.value) != 1:
+                raise ConstructorError(
+                    'while constructing an ordered map',
+                    node.start_mark,
+                    'expected a single mapping item, but found %d items' % len(subnode.value),
+                    subnode.start_mark,
+                )
+            key_node, value_node = subnode.value[0]
+            key = self.construct_object(key_node)
+            assert key not in omap
+            value = self.construct_object(value_node)
+            if key_node.comment:
+                omap._yaml_add_comment(key_node.comment, key=key)
+            if subnode.comment:
+                omap._yaml_add_comment(subnode.comment, key=key)
+            if value_node.comment:
+                omap._yaml_add_comment(value_node.comment, value=key)
+            omap[key] = value
+
+    def construct_yaml_set(self, node):
+        # type: (Any) -> Any
+        data = CommentedSet()
+        data._yaml_set_line_col(node.start_mark.line, node.start_mark.column)
+        yield data
+        self.construct_setting(node, data)
+
+    def construct_undefined(self, node):
+        # type: (Any) -> Any
+        try:
+            if isinstance(node, MappingNode):
+                data = CommentedMap()
+                data._yaml_set_line_col(node.start_mark.line, node.start_mark.column)
+                if node.flow_style is True:
+                    data.fa.set_flow_style()
+                elif node.flow_style is False:
+                    data.fa.set_block_style()
+                data.yaml_set_tag(node.tag)
+                yield data
+                if node.anchor:
+                    data.yaml_set_anchor(node.anchor)
+                self.construct_mapping(node, data)
+                return
+            elif isinstance(node, ScalarNode):
+                data2 = TaggedScalar()
+                data2.value = self.construct_scalar(node)
+                data2.style = node.style
+                data2.yaml_set_tag(node.tag)
+                yield data2
+                if node.anchor:
+                    data2.yaml_set_anchor(node.anchor, always_dump=True)
+                return
+            elif isinstance(node, SequenceNode):
+                data3 = CommentedSeq()
+                data3._yaml_set_line_col(node.start_mark.line, node.start_mark.column)
+                if node.flow_style is True:
+                    data3.fa.set_flow_style()
+                elif node.flow_style is False:
+                    data3.fa.set_block_style()
+                data3.yaml_set_tag(node.tag)
+                yield data3
+                if node.anchor:
+                    data3.yaml_set_anchor(node.anchor)
+                data3.extend(self.construct_sequence(node))
+                return
+        except:  # NOQA
+            pass
+        raise ConstructorError(
+            None,
+            None,
+            'could not determine a constructor for the tag %r' % utf8(node.tag),
+            node.start_mark,
+        )
+
+    def construct_yaml_timestamp(self, node, values=None):
+        # type: (Any, Any) -> Any
+        try:
+            match = self.timestamp_regexp.match(node.value)
+        except TypeError:
+            match = None
+        if match is None:
+            raise ConstructorError(
+                None,
+                None,
+                'failed to construct timestamp from "{}"'.format(node.value),
+                node.start_mark,
+            )
+        values = match.groupdict()
+        if not values['hour']:
+            return SafeConstructor.construct_yaml_timestamp(self, node, values)
+        for part in ['t', 'tz_sign', 'tz_hour', 'tz_minute']:
+            if values[part]:
+                break
+        else:
+            return SafeConstructor.construct_yaml_timestamp(self, node, values)
+        year = int(values['year'])
+        month = int(values['month'])
+        day = int(values['day'])
+        hour = int(values['hour'])
+        minute = int(values['minute'])
+        second = int(values['second'])
+        fraction = 0
+        if values['fraction']:
+            fraction_s = values['fraction'][:6]
+            while len(fraction_s) < 6:
+                fraction_s += '0'
+            fraction = int(fraction_s)
+            if len(values['fraction']) > 6 and int(values['fraction'][6]) > 4:
+                fraction += 1
+        delta = None
+        if values['tz_sign']:
+            tz_hour = int(values['tz_hour'])
+            minutes = values['tz_minute']
+            tz_minute = int(minutes) if minutes else 0
+            delta = datetime.timedelta(hours=tz_hour, minutes=tz_minute)
+            if values['tz_sign'] == '-':
+                delta = -delta
+        if delta:
+            dt = datetime.datetime(year, month, day, hour, minute)
+            dt -= delta
+            data = TimeStamp(dt.year, dt.month, dt.day, dt.hour, dt.minute, second, fraction)
+            data._yaml['delta'] = delta
+            tz = values['tz_sign'] + values['tz_hour']
+            if values['tz_minute']:
+                tz += ':' + values['tz_minute']
+            data._yaml['tz'] = tz
+        else:
+            data = TimeStamp(year, month, day, hour, minute, second, fraction)
+            if values['tz']:  # no delta
+                data._yaml['tz'] = values['tz']
+
+        if values['t']:
+            data._yaml['t'] = True
+        return data
+
+    def construct_yaml_bool(self, node):
+        # type: (Any) -> Any
+        b = SafeConstructor.construct_yaml_bool(self, node)
+        if node.anchor:
+            return ScalarBoolean(b, anchor=node.anchor)
+        return b
+
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:null', RoundTripConstructor.construct_yaml_null
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:bool', RoundTripConstructor.construct_yaml_bool
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:int', RoundTripConstructor.construct_yaml_int
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:float', RoundTripConstructor.construct_yaml_float
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:binary', RoundTripConstructor.construct_yaml_binary
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:timestamp', RoundTripConstructor.construct_yaml_timestamp
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:omap', RoundTripConstructor.construct_yaml_omap
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:pairs', RoundTripConstructor.construct_yaml_pairs
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:set', RoundTripConstructor.construct_yaml_set
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:str', RoundTripConstructor.construct_yaml_str
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:seq', RoundTripConstructor.construct_yaml_seq
+)
+
+RoundTripConstructor.add_constructor(
+    u'tag:yaml.org,2002:map', RoundTripConstructor.construct_yaml_map
+)
+
+RoundTripConstructor.add_constructor(None, RoundTripConstructor.construct_undefined)