path: root/constructor.py

# 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
                                ordereddict, text_type, nprint, version_tnf, Hashable)
from ruamel.yaml.comments import *                               # NOQA
from ruamel.yaml.comments import (CommentedMap, CommentedOrderedMap, CommentedSet,
                                  CommentedKeySeq, CommentedSeq, TaggedScalar)
from ruamel.yaml.scalarstring import *                           # NOQA
from ruamel.yaml.scalarstring import (PreservedScalarString, SingleQuotedScalarString,
                                      DoubleQuotedScalarString, ScalarString)
from ruamel.yaml.scalarint import ScalarInt, BinaryInt, OctalInt, HexInt, HexCapsInt
from ruamel.yaml.scalarfloat import ScalarFloat
from ruamel.yaml.timestamp import TimeStamp
from ruamel.yaml.util import RegExp

if False:  # MYPY
    from typing import Any, Dict, List, Set, Generator, Union  # 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: (Union[None, 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.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:
            print('slt', type(self))
            print('slc', self.loader._composer)
            print(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:
            raise ConstructorError(
                None, None, 'found unconstructable recursive node', node.start_mark
            )
        self.recursive_objects[node] = None
        constructor = None  # type: Any
        tag_suffix = None
        if node.tag in self.yaml_constructors:
            constructor = self.yaml_constructors[node.tag]
        else:
            for tag_prefix in self.yaml_multi_constructors:
                if node.tag.startswith(tag_prefix):
                    tag_suffix = node.tag[len(tag_prefix) :]
                    constructor = self.yaml_multi_constructors[tag_prefix]
                    break
            else:
                if None in self.yaml_multi_constructors:
                    tag_suffix = node.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  # type: ignore
                elif isinstance(node, SequenceNode):
                    constructor = self.__class__.construct_sequence  # type: ignore
                elif isinstance(node, MappingNode):
                    constructor = self.__class__.construct_mapping  # type: ignore
        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)
        self.constructed_objects[node] = data
        del self.recursive_objects[node]
        if deep:
            self.deep_construct = old_deep
        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 = {}
        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 = {}  # 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:
                    self.check_mapping_key(node, key_node, mapping, key, value)
                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) -> None
        if key in mapping:
            if not self.allow_duplicate_keys:
                args = [
                    'while constructing a mapping',
                    node.start_mark,
                    'found duplicate key "{}" with value "{}" '
                    '(original value: "{}")'.format(key, value, mapping.get(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':
                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'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, 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
        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
        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 = []  # type: List[Any]
        yield data
        data.extend(self.construct_sequence(node))

    def construct_yaml_map(self, node):
        # type: (Any) -> Any
        data = {}  # 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:
            module_name, object_name = name.rsplit('.', 1)
        else:
            module_name = builtins_module
            object_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]
        if not hasattr(module, object_name):
            raise ConstructorError(
                'while constructing a Python object',
                mark,
                'cannot find %r in the module %r' % (utf8(object_name), module.__name__),
                mark,
            )
        return getattr(module, object_name)

    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)
        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):
            pss = PreservedScalarString(node.value)
            if node.comment and node.comment[1]:
                pss.comment = node.comment[1][0]
            return pss
        elif bool(self._preserve_quotes) and isinstance(node.value, text_type):
            if node.style == "'":
                return SingleQuotedScalarString(node.value)
            if node.style == '"':
                return DoubleQuotedScalarString(node.value)
        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(  # type: ignore
                sign * int(value_s[2:], 2), width=width, underscore=underscore
            )
        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)
        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(  # type: ignore
                sign * int(value_s[2:], 8), width=width, underscore=underscore
            )
        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(  # type: ignore
                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(  # type: ignore
                sign * int(value_s), width=None, underscore=underscore
            )
        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 '+-'
            # print('sf', width, prec, m_sign, exp, e_width, e_sign)
            return ScalarFloat(  # type: ignore
                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,
            )
        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(  # type: ignore
            sign * float(value_s), width=width, prec=prec, m_sign=m_sign, m_lead0=lead0
        )

    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 = []
        index = 0
        while index < len(node.value):
            key_node, value_node = node.value[index]
            if key_node.tag == u'tag:yaml.org,2002:merge':
                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=None, 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, list):
                    key_a = CommentedKeySeq(key)
                    if key_node.flow_style is True:
                        key_a.fa.set_flow_style()
                    elif key_node.flow_style is False:
                        key_a.fa.set_block_style()
                    key = key_a
                    # 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)
            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_mapping_key(node, key_node, typ, key, value)
            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.flow_style is True:
            data.fa.set_flow_style()
        elif node.flow_style is False:
            data.fa.set_block_style()
        if node.comment:
            data._yaml_add_comment(node.comment)
        yield data
        data.extend(self.construct_rt_sequence(node, data))

    def construct_yaml_map(self, node):
        # type: (Any) -> Any
        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()
        yield data
        self.construct_mapping(node, data)

    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
                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
                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


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)