<filename>pytools/tag.py
"""

Tag Interface
---------------
.. ``normalize_tags`` undocumented for now. (Not ready to commit.)

.. autofunction:: check_tag_uniqueness
.. autoclass:: Taggable
.. autoclass:: Tag
.. autoclass:: UniqueTag

Supporting Functionality
------------------------

.. autoclass:: DottedName
.. autoclass:: NonUniqueTagError


Internal stuff that is only here because the documentation tool wants it
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. class:: T_co

    A covariant type variable used in, e.g. :meth:`Taggable.copy`.


.. class:: TagsOfTypeT

    A type variable used in :meth:`Taggable.tags_of_type`.
"""

from dataclasses import dataclass
from typing import (Tuple, Set, Any, FrozenSet, Union, Iterable,  # noqa: F401
                    TypeVar, Type)
from pytools import memoize, memoize_method
from abc import ABC, abstractmethod

__copyright__ = """
Copyright (C) 2020 <NAME>
Copyright (C) 2020 <NAME>
Copyright (C) 2020 <NAME>
Copyright (C) 2020 <NAME>
"""

__license__ = """
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""


#  {{{ dotted name

class DottedName:
    """
    .. attribute:: name_parts

        A tuple of strings, each of which is a valid
        Python identifier. No name part may start with
        a double underscore.

    The name (at least morally) exists in the
    name space defined by the Python module system.
    It need not necessarily identify an importable
    object.

    .. automethod:: from_class
    """

    def __init__(self, name_parts: Tuple[str, ...]):
        if len(name_parts) == 0:
            raise ValueError("empty name parts")

        for p in name_parts:
            if not p.isidentifier():
                raise ValueError(f"{p} is not a Python identifier")

        self.name_parts = name_parts

    @classmethod
    def from_class(cls, argcls: Any) -> "DottedName":
        name_parts = tuple(
                [str(part) for part in argcls.__module__.split(".")]
                + [str(argcls.__name__)])
        if not all(not npart.startswith("__") for npart in name_parts):
            raise ValueError(f"some name parts of {'.'.join(name_parts)} "
                             "start with double underscores")
        return cls(name_parts)


# }}}


# {{{ tag

tag_dataclass = dataclass(init=True, eq=True, frozen=True, repr=True)


@tag_dataclass
class Tag:
    """
    Generic metadata, applied to, among other things,
    pytato Arrays.

    .. attribute:: tag_name

        A fully qualified :class:`DottedName` that reflects
        the class name of the tag.

    Instances of this type must be immutable, hashable,
    picklable, and have a reasonably concise :meth:`__repr__`
    of the form ``dotted.name(attr1=value1, attr2=value2)``.
    Positional arguments are not allowed.

   .. automethod:: __repr__
    """

    @property
    def tag_name(self) -> DottedName:
        return DottedName.from_class(type(self))

    def update_persistent_hash(self, key_hash, key_builder):
        key_builder.rec(key_hash,
                (self.__class__.__module__, self.__class__.__qualname__))

        from dataclasses import fields
        # Fields are ordered consistently, so ordered hashing is OK.
        #
        # No need to dispatch to superclass: fields() automatically gives us
        # fields from the entire class hierarchy.
        for f in fields(self):
            key_builder.rec(key_hash, getattr(self, f.name))

# }}}


# {{{ unique tag

class UniqueTag(Tag):
    """
    A superclass for tags that are unique on each :class:`Taggable`.

    Each instance of :class:`Taggable` may have no more than one
    instance of each subclass of :class:`UniqueTag` in its
    set of `tags`. Multiple `UniqueTag` instances of
    different (immediate) subclasses are allowed.
    """
    pass

# }}}


TagsType = FrozenSet[Tag]
TagOrIterableType = Union[Iterable[Tag], Tag, None]
T_co = TypeVar("T_co", bound="Taggable")
TagsOfTypeT = TypeVar("TagsOfTypeT", bound="Type[Tag]")


# {{{ UniqueTag rules checking

@memoize
def _immediate_unique_tag_descendants(cls):
    if UniqueTag in cls.__bases__:
        return frozenset([cls])
    else:
        result = frozenset()
        for base in cls.__bases__:
            result = result | _immediate_unique_tag_descendants(base)
        return result


class NonUniqueTagError(ValueError):
    """
    Raised when a :class:`Taggable` object is instantiated with more
    than one :class:`UniqueTag` instances of the same subclass in
    its set of tags.
    """
    pass


def check_tag_uniqueness(tags: TagsType):
    """Ensure that *tags* obeys the rules set forth in :class:`UniqueTag`.
    If not, raise :exc:`NonUniqueTagError`. If any *tags* are not
    subclasses of :class:`Tag`, a :exc:`TypeError` will be raised.

    :returns: *tags*
    """
    unique_tag_descendants: Set[Tag] = set()
    for tag in tags:
        if not isinstance(tag, Tag):
            raise TypeError(f"'{tag}' is not an instance of pytools.tag.Tag")
        tag_unique_tag_descendants = _immediate_unique_tag_descendants(
                type(tag))
        intersection = unique_tag_descendants & tag_unique_tag_descendants
        if intersection:
            raise NonUniqueTagError("Multiple tags are direct subclasses of "
                    "the following UniqueTag(s): "
                    f"{', '.join(d.__name__ for d in intersection)}")
        else:
            unique_tag_descendants.update(tag_unique_tag_descendants)

    return tags

# }}}


def normalize_tags(tags: TagOrIterableType) -> TagsType:
    if isinstance(tags, Tag):
        tags = frozenset([tags])
    elif tags is None:
        tags = frozenset()
    else:
        tags = frozenset(tags)
    return tags


# {{{ taggable

class Taggable(ABC):
    """
    Parent class for objects with a `tags` attribute.

    .. attribute:: tags

        A :class:`frozenset` of :class:`Tag` instances

    .. automethod:: __init__

    .. automethod:: copy
    .. automethod:: tagged
    .. automethod:: without_tags
    .. automethod:: tags_of_type

    .. versionadded:: 2021.1
    """

    # ReST references in docstrings must be fully qualified, as docstrings may
    # be inherited and appear in different contexts.

    def __init__(self, tags: TagsType = frozenset()):
        """
        Constructor for all objects that possess a `tags` attribute.

        :arg tags: a :class:`frozenset` of :class:`~pytools.tag.Tag` objects.
            Tags can be modified via the :meth:`~pytools.tag.Taggable.tagged` and
            :meth:`~pytools.tag.Taggable.without_tags` routines. Input checking
            of *tags* should be performed before creating a
            :class:`~pytools.tag.Taggable` instance, using
            :func:`~pytools.tag.check_tag_uniqueness`.
        """
        self.tags = tags

    @abstractmethod
    def copy(self: T_co, **kwargs: Any) -> T_co:
        """
        Returns of copy of *self* with the specified tags. This method
        should be overridden by subclasses.
        """

    def tagged(self: T_co, tags: TagOrIterableType) -> T_co:
        """
        Return a copy of *self* with the specified
        tag or tags unioned. If *tags* is a :class:`pytools.tag.UniqueTag`
        and other tags of this type are already present, an error is raised
        Assumes `self.copy(tags=<NEW VALUE>)` is implemented.

        :arg tags: An instance of :class:`~pytools.tag.Tag` or
            an iterable with instances therein.
        """
        return self.copy(
                tags=check_tag_uniqueness(normalize_tags(tags) | self.tags))

    def without_tags(self: T_co,
            tags: TagOrIterableType, verify_existence: bool = True) -> T_co:
        """
        Return a copy of *self* without the specified tags.
        `self.copy(tags=<NEW VALUE>)` is implemented.

        :arg tags: An instance of :class:`~pytools.tag.Tag` or an iterable with
            instances therein.
        :arg verify_existence: If set to `True`, this method raises
            an exception if not all tags specified for removal are
            present in the original set of tags. Default `True`.
        """

        to_remove = normalize_tags(tags)
        new_tags = self.tags - to_remove
        if verify_existence and len(new_tags) > len(self.tags) - len(to_remove):
            raise ValueError("A tag specified for removal was not present.")

        return self.copy(tags=check_tag_uniqueness(new_tags))

    @memoize_method
    def tags_of_type(self, tag_t: TagsOfTypeT) -> FrozenSet[TagsOfTypeT]:
        """
        Returns *self*'s tags of type *tag_t*.
        """
        # type-ignore reason: mypy can't tell the generator has elements of
        # type 'TagsOfTypeT' (infers it as elements of type 'Tag')
        return frozenset(tag  # type: ignore[misc]
                         for tag in self.tags
                         if isinstance(tag, tag_t))

# }}}

# vim: foldmethod=marker

<filename>pytools/tag.py
"""

Tag Interface
---------------
.. ``normalize_tags`` undocumented for now. (Not ready to commit.)

.. autofunction:: check_tag_uniqueness
.. autoclass:: Taggable
.. autoclass:: Tag
.. autoclass:: UniqueTag

Supporting Functionality
------------------------

.. autoclass:: DottedName
.. autoclass:: NonUniqueTagError


Internal stuff that is only here because the documentation tool wants it
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. class:: T_co

    A covariant type variable used in, e.g. :meth:`Taggable.copy`.


.. class:: TagsOfTypeT

    A type variable used in :meth:`Taggable.tags_of_type`.
"""

from dataclasses import dataclass
from typing import (Tuple, Set, Any, FrozenSet, Union, Iterable,  # noqa: F401
                    TypeVar, Type)
from pytools import memoize, memoize_method
from abc import ABC, abstractmethod

__copyright__ = """
Copyright (C) 2020 <NAME>
Copyright (C) 2020 <NAME>
Copyright (C) 2020 <NAME>
Copyright (C) 2020 <NAME>
"""

__license__ = """
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""


#  {{{ dotted name

class DottedName:
    """
    .. attribute:: name_parts

        A tuple of strings, each of which is a valid
        Python identifier. No name part may start with
        a double underscore.

    The name (at least morally) exists in the
    name space defined by the Python module system.
    It need not necessarily identify an importable
    object.

    .. automethod:: from_class
    """

    def __init__(self, name_parts: Tuple[str, ...]):
        if len(name_parts) == 0:
            raise ValueError("empty name parts")

        for p in name_parts:
            if not p.isidentifier():
                raise ValueError(f"{p} is not a Python identifier")

        self.name_parts = name_parts

    @classmethod
    def from_class(cls, argcls: Any) -> "DottedName":
        name_parts = tuple(
                [str(part) for part in argcls.__module__.split(".")]
                + [str(argcls.__name__)])
        if not all(not npart.startswith("__") for npart in name_parts):
            raise ValueError(f"some name parts of {'.'.join(name_parts)} "
                             "start with double underscores")
        return cls(name_parts)


# }}}


# {{{ tag

tag_dataclass = dataclass(init=True, eq=True, frozen=True, repr=True)


@tag_dataclass
class Tag:
    """
    Generic metadata, applied to, among other things,
    pytato Arrays.

    .. attribute:: tag_name

        A fully qualified :class:`DottedName` that reflects
        the class name of the tag.

    Instances of this type must be immutable, hashable,
    picklable, and have a reasonably concise :meth:`__repr__`
    of the form ``dotted.name(attr1=value1, attr2=value2)``.
    Positional arguments are not allowed.

   .. automethod:: __repr__
    """

    @property
    def tag_name(self) -> DottedName:
        return DottedName.from_class(type(self))

    def update_persistent_hash(self, key_hash, key_builder):
        key_builder.rec(key_hash,
                (self.__class__.__module__, self.__class__.__qualname__))

        from dataclasses import fields
        # Fields are ordered consistently, so ordered hashing is OK.
        #
        # No need to dispatch to superclass: fields() automatically gives us
        # fields from the entire class hierarchy.
        for f in fields(self):
            key_builder.rec(key_hash, getattr(self, f.name))

# }}}


# {{{ unique tag

class UniqueTag(Tag):
    """
    A superclass for tags that are unique on each :class:`Taggable`.

    Each instance of :class:`Taggable` may have no more than one
    instance of each subclass of :class:`UniqueTag` in its
    set of `tags`. Multiple `UniqueTag` instances of
    different (immediate) subclasses are allowed.
    """
    pass

# }}}


TagsType = FrozenSet[Tag]
TagOrIterableType = Union[Iterable[Tag], Tag, None]
T_co = TypeVar("T_co", bound="Taggable")
TagsOfTypeT = TypeVar("TagsOfTypeT", bound="Type[Tag]")


# {{{ UniqueTag rules checking

@memoize
def _immediate_unique_tag_descendants(cls):
    if UniqueTag in cls.__bases__:
        return frozenset([cls])
    else:
        result = frozenset()
        for base in cls.__bases__:
            result = result | _immediate_unique_tag_descendants(base)
        return result


class NonUniqueTagError(ValueError):
    """
    Raised when a :class:`Taggable` object is instantiated with more
    than one :class:`UniqueTag` instances of the same subclass in
    its set of tags.
    """
    pass


def check_tag_uniqueness(tags: TagsType):
    """Ensure that *tags* obeys the rules set forth in :class:`UniqueTag`.
    If not, raise :exc:`NonUniqueTagError`. If any *tags* are not
    subclasses of :class:`Tag`, a :exc:`TypeError` will be raised.

    :returns: *tags*
    """
    unique_tag_descendants: Set[Tag] = set()
    for tag in tags:
        if not isinstance(tag, Tag):
            raise TypeError(f"'{tag}' is not an instance of pytools.tag.Tag")
        tag_unique_tag_descendants = _immediate_unique_tag_descendants(
                type(tag))
        intersection = unique_tag_descendants & tag_unique_tag_descendants
        if intersection:
            raise NonUniqueTagError("Multiple tags are direct subclasses of "
                    "the following UniqueTag(s): "
                    f"{', '.join(d.__name__ for d in intersection)}")
        else:
            unique_tag_descendants.update(tag_unique_tag_descendants)

    return tags

# }}}


def normalize_tags(tags: TagOrIterableType) -> TagsType:
    if isinstance(tags, Tag):
        tags = frozenset([tags])
    elif tags is None:
        tags = frozenset()
    else:
        tags = frozenset(tags)
    return tags


# {{{ taggable

class Taggable(ABC):
    """
    Parent class for objects with a `tags` attribute.

    .. attribute:: tags

        A :class:`frozenset` of :class:`Tag` instances

    .. automethod:: __init__

    .. automethod:: copy
    .. automethod:: tagged
    .. automethod:: without_tags
    .. automethod:: tags_of_type

    .. versionadded:: 2021.1
    """

    # ReST references in docstrings must be fully qualified, as docstrings may
    # be inherited and appear in different contexts.

    def __init__(self, tags: TagsType = frozenset()):
        """
        Constructor for all objects that possess a `tags` attribute.

        :arg tags: a :class:`frozenset` of :class:`~pytools.tag.Tag` objects.
            Tags can be modified via the :meth:`~pytools.tag.Taggable.tagged` and
            :meth:`~pytools.tag.Taggable.without_tags` routines. Input checking
            of *tags* should be performed before creating a
            :class:`~pytools.tag.Taggable` instance, using
            :func:`~pytools.tag.check_tag_uniqueness`.
        """
        self.tags = tags

    @abstractmethod
    def copy(self: T_co, **kwargs: Any) -> T_co:
        """
        Returns of copy of *self* with the specified tags. This method
        should be overridden by subclasses.
        """

    def tagged(self: T_co, tags: TagOrIterableType) -> T_co:
        """
        Return a copy of *self* with the specified
        tag or tags unioned. If *tags* is a :class:`pytools.tag.UniqueTag`
        and other tags of this type are already present, an error is raised
        Assumes `self.copy(tags=<NEW VALUE>)` is implemented.

        :arg tags: An instance of :class:`~pytools.tag.Tag` or
            an iterable with instances therein.
        """
        return self.copy(
                tags=check_tag_uniqueness(normalize_tags(tags) | self.tags))

    def without_tags(self: T_co,
            tags: TagOrIterableType, verify_existence: bool = True) -> T_co:
        """
        Return a copy of *self* without the specified tags.
        `self.copy(tags=<NEW VALUE>)` is implemented.

        :arg tags: An instance of :class:`~pytools.tag.Tag` or an iterable with
            instances therein.
        :arg verify_existence: If set to `True`, this method raises
            an exception if not all tags specified for removal are
            present in the original set of tags. Default `True`.
        """

        to_remove = normalize_tags(tags)
        new_tags = self.tags - to_remove
        if verify_existence and len(new_tags) > len(self.tags) - len(to_remove):
            raise ValueError("A tag specified for removal was not present.")

        return self.copy(tags=check_tag_uniqueness(new_tags))

    @memoize_method
    def tags_of_type(self, tag_t: TagsOfTypeT) -> FrozenSet[TagsOfTypeT]:
        """
        Returns *self*'s tags of type *tag_t*.
        """
        # type-ignore reason: mypy can't tell the generator has elements of
        # type 'TagsOfTypeT' (infers it as elements of type 'Tag')
        return frozenset(tag  # type: ignore[misc]
                         for tag in self.tags
                         if isinstance(tag, tag_t))

# }}}

# vim: foldmethod=marker

Tag Interface --------------- .. ``normalize_tags`` undocumented for now. (Not ready to commit.)  .. autofunction:: check_tag_uniqueness .. autoclass:: Taggable .. autoclass:: Tag .. autoclass:: UniqueTag  Supporting Functionality ------------------------  .. autoclass:: DottedName .. autoclass:: NonUniqueTagError   Internal stuff that is only here because the documentation tool wants it ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  .. class:: T_co      A covariant type variable used in, e.g. :meth:`Taggable.copy`.   .. class:: TagsOfTypeT      A type variable used in :meth:`Taggable.tags_of_type`. # noqa: F401 Copyright (C) 2020 <NAME> Copyright (C) 2020 <NAME> Copyright (C) 2020 <NAME> Copyright (C) 2020 <NAME> Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:  The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. #  {{{ dotted name .. attribute:: name_parts          A tuple of strings, each of which is a valid         Python identifier. No name part may start with         a double underscore.      The name (at least morally) exists in the     name space defined by the Python module system.     It need not necessarily identify an importable     object.      .. automethod:: from_class # }}} # {{{ tag Generic metadata, applied to, among other things,     pytato Arrays.      .. attribute:: tag_name          A fully qualified :class:`DottedName` that reflects         the class name of the tag.      Instances of this type must be immutable, hashable,     picklable, and have a reasonably concise :meth:`__repr__`     of the form ``dotted.name(attr1=value1, attr2=value2)``.     Positional arguments are not allowed.     .. automethod:: __repr__ # Fields are ordered consistently, so ordered hashing is OK. # # No need to dispatch to superclass: fields() automatically gives us # fields from the entire class hierarchy. # }}} # {{{ unique tag A superclass for tags that are unique on each :class:`Taggable`.      Each instance of :class:`Taggable` may have no more than one     instance of each subclass of :class:`UniqueTag` in its     set of `tags`. Multiple `UniqueTag` instances of     different (immediate) subclasses are allowed. # }}} # {{{ UniqueTag rules checking Raised when a :class:`Taggable` object is instantiated with more     than one :class:`UniqueTag` instances of the same subclass in     its set of tags. Ensure that *tags* obeys the rules set forth in :class:`UniqueTag`.     If not, raise :exc:`NonUniqueTagError`. If any *tags* are not     subclasses of :class:`Tag`, a :exc:`TypeError` will be raised.      :returns: *tags* # }}} # {{{ taggable Parent class for objects with a `tags` attribute.      .. attribute:: tags          A :class:`frozenset` of :class:`Tag` instances      .. automethod:: __init__      .. automethod:: copy     .. automethod:: tagged     .. automethod:: without_tags     .. automethod:: tags_of_type      .. versionadded:: 2021.1 # ReST references in docstrings must be fully qualified, as docstrings may # be inherited and appear in different contexts. Constructor for all objects that possess a `tags` attribute.          :arg tags: a :class:`frozenset` of :class:`~pytools.tag.Tag` objects.             Tags can be modified via the :meth:`~pytools.tag.Taggable.tagged` and             :meth:`~pytools.tag.Taggable.without_tags` routines. Input checking             of *tags* should be performed before creating a             :class:`~pytools.tag.Taggable` instance, using             :func:`~pytools.tag.check_tag_uniqueness`. Returns of copy of *self* with the specified tags. This method         should be overridden by subclasses. Return a copy of *self* with the specified         tag or tags unioned. If *tags* is a :class:`pytools.tag.UniqueTag`         and other tags of this type are already present, an error is raised         Assumes `self.copy(tags=<NEW VALUE>)` is implemented.          :arg tags: An instance of :class:`~pytools.tag.Tag` or             an iterable with instances therein. Return a copy of *self* without the specified tags.         `self.copy(tags=<NEW VALUE>)` is implemented.          :arg tags: An instance of :class:`~pytools.tag.Tag` or an iterable with             instances therein.         :arg verify_existence: If set to `True`, this method raises             an exception if not all tags specified for removal are             present in the original set of tags. Default `True`. Returns *self*'s tags of type *tag_t*. # type-ignore reason: mypy can't tell the generator has elements of # type 'TagsOfTypeT' (infers it as elements of type 'Tag') # type: ignore[misc] # }}} # vim: foldmethod=marker