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specifiers.py39.0 KB · 1031 lines
# This file is dual licensed under the terms of the Apache License, Version# 2.0, and the BSD License. See the LICENSE file in the root of this repository# for complete details.""".. testsetup::     from packaging.specifiers import Specifier, SpecifierSet, InvalidSpecifier    from packaging.version import Version""" import abcimport itertoolsimport refrom typing import (    Callable,    Iterable,    Iterator,    List,    Optional,    Set,    Tuple,    TypeVar,    Union,) from .utils import canonicalize_versionfrom .version import Version UnparsedVersion = Union[Version, str]UnparsedVersionVar = TypeVar("UnparsedVersionVar", bound=UnparsedVersion)CallableOperator = Callable[[Version, str], bool]  def _coerce_version(version: UnparsedVersion) -> Version:    if not isinstance(version, Version):        version = Version(version)    return version  class InvalidSpecifier(ValueError):    """    Raised when attempting to create a :class:`Specifier` with a specifier    string that is invalid.     >>> Specifier("lolwat")    Traceback (most recent call last):        ...    packaging.specifiers.InvalidSpecifier: Invalid specifier: 'lolwat'    """  class BaseSpecifier(metaclass=abc.ABCMeta):    @abc.abstractmethod    def __str__(self) -> str:        """        Returns the str representation of this Specifier-like object. This        should be representative of the Specifier itself.        """     @abc.abstractmethod    def __hash__(self) -> int:        """        Returns a hash value for this Specifier-like object.        """     @abc.abstractmethod    def __eq__(self, other: object) -> bool:        """        Returns a boolean representing whether or not the two Specifier-like        objects are equal.         :param other: The other object to check against.        """     @property    @abc.abstractmethod    def prereleases(self) -> Optional[bool]:        """Whether or not pre-releases as a whole are allowed.         This can be set to either ``True`` or ``False`` to explicitly enable or disable        prereleases or it can be set to ``None`` (the default) to use default semantics.        """     @prereleases.setter    def prereleases(self, value: bool) -> None:        """Setter for :attr:`prereleases`.         :param value: The value to set.        """     @abc.abstractmethod    def contains(self, item: str, prereleases: Optional[bool] = None) -> bool:        """        Determines if the given item is contained within this specifier.        """     @abc.abstractmethod    def filter(        self, iterable: Iterable[UnparsedVersionVar], prereleases: Optional[bool] = None    ) -> Iterator[UnparsedVersionVar]:        """        Takes an iterable of items and filters them so that only items which        are contained within this specifier are allowed in it.        """  class Specifier(BaseSpecifier):    """This class abstracts handling of version specifiers.     .. tip::         It is generally not required to instantiate this manually. You should instead        prefer to work with :class:`SpecifierSet` instead, which can parse        comma-separated version specifiers (which is what package metadata contains).    """     _operator_regex_str = r"""        (?P<operator>(~=|==|!=|<=|>=|<|>|===))        """    _version_regex_str = r"""        (?P<version>            (?:                # The identity operators allow for an escape hatch that will                # do an exact string match of the version you wish to install.                # This will not be parsed by PEP 440 and we cannot determine                # any semantic meaning from it. This operator is discouraged                # but included entirely as an escape hatch.                (?<====)  # Only match for the identity operator                \s*                [^\s;)]*  # The arbitrary version can be just about anything,                          # we match everything except for whitespace, a                          # semi-colon for marker support, and a closing paren                          # since versions can be enclosed in them.            )            |            (?:                # The (non)equality operators allow for wild card and local                # versions to be specified so we have to define these two                # operators separately to enable that.                (?<===|!=)            # Only match for equals and not equals                 \s*                v?                (?:[0-9]+!)?          # epoch                [0-9]+(?:\.[0-9]+)*   # release                 # You cannot use a wild card and a pre-release, post-release, a dev or                # local version together so group them with a | and make them optional.                (?:                    \.\*  # Wild card syntax of .*                    |                    (?:                                  # pre release                        [-_\.]?                        (alpha|beta|preview|pre|a|b|c|rc)                        [-_\.]?                        [0-9]*                    )?                    (?:                                  # post release                        (?:-[0-9]+)|(?:[-_\.]?(post|rev|r)[-_\.]?[0-9]*)                    )?                    (?:[-_\.]?dev[-_\.]?[0-9]*)?         # dev release                    (?:\+[a-z0-9]+(?:[-_\.][a-z0-9]+)*)? # local                )?            )            |            (?:                # The compatible operator requires at least two digits in the                # release segment.                (?<=~=)               # Only match for the compatible operator                 \s*                v?                (?:[0-9]+!)?          # epoch                [0-9]+(?:\.[0-9]+)+   # release  (We have a + instead of a *)                (?:                   # pre release                    [-_\.]?                    (alpha|beta|preview|pre|a|b|c|rc)                    [-_\.]?                    [0-9]*                )?                (?:                                   # post release                    (?:-[0-9]+)|(?:[-_\.]?(post|rev|r)[-_\.]?[0-9]*)                )?                (?:[-_\.]?dev[-_\.]?[0-9]*)?          # dev release            )            |            (?:                # All other operators only allow a sub set of what the                # (non)equality operators do. Specifically they do not allow                # local versions to be specified nor do they allow the prefix                # matching wild cards.                (?<!==|!=|~=)         # We have special cases for these                                      # operators so we want to make sure they                                      # don't match here.                 \s*                v?                (?:[0-9]+!)?          # epoch                [0-9]+(?:\.[0-9]+)*   # release                (?:                   # pre release                    [-_\.]?                    (alpha|beta|preview|pre|a|b|c|rc)                    [-_\.]?                    [0-9]*                )?                (?:                                   # post release                    (?:-[0-9]+)|(?:[-_\.]?(post|rev|r)[-_\.]?[0-9]*)                )?                (?:[-_\.]?dev[-_\.]?[0-9]*)?          # dev release            )        )        """     _regex = re.compile(        r"^\s*" + _operator_regex_str + _version_regex_str + r"\s*$",        re.VERBOSE | re.IGNORECASE,    )     _operators = {        "~=": "compatible",        "==": "equal",        "!=": "not_equal",        "<=": "less_than_equal",        ">=": "greater_than_equal",        "<": "less_than",        ">": "greater_than",        "===": "arbitrary",    }     def __init__(self, spec: str = "", prereleases: Optional[bool] = None) -> None:        """Initialize a Specifier instance.         :param spec:            The string representation of a specifier which will be parsed and            normalized before use.        :param prereleases:            This tells the specifier if it should accept prerelease versions if            applicable or not. The default of ``None`` will autodetect it from the            given specifiers.        :raises InvalidSpecifier:            If the given specifier is invalid (i.e. bad syntax).        """        match = self._regex.search(spec)        if not match:            raise InvalidSpecifier(f"Invalid specifier: '{spec}'")         self._spec: Tuple[str, str] = (            match.group("operator").strip(),            match.group("version").strip(),        )         # Store whether or not this Specifier should accept prereleases        self._prereleases = prereleases     # https://github.com/python/mypy/pull/13475#pullrequestreview-1079784515    @property  # type: ignore[override]    def prereleases(self) -> bool:        # If there is an explicit prereleases set for this, then we'll just        # blindly use that.        if self._prereleases is not None:            return self._prereleases         # Look at all of our specifiers and determine if they are inclusive        # operators, and if they are if they are including an explicit        # prerelease.        operator, version = self._spec        if operator in ["==", ">=", "<=", "~=", "==="]:            # The == specifier can include a trailing .*, if it does we            # want to remove before parsing.            if operator == "==" and version.endswith(".*"):                version = version[:-2]             # Parse the version, and if it is a pre-release than this            # specifier allows pre-releases.            if Version(version).is_prerelease:                return True         return False     @prereleases.setter    def prereleases(self, value: bool) -> None:        self._prereleases = value     @property    def operator(self) -> str:        """The operator of this specifier.         >>> Specifier("==1.2.3").operator        '=='        """        return self._spec[0]     @property    def version(self) -> str:        """The version of this specifier.         >>> Specifier("==1.2.3").version        '1.2.3'        """        return self._spec[1]     def __repr__(self) -> str:        """A representation of the Specifier that shows all internal state.         >>> Specifier('>=1.0.0')        <Specifier('>=1.0.0')>        >>> Specifier('>=1.0.0', prereleases=False)        <Specifier('>=1.0.0', prereleases=False)>        >>> Specifier('>=1.0.0', prereleases=True)        <Specifier('>=1.0.0', prereleases=True)>        """        pre = (            f", prereleases={self.prereleases!r}"            if self._prereleases is not None            else ""        )         return f"<{self.__class__.__name__}({str(self)!r}{pre})>"     def __str__(self) -> str:        """A string representation of the Specifier that can be round-tripped.         >>> str(Specifier('>=1.0.0'))        '>=1.0.0'        >>> str(Specifier('>=1.0.0', prereleases=False))        '>=1.0.0'        """        return "{}{}".format(*self._spec)     @property    def _canonical_spec(self) -> Tuple[str, str]:        canonical_version = canonicalize_version(            self._spec[1],            strip_trailing_zero=(self._spec[0] != "~="),        )        return self._spec[0], canonical_version     def __hash__(self) -> int:        return hash(self._canonical_spec)     def __eq__(self, other: object) -> bool:        """Whether or not the two Specifier-like objects are equal.         :param other: The other object to check against.         The value of :attr:`prereleases` is ignored.         >>> Specifier("==1.2.3") == Specifier("== 1.2.3.0")        True        >>> (Specifier("==1.2.3", prereleases=False) ==        ...  Specifier("==1.2.3", prereleases=True))        True        >>> Specifier("==1.2.3") == "==1.2.3"        True        >>> Specifier("==1.2.3") == Specifier("==1.2.4")        False        >>> Specifier("==1.2.3") == Specifier("~=1.2.3")        False        """        if isinstance(other, str):            try:                other = self.__class__(str(other))            except InvalidSpecifier:                return NotImplemented        elif not isinstance(other, self.__class__):            return NotImplemented         return self._canonical_spec == other._canonical_spec     def _get_operator(self, op: str) -> CallableOperator:        operator_callable: CallableOperator = getattr(            self, f"_compare_{self._operators[op]}"        )        return operator_callable     def _compare_compatible(self, prospective: Version, spec: str) -> bool:         # Compatible releases have an equivalent combination of >= and ==. That        # is that ~=2.2 is equivalent to >=2.2,==2.*. This allows us to        # implement this in terms of the other specifiers instead of        # implementing it ourselves. The only thing we need to do is construct        # the other specifiers.         # We want everything but the last item in the version, but we want to        # ignore suffix segments.        prefix = _version_join(            list(itertools.takewhile(_is_not_suffix, _version_split(spec)))[:-1]        )         # Add the prefix notation to the end of our string        prefix += ".*"         return self._get_operator(">=")(prospective, spec) and self._get_operator("==")(            prospective, prefix        )     def _compare_equal(self, prospective: Version, spec: str) -> bool:         # We need special logic to handle prefix matching        if spec.endswith(".*"):            # In the case of prefix matching we want to ignore local segment.            normalized_prospective = canonicalize_version(                prospective.public, strip_trailing_zero=False            )            # Get the normalized version string ignoring the trailing .*            normalized_spec = canonicalize_version(spec[:-2], strip_trailing_zero=False)            # Split the spec out by bangs and dots, and pretend that there is            # an implicit dot in between a release segment and a pre-release segment.            split_spec = _version_split(normalized_spec)             # Split the prospective version out by bangs and dots, and pretend            # that there is an implicit dot in between a release segment and            # a pre-release segment.            split_prospective = _version_split(normalized_prospective)             # 0-pad the prospective version before shortening it to get the correct            # shortened version.            padded_prospective, _ = _pad_version(split_prospective, split_spec)             # Shorten the prospective version to be the same length as the spec            # so that we can determine if the specifier is a prefix of the            # prospective version or not.            shortened_prospective = padded_prospective[: len(split_spec)]             return shortened_prospective == split_spec        else:            # Convert our spec string into a Version            spec_version = Version(spec)             # If the specifier does not have a local segment, then we want to            # act as if the prospective version also does not have a local            # segment.            if not spec_version.local:                prospective = Version(prospective.public)             return prospective == spec_version     def _compare_not_equal(self, prospective: Version, spec: str) -> bool:        return not self._compare_equal(prospective, spec)     def _compare_less_than_equal(self, prospective: Version, spec: str) -> bool:         # NB: Local version identifiers are NOT permitted in the version        # specifier, so local version labels can be universally removed from        # the prospective version.        return Version(prospective.public) <= Version(spec)     def _compare_greater_than_equal(self, prospective: Version, spec: str) -> bool:         # NB: Local version identifiers are NOT permitted in the version        # specifier, so local version labels can be universally removed from        # the prospective version.        return Version(prospective.public) >= Version(spec)     def _compare_less_than(self, prospective: Version, spec_str: str) -> bool:         # Convert our spec to a Version instance, since we'll want to work with        # it as a version.        spec = Version(spec_str)         # Check to see if the prospective version is less than the spec        # version. If it's not we can short circuit and just return False now        # instead of doing extra unneeded work.        if not prospective < spec:            return False         # This special case is here so that, unless the specifier itself        # includes is a pre-release version, that we do not accept pre-release        # versions for the version mentioned in the specifier (e.g. <3.1 should        # not match 3.1.dev0, but should match 3.0.dev0).        if not spec.is_prerelease and prospective.is_prerelease:            if Version(prospective.base_version) == Version(spec.base_version):                return False         # If we've gotten to here, it means that prospective version is both        # less than the spec version *and* it's not a pre-release of the same        # version in the spec.        return True     def _compare_greater_than(self, prospective: Version, spec_str: str) -> bool:         # Convert our spec to a Version instance, since we'll want to work with        # it as a version.        spec = Version(spec_str)         # Check to see if the prospective version is greater than the spec        # version. If it's not we can short circuit and just return False now        # instead of doing extra unneeded work.        if not prospective > spec:            return False         # This special case is here so that, unless the specifier itself        # includes is a post-release version, that we do not accept        # post-release versions for the version mentioned in the specifier        # (e.g. >3.1 should not match 3.0.post0, but should match 3.2.post0).        if not spec.is_postrelease and prospective.is_postrelease:            if Version(prospective.base_version) == Version(spec.base_version):                return False         # Ensure that we do not allow a local version of the version mentioned        # in the specifier, which is technically greater than, to match.        if prospective.local is not None:            if Version(prospective.base_version) == Version(spec.base_version):                return False         # If we've gotten to here, it means that prospective version is both        # greater than the spec version *and* it's not a pre-release of the        # same version in the spec.        return True     def _compare_arbitrary(self, prospective: Version, spec: str) -> bool:        return str(prospective).lower() == str(spec).lower()     def __contains__(self, item: Union[str, Version]) -> bool:        """Return whether or not the item is contained in this specifier.         :param item: The item to check for.         This is used for the ``in`` operator and behaves the same as        :meth:`contains` with no ``prereleases`` argument passed.         >>> "1.2.3" in Specifier(">=1.2.3")        True        >>> Version("1.2.3") in Specifier(">=1.2.3")        True        >>> "1.0.0" in Specifier(">=1.2.3")        False        >>> "1.3.0a1" in Specifier(">=1.2.3")        False        >>> "1.3.0a1" in Specifier(">=1.2.3", prereleases=True)        True        """        return self.contains(item)     def contains(        self, item: UnparsedVersion, prereleases: Optional[bool] = None    ) -> bool:        """Return whether or not the item is contained in this specifier.         :param item:            The item to check for, which can be a version string or a            :class:`Version` instance.        :param prereleases:            Whether or not to match prereleases with this Specifier. If set to            ``None`` (the default), it uses :attr:`prereleases` to determine            whether or not prereleases are allowed.         >>> Specifier(">=1.2.3").contains("1.2.3")        True        >>> Specifier(">=1.2.3").contains(Version("1.2.3"))        True        >>> Specifier(">=1.2.3").contains("1.0.0")        False        >>> Specifier(">=1.2.3").contains("1.3.0a1")        False        >>> Specifier(">=1.2.3", prereleases=True).contains("1.3.0a1")        True        >>> Specifier(">=1.2.3").contains("1.3.0a1", prereleases=True)        True        """         # Determine if prereleases are to be allowed or not.        if prereleases is None:            prereleases = self.prereleases         # Normalize item to a Version, this allows us to have a shortcut for        # "2.0" in Specifier(">=2")        normalized_item = _coerce_version(item)         # Determine if we should be supporting prereleases in this specifier        # or not, if we do not support prereleases than we can short circuit        # logic if this version is a prereleases.        if normalized_item.is_prerelease and not prereleases:            return False         # Actually do the comparison to determine if this item is contained        # within this Specifier or not.        operator_callable: CallableOperator = self._get_operator(self.operator)        return operator_callable(normalized_item, self.version)     def filter(        self, iterable: Iterable[UnparsedVersionVar], prereleases: Optional[bool] = None    ) -> Iterator[UnparsedVersionVar]:        """Filter items in the given iterable, that match the specifier.         :param iterable:            An iterable that can contain version strings and :class:`Version` instances.            The items in the iterable will be filtered according to the specifier.        :param prereleases:            Whether or not to allow prereleases in the returned iterator. If set to            ``None`` (the default), it will be intelligently decide whether to allow            prereleases or not (based on the :attr:`prereleases` attribute, and            whether the only versions matching are prereleases).         This method is smarter than just ``filter(Specifier().contains, [...])``        because it implements the rule from :pep:`440` that a prerelease item        SHOULD be accepted if no other versions match the given specifier.         >>> list(Specifier(">=1.2.3").filter(["1.2", "1.3", "1.5a1"]))        ['1.3']        >>> list(Specifier(">=1.2.3").filter(["1.2", "1.2.3", "1.3", Version("1.4")]))        ['1.2.3', '1.3', <Version('1.4')>]        >>> list(Specifier(">=1.2.3").filter(["1.2", "1.5a1"]))        ['1.5a1']        >>> list(Specifier(">=1.2.3").filter(["1.3", "1.5a1"], prereleases=True))        ['1.3', '1.5a1']        >>> list(Specifier(">=1.2.3", prereleases=True).filter(["1.3", "1.5a1"]))        ['1.3', '1.5a1']        """         yielded = False        found_prereleases = []         kw = {"prereleases": prereleases if prereleases is not None else True}         # Attempt to iterate over all the values in the iterable and if any of        # them match, yield them.        for version in iterable:            parsed_version = _coerce_version(version)             if self.contains(parsed_version, **kw):                # If our version is a prerelease, and we were not set to allow                # prereleases, then we'll store it for later in case nothing                # else matches this specifier.                if parsed_version.is_prerelease and not (                    prereleases or self.prereleases                ):                    found_prereleases.append(version)                # Either this is not a prerelease, or we should have been                # accepting prereleases from the beginning.                else:                    yielded = True                    yield version         # Now that we've iterated over everything, determine if we've yielded        # any values, and if we have not and we have any prereleases stored up        # then we will go ahead and yield the prereleases.        if not yielded and found_prereleases:            for version in found_prereleases:                yield version  _prefix_regex = re.compile(r"^([0-9]+)((?:a|b|c|rc)[0-9]+)$")  def _version_split(version: str) -> List[str]:    """Split version into components.     The split components are intended for version comparison. The logic does    not attempt to retain the original version string, so joining the    components back with :func:`_version_join` may not produce the original    version string.    """    result: List[str] = []     epoch, _, rest = version.rpartition("!")    result.append(epoch or "0")     for item in rest.split("."):        match = _prefix_regex.search(item)        if match:            result.extend(match.groups())        else:            result.append(item)    return result  def _version_join(components: List[str]) -> str:    """Join split version components into a version string.     This function assumes the input came from :func:`_version_split`, where the    first component must be the epoch (either empty or numeric), and all other    components numeric.    """    epoch, *rest = components    return f"{epoch}!{'.'.join(rest)}"  def _is_not_suffix(segment: str) -> bool:    return not any(        segment.startswith(prefix) for prefix in ("dev", "a", "b", "rc", "post")    )  def _pad_version(left: List[str], right: List[str]) -> Tuple[List[str], List[str]]:    left_split, right_split = [], []     # Get the release segment of our versions    left_split.append(list(itertools.takewhile(lambda x: x.isdigit(), left)))    right_split.append(list(itertools.takewhile(lambda x: x.isdigit(), right)))     # Get the rest of our versions    left_split.append(left[len(left_split[0]) :])    right_split.append(right[len(right_split[0]) :])     # Insert our padding    left_split.insert(1, ["0"] * max(0, len(right_split[0]) - len(left_split[0])))    right_split.insert(1, ["0"] * max(0, len(left_split[0]) - len(right_split[0])))     return (list(itertools.chain(*left_split)), list(itertools.chain(*right_split)))  class SpecifierSet(BaseSpecifier):    """This class abstracts handling of a set of version specifiers.     It can be passed a single specifier (``>=3.0``), a comma-separated list of    specifiers (``>=3.0,!=3.1``), or no specifier at all.    """     def __init__(        self, specifiers: str = "", prereleases: Optional[bool] = None    ) -> None:        """Initialize a SpecifierSet instance.         :param specifiers:            The string representation of a specifier or a comma-separated list of            specifiers which will be parsed and normalized before use.        :param prereleases:            This tells the SpecifierSet if it should accept prerelease versions if            applicable or not. The default of ``None`` will autodetect it from the            given specifiers.         :raises InvalidSpecifier:            If the given ``specifiers`` are not parseable than this exception will be            raised.        """         # Split on `,` to break each individual specifier into it's own item, and        # strip each item to remove leading/trailing whitespace.        split_specifiers = [s.strip() for s in specifiers.split(",") if s.strip()]         # Parsed each individual specifier, attempting first to make it a        # Specifier.        parsed: Set[Specifier] = set()        for specifier in split_specifiers:            parsed.add(Specifier(specifier))         # Turn our parsed specifiers into a frozen set and save them for later.        self._specs = frozenset(parsed)         # Store our prereleases value so we can use it later to determine if        # we accept prereleases or not.        self._prereleases = prereleases     @property    def prereleases(self) -> Optional[bool]:        # If we have been given an explicit prerelease modifier, then we'll        # pass that through here.        if self._prereleases is not None:            return self._prereleases         # If we don't have any specifiers, and we don't have a forced value,        # then we'll just return None since we don't know if this should have        # pre-releases or not.        if not self._specs:            return None         # Otherwise we'll see if any of the given specifiers accept        # prereleases, if any of them do we'll return True, otherwise False.        return any(s.prereleases for s in self._specs)     @prereleases.setter    def prereleases(self, value: bool) -> None:        self._prereleases = value     def __repr__(self) -> str:        """A representation of the specifier set that shows all internal state.         Note that the ordering of the individual specifiers within the set may not        match the input string.         >>> SpecifierSet('>=1.0.0,!=2.0.0')        <SpecifierSet('!=2.0.0,>=1.0.0')>        >>> SpecifierSet('>=1.0.0,!=2.0.0', prereleases=False)        <SpecifierSet('!=2.0.0,>=1.0.0', prereleases=False)>        >>> SpecifierSet('>=1.0.0,!=2.0.0', prereleases=True)        <SpecifierSet('!=2.0.0,>=1.0.0', prereleases=True)>        """        pre = (            f", prereleases={self.prereleases!r}"            if self._prereleases is not None            else ""        )         return f"<SpecifierSet({str(self)!r}{pre})>"     def __str__(self) -> str:        """A string representation of the specifier set that can be round-tripped.         Note that the ordering of the individual specifiers within the set may not        match the input string.         >>> str(SpecifierSet(">=1.0.0,!=1.0.1"))        '!=1.0.1,>=1.0.0'        >>> str(SpecifierSet(">=1.0.0,!=1.0.1", prereleases=False))        '!=1.0.1,>=1.0.0'        """        return ",".join(sorted(str(s) for s in self._specs))     def __hash__(self) -> int:        return hash(self._specs)     def __and__(self, other: Union["SpecifierSet", str]) -> "SpecifierSet":        """Return a SpecifierSet which is a combination of the two sets.         :param other: The other object to combine with.         >>> SpecifierSet(">=1.0.0,!=1.0.1") & '<=2.0.0,!=2.0.1'        <SpecifierSet('!=1.0.1,!=2.0.1,<=2.0.0,>=1.0.0')>        >>> SpecifierSet(">=1.0.0,!=1.0.1") & SpecifierSet('<=2.0.0,!=2.0.1')        <SpecifierSet('!=1.0.1,!=2.0.1,<=2.0.0,>=1.0.0')>        """        if isinstance(other, str):            other = SpecifierSet(other)        elif not isinstance(other, SpecifierSet):            return NotImplemented         specifier = SpecifierSet()        specifier._specs = frozenset(self._specs | other._specs)         if self._prereleases is None and other._prereleases is not None:            specifier._prereleases = other._prereleases        elif self._prereleases is not None and other._prereleases is None:            specifier._prereleases = self._prereleases        elif self._prereleases == other._prereleases:            specifier._prereleases = self._prereleases        else:            raise ValueError(                "Cannot combine SpecifierSets with True and False prerelease "                "overrides."            )         return specifier     def __eq__(self, other: object) -> bool:        """Whether or not the two SpecifierSet-like objects are equal.         :param other: The other object to check against.         The value of :attr:`prereleases` is ignored.         >>> SpecifierSet(">=1.0.0,!=1.0.1") == SpecifierSet(">=1.0.0,!=1.0.1")        True        >>> (SpecifierSet(">=1.0.0,!=1.0.1", prereleases=False) ==        ...  SpecifierSet(">=1.0.0,!=1.0.1", prereleases=True))        True        >>> SpecifierSet(">=1.0.0,!=1.0.1") == ">=1.0.0,!=1.0.1"        True        >>> SpecifierSet(">=1.0.0,!=1.0.1") == SpecifierSet(">=1.0.0")        False        >>> SpecifierSet(">=1.0.0,!=1.0.1") == SpecifierSet(">=1.0.0,!=1.0.2")        False        """        if isinstance(other, (str, Specifier)):            other = SpecifierSet(str(other))        elif not isinstance(other, SpecifierSet):            return NotImplemented         return self._specs == other._specs     def __len__(self) -> int:        """Returns the number of specifiers in this specifier set."""        return len(self._specs)     def __iter__(self) -> Iterator[Specifier]:        """        Returns an iterator over all the underlying :class:`Specifier` instances        in this specifier set.         >>> sorted(SpecifierSet(">=1.0.0,!=1.0.1"), key=str)        [<Specifier('!=1.0.1')>, <Specifier('>=1.0.0')>]        """        return iter(self._specs)     def __contains__(self, item: UnparsedVersion) -> bool:        """Return whether or not the item is contained in this specifier.         :param item: The item to check for.         This is used for the ``in`` operator and behaves the same as        :meth:`contains` with no ``prereleases`` argument passed.         >>> "1.2.3" in SpecifierSet(">=1.0.0,!=1.0.1")        True        >>> Version("1.2.3") in SpecifierSet(">=1.0.0,!=1.0.1")        True        >>> "1.0.1" in SpecifierSet(">=1.0.0,!=1.0.1")        False        >>> "1.3.0a1" in SpecifierSet(">=1.0.0,!=1.0.1")        False        >>> "1.3.0a1" in SpecifierSet(">=1.0.0,!=1.0.1", prereleases=True)        True        """        return self.contains(item)     def contains(        self,        item: UnparsedVersion,        prereleases: Optional[bool] = None,        installed: Optional[bool] = None,    ) -> bool:        """Return whether or not the item is contained in this SpecifierSet.         :param item:            The item to check for, which can be a version string or a            :class:`Version` instance.        :param prereleases:            Whether or not to match prereleases with this SpecifierSet. If set to            ``None`` (the default), it uses :attr:`prereleases` to determine            whether or not prereleases are allowed.         >>> SpecifierSet(">=1.0.0,!=1.0.1").contains("1.2.3")        True        >>> SpecifierSet(">=1.0.0,!=1.0.1").contains(Version("1.2.3"))        True        >>> SpecifierSet(">=1.0.0,!=1.0.1").contains("1.0.1")        False        >>> SpecifierSet(">=1.0.0,!=1.0.1").contains("1.3.0a1")        False        >>> SpecifierSet(">=1.0.0,!=1.0.1", prereleases=True).contains("1.3.0a1")        True        >>> SpecifierSet(">=1.0.0,!=1.0.1").contains("1.3.0a1", prereleases=True)        True        """        # Ensure that our item is a Version instance.        if not isinstance(item, Version):            item = Version(item)         # Determine if we're forcing a prerelease or not, if we're not forcing        # one for this particular filter call, then we'll use whatever the        # SpecifierSet thinks for whether or not we should support prereleases.        if prereleases is None:            prereleases = self.prereleases         # We can determine if we're going to allow pre-releases by looking to        # see if any of the underlying items supports them. If none of them do        # and this item is a pre-release then we do not allow it and we can        # short circuit that here.        # Note: This means that 1.0.dev1 would not be contained in something        #       like >=1.0.devabc however it would be in >=1.0.debabc,>0.0.dev0        if not prereleases and item.is_prerelease:            return False         if installed and item.is_prerelease:            item = Version(item.base_version)         # We simply dispatch to the underlying specs here to make sure that the        # given version is contained within all of them.        # Note: This use of all() here means that an empty set of specifiers        #       will always return True, this is an explicit design decision.        return all(s.contains(item, prereleases=prereleases) for s in self._specs)     def filter(        self, iterable: Iterable[UnparsedVersionVar], prereleases: Optional[bool] = None    ) -> Iterator[UnparsedVersionVar]:        """Filter items in the given iterable, that match the specifiers in this set.         :param iterable:            An iterable that can contain version strings and :class:`Version` instances.            The items in the iterable will be filtered according to the specifier.        :param prereleases:            Whether or not to allow prereleases in the returned iterator. If set to            ``None`` (the default), it will be intelligently decide whether to allow            prereleases or not (based on the :attr:`prereleases` attribute, and            whether the only versions matching are prereleases).         This method is smarter than just ``filter(SpecifierSet(...).contains, [...])``        because it implements the rule from :pep:`440` that a prerelease item        SHOULD be accepted if no other versions match the given specifier.         >>> list(SpecifierSet(">=1.2.3").filter(["1.2", "1.3", "1.5a1"]))        ['1.3']        >>> list(SpecifierSet(">=1.2.3").filter(["1.2", "1.3", Version("1.4")]))        ['1.3', <Version('1.4')>]        >>> list(SpecifierSet(">=1.2.3").filter(["1.2", "1.5a1"]))        []        >>> list(SpecifierSet(">=1.2.3").filter(["1.3", "1.5a1"], prereleases=True))        ['1.3', '1.5a1']        >>> list(SpecifierSet(">=1.2.3", prereleases=True).filter(["1.3", "1.5a1"]))        ['1.3', '1.5a1']         An "empty" SpecifierSet will filter items based on the presence of prerelease        versions in the set.         >>> list(SpecifierSet("").filter(["1.3", "1.5a1"]))        ['1.3']        >>> list(SpecifierSet("").filter(["1.5a1"]))        ['1.5a1']        >>> list(SpecifierSet("", prereleases=True).filter(["1.3", "1.5a1"]))        ['1.3', '1.5a1']        >>> list(SpecifierSet("").filter(["1.3", "1.5a1"], prereleases=True))        ['1.3', '1.5a1']        """        # Determine if we're forcing a prerelease or not, if we're not forcing        # one for this particular filter call, then we'll use whatever the        # SpecifierSet thinks for whether or not we should support prereleases.        if prereleases is None:            prereleases = self.prereleases         # If we have any specifiers, then we want to wrap our iterable in the        # filter method for each one, this will act as a logical AND amongst        # each specifier.        if self._specs:            for spec in self._specs:                iterable = spec.filter(iterable, prereleases=bool(prereleases))            return iter(iterable)        # If we do not have any specifiers, then we need to have a rough filter        # which will filter out any pre-releases, unless there are no final        # releases.        else:            filtered: List[UnparsedVersionVar] = []            found_prereleases: List[UnparsedVersionVar] = []             for item in iterable:                parsed_version = _coerce_version(item)                 # Store any item which is a pre-release for later unless we've                # already found a final version or we are accepting prereleases                if parsed_version.is_prerelease and not prereleases:                    if not filtered:                        found_prereleases.append(item)                else:                    filtered.append(item)             # If we've found no items except for pre-releases, then we'll go            # ahead and use the pre-releases            if not filtered and found_prereleases and prereleases is None:                return iter(found_prereleases)             return iter(filtered)