Vendor resolvelib 1.1.0

docs/html/topics/more-dependency-resolution.md

@@ -160,8 +160,6 @@ follows:
     explicit URL.
 * If equal, prefer if any requirement is "pinned", i.e. contains
     operator ``===`` or ``==``.
-* If equal, calculate an approximate "depth" and resolve requirements
-    closer to the user-specified requirements first.
 * Order user-specified requirements by the order they are specified.
 * If equal, prefers "non-free" requirements, i.e. contains at least one
     operator, such as ``>=`` or ``<``.

news/13001.bugfix.rst

@@ -0,0 +1,5 @@
+Resolvelib 1.1.0 fixes a known issue where pip would report a
+ResolutionImpossible error even though there is a valid solution.
+However, the performance of some very complex dependency resolutions
+that previously resolved may be slower or result in a ResolutionTooDeep
+error.

news/resolvelib.vendor.rst

@@ -0,0 +1 @@
+Upgrade resolvelib to 1.1.0.

src/pip/_internal/resolution/resolvelib/factory.py

@@ -748,7 +748,7 @@ def get_installation_error(
         # The simplest case is when we have *one* cause that can't be
         # satisfied. We just report that case.
         if len(e.causes) == 1:
-            req, parent = e.causes[0]
+            req, parent = next(iter(e.causes))
             if req.name not in constraints:
                 return self._report_single_requirement_conflict(req, parent)
 

src/pip/_internal/resolution/resolvelib/provider.py

@@ -1,4 +1,3 @@
-import collections
 import math
 from functools import lru_cache
 from typing import (
@@ -100,7 +99,6 @@ def __init__(
         self._ignore_dependencies = ignore_dependencies
         self._upgrade_strategy = upgrade_strategy
         self._user_requested = user_requested
-        self._known_depths: Dict[str, float] = collections.defaultdict(lambda: math.inf)
 
     def identify(self, requirement_or_candidate: Union[Requirement, Candidate]) -> str:
         return requirement_or_candidate.name
@@ -124,10 +122,6 @@ def get_preference(
           explicit URL.
         * If equal, prefer if any requirement is "pinned", i.e. contains
           operator ``===`` or ``==``.
-        * If equal, calculate an approximate "depth" and resolve requirements
-          closer to the user-specified requirements first. If the depth cannot
-          by determined (eg: due to no matching parents), it is considered
-          infinite.
         * Order user-specified requirements by the order they are specified.
         * If equal, prefers "non-free" requirements, i.e. contains at least one
           operator, such as ``>=`` or ``<``.
@@ -157,23 +151,6 @@ def get_preference(
         direct = candidate is not None
         pinned = any(op[:2] == "==" for op in operators)
         unfree = bool(operators)
-
-        try:
-            requested_order: Union[int, float] = self._user_requested[identifier]
-        except KeyError:
-            requested_order = math.inf
-            if has_information:
-                parent_depths = (
-                    self._known_depths[parent.name] if parent is not None else 0.0
-                    for _, parent in information[identifier]
-                )
-                inferred_depth = min(d for d in parent_depths) + 1.0
-            else:
-                inferred_depth = math.inf
-        else:
-            inferred_depth = 1.0
-        self._known_depths[identifier] = inferred_depth
-
         requested_order = self._user_requested.get(identifier, math.inf)
 
         # Requires-Python has only one candidate and the check is basically
@@ -190,7 +167,6 @@ def get_preference(
             not direct,
             not pinned,
             not backtrack_cause,
-            inferred_depth,
             requested_order,
             not unfree,
             identifier,

src/pip/_internal/resolution/resolvelib/reporter.py

@@ -1,6 +1,6 @@
 from collections import defaultdict
 from logging import getLogger
-from typing import Any, DefaultDict
+from typing import Any, DefaultDict, Optional
 
 from pip._vendor.resolvelib.reporters import BaseReporter
 
@@ -9,7 +9,7 @@
 logger = getLogger(__name__)
 
 
-class PipReporter(BaseReporter):
+class PipReporter(BaseReporter[Requirement, Candidate, str]):
     def __init__(self) -> None:
         self.reject_count_by_package: DefaultDict[str, int] = defaultdict(int)
 
@@ -55,7 +55,7 @@ def rejecting_candidate(self, criterion: Any, candidate: Candidate) -> None:
         logger.debug(msg)
 
 
-class PipDebuggingReporter(BaseReporter):
+class PipDebuggingReporter(BaseReporter[Requirement, Candidate, str]):
     """A reporter that does an info log for every event it sees."""
 
     def starting(self) -> None:
@@ -71,7 +71,9 @@ def ending_round(self, index: int, state: Any) -> None:
     def ending(self, state: Any) -> None:
         logger.info("Reporter.ending(%r)", state)
 
-    def adding_requirement(self, requirement: Requirement, parent: Candidate) -> None:
+    def adding_requirement(
+        self, requirement: Requirement, parent: Optional[Candidate]
+    ) -> None:
         logger.info("Reporter.adding_requirement(%r, %r)", requirement, parent)
 
     def rejecting_candidate(self, criterion: Any, candidate: Candidate) -> None:

src/pip/_internal/resolution/resolvelib/resolver.py

@@ -82,7 +82,7 @@ def resolve(
             user_requested=collected.user_requested,
         )
         if "PIP_RESOLVER_DEBUG" in os.environ:
-            reporter: BaseReporter = PipDebuggingReporter()
+            reporter: BaseReporter[Requirement, Candidate, str] = PipDebuggingReporter()
         else:
             reporter = PipReporter()
         resolver: RLResolver[Requirement, Candidate, str] = RLResolver(

src/pip/_vendor/resolvelib/__init__.py

@@ -11,12 +11,13 @@
     "ResolutionTooDeep",
 ]
 
-__version__ = "1.0.1"
+__version__ = "1.1.0"
 
 
-from .providers import AbstractProvider, AbstractResolver
+from .providers import AbstractProvider
 from .reporters import BaseReporter
 from .resolvers import (
+    AbstractResolver,
     InconsistentCandidate,
     RequirementsConflicted,
     ResolutionError,

src/pip/_vendor/resolvelib/providers.py

@@ -1,39 +1,68 @@
-class AbstractProvider(object):
+from __future__ import annotations
+
+from typing import (
+    TYPE_CHECKING,
+    Generic,
+    Iterable,
+    Iterator,
+    Mapping,
+    Sequence,
+)
+
+from .structs import CT, KT, RT, Matches, RequirementInformation
+
+if TYPE_CHECKING:
+    from typing import Any, Protocol
+
+    class Preference(Protocol):
+        def __lt__(self, __other: Any) -> bool: ...
+
+
+class AbstractProvider(Generic[RT, CT, KT]):
     """Delegate class to provide the required interface for the resolver."""
 
-    def identify(self, requirement_or_candidate):
-        """Given a requirement, return an identifier for it.
+    def identify(self, requirement_or_candidate: RT | CT) -> KT:
+        """Given a requirement or candidate, return an identifier for it.
 
-        This is used to identify a requirement, e.g. whether two requirements
-        should have their specifier parts merged.
+        This is used to identify, e.g. whether two requirements
+        should have their specifier parts merged or a candidate matches a
+        requirement via ``find_matches()``.
         """
         raise NotImplementedError
 
     def get_preference(
         self,
-        identifier,
-        resolutions,
-        candidates,
-        information,
-        backtrack_causes,
-    ):
+        identifier: KT,
+        resolutions: Mapping[KT, CT],
+        candidates: Mapping[KT, Iterator[CT]],
+        information: Mapping[KT, Iterator[RequirementInformation[RT, CT]]],
+        backtrack_causes: Sequence[RequirementInformation[RT, CT]],
+    ) -> Preference:
         """Produce a sort key for given requirement based on preference.
 
+        As this is a sort key it will be called O(n) times per backtrack
+        step, where n is the number of `identifier`s, if you have a check
+        which is expensive in some sense. E.g. It needs to make O(n) checks
+        per call or takes significant wall clock time, consider using
+        `narrow_requirement_selection` to filter the `identifier`s, which
+        is applied before this sort key is called.
+
         The preference is defined as "I think this requirement should be
         resolved first". The lower the return value is, the more preferred
         this group of arguments is.
 
         :param identifier: An identifier as returned by ``identify()``. This
-            identifies the dependency matches which should be returned.
+            identifies the requirement being considered.
         :param resolutions: Mapping of candidates currently pinned by the
             resolver. Each key is an identifier, and the value is a candidate.
             The candidate may conflict with requirements from ``information``.
         :param candidates: Mapping of each dependency's possible candidates.
             Each value is an iterator of candidates.
         :param information: Mapping of requirement information of each package.
             Each value is an iterator of *requirement information*.
-        :param backtrack_causes: Sequence of requirement information that were
-            the requirements that caused the resolver to most recently backtrack.
+        :param backtrack_causes: Sequence of *requirement information* that are
+            the requirements that caused the resolver to most recently
+            backtrack.
 
         A *requirement information* instance is a named tuple with two members:
 
@@ -60,15 +89,21 @@ def get_preference(
         """
         raise NotImplementedError
 
-    def find_matches(self, identifier, requirements, incompatibilities):
+    def find_matches(
+        self,
+        identifier: KT,
+        requirements: Mapping[KT, Iterator[RT]],
+        incompatibilities: Mapping[KT, Iterator[CT]],
+    ) -> Matches[CT]:
         """Find all possible candidates that satisfy the given constraints.
 
-        :param identifier: An identifier as returned by ``identify()``. This
-            identifies the dependency matches of which should be returned.
+        :param identifier: An identifier as returned by ``identify()``. All
+            candidates returned by this method should produce the same
+            identifier.
         :param requirements: A mapping of requirements that all returned
             candidates must satisfy. Each key is an identifier, and the value
             an iterator of requirements for that dependency.
-        :param incompatibilities: A mapping of known incompatibilities of
+        :param incompatibilities: A mapping of known incompatibile candidates of
             each dependency. Each key is an identifier, and the value an
             iterator of incompatibilities known to the resolver. All
             incompatibilities *must* be excluded from the return value.
@@ -89,7 +124,7 @@ def find_matches(self, identifier, requirements, incompatibilities):
         """
         raise NotImplementedError
 
-    def is_satisfied_by(self, requirement, candidate):
+    def is_satisfied_by(self, requirement: RT, candidate: CT) -> bool:
         """Whether the given requirement can be satisfied by a candidate.
 
         The candidate is guaranteed to have been generated from the
@@ -100,34 +135,62 @@ def is_satisfied_by(self, requirement, candidate):
         """
         raise NotImplementedError
 
-    def get_dependencies(self, candidate):
+    def get_dependencies(self, candidate: CT) -> Iterable[RT]:
         """Get dependencies of a candidate.
 
         This should return a collection of requirements that `candidate`
         specifies as its dependencies.
         """
         raise NotImplementedError
 
+    def narrow_requirement_selection(
+        self,
+        identifiers: Iterable[KT],
+        resolutions: Mapping[KT, CT],
+        candidates: Mapping[KT, Iterator[CT]],
+        information: Mapping[KT, Iterator[RequirementInformation[RT, CT]]],
+        backtrack_causes: Sequence[RequirementInformation[RT, CT]],
+    ) -> Iterable[KT]:
+        """
+        An optional method to narrow the selection of requirements being
+        considered during resolution. This method is called O(1) time per
+        backtrack step.
+
+        :param identifiers: An iterable of `identifiers` as returned by
+            ``identify()``. These identify all requirements currently being
+            considered.
+        :param resolutions: A mapping of candidates currently pinned by the
+            resolver. Each key is an identifier, and the value is a candidate
+            that may conflict with requirements from ``information``.
+        :param candidates: A mapping of each dependency's possible candidates.
+            Each value is an iterator of candidates.
+        :param information: A mapping of requirement information for each package.
+            Each value is an iterator of *requirement information*.
+        :param backtrack_causes: A sequence of *requirement information* that are
+            the requirements causing the resolver to most recently
+            backtrack.
 
-class AbstractResolver(object):
-    """The thing that performs the actual resolution work."""
-
-    base_exception = Exception
-
-    def __init__(self, provider, reporter):
-        self.provider = provider
-        self.reporter = reporter
-
-    def resolve(self, requirements, **kwargs):
-        """Take a collection of constraints, spit out the resolution result.
-
-        This returns a representation of the final resolution state, with one
-        guarenteed attribute ``mapping`` that contains resolved candidates as
-        values. The keys are their respective identifiers.
-
-        :param requirements: A collection of constraints.
-        :param kwargs: Additional keyword arguments that subclasses may accept.
+        A *requirement information* instance is a named tuple with two members:
 
-        :raises: ``self.base_exception`` or its subclass.
+        * ``requirement`` specifies a requirement contributing to the current
+          list of candidates.
+        * ``parent`` specifies the candidate that provides (is depended on for)
+          the requirement, or ``None`` to indicate a root requirement.
+
+        Must return a non-empty subset of `identifiers`, with the default
+        implementation being to return `identifiers` unchanged. Those `identifiers`
+        will then be passed to the sort key `get_preference` to pick the most
+        prefered requirement to attempt to pin, unless `narrow_requirement_selection`
+        returns only 1 requirement, in which case that will be used without
+        calling the sort key `get_preference`.
+
+        This method is designed to be used by the provider to optimize the
+        dependency resolution, e.g. if a check cost is O(m) and it can be done
+        against all identifiers at once then filtering the requirement selection
+        here will cost O(m) but making it part of the sort key in `get_preference`
+        will cost O(m*n), where n is the number of `identifiers`.
+
+        Returns:
+            Iterable[KT]: A non-empty subset of `identifiers`.
         """
-        raise NotImplementedError
+        return identifiers

src/pip/_vendor/resolvelib/reporters.py

@@ -1,26 +1,36 @@
-class BaseReporter(object):
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Collection, Generic
+
+from .structs import CT, KT, RT, RequirementInformation, State
+
+if TYPE_CHECKING:
+    from .resolvers import Criterion
+
+
+class BaseReporter(Generic[RT, CT, KT]):
     """Delegate class to provider progress reporting for the resolver."""
 
-    def starting(self):
+    def starting(self) -> None:
         """Called before the resolution actually starts."""
 
-    def starting_round(self, index):
+    def starting_round(self, index: int) -> None:
         """Called before each round of resolution starts.
 
         The index is zero-based.
         """
 
-    def ending_round(self, index, state):
+    def ending_round(self, index: int, state: State[RT, CT, KT]) -> None:
         """Called before each round of resolution ends.
 
         This is NOT called if the resolution ends at this round. Use `ending`
         if you want to report finalization. The index is zero-based.
         """
 
-    def ending(self, state):
+    def ending(self, state: State[RT, CT, KT]) -> None:
         """Called before the resolution ends successfully."""
 
-    def adding_requirement(self, requirement, parent):
+    def adding_requirement(self, requirement: RT, parent: CT | None) -> None:
         """Called when adding a new requirement into the resolve criteria.
 
         :param requirement: The additional requirement to be applied to filter
@@ -30,14 +40,16 @@ def adding_requirement(self, requirement, parent):
             requirements passed in from ``Resolver.resolve()``.
         """
 
-    def resolving_conflicts(self, causes):
+    def resolving_conflicts(
+        self, causes: Collection[RequirementInformation[RT, CT]]
+    ) -> None:
         """Called when starting to attempt requirement conflict resolution.
 
         :param causes: The information on the collision that caused the backtracking.
         """
 
-    def rejecting_candidate(self, criterion, candidate):
+    def rejecting_candidate(self, criterion: Criterion[RT, CT], candidate: CT) -> None:
         """Called when rejecting a candidate during backtracking."""
 
-    def pinning(self, candidate):
+    def pinning(self, candidate: CT) -> None:
         """Called when adding a candidate to the potential solution."""

src/pip/_vendor/resolvelib/resolvers/__init__.py

@@ -0,0 +1,27 @@
+from ..structs import RequirementInformation
+from .abstract import AbstractResolver, Result
+from .criterion import Criterion
+from .exceptions import (
+    InconsistentCandidate,
+    RequirementsConflicted,
+    ResolutionError,
+    ResolutionImpossible,
+    ResolutionTooDeep,
+    ResolverException,
+)
+from .resolution import Resolution, Resolver
+
+__all__ = [
+    "AbstractResolver",
+    "InconsistentCandidate",
+    "Resolver",
+    "Resolution",
+    "RequirementsConflicted",
+    "ResolutionError",
+    "ResolutionImpossible",
+    "ResolutionTooDeep",
+    "RequirementInformation",
+    "ResolverException",
+    "Result",
+    "Criterion",
+]

src/pip/_vendor/resolvelib/resolvers/abstract.py

@@ -0,0 +1,47 @@
+from __future__ import annotations
+
+import collections
+from typing import TYPE_CHECKING, Any, Generic, Iterable, Mapping, NamedTuple
+
+from ..structs import CT, KT, RT, DirectedGraph
+
+if TYPE_CHECKING:
+    from ..providers import AbstractProvider
+    from ..reporters import BaseReporter
+    from .criterion import Criterion
+
+    class Result(NamedTuple, Generic[RT, CT, KT]):
+        mapping: Mapping[KT, CT]
+        graph: DirectedGraph[KT | None]
+        criteria: Mapping[KT, Criterion[RT, CT]]
+
+else:
+    Result = collections.namedtuple("Result", ["mapping", "graph", "criteria"])
+
+
+class AbstractResolver(Generic[RT, CT, KT]):
+    """The thing that performs the actual resolution work."""
+
+    base_exception = Exception
+
+    def __init__(
+        self,
+        provider: AbstractProvider[RT, CT, KT],
+        reporter: BaseReporter[RT, CT, KT],
+    ) -> None:
+        self.provider = provider
+        self.reporter = reporter
+
+    def resolve(self, requirements: Iterable[RT], **kwargs: Any) -> Result[RT, CT, KT]:
+        """Take a collection of constraints, spit out the resolution result.
+
+        This returns a representation of the final resolution state, with one
+        guarenteed attribute ``mapping`` that contains resolved candidates as
+        values. The keys are their respective identifiers.
+
+        :param requirements: A collection of constraints.
+        :param kwargs: Additional keyword arguments that subclasses may accept.
+
+        :raises: ``self.base_exception`` or its subclass.
+        """
+        raise NotImplementedError

src/pip/_vendor/resolvelib/resolvers/criterion.py

@@ -0,0 +1,48 @@
+from __future__ import annotations
+
+from typing import Collection, Generic, Iterable, Iterator
+
+from ..structs import CT, RT, RequirementInformation
+
+
+class Criterion(Generic[RT, CT]):
+    """Representation of possible resolution results of a package.
+
+    This holds three attributes:
+
+    * `information` is a collection of `RequirementInformation` pairs.
+      Each pair is a requirement contributing to this criterion, and the
+      candidate that provides the requirement.
+    * `incompatibilities` is a collection of all known not-to-work candidates
+      to exclude from consideration.
+    * `candidates` is a collection containing all possible candidates deducted
+      from the union of contributing requirements and known incompatibilities.
+      It should never be empty, except when the criterion is an attribute of a
+      raised `RequirementsConflicted` (in which case it is always empty).
+
+    .. note::
+        This class is intended to be externally immutable. **Do not** mutate
+        any of its attribute containers.
+    """
+
+    def __init__(
+        self,
+        candidates: Iterable[CT],
+        information: Collection[RequirementInformation[RT, CT]],
+        incompatibilities: Collection[CT],
+    ) -> None:
+        self.candidates = candidates
+        self.information = information
+        self.incompatibilities = incompatibilities
+
+    def __repr__(self) -> str:
+        requirements = ", ".join(
+            f"({req!r}, via={parent!r})" for req, parent in self.information
+        )
+        return f"Criterion({requirements})"
+
+    def iter_requirement(self) -> Iterator[RT]:
+        return (i.requirement for i in self.information)
+
+    def iter_parent(self) -> Iterator[CT | None]:
+        return (i.parent for i in self.information)

src/pip/_vendor/resolvelib/resolvers/exceptions.py

@@ -0,0 +1,57 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Collection, Generic
+
+from ..structs import CT, RT, RequirementInformation
+
+if TYPE_CHECKING:
+    from .criterion import Criterion
+
+
+class ResolverException(Exception):
+    """A base class for all exceptions raised by this module.
+
+    Exceptions derived by this class should all be handled in this module. Any
+    bubbling pass the resolver should be treated as a bug.
+    """
+
+
+class RequirementsConflicted(ResolverException, Generic[RT, CT]):
+    def __init__(self, criterion: Criterion[RT, CT]) -> None:
+        super().__init__(criterion)
+        self.criterion = criterion
+
+    def __str__(self) -> str:
+        return "Requirements conflict: {}".format(
+            ", ".join(repr(r) for r in self.criterion.iter_requirement()),
+        )
+
+
+class InconsistentCandidate(ResolverException, Generic[RT, CT]):
+    def __init__(self, candidate: CT, criterion: Criterion[RT, CT]):
+        super().__init__(candidate, criterion)
+        self.candidate = candidate
+        self.criterion = criterion
+
+    def __str__(self) -> str:
+        return "Provided candidate {!r} does not satisfy {}".format(
+            self.candidate,
+            ", ".join(repr(r) for r in self.criterion.iter_requirement()),
+        )
+
+
+class ResolutionError(ResolverException):
+    pass
+
+
+class ResolutionImpossible(ResolutionError, Generic[RT, CT]):
+    def __init__(self, causes: Collection[RequirementInformation[RT, CT]]):
+        super().__init__(causes)
+        # causes is a list of RequirementInformation objects
+        self.causes = causes
+
+
+class ResolutionTooDeep(ResolutionError):
+    def __init__(self, round_count: int) -> None:
+        super().__init__(round_count)
+        self.round_count = round_count

src/pip/_vendor/resolvelib/structs.py

@@ -1,53 +1,92 @@
-import itertools
-
-from .compat import collections_abc
-
+from __future__ import annotations
 
-class DirectedGraph(object):
+import itertools
+from collections import namedtuple
+from typing import (
+    TYPE_CHECKING,
+    Callable,
+    Generic,
+    Iterable,
+    Iterator,
+    Mapping,
+    NamedTuple,
+    Sequence,
+    TypeVar,
+    Union,
+)
+
+KT = TypeVar("KT")  # Identifier.
+RT = TypeVar("RT")  # Requirement.
+CT = TypeVar("CT")  # Candidate.
+
+Matches = Union[Iterable[CT], Callable[[], Iterable[CT]]]
+
+if TYPE_CHECKING:
+    from .resolvers.criterion import Criterion
+
+    class RequirementInformation(NamedTuple, Generic[RT, CT]):
+        requirement: RT
+        parent: CT | None
+
+    class State(NamedTuple, Generic[RT, CT, KT]):
+        """Resolution state in a round."""
+
+        mapping: dict[KT, CT]
+        criteria: dict[KT, Criterion[RT, CT]]
+        backtrack_causes: list[RequirementInformation[RT, CT]]
+
+else:
+    RequirementInformation = namedtuple(
+        "RequirementInformation", ["requirement", "parent"]
+    )
+    State = namedtuple("State", ["mapping", "criteria", "backtrack_causes"])
+
+
+class DirectedGraph(Generic[KT]):
     """A graph structure with directed edges."""
 
-    def __init__(self):
-        self._vertices = set()
-        self._forwards = {}  # <key> -> Set[<key>]
-        self._backwards = {}  # <key> -> Set[<key>]
+    def __init__(self) -> None:
+        self._vertices: set[KT] = set()
+        self._forwards: dict[KT, set[KT]] = {}  # <key> -> Set[<key>]
+        self._backwards: dict[KT, set[KT]] = {}  # <key> -> Set[<key>]
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[KT]:
         return iter(self._vertices)
 
-    def __len__(self):
+    def __len__(self) -> int:
         return len(self._vertices)
 
-    def __contains__(self, key):
+    def __contains__(self, key: KT) -> bool:
         return key in self._vertices
 
-    def copy(self):
+    def copy(self) -> DirectedGraph[KT]:
         """Return a shallow copy of this graph."""
-        other = DirectedGraph()
+        other = type(self)()
         other._vertices = set(self._vertices)
         other._forwards = {k: set(v) for k, v in self._forwards.items()}
         other._backwards = {k: set(v) for k, v in self._backwards.items()}
         return other
 
-    def add(self, key):
+    def add(self, key: KT) -> None:
         """Add a new vertex to the graph."""
         if key in self._vertices:
             raise ValueError("vertex exists")
         self._vertices.add(key)
         self._forwards[key] = set()
         self._backwards[key] = set()
 
-    def remove(self, key):
+    def remove(self, key: KT) -> None:
         """Remove a vertex from the graph, disconnecting all edges from/to it."""
         self._vertices.remove(key)
         for f in self._forwards.pop(key):
             self._backwards[f].remove(key)
         for t in self._backwards.pop(key):
             self._forwards[t].remove(key)
 
-    def connected(self, f, t):
+    def connected(self, f: KT, t: KT) -> bool:
         return f in self._backwards[t] and t in self._forwards[f]
 
-    def connect(self, f, t):
+    def connect(self, f: KT, t: KT) -> None:
         """Connect two existing vertices.
 
         Nothing happens if the vertices are already connected.
@@ -57,56 +96,59 @@ def connect(self, f, t):
         self._forwards[f].add(t)
         self._backwards[t].add(f)
 
-    def iter_edges(self):
+    def iter_edges(self) -> Iterator[tuple[KT, KT]]:
         for f, children in self._forwards.items():
             for t in children:
                 yield f, t
 
-    def iter_children(self, key):
+    def iter_children(self, key: KT) -> Iterator[KT]:
         return iter(self._forwards[key])
 
-    def iter_parents(self, key):
+    def iter_parents(self, key: KT) -> Iterator[KT]:
         return iter(self._backwards[key])
 
 
-class IteratorMapping(collections_abc.Mapping):
-    def __init__(self, mapping, accessor, appends=None):
+class IteratorMapping(Mapping[KT, Iterator[CT]], Generic[RT, CT, KT]):
+    def __init__(
+        self,
+        mapping: Mapping[KT, RT],
+        accessor: Callable[[RT], Iterable[CT]],
+        appends: Mapping[KT, Iterable[CT]] | None = None,
+    ) -> None:
         self._mapping = mapping
         self._accessor = accessor
-        self._appends = appends or {}
+        self._appends: Mapping[KT, Iterable[CT]] = appends or {}
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return "IteratorMapping({!r}, {!r}, {!r})".format(
             self._mapping,
             self._accessor,
             self._appends,
         )
 
-    def __bool__(self):
+    def __bool__(self) -> bool:
         return bool(self._mapping or self._appends)
 
-    __nonzero__ = __bool__  # XXX: Python 2.
-
-    def __contains__(self, key):
+    def __contains__(self, key: object) -> bool:
         return key in self._mapping or key in self._appends
 
-    def __getitem__(self, k):
+    def __getitem__(self, k: KT) -> Iterator[CT]:
         try:
             v = self._mapping[k]
         except KeyError:
             return iter(self._appends[k])
         return itertools.chain(self._accessor(v), self._appends.get(k, ()))
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[KT]:
         more = (k for k in self._appends if k not in self._mapping)
         return itertools.chain(self._mapping, more)
 
-    def __len__(self):
+    def __len__(self) -> int:
         more = sum(1 for k in self._appends if k not in self._mapping)
         return len(self._mapping) + more
 
 
-class _FactoryIterableView(object):
+class _FactoryIterableView(Iterable[RT]):
     """Wrap an iterator factory returned by `find_matches()`.
 
     Calling `iter()` on this class would invoke the underlying iterator
@@ -115,56 +157,53 @@ class _FactoryIterableView(object):
     built-in Python sequence types.
     """
 
-    def __init__(self, factory):
+    def __init__(self, factory: Callable[[], Iterable[RT]]) -> None:
         self._factory = factory
-        self._iterable = None
+        self._iterable: Iterable[RT] | None = None
 
-    def __repr__(self):
-        return "{}({})".format(type(self).__name__, list(self))
+    def __repr__(self) -> str:
+        return f"{type(self).__name__}({list(self)})"
 
-    def __bool__(self):
+    def __bool__(self) -> bool:
         try:
             next(iter(self))
         except StopIteration:
             return False
         return True
 
-    __nonzero__ = __bool__  # XXX: Python 2.
-
-    def __iter__(self):
-        iterable = (
-            self._factory() if self._iterable is None else self._iterable
-        )
+    def __iter__(self) -> Iterator[RT]:
+        iterable = self._factory() if self._iterable is None else self._iterable
         self._iterable, current = itertools.tee(iterable)
         return current
 
 
-class _SequenceIterableView(object):
+class _SequenceIterableView(Iterable[RT]):
     """Wrap an iterable returned by find_matches().
 
     This is essentially just a proxy to the underlying sequence that provides
     the same interface as `_FactoryIterableView`.
     """
 
-    def __init__(self, sequence):
+    def __init__(self, sequence: Sequence[RT]):
         self._sequence = sequence
 
-    def __repr__(self):
-        return "{}({})".format(type(self).__name__, self._sequence)
+    def __repr__(self) -> str:
+        return f"{type(self).__name__}({self._sequence})"
 
-    def __bool__(self):
+    def __bool__(self) -> bool:
         return bool(self._sequence)
 
-    __nonzero__ = __bool__  # XXX: Python 2.
-
-    def __iter__(self):
+    def __iter__(self) -> Iterator[RT]:
         return iter(self._sequence)
 
 
-def build_iter_view(matches):
+def build_iter_view(matches: Matches[CT]) -> Iterable[CT]:
     """Build an iterable view from the value returned by `find_matches()`."""
     if callable(matches):
         return _FactoryIterableView(matches)
-    if not isinstance(matches, collections_abc.Sequence):
+    if not isinstance(matches, Sequence):
         matches = list(matches)
     return _SequenceIterableView(matches)
+
+
+IterableView = Iterable

src/pip/_vendor/vendor.txt

@@ -12,7 +12,7 @@ requests==2.32.3
 rich==13.9.4
     pygments==2.18.0
     typing_extensions==4.12.2
-resolvelib==1.0.1
+resolvelib==1.1.0
 setuptools==70.3.0
 tomli==2.2.1
 truststore==0.10.0