2.0

10 files changed, 801 insertions, 0 deletions

diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__init__.py b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__init__.py
new file mode 100644
index 0000000..b249221
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/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",
+    "Criterion",
+    "InconsistentCandidate",
+    "RequirementInformation",
+    "RequirementsConflicted",
+    "Resolution",
+    "ResolutionError",
+    "ResolutionImpossible",
+    "ResolutionTooDeep",
+    "Resolver",
+    "ResolverException",
+    "Result",
+]
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/__init__.cpython-312.pyc b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/__init__.cpython-312.pyc
new file mode 100644
index 0000000..9401280
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/__init__.cpython-312.pyc
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/abstract.cpython-312.pyc b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/abstract.cpython-312.pyc
new file mode 100644
index 0000000..b6e0cbc
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/abstract.cpython-312.pyc
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/criterion.cpython-312.pyc b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/criterion.cpython-312.pyc
new file mode 100644
index 0000000..2f17d80
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/criterion.cpython-312.pyc
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/exceptions.cpython-312.pyc b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/exceptions.cpython-312.pyc
new file mode 100644
index 0000000..7e10f00
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/exceptions.cpython-312.pyc
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/resolution.cpython-312.pyc b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/resolution.cpython-312.pyc
new file mode 100644
index 0000000..3e7c9b4
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/__pycache__/resolution.cpython-312.pyc
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/abstract.py b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/abstract.py
new file mode 100644
index 0000000..f9b5a7a
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/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
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/criterion.py b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/criterion.py
new file mode 100644
index 0000000..ee5019c
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/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)
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/exceptions.py b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/exceptions.py
new file mode 100644
index 0000000..35e2755
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/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
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/resolution.py b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/resolution.py
new file mode 100644
index 0000000..f55ac7a
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/pip/_vendor/resolvelib/resolvers/resolution.py
@@ -0,0 +1,622 @@
+from __future__ import annotations
+
+import collections
+import itertools
+import operator
+from typing import TYPE_CHECKING, Generic
+
+from ..structs import (
+    CT,
+    KT,
+    RT,
+    DirectedGraph,
+    IterableView,
+    IteratorMapping,
+    RequirementInformation,
+    State,
+    build_iter_view,
+)
+from .abstract import AbstractResolver, Result
+from .criterion import Criterion
+from .exceptions import (
+    InconsistentCandidate,
+    RequirementsConflicted,
+    ResolutionImpossible,
+    ResolutionTooDeep,
+    ResolverException,
+)
+
+if TYPE_CHECKING:
+    from collections.abc import Collection, Iterable, Mapping
+
+    from ..providers import AbstractProvider, Preference
+    from ..reporters import BaseReporter
+
+_OPTIMISTIC_BACKJUMPING_RATIO: float = 0.1
+
+
+def _build_result(state: State[RT, CT, KT]) -> Result[RT, CT, KT]:
+    mapping = state.mapping
+    all_keys: dict[int, KT | None] = {id(v): k for k, v in mapping.items()}
+    all_keys[id(None)] = None
+
+    graph: DirectedGraph[KT | None] = DirectedGraph()
+    graph.add(None)  # Sentinel as root dependencies' parent.
+
+    connected: set[KT | None] = {None}
+    for key, criterion in state.criteria.items():
+        if not _has_route_to_root(state.criteria, key, all_keys, connected):
+            continue
+        if key not in graph:
+            graph.add(key)
+        for p in criterion.iter_parent():
+            try:
+                pkey = all_keys[id(p)]
+            except KeyError:
+                continue
+            if pkey not in graph:
+                graph.add(pkey)
+            graph.connect(pkey, key)
+
+    return Result(
+        mapping={k: v for k, v in mapping.items() if k in connected},
+        graph=graph,
+        criteria=state.criteria,
+    )
+
+
+class Resolution(Generic[RT, CT, KT]):
+    """Stateful resolution object.
+
+    This is designed as a one-off object that holds information to kick start
+    the resolution process, and holds the results afterwards.
+    """
+
+    def __init__(
+        self,
+        provider: AbstractProvider[RT, CT, KT],
+        reporter: BaseReporter[RT, CT, KT],
+    ) -> None:
+        self._p = provider
+        self._r = reporter
+        self._states: list[State[RT, CT, KT]] = []
+
+        # Optimistic backjumping variables
+        self._optimistic_backjumping_ratio = _OPTIMISTIC_BACKJUMPING_RATIO
+        self._save_states: list[State[RT, CT, KT]] | None = None
+        self._optimistic_start_round: int | None = None
+
+    @property
+    def state(self) -> State[RT, CT, KT]:
+        try:
+            return self._states[-1]
+        except IndexError as e:
+            raise AttributeError("state") from e
+
+    def _push_new_state(self) -> None:
+        """Push a new state into history.
+
+        This new state will be used to hold resolution results of the next
+        coming round.
+        """
+        base = self._states[-1]
+        state = State(
+            mapping=base.mapping.copy(),
+            criteria=base.criteria.copy(),
+            backtrack_causes=base.backtrack_causes[:],
+        )
+        self._states.append(state)
+
+    def _add_to_criteria(
+        self,
+        criteria: dict[KT, Criterion[RT, CT]],
+        requirement: RT,
+        parent: CT | None,
+    ) -> None:
+        self._r.adding_requirement(requirement=requirement, parent=parent)
+
+        identifier = self._p.identify(requirement_or_candidate=requirement)
+        criterion = criteria.get(identifier)
+        if criterion:
+            incompatibilities = list(criterion.incompatibilities)
+        else:
+            incompatibilities = []
+
+        matches = self._p.find_matches(
+            identifier=identifier,
+            requirements=IteratorMapping(
+                criteria,
+                operator.methodcaller("iter_requirement"),
+                {identifier: [requirement]},
+            ),
+            incompatibilities=IteratorMapping(
+                criteria,
+                operator.attrgetter("incompatibilities"),
+                {identifier: incompatibilities},
+            ),
+        )
+
+        if criterion:
+            information = list(criterion.information)
+            information.append(RequirementInformation(requirement, parent))
+        else:
+            information = [RequirementInformation(requirement, parent)]
+
+        criterion = Criterion(
+            candidates=build_iter_view(matches),
+            information=information,
+            incompatibilities=incompatibilities,
+        )
+        if not criterion.candidates:
+            raise RequirementsConflicted(criterion)
+        criteria[identifier] = criterion
+
+    def _remove_information_from_criteria(
+        self, criteria: dict[KT, Criterion[RT, CT]], parents: Collection[KT]
+    ) -> None:
+        """Remove information from parents of criteria.
+
+        Concretely, removes all values from each criterion's ``information``
+        field that have one of ``parents`` as provider of the requirement.
+
+        :param criteria: The criteria to update.
+        :param parents: Identifiers for which to remove information from all criteria.
+        """
+        if not parents:
+            return
+        for key, criterion in criteria.items():
+            criteria[key] = Criterion(
+                criterion.candidates,
+                [
+                    information
+                    for information in criterion.information
+                    if (
+                        information.parent is None
+                        or self._p.identify(information.parent) not in parents
+                    )
+                ],
+                criterion.incompatibilities,
+            )
+
+    def _get_preference(self, name: KT) -> Preference:
+        return self._p.get_preference(
+            identifier=name,
+            resolutions=self.state.mapping,
+            candidates=IteratorMapping(
+                self.state.criteria,
+                operator.attrgetter("candidates"),
+            ),
+            information=IteratorMapping(
+                self.state.criteria,
+                operator.attrgetter("information"),
+            ),
+            backtrack_causes=self.state.backtrack_causes,
+        )
+
+    def _is_current_pin_satisfying(
+        self, name: KT, criterion: Criterion[RT, CT]
+    ) -> bool:
+        try:
+            current_pin = self.state.mapping[name]
+        except KeyError:
+            return False
+        return all(
+            self._p.is_satisfied_by(requirement=r, candidate=current_pin)
+            for r in criterion.iter_requirement()
+        )
+
+    def _get_updated_criteria(self, candidate: CT) -> dict[KT, Criterion[RT, CT]]:
+        criteria = self.state.criteria.copy()
+        for requirement in self._p.get_dependencies(candidate=candidate):
+            self._add_to_criteria(criteria, requirement, parent=candidate)
+        return criteria
+
+    def _attempt_to_pin_criterion(self, name: KT) -> list[Criterion[RT, CT]]:
+        criterion = self.state.criteria[name]
+
+        causes: list[Criterion[RT, CT]] = []
+        for candidate in criterion.candidates:
+            try:
+                criteria = self._get_updated_criteria(candidate)
+            except RequirementsConflicted as e:
+                self._r.rejecting_candidate(e.criterion, candidate)
+                causes.append(e.criterion)
+                continue
+
+            # Check the newly-pinned candidate actually works. This should
+            # always pass under normal circumstances, but in the case of a
+            # faulty provider, we will raise an error to notify the implementer
+            # to fix find_matches() and/or is_satisfied_by().
+            satisfied = all(
+                self._p.is_satisfied_by(requirement=r, candidate=candidate)
+                for r in criterion.iter_requirement()
+            )
+            if not satisfied:
+                raise InconsistentCandidate(candidate, criterion)
+
+            self._r.pinning(candidate=candidate)
+            self.state.criteria.update(criteria)
+
+            # Put newly-pinned candidate at the end. This is essential because
+            # backtracking looks at this mapping to get the last pin.
+            self.state.mapping.pop(name, None)
+            self.state.mapping[name] = candidate
+
+            return []
+
+        # All candidates tried, nothing works. This criterion is a dead
+        # end, signal for backtracking.
+        return causes
+
+    def _patch_criteria(
+        self, incompatibilities_from_broken: list[tuple[KT, list[CT]]]
+    ) -> bool:
+        # Create a new state from the last known-to-work one, and apply
+        # the previously gathered incompatibility information.
+        for k, incompatibilities in incompatibilities_from_broken:
+            if not incompatibilities:
+                continue
+            try:
+                criterion = self.state.criteria[k]
+            except KeyError:
+                continue
+            matches = self._p.find_matches(
+                identifier=k,
+                requirements=IteratorMapping(
+                    self.state.criteria,
+                    operator.methodcaller("iter_requirement"),
+                ),
+                incompatibilities=IteratorMapping(
+                    self.state.criteria,
+                    operator.attrgetter("incompatibilities"),
+                    {k: incompatibilities},
+                ),
+            )
+            candidates: IterableView[CT] = build_iter_view(matches)
+            if not candidates:
+                return False
+            incompatibilities.extend(criterion.incompatibilities)
+            self.state.criteria[k] = Criterion(
+                candidates=candidates,
+                information=list(criterion.information),
+                incompatibilities=incompatibilities,
+            )
+        return True
+
+    def _save_state(self) -> None:
+        """Save states for potential rollback if optimistic backjumping fails."""
+        if self._save_states is None:
+            self._save_states = [
+                State(
+                    mapping=s.mapping.copy(),
+                    criteria=s.criteria.copy(),
+                    backtrack_causes=s.backtrack_causes[:],
+                )
+                for s in self._states
+            ]
+
+    def _rollback_states(self) -> None:
+        """Rollback states and disable optimistic backjumping."""
+        self._optimistic_backjumping_ratio = 0.0
+        if self._save_states:
+            self._states = self._save_states
+            self._save_states = None
+
+    def _backjump(self, causes: list[RequirementInformation[RT, CT]]) -> bool:
+        """Perform backjumping.
+
+        When we enter here, the stack is like this::
+
+            [ state Z ]
+            [ state Y ]
+            [ state X ]
+            .... earlier states are irrelevant.
+
+        1. No pins worked for Z, so it does not have a pin.
+        2. We want to reset state Y to unpinned, and pin another candidate.
+        3. State X holds what state Y was before the pin, but does not
+           have the incompatibility information gathered in state Y.
+
+        Each iteration of the loop will:
+
+        1.  Identify Z. The incompatibility is not always caused by the latest
+            state. For example, given three requirements A, B and C, with
+            dependencies A1, B1 and C1, where A1 and B1 are incompatible: the
+            last state might be related to C, so we want to discard the
+            previous state.
+        2.  Discard Z.
+        3.  Discard Y but remember its incompatibility information gathered
+            previously, and the failure we're dealing with right now.
+        4.  Push a new state Y' based on X, and apply the incompatibility
+            information from Y to Y'.
+        5a. If this causes Y' to conflict, we need to backtrack again. Make Y'
+            the new Z and go back to step 2.
+        5b. If the incompatibilities apply cleanly, end backtracking.
+        """
+        incompatible_reqs: Iterable[CT | RT] = itertools.chain(
+            (c.parent for c in causes if c.parent is not None),
+            (c.requirement for c in causes),
+        )
+        incompatible_deps = {self._p.identify(r) for r in incompatible_reqs}
+        while len(self._states) >= 3:
+            # Remove the state that triggered backtracking.
+            del self._states[-1]
+
+            # Optimistically backtrack to a state that caused the incompatibility
+            broken_state = self.state
+            while True:
+                # Retrieve the last candidate pin and known incompatibilities.
+                try:
+                    broken_state = self._states.pop()
+                    name, candidate = broken_state.mapping.popitem()
+                except (IndexError, KeyError):
+                    raise ResolutionImpossible(causes) from None
+
+                if (
+                    not self._optimistic_backjumping_ratio
+                    and name not in incompatible_deps
+                ):
+                    # For safe backjumping only backjump if the current dependency
+                    # is not the same as the incompatible dependency
+                    break
+
+                # On the first time a non-safe backjump is done the state
+                # is saved so we can restore it later if the resolution fails
+                if (
+                    self._optimistic_backjumping_ratio
+                    and self._save_states is None
+                    and name not in incompatible_deps
+                ):
+                    self._save_state()
+
+                # If the current dependencies and the incompatible dependencies
+                # are overlapping then we have likely found a cause of the
+                # incompatibility
+                current_dependencies = {
+                    self._p.identify(d) for d in self._p.get_dependencies(candidate)
+                }
+                if not current_dependencies.isdisjoint(incompatible_deps):
+                    break
+
+                # Fallback: We should not backtrack to the point where
+                # broken_state.mapping is empty, so stop backtracking for
+                # a chance for the resolution to recover
+                if not broken_state.mapping:
+                    break
+
+            incompatibilities_from_broken = [
+                (k, list(v.incompatibilities)) for k, v in broken_state.criteria.items()
+            ]
+
+            # Also mark the newly known incompatibility.
+            incompatibilities_from_broken.append((name, [candidate]))
+
+            self._push_new_state()
+            success = self._patch_criteria(incompatibilities_from_broken)
+
+            # It works! Let's work on this new state.
+            if success:
+                return True
+
+            # State does not work after applying known incompatibilities.
+            # Try the still previous state.
+
+        # No way to backtrack anymore.
+        return False
+
+    def _extract_causes(
+        self, criteron: list[Criterion[RT, CT]]
+    ) -> list[RequirementInformation[RT, CT]]:
+        """Extract causes from list of criterion and deduplicate"""
+        return list({id(i): i for c in criteron for i in c.information}.values())
+
+    def resolve(self, requirements: Iterable[RT], max_rounds: int) -> State[RT, CT, KT]:
+        if self._states:
+            raise RuntimeError("already resolved")
+
+        self._r.starting()
+
+        # Initialize the root state.
+        self._states = [
+            State(
+                mapping=collections.OrderedDict(),
+                criteria={},
+                backtrack_causes=[],
+            )
+        ]
+        for r in requirements:
+            try:
+                self._add_to_criteria(self.state.criteria, r, parent=None)
+            except RequirementsConflicted as e:
+                raise ResolutionImpossible(e.criterion.information) from e
+
+        # The root state is saved as a sentinel so the first ever pin can have
+        # something to backtrack to if it fails. The root state is basically
+        # pinning the virtual "root" package in the graph.
+        self._push_new_state()
+
+        # Variables for optimistic backjumping
+        optimistic_rounds_cutoff: int | None = None
+        optimistic_backjumping_start_round: int | None = None
+
+        for round_index in range(max_rounds):
+            self._r.starting_round(index=round_index)
+
+            # Handle if optimistic backjumping has been running for too long
+            if self._optimistic_backjumping_ratio and self._save_states is not None:
+                if optimistic_backjumping_start_round is None:
+                    optimistic_backjumping_start_round = round_index
+                    optimistic_rounds_cutoff = int(
+                        (max_rounds - round_index) * self._optimistic_backjumping_ratio
+                    )
+
+                    if optimistic_rounds_cutoff <= 0:
+                        self._rollback_states()
+                        continue
+                elif optimistic_rounds_cutoff is not None:
+                    if (
+                        round_index - optimistic_backjumping_start_round
+                        >= optimistic_rounds_cutoff
+                    ):
+                        self._rollback_states()
+                        continue
+
+            unsatisfied_names = [
+                key
+                for key, criterion in self.state.criteria.items()
+                if not self._is_current_pin_satisfying(key, criterion)
+            ]
+
+            # All criteria are accounted for. Nothing more to pin, we are done!
+            if not unsatisfied_names:
+                self._r.ending(state=self.state)
+                return self.state
+
+            # keep track of satisfied names to calculate diff after pinning
+            satisfied_names = set(self.state.criteria.keys()) - set(unsatisfied_names)
+
+            if len(unsatisfied_names) > 1:
+                narrowed_unstatisfied_names = list(
+                    self._p.narrow_requirement_selection(
+                        identifiers=unsatisfied_names,
+                        resolutions=self.state.mapping,
+                        candidates=IteratorMapping(
+                            self.state.criteria,
+                            operator.attrgetter("candidates"),
+                        ),
+                        information=IteratorMapping(
+                            self.state.criteria,
+                            operator.attrgetter("information"),
+                        ),
+                        backtrack_causes=self.state.backtrack_causes,
+                    )
+                )
+            else:
+                narrowed_unstatisfied_names = unsatisfied_names
+
+            # If there are no unsatisfied names use unsatisfied names
+            if not narrowed_unstatisfied_names:
+                raise RuntimeError("narrow_requirement_selection returned 0 names")
+
+            # If there is only 1 unsatisfied name skip calling self._get_preference
+            if len(narrowed_unstatisfied_names) > 1:
+                # Choose the most preferred unpinned criterion to try.
+                name = min(narrowed_unstatisfied_names, key=self._get_preference)
+            else:
+                name = narrowed_unstatisfied_names[0]
+
+            failure_criterion = self._attempt_to_pin_criterion(name)
+
+            if failure_criterion:
+                causes = self._extract_causes(failure_criterion)
+                # Backjump if pinning fails. The backjump process puts us in
+                # an unpinned state, so we can work on it in the next round.
+                self._r.resolving_conflicts(causes=causes)
+
+                try:
+                    success = self._backjump(causes)
+                except ResolutionImpossible:
+                    if self._optimistic_backjumping_ratio and self._save_states:
+                        failed_optimistic_backjumping = True
+                    else:
+                        raise
+                else:
+                    failed_optimistic_backjumping = bool(
+                        not success
+                        and self._optimistic_backjumping_ratio
+                        and self._save_states
+                    )
+
+                if failed_optimistic_backjumping and self._save_states:
+                    self._rollback_states()
+                else:
+                    self.state.backtrack_causes[:] = causes
+
+                    # Dead ends everywhere. Give up.
+                    if not success:
+                        raise ResolutionImpossible(self.state.backtrack_causes)
+            else:
+                # discard as information sources any invalidated names
+                # (unsatisfied names that were previously satisfied)
+                newly_unsatisfied_names = {
+                    key
+                    for key, criterion in self.state.criteria.items()
+                    if key in satisfied_names
+                    and not self._is_current_pin_satisfying(key, criterion)
+                }
+                self._remove_information_from_criteria(
+                    self.state.criteria, newly_unsatisfied_names
+                )
+                # Pinning was successful. Push a new state to do another pin.
+                self._push_new_state()
+
+            self._r.ending_round(index=round_index, state=self.state)
+
+        raise ResolutionTooDeep(max_rounds)
+
+
+class Resolver(AbstractResolver[RT, CT, KT]):
+    """The thing that performs the actual resolution work."""
+
+    base_exception = ResolverException
+
+    def resolve(  # type: ignore[override]
+        self,
+        requirements: Iterable[RT],
+        max_rounds: int = 100,
+    ) -> Result[RT, CT, KT]:
+        """Take a collection of constraints, spit out the resolution result.
+
+        The return value is a representation to the final resolution result. It
+        is a tuple subclass with three public members:
+
+        * `mapping`: A dict of resolved candidates. Each key is an identifier
+            of a requirement (as returned by the provider's `identify` method),
+            and the value is the resolved candidate.
+        * `graph`: A `DirectedGraph` instance representing the dependency tree.
+            The vertices are keys of `mapping`, and each edge represents *why*
+            a particular package is included. A special vertex `None` is
+            included to represent parents of user-supplied requirements.
+        * `criteria`: A dict of "criteria" that hold detailed information on
+            how edges in the graph are derived. Each key is an identifier of a
+            requirement, and the value is a `Criterion` instance.
+
+        The following exceptions may be raised if a resolution cannot be found:
+
+        * `ResolutionImpossible`: A resolution cannot be found for the given
+            combination of requirements. The `causes` attribute of the
+            exception is a list of (requirement, parent), giving the
+            requirements that could not be satisfied.
+        * `ResolutionTooDeep`: The dependency tree is too deeply nested and
+            the resolver gave up. This is usually caused by a circular
+            dependency, but you can try to resolve this by increasing the
+            `max_rounds` argument.
+        """
+        resolution = Resolution(self.provider, self.reporter)
+        state = resolution.resolve(requirements, max_rounds=max_rounds)
+        return _build_result(state)
+
+
+def _has_route_to_root(
+    criteria: Mapping[KT, Criterion[RT, CT]],
+    key: KT | None,
+    all_keys: dict[int, KT | None],
+    connected: set[KT | None],
+) -> bool:
+    if key in connected:
+        return True
+    if key not in criteria:
+        return False
+    assert key is not None
+    for p in criteria[key].iter_parent():
+        try:
+            pkey = all_keys[id(p)]
+        except KeyError:
+            continue
+        if pkey in connected:
+            connected.add(key)
+            return True
+        if _has_route_to_root(criteria, pkey, all_keys, connected):
+            connected.add(key)
+            return True
+    return False