from pip._vendor.resolvelib.providers import AbstractProvider from pip._internal.utils.typing import MYPY_CHECK_RUNNING from .base import Constraint if MYPY_CHECK_RUNNING: from typing import Any, Dict, Iterable, Optional, Sequence, Set, Tuple, Union from .base import Candidate, Requirement from .factory import Factory # Notes on the relationship between the provider, the factory, and the # candidate and requirement classes. # # The provider is a direct implementation of the resolvelib class. Its role # is to deliver the API that resolvelib expects. # # Rather than work with completely abstract "requirement" and "candidate" # concepts as resolvelib does, pip has concrete classes implementing these two # ideas. The API of Requirement and Candidate objects are defined in the base # classes, but essentially map fairly directly to the equivalent provider # methods. In particular, `find_matches` and `is_satisfied_by` are # requirement methods, and `get_dependencies` is a candidate method. # # The factory is the interface to pip's internal mechanisms. It is stateless, # and is created by the resolver and held as a property of the provider. It is # responsible for creating Requirement and Candidate objects, and provides # services to those objects (access to pip's finder and preparer). class PipProvider(AbstractProvider): """Pip's provider implementation for resolvelib. :params constraints: A mapping of constraints specified by the user. Keys are canonicalized project names. :params ignore_dependencies: Whether the user specified ``--no-deps``. :params upgrade_strategy: The user-specified upgrade strategy. :params user_requested: A set of canonicalized package names that the user supplied for pip to install/upgrade. """ def __init__( self, factory, # type: Factory constraints, # type: Dict[str, Constraint] ignore_dependencies, # type: bool upgrade_strategy, # type: str user_requested, # type: Set[str] ): # type: (...) -> None self._factory = factory self._constraints = constraints self._ignore_dependencies = ignore_dependencies self._upgrade_strategy = upgrade_strategy self._user_requested = user_requested def identify(self, dependency): # type: (Union[Requirement, Candidate]) -> str return dependency.name def get_preference( self, resolution, # type: Optional[Candidate] candidates, # type: Sequence[Candidate] information # type: Sequence[Tuple[Requirement, Candidate]] ): # type: (...) -> Any """Produce a sort key for given requirement based on preference. The lower the return value is, the more preferred this group of arguments is. Currently pip considers the followings in order: * Prefer if any of the known requirements points to an explicit URL. * If equal, prefer if any requirements contain ``===`` and ``==``. * If equal, prefer if requirements include version constraints, e.g. ``>=`` and ``<``. * If equal, prefer user-specified (non-transitive) requirements. * If equal, order alphabetically for consistency (helps debuggability). """ def _get_restrictive_rating(requirements): # type: (Iterable[Requirement]) -> int """Rate how restrictive a set of requirements are. ``Requirement.get_candidate_lookup()`` returns a 2-tuple for lookup. The first element is ``Optional[Candidate]`` and the second ``Optional[InstallRequirement]``. * If the requirement is an explicit one, the explicitly-required candidate is returned as the first element. * If the requirement is based on a PEP 508 specifier, the backing ``InstallRequirement`` is returned as the second element. We use the first element to check whether there is an explicit requirement, and the second for equality operator. """ lookups = (r.get_candidate_lookup() for r in requirements) cands, ireqs = zip(*lookups) if any(cand is not None for cand in cands): return 0 spec_sets = (ireq.specifier for ireq in ireqs if ireq) operators = [ specifier.operator for spec_set in spec_sets for specifier in spec_set ] if any(op in ("==", "===") for op in operators): return 1 if operators: return 2 # A "bare" requirement without any version requirements. return 3 restrictive = _get_restrictive_rating(req for req, _ in information) transitive = all(parent is not None for _, parent in information) key = next(iter(candidates)).name if candidates else "" # HACK: Setuptools have a very long and solid backward compatibility # track record, and extremely few projects would request a narrow, # non-recent version range of it since that would break a lot things. # (Most projects specify it only to request for an installer feature, # which does not work, but that's another topic.) Intentionally # delaying Setuptools helps reduce branches the resolver has to check. # This serves as a temporary fix for issues like "apache-airlfow[all]" # while we work on "proper" branch pruning techniques. delay_this = (key == "setuptools") return (delay_this, restrictive, transitive, key) def find_matches(self, requirements): # type: (Sequence[Requirement]) -> Iterable[Candidate] if not requirements: return [] name = requirements[0].project_name def _eligible_for_upgrade(name): # type: (str) -> bool """Are upgrades allowed for this project? This checks the upgrade strategy, and whether the project was one that the user specified in the command line, in order to decide whether we should upgrade if there's a newer version available. (Note that we don't need access to the `--upgrade` flag, because an upgrade strategy of "to-satisfy-only" means that `--upgrade` was not specified). """ if self._upgrade_strategy == "eager": return True elif self._upgrade_strategy == "only-if-needed": return (name in self._user_requested) return False return self._factory.find_candidates( requirements, constraint=self._constraints.get(name, Constraint.empty()), prefers_installed=(not _eligible_for_upgrade(name)), ) def is_satisfied_by(self, requirement, candidate): # type: (Requirement, Candidate) -> bool return requirement.is_satisfied_by(candidate) def get_dependencies(self, candidate): # type: (Candidate) -> Sequence[Requirement] with_requires = not self._ignore_dependencies return [ r for r in candidate.iter_dependencies(with_requires) if r is not None ]