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)
|