Move to modern typing syntax

This moves the type information from the `.pyi` files to inline
annotations, since the project now supports Python 3.7+.

Signed-off-by: Frost Ming <[email protected]>
Signed-off-by: Pradyun Gedam <[email protected]>

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ['setuptools>=36.2.2', 'wheel>=0.28.0']
+requires = ['setuptools>=62', 'wheel']
 
 [tool.black]
 line-length = 79

src/resolvelib/__init__.py

@@ -14,9 +14,10 @@
 __version__ = "1.0.2.dev0"
 
 
-from .providers import AbstractProvider, AbstractResolver
+from .providers import AbstractProvider
 from .reporters import BaseReporter
 from .resolvers import (
+    AbstractResolver,
     InconsistentCandidate,
     RequirementsConflicted,
     ResolutionError,

src/resolvelib/providers.py

@@ -1,7 +1,28 @@
-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):
+    def identify(self, requirement_or_candidate: RT | CT) -> KT:
         """Given a requirement or candidate, return an identifier for it.
 
         This is used to identify, e.g. whether two requirements
@@ -12,13 +33,13 @@ def identify(self, requirement_or_candidate):
 
     def get_preference(
         self,
-        identifier,
-        resolutions,
-        candidates,
-        information,
-        backtrack_causes,
-    ):
-        """Produce a sort key for the given requirement based on preference.
+        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.
 
         The preference is defined as "I think this requirement should be
         resolved first". The lower the return value is, the more preferred
@@ -62,7 +83,12 @@ 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:
         """Find all possible candidates that satisfy the given constraints.
 
         :param identifier: An identifier as returned by ``identify()``. All
@@ -92,7 +118,7 @@ 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
@@ -103,34 +129,10 @@ 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
-
-
-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
-        guaranteed 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/resolvelib/reporters.py

@@ -1,26 +1,41 @@
-class BaseReporter(object):
+from __future__ import annotations
+
+from typing import Generic
+
+from .structs import (
+    CT,
+    KT,
+    RT,
+    Collection,
+    Criterion,
+    RequirementInformation,
+    State,
+)
+
+
+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 +45,18 @@ 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."""