resolvelib_dependency_resolver_with_custom_provider_and_candidates.py

1from resolvelib import Resolver
2
3# 1. Define the Provider.
4# A provider is responsible for providing candidates for a given requirement,
5# and information about those candidates.
6class MyProvider:
7    def identify(self, requirement_or_candidate):
8        return requirement_or_candidate.name
9
10    def get_preference(self, identifier, resolutions, candidates, information, backtrack_causes):
11        return 0
12
13    def find_matches(self, identifier, requirements, incompatibilities):
14        # Return candidates matching the requirements.
15        # In a real app, you'd search a package index.
16        return [c for c in ALL_CANDIDATES[identifier] if all(r.satisfied_by(c) for r in requirements[identifier])]
17
18    def is_satisfied_by(self, requirement, candidate):
19        return requirement.satisfied_by(candidate)
20
21    def get_dependencies(self, candidate):
22        return candidate.dependencies
23
24# 2. Define simple Requirement and Candidate classes.
25class Requirement:
26    def __init__(self, name, spec):
27        self.name = name
28        self.spec = spec
29    def satisfied_by(self, candidate):
30        return candidate.version in self.spec
31
32class Candidate:
33    def __init__(self, name, version, dependencies=None):
34        self.name = name
35        self.version = version
36        self.dependencies = dependencies or []
37    def __repr__(self):
38        return f"Candidate({self.name}, {self.version})"
39
40# 3. Setup dummy data.
41ALL_CANDIDATES = {
42    "foo": [Candidate("foo", "1.0"), Candidate("foo", "2.0")],
43    "bar": [Candidate("bar", "1.0", dependencies=[Requirement("foo", ["1.0"])])],
44}
45
46# 4. Initialize and run the resolver.
47provider = MyProvider()
48resolver = Resolver(provider, reporter=None)
49
50requirements = [Requirement("bar", ["1.0"])]
51result = resolver.resolve(requirements)
52
53print(result.mapping)