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from collections import namedtuple
from packaging.specifiers import SpecifierSet
from packaging.version import Version
import resolvelib
index = """
first 1.0.0
second == 1.0.0
first 2.0.0
second == 2.0.0
third == 1.0.0
first 3.0.0
second == 3.0.0
third == 2.0.0
second 1.0.0
third == 1.0.0
second 2.0.0
third == 2.0.0
second 3.0.0
third == 3.0.0
third 1.0.0
third 2.0.0
third 3.0.0
"""
class Requirement(namedtuple("Requirement", "name specifier")):
def __repr__(self):
return f"<Requirement({self.name}{self.specifier})>"
class Candidate(namedtuple("Candidate", "name version")):
def __repr__(self):
return f"<{self.name}=={self.version}>"
def splitstrip(s, parts):
return [item.strip() for item in s.strip().split(maxsplit=parts - 1)]
def read_spec(lines):
candidates = {}
latest = None
for line in lines:
if not line or line.startswith("#"):
continue
if not line.startswith(" "):
name, version = splitstrip(line, 2)
version = Version(version)
latest = Candidate(name, version)
candidates[latest] = set()
else:
if latest is None:
raise RuntimeError("Spec has dependencies before first candidate")
name, specifier = splitstrip(line, 2)
specifier = SpecifierSet(specifier)
candidates[latest].add(Requirement(name, specifier))
return candidates
class Provider(resolvelib.AbstractProvider):
def __init__(self, index):
self.candidates = read_spec(index)
def identify(self, requirement_or_candidate):
return requirement_or_candidate.name
def get_preference(
self,
identifier,
resolutions,
candidates,
information,
backtrack_causes,
):
return sum(1 for _ in candidates[identifier])
def find_matches(self, identifier, requirements, incompatibilities):
name = identifier
return sorted(
c
for c in self.candidates
if all(self.is_satisfied_by(r, c) for r in requirements[name])
and all(c.version != i.version for i in incompatibilities[name])
)
def is_satisfied_by(self, requirement, candidate):
return (
candidate.name == requirement.name
and candidate.version in requirement.specifier
)
def get_dependencies(self, candidate):
return self.candidates[candidate]
class Reporter(resolvelib.BaseReporter):
def starting(self):
print("starting()")
def starting_round(self, index):
print(f"starting_round({index})")
def ending_round(self, index, state):
print(f"ending_round({index}, ...)")
def ending(self, state):
print("ending(...)")
def adding_requirement(self, requirement, parent):
print(f" adding_requirement({requirement}, {parent})")
def backtracking(self, candidate):
print(f" backtracking({candidate})")
def pinning(self, candidate):
print(f" pinning({candidate})")
if __name__ == "__main__":
from pprint import pprint
provider = Provider(index.splitlines())
reporter = Reporter()
resolver = resolvelib.Resolver(provider, reporter)
root_reqs = [Requirement("first", SpecifierSet())]
result = resolver.resolve(root_reqs)
pprint(result.mapping)
|
