def _iter_candidates_from_constraints(
self,
identifier: str,
constraint: Constraint,
template: InstallRequirement,
) -> Iterator[Candidate]:
"""Produce explicit candidates from constraints.
This creates "fake" InstallRequirement objects that are basically clones
of what "should" be the template, but with original_link set to link.
"""
for link in constraint.links:
self._fail_if_link_is_unsupported_wheel(link)
candidate = self._make_candidate_from_link(
link,
extras=frozenset(),
template=install_req_from_link_and_ireq(link, template),
name=canonicalize_name(identifier),
version=None,
)
if candidate:
yield candidate
def find_candidates(
self,
identifier: str,
requirements: Mapping[str, Iterator[Requirement]],
incompatibilities: Mapping[str, Iterator[Candidate]],
constraint: Constraint,
prefers_installed: bool,
) -> Iterable[Candidate]:
# Since we cache all the candidates, incompatibility identification
# can be made quicker by comparing only the id() values.
incompat_ids = {id(c) for c in incompatibilities.get(identifier, ())}
explicit_candidates = set() # type: Set[Candidate]
ireqs = [] # type: List[InstallRequirement]
for req in requirements[identifier]:
cand, ireq = req.get_candidate_lookup()
if cand is not None and id(cand) not in incompat_ids:
explicit_candidates.add(cand)
if ireq is not None:
ireqs.append(ireq)
for link in constraint.links:
if not ireqs:
# If we hit this condition, then we cannot construct a candidate.
# However, if we hit this condition, then none of the requirements
# provided an ireq, so they must have provided an explicit candidate.
# In that case, either the candidate matches, in which case this loop
# doesn't need to do anything, or it doesn't, in which case there's
# nothing this loop can do to recover.
break
if link.is_wheel:
wheel = Wheel(link.filename)
# Check whether the provided wheel is compatible with the target
# platform.
if not wheel.supported(self._finder.target_python.get_tags()):
# We are constrained to install a wheel that is incompatible with
# the target architecture, so there are no valid candidates.
# Return early, with no candidates.
return ()
# Create a "fake" InstallRequirement that's basically a clone of
# what "should" be the template, but with original_link set to link.
# Using the given requirement is necessary for preserving hash
# requirements, but without the original_link, direct_url.json
# won't be created.
ireq = install_req_from_link_and_ireq(link, ireqs[0])
candidate = self._make_candidate_from_link(
link,
extras=frozenset(),
template=ireq,
name=canonicalize_name(ireq.name) if ireq.name else None,
version=None,
)
if candidate is None:
# _make_candidate_from_link returns None if the wheel fails to build.
# We are constrained to install this wheel, so there are no valid
# candidates.
# Return early, with no candidates.
return ()
explicit_candidates.add(candidate)
# If none of the requirements want an explicit candidate, we can ask
# the finder for candidates.
if not explicit_candidates:
return self._iter_found_candidates(
ireqs,
constraint.specifier,
constraint.hashes,
prefers_installed,
incompat_ids,
)
return (c for c in explicit_candidates
if constraint.is_satisfied_by(c) and all(
req.is_satisfied_by(c)
for req in requirements[identifier]))
