venv/lib/python3.8/site-packages/pip/_internal/resolution/resolvelib/base.py

from pip._vendor.packaging.utils import canonicalize_name

from pip._internal.utils.typing import MYPY_CHECK_RUNNING

if MYPY_CHECK_RUNNING:
    from typing import FrozenSet, Iterable, Optional, Tuple

    from pip._vendor.packaging.version import _BaseVersion

    from pip._internal.models.link import Link
    from pip._internal.req.req_install import InstallRequirement

    CandidateLookup = Tuple[
        Optional["Candidate"],
        Optional[InstallRequirement],
    ]


def format_name(project, extras):
    # type: (str, FrozenSet[str]) -> str
    if not extras:
        return project
    canonical_extras = sorted(canonicalize_name(e) for e in extras)
    return "{}[{}]".format(project, ",".join(canonical_extras))


class Requirement(object):
    @property
    def name(self):
        # type: () -> str
        raise NotImplementedError("Subclass should override")

    def is_satisfied_by(self, candidate):
        # type: (Candidate) -> bool
        return False

    def get_candidate_lookup(self):
        # type: () -> CandidateLookup
        raise NotImplementedError("Subclass should override")

    def format_for_error(self):
        # type: () -> str
        raise NotImplementedError("Subclass should override")


class Candidate(object):
    @property
    def name(self):
        # type: () -> str
        raise NotImplementedError("Override in subclass")

    @property
    def version(self):
        # type: () -> _BaseVersion
        raise NotImplementedError("Override in subclass")

    @property
    def is_installed(self):
        # type: () -> bool
        raise NotImplementedError("Override in subclass")

    @property
    def is_editable(self):
        # type: () -> bool
        raise NotImplementedError("Override in subclass")

    @property
    def source_link(self):
        # type: () -> Optional[Link]
        raise NotImplementedError("Override in subclass")

    def iter_dependencies(self, with_requires):
        # type: (bool) -> Iterable[Optional[Requirement]]
        raise NotImplementedError("Override in subclass")

    def get_install_requirement(self):
        # type: () -> Optional[InstallRequirement]
        raise NotImplementedError("Override in subclass")

    def format_for_error(self):
        # type: () -> str
        raise NotImplementedError("Subclass should override")