Mini Shell

"""Execute exactly this copy of pip, within a different environment.

This file is named as it is, to ensure that this module can't be imported via
an import statement.
"""

import runpy
import sys
import types
from importlib.machinery import ModuleSpec, PathFinder
from os.path import dirname
from typing import Optional, Sequence, Union

PIP_SOURCES_ROOT = dirname(dirname(__file__))


class PipImportRedirectingFinder:
    @classmethod
    def find_spec(
        self,
        fullname: str,
        path: Optional[Sequence[Union[bytes, str]]] = None,
        target: Optional[types.ModuleType] = None,
    ) -> Optional[ModuleSpec]:
        if fullname != "pip":
            return None

        spec = PathFinder.find_spec(fullname, [PIP_SOURCES_ROOT], target)
        assert spec, (PIP_SOURCES_ROOT, fullname)
        return spec


# TODO https://github.com/pypa/pip/issues/11294
sys.meta_path.insert(0, PipImportRedirectingFinder())

assert __name__ == "__main__", "Cannot run __pip-runner__.py as a non-main module"
runpy.run_module("pip", run_name="__main__", alter_sys=True)