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import os | |
from collections import namedtuple | |
from typing import Any, List, Optional | |
from pip._vendor import tomli | |
from pip._vendor.packaging.requirements import InvalidRequirement, Requirement | |
from pip._internal.exceptions import InstallationError | |
def _is_list_of_str(obj): | |
# type: (Any) -> bool | |
return ( | |
isinstance(obj, list) and | |
all(isinstance(item, str) for item in obj) | |
) | |
def make_pyproject_path(unpacked_source_directory): | |
# type: (str) -> str | |
return os.path.join(unpacked_source_directory, 'pyproject.toml') | |
BuildSystemDetails = namedtuple('BuildSystemDetails', [ | |
'requires', 'backend', 'check', 'backend_path' | |
]) | |
def load_pyproject_toml( | |
use_pep517, # type: Optional[bool] | |
pyproject_toml, # type: str | |
setup_py, # type: str | |
req_name # type: str | |
): | |
# type: (...) -> Optional[BuildSystemDetails] | |
"""Load the pyproject.toml file. | |
Parameters: | |
use_pep517 - Has the user requested PEP 517 processing? None | |
means the user hasn't explicitly specified. | |
pyproject_toml - Location of the project's pyproject.toml file | |
setup_py - Location of the project's setup.py file | |
req_name - The name of the requirement we're processing (for | |
error reporting) | |
Returns: | |
None if we should use the legacy code path, otherwise a tuple | |
( | |
requirements from pyproject.toml, | |
name of PEP 517 backend, | |
requirements we should check are installed after setting | |
up the build environment | |
directory paths to import the backend from (backend-path), | |
relative to the project root. | |
) | |
""" | |
has_pyproject = os.path.isfile(pyproject_toml) | |
has_setup = os.path.isfile(setup_py) | |
if has_pyproject: | |
with open(pyproject_toml, encoding="utf-8") as f: | |
pp_toml = tomli.load(f) | |
build_system = pp_toml.get("build-system") | |
else: | |
build_system = None | |
# The following cases must use PEP 517 | |
# We check for use_pep517 being non-None and falsey because that means | |
# the user explicitly requested --no-use-pep517. The value 0 as | |
# opposed to False can occur when the value is provided via an | |
# environment variable or config file option (due to the quirk of | |
# strtobool() returning an integer in pip's configuration code). | |
if has_pyproject and not has_setup: | |
if use_pep517 is not None and not use_pep517: | |
raise InstallationError( | |
"Disabling PEP 517 processing is invalid: " | |
"project does not have a setup.py" | |
) | |
use_pep517 = True | |
elif build_system and "build-backend" in build_system: | |
if use_pep517 is not None and not use_pep517: | |
raise InstallationError( | |
"Disabling PEP 517 processing is invalid: " | |
"project specifies a build backend of {} " | |
"in pyproject.toml".format( | |
build_system["build-backend"] | |
) | |
) | |
use_pep517 = True | |
# If we haven't worked out whether to use PEP 517 yet, | |
# and the user hasn't explicitly stated a preference, | |
# we do so if the project has a pyproject.toml file. | |
elif use_pep517 is None: | |
use_pep517 = has_pyproject | |
# At this point, we know whether we're going to use PEP 517. | |
assert use_pep517 is not None | |
# If we're using the legacy code path, there is nothing further | |
# for us to do here. | |
if not use_pep517: | |
return None | |
if build_system is None: | |
# Either the user has a pyproject.toml with no build-system | |
# section, or the user has no pyproject.toml, but has opted in | |
# explicitly via --use-pep517. | |
# In the absence of any explicit backend specification, we | |
# assume the setuptools backend that most closely emulates the | |
# traditional direct setup.py execution, and require wheel and | |
# a version of setuptools that supports that backend. | |
build_system = { | |
"requires": ["setuptools>=40.8.0", "wheel"], | |
"build-backend": "setuptools.build_meta:__legacy__", | |
} | |
# If we're using PEP 517, we have build system information (either | |
# from pyproject.toml, or defaulted by the code above). | |
# Note that at this point, we do not know if the user has actually | |
# specified a backend, though. | |
assert build_system is not None | |
# Ensure that the build-system section in pyproject.toml conforms | |
# to PEP 518. | |
error_template = ( | |
"{package} has a pyproject.toml file that does not comply " | |
"with PEP 518: {reason}" | |
) | |
# Specifying the build-system table but not the requires key is invalid | |
if "requires" not in build_system: | |
raise InstallationError( | |
error_template.format(package=req_name, reason=( | |
"it has a 'build-system' table but not " | |
"'build-system.requires' which is mandatory in the table" | |
)) | |
) | |
# Error out if requires is not a list of strings | |
requires = build_system["requires"] | |
if not _is_list_of_str(requires): | |
raise InstallationError(error_template.format( | |
package=req_name, | |
reason="'build-system.requires' is not a list of strings.", | |
)) | |
# Each requirement must be valid as per PEP 508 | |
for requirement in requires: | |
try: | |
Requirement(requirement) | |
except InvalidRequirement: | |
raise InstallationError( | |
error_template.format( | |
package=req_name, | |
reason=( | |
"'build-system.requires' contains an invalid " | |
"requirement: {!r}".format(requirement) | |
), | |
) | |
) | |
backend = build_system.get("build-backend") | |
backend_path = build_system.get("backend-path", []) | |
check = [] # type: List[str] | |
if backend is None: | |
# If the user didn't specify a backend, we assume they want to use | |
# the setuptools backend. But we can't be sure they have included | |
# a version of setuptools which supplies the backend, or wheel | |
# (which is needed by the backend) in their requirements. So we | |
# make a note to check that those requirements are present once | |
# we have set up the environment. | |
# This is quite a lot of work to check for a very specific case. But | |
# the problem is, that case is potentially quite common - projects that | |
# adopted PEP 518 early for the ability to specify requirements to | |
# execute setup.py, but never considered needing to mention the build | |
# tools themselves. The original PEP 518 code had a similar check (but | |
# implemented in a different way). | |
backend = "setuptools.build_meta:__legacy__" | |
check = ["setuptools>=40.8.0", "wheel"] | |
return BuildSystemDetails(requires, backend, check, backend_path) | |