from contextlib import contextmanager import os from os.path import dirname, abspath, join as pjoin import shutil from subprocess import check_call import sys from tempfile import mkdtemp from . import compat _in_proc_script = pjoin(dirname(abspath(__file__)), '_in_process.py') @contextmanager def tempdir(): td = mkdtemp() try: yield td finally: shutil.rmtree(td) class BackendUnavailable(Exception): """Will be raised if the backend cannot be imported in the hook process.""" class UnsupportedOperation(Exception): """May be raised by build_sdist if the backend indicates that it can't.""" def default_subprocess_runner(cmd, cwd=None, extra_environ=None): """The default method of calling the wrapper subprocess.""" env = os.environ.copy() if extra_environ: env.update(extra_environ) check_call(cmd, cwd=cwd, env=env) class Pep517HookCaller(object): """A wrapper around a source directory to be built with a PEP 517 backend. source_dir : The path to the source directory, containing pyproject.toml. backend : The build backend spec, as per PEP 517, from pyproject.toml. """ def __init__(self, source_dir, build_backend): self.source_dir = abspath(source_dir) self.build_backend = build_backend self._subprocess_runner = default_subprocess_runner # TODO: Is this over-engineered? Maybe frontends only need to # set this when creating the wrapper, not on every call. @contextmanager def subprocess_runner(self, runner): prev = self._subprocess_runner self._subprocess_runner = runner yield self._subprocess_runner = prev def get_requires_for_build_wheel(self, config_settings=None): """Identify packages required for building a wheel Returns a list of dependency specifications, e.g.: ["wheel >= 0.25", "setuptools"] This does not include requirements specified in pyproject.toml. It returns the result of calling the equivalently named hook in a subprocess. """ return self._call_hook('get_requires_for_build_wheel', { 'config_settings': config_settings }) def prepare_metadata_for_build_wheel(self, metadata_directory, config_settings=None): """Prepare a *.dist-info folder with metadata for this project. Returns the name of the newly created folder. If the build backend defines a hook with this name, it will be called in a subprocess. If not, the backend will be asked to build a wheel, and the dist-info extracted from that. """ return self._call_hook('prepare_metadata_for_build_wheel', { 'metadata_directory': abspath(metadata_directory), 'config_settings': config_settings, }) def build_wheel(self, wheel_directory, config_settings=None, metadata_directory=None): """Build a wheel from this project. Returns the name of the newly created file. In general, this will call the 'build_wheel' hook in the backend. However, if that was previously called by 'prepare_metadata_for_build_wheel', and the same metadata_directory is used, the previously built wheel will be copied to wheel_directory. """ if metadata_directory is not None: metadata_directory = abspath(metadata_directory) return self._call_hook('build_wheel', { 'wheel_directory': abspath(wheel_directory), 'config_settings': config_settings, 'metadata_directory': metadata_directory, }) def get_requires_for_build_sdist(self, config_settings=None): """Identify packages required for building a wheel Returns a list of dependency specifications, e.g.: ["setuptools >= 26"] This does not include requirements specified in pyproject.toml. It returns the result of calling the equivalently named hook in a subprocess. """ return self._call_hook('get_requires_for_build_sdist', { 'config_settings': config_settings }) def build_sdist(self, sdist_directory, config_settings=None): """Build an sdist from this project. Returns the name of the newly created file. This calls the 'build_sdist' backend hook in a subprocess. """ return self._call_hook('build_sdist', { 'sdist_directory': abspath(sdist_directory), 'config_settings': config_settings, }) def _call_hook(self, hook_name, kwargs): # On Python 2, pytoml returns Unicode values (which is correct) but the # environment passed to check_call needs to contain string values. We # convert here by encoding using ASCII (the backend can only contain # letters, digits and _, . and : characters, and will be used as a # Python identifier, so non-ASCII content is wrong on Python 2 in # any case). if sys.version_info[0] == 2: build_backend = self.build_backend.encode('ASCII') else: build_backend = self.build_backend with tempdir() as td: compat.write_json({'kwargs': kwargs}, pjoin(td, 'input.json'), indent=2) # Run the hook in a subprocess self._subprocess_runner( [sys.executable, _in_proc_script, hook_name, td], cwd=self.source_dir, extra_environ={'PEP517_BUILD_BACKEND': build_backend} ) data = compat.read_json(pjoin(td, 'output.json')) if data.get('unsupported'): raise UnsupportedOperation if data.get('no_backend'): raise BackendUnavailable return data['return_val']