diff options
Diffstat (limited to 'Lib/importlib/metadata')
| -rw-r--r-- | Lib/importlib/metadata/__init__.py | 394 |
1 files changed, 394 insertions, 0 deletions
diff --git a/Lib/importlib/metadata/__init__.py b/Lib/importlib/metadata/__init__.py new file mode 100644 index 0000000..24d45d2 --- /dev/null +++ b/Lib/importlib/metadata/__init__.py @@ -0,0 +1,394 @@ +import io +import re +import abc +import csv +import sys +import email +import pathlib +import operator +import functools +import itertools +import collections + +from configparser import ConfigParser +from contextlib import suppress +from importlib import import_module +from importlib.abc import MetaPathFinder +from itertools import starmap + + +__all__ = [ + 'Distribution', + 'PackageNotFoundError', + 'distribution', + 'distributions', + 'entry_points', + 'files', + 'metadata', + 'requires', + 'version', + ] + + +class PackageNotFoundError(ModuleNotFoundError): + """The package was not found.""" + + +class EntryPoint(collections.namedtuple('EntryPointBase', 'name value group')): + """An entry point as defined by Python packaging conventions. + + See `the packaging docs on entry points + <https://packaging.python.org/specifications/entry-points/>`_ + for more information. + """ + + pattern = re.compile( + r'(?P<module>[\w.]+)\s*' + r'(:\s*(?P<attr>[\w.]+))?\s*' + r'(?P<extras>\[.*\])?\s*$' + ) + """ + A regular expression describing the syntax for an entry point, + which might look like: + + - module + - package.module + - package.module:attribute + - package.module:object.attribute + - package.module:attr [extra1, extra2] + + Other combinations are possible as well. + + The expression is lenient about whitespace around the ':', + following the attr, and following any extras. + """ + + def load(self): + """Load the entry point from its definition. If only a module + is indicated by the value, return that module. Otherwise, + return the named object. + """ + match = self.pattern.match(self.value) + module = import_module(match.group('module')) + attrs = filter(None, (match.group('attr') or '').split('.')) + return functools.reduce(getattr, attrs, module) + + @property + def extras(self): + match = self.pattern.match(self.value) + return list(re.finditer(r'\w+', match.group('extras') or '')) + + @classmethod + def _from_config(cls, config): + return [ + cls(name, value, group) + for group in config.sections() + for name, value in config.items(group) + ] + + @classmethod + def _from_text(cls, text): + config = ConfigParser() + try: + config.read_string(text) + except AttributeError: # pragma: nocover + # Python 2 has no read_string + config.readfp(io.StringIO(text)) + return EntryPoint._from_config(config) + + def __iter__(self): + """ + Supply iter so one may construct dicts of EntryPoints easily. + """ + return iter((self.name, self)) + + +class PackagePath(pathlib.PurePosixPath): + """A reference to a path in a package""" + + def read_text(self, encoding='utf-8'): + with self.locate().open(encoding=encoding) as stream: + return stream.read() + + def read_binary(self): + with self.locate().open('rb') as stream: + return stream.read() + + def locate(self): + """Return a path-like object for this path""" + return self.dist.locate_file(self) + + +class FileHash: + def __init__(self, spec): + self.mode, _, self.value = spec.partition('=') + + def __repr__(self): + return '<FileHash mode: {} value: {}>'.format(self.mode, self.value) + + +class Distribution: + """A Python distribution package.""" + + @abc.abstractmethod + def read_text(self, filename): + """Attempt to load metadata file given by the name. + + :param filename: The name of the file in the distribution info. + :return: The text if found, otherwise None. + """ + + @abc.abstractmethod + def locate_file(self, path): + """ + Given a path to a file in this distribution, return a path + to it. + """ + + @classmethod + def from_name(cls, name): + """Return the Distribution for the given package name. + + :param name: The name of the distribution package to search for. + :return: The Distribution instance (or subclass thereof) for the named + package, if found. + :raises PackageNotFoundError: When the named package's distribution + metadata cannot be found. + """ + for resolver in cls._discover_resolvers(): + dists = resolver(name) + dist = next(dists, None) + if dist is not None: + return dist + else: + raise PackageNotFoundError(name) + + @classmethod + def discover(cls): + """Return an iterable of Distribution objects for all packages. + + :return: Iterable of Distribution objects for all packages. + """ + return itertools.chain.from_iterable( + resolver() + for resolver in cls._discover_resolvers() + ) + + @staticmethod + def _discover_resolvers(): + """Search the meta_path for resolvers.""" + declared = ( + getattr(finder, 'find_distributions', None) + for finder in sys.meta_path + ) + return filter(None, declared) + + @property + def metadata(self): + """Return the parsed metadata for this Distribution. + + The returned object will have keys that name the various bits of + metadata. See PEP 566 for details. + """ + text = ( + self.read_text('METADATA') + or self.read_text('PKG-INFO') + # This last clause is here to support old egg-info files. Its + # effect is to just end up using the PathDistribution's self._path + # (which points to the egg-info file) attribute unchanged. + or self.read_text('') + ) + return email.message_from_string(text) + + @property + def version(self): + """Return the 'Version' metadata for the distribution package.""" + return self.metadata['Version'] + + @property + def entry_points(self): + return EntryPoint._from_text(self.read_text('entry_points.txt')) + + @property + def files(self): + file_lines = self._read_files_distinfo() or self._read_files_egginfo() + + def make_file(name, hash=None, size_str=None): + result = PackagePath(name) + result.hash = FileHash(hash) if hash else None + result.size = int(size_str) if size_str else None + result.dist = self + return result + + return file_lines and starmap(make_file, csv.reader(file_lines)) + + def _read_files_distinfo(self): + """ + Read the lines of RECORD + """ + text = self.read_text('RECORD') + return text and text.splitlines() + + def _read_files_egginfo(self): + """ + SOURCES.txt might contain literal commas, so wrap each line + in quotes. + """ + text = self.read_text('SOURCES.txt') + return text and map('"{}"'.format, text.splitlines()) + + @property + def requires(self): + """Generated requirements specified for this Distribution""" + return self._read_dist_info_reqs() or self._read_egg_info_reqs() + + def _read_dist_info_reqs(self): + spec = self.metadata['Requires-Dist'] + return spec and filter(None, spec.splitlines()) + + def _read_egg_info_reqs(self): + source = self.read_text('requires.txt') + return source and self._deps_from_requires_text(source) + + @classmethod + def _deps_from_requires_text(cls, source): + section_pairs = cls._read_sections(source.splitlines()) + sections = { + section: list(map(operator.itemgetter('line'), results)) + for section, results in + itertools.groupby(section_pairs, operator.itemgetter('section')) + } + return cls._convert_egg_info_reqs_to_simple_reqs(sections) + + @staticmethod + def _read_sections(lines): + section = None + for line in filter(None, lines): + section_match = re.match(r'\[(.*)\]$', line) + if section_match: + section = section_match.group(1) + continue + yield locals() + + @staticmethod + def _convert_egg_info_reqs_to_simple_reqs(sections): + """ + Historically, setuptools would solicit and store 'extra' + requirements, including those with environment markers, + in separate sections. More modern tools expect each + dependency to be defined separately, with any relevant + extras and environment markers attached directly to that + requirement. This method converts the former to the + latter. See _test_deps_from_requires_text for an example. + """ + def make_condition(name): + return name and 'extra == "{name}"'.format(name=name) + + def parse_condition(section): + section = section or '' + extra, sep, markers = section.partition(':') + if extra and markers: + markers = '({markers})'.format(markers=markers) + conditions = list(filter(None, [markers, make_condition(extra)])) + return '; ' + ' and '.join(conditions) if conditions else '' + + for section, deps in sections.items(): + for dep in deps: + yield dep + parse_condition(section) + + +class DistributionFinder(MetaPathFinder): + """ + A MetaPathFinder capable of discovering installed distributions. + """ + + @abc.abstractmethod + def find_distributions(self, name=None, path=None): + """ + Find distributions. + + Return an iterable of all Distribution instances capable of + loading the metadata for packages matching the ``name`` + (or all names if not supplied) along the paths in the list + of directories ``path`` (defaults to sys.path). + """ + + +class PathDistribution(Distribution): + def __init__(self, path): + """Construct a distribution from a path to the metadata directory.""" + self._path = path + + def read_text(self, filename): + with suppress(FileNotFoundError, NotADirectoryError, KeyError): + return self._path.joinpath(filename).read_text(encoding='utf-8') + read_text.__doc__ = Distribution.read_text.__doc__ + + def locate_file(self, path): + return self._path.parent / path + + +def distribution(package): + """Get the ``Distribution`` instance for the given package. + + :param package: The name of the package as a string. + :return: A ``Distribution`` instance (or subclass thereof). + """ + return Distribution.from_name(package) + + +def distributions(): + """Get all ``Distribution`` instances in the current environment. + + :return: An iterable of ``Distribution`` instances. + """ + return Distribution.discover() + + +def metadata(package): + """Get the metadata for the package. + + :param package: The name of the distribution package to query. + :return: An email.Message containing the parsed metadata. + """ + return Distribution.from_name(package).metadata + + +def version(package): + """Get the version string for the named package. + + :param package: The name of the distribution package to query. + :return: The version string for the package as defined in the package's + "Version" metadata key. + """ + return distribution(package).version + + +def entry_points(): + """Return EntryPoint objects for all installed packages. + + :return: EntryPoint objects for all installed packages. + """ + eps = itertools.chain.from_iterable( + dist.entry_points for dist in distributions()) + by_group = operator.attrgetter('group') + ordered = sorted(eps, key=by_group) + grouped = itertools.groupby(ordered, by_group) + return { + group: tuple(eps) + for group, eps in grouped + } + + +def files(package): + return distribution(package).files + + +def requires(package): + """ + Return a list of requirements for the indicated distribution. + + :return: An iterator of requirements, suitable for + packaging.requirement.Requirement. + """ + return distribution(package).requires |