path: root/contrib/tools/python3/src/Lib/importlib/metadata.py

import io 
import os 
import re 
import abc 
import csv 
import sys 
import email 
import pathlib 
import zipfile 
import operator 
import functools 
import itertools 
import posixpath 
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', 
    'DistributionFinder', 
    '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 module(self): 
        match = self.pattern.match(self.value) 
        return match.group('module') 
 
    @property 
    def attr(self): 
        match = self.pattern.match(self.value) 
        return match.group('attr') 
 
    @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(delimiters='=') 
        # case sensitive: https://stackoverflow.com/q/1611799/812183 
        config.optionxform = str 
        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)) 
 
    def __reduce__(self): 
        return ( 
            self.__class__, 
            (self.name, self.value, self.group), 
            ) 
 
 
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(DistributionFinder.Context(name=name)) 
            dist = next(iter(dists), None) 
            if dist is not None: 
                return dist 
        else: 
            raise PackageNotFoundError(name) 
 
    @classmethod 
    def discover(cls, **kwargs): 
        """Return an iterable of Distribution objects for all packages. 
 
        Pass a ``context`` or pass keyword arguments for constructing 
        a context. 
 
        :context: A ``DistributionFinder.Context`` object. 
        :return: Iterable of Distribution objects for all packages. 
        """ 
        context = kwargs.pop('context', None) 
        if context and kwargs: 
            raise ValueError("cannot accept context and kwargs") 
        context = context or DistributionFinder.Context(**kwargs) 
        return itertools.chain.from_iterable( 
            resolver(context) 
            for resolver in cls._discover_resolvers() 
            ) 
 
    @staticmethod 
    def at(path): 
        """Return a Distribution for the indicated metadata path 
 
        :param path: a string or path-like object 
        :return: a concrete Distribution instance for the path 
        """ 
        return PathDistribution(pathlib.Path(path)) 
 
    @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) 
 
    @classmethod 
    def _local(cls, root='.'): 
        from pep517 import build, meta 
        system = build.compat_system(root) 
        builder = functools.partial( 
            meta.build, 
            source_dir=root, 
            system=system, 
            ) 
        return PathDistribution(zipfile.Path(meta.build_as_zip(builder))) 
 
    @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): 
        """Files in this distribution. 
 
        :return: List of PackagePath for this distribution or None 
 
        Result is `None` if the metadata file that enumerates files 
        (i.e. RECORD for dist-info or SOURCES.txt for egg-info) is 
        missing. 
        Result may be empty if the metadata exists but is empty. 
        """ 
        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 list(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""" 
        reqs = self._read_dist_info_reqs() or self._read_egg_info_reqs() 
        return reqs and list(reqs) 
 
    def _read_dist_info_reqs(self): 
        return self.metadata.get_all('Requires-Dist') 
 
    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 quoted_marker(section): 
            section = section or '' 
            extra, sep, markers = section.partition(':') 
            if extra and markers: 
                markers = f'({markers})' 
            conditions = list(filter(None, [markers, make_condition(extra)])) 
            return '; ' + ' and '.join(conditions) if conditions else '' 
 
        def url_req_space(req): 
            """ 
            PEP 508 requires a space between the url_spec and the quoted_marker. 
            Ref python/importlib_metadata#357. 
            """ 
            # '@' is uniquely indicative of a url_req. 
            return ' ' * ('@' in req) 
 
        for section, deps in sections.items(): 
            for dep in deps: 
                space = url_req_space(dep) 
                yield dep + space + quoted_marker(section) 
 
 
class DistributionFinder(MetaPathFinder): 
    """ 
    A MetaPathFinder capable of discovering installed distributions. 
    """ 
 
    class Context: 
        """ 
        Keyword arguments presented by the caller to 
        ``distributions()`` or ``Distribution.discover()`` 
        to narrow the scope of a search for distributions 
        in all DistributionFinders. 
 
        Each DistributionFinder may expect any parameters 
        and should attempt to honor the canonical 
        parameters defined below when appropriate. 
        """ 
 
        name = None 
        """ 
        Specific name for which a distribution finder should match. 
        A name of ``None`` matches all distributions. 
        """ 
 
        def __init__(self, **kwargs): 
            vars(self).update(kwargs) 
 
        @property 
        def path(self): 
            """ 
            The path that a distribution finder should search. 
 
            Typically refers to Python package paths and defaults 
            to ``sys.path``. 
            """ 
            return vars(self).get('path', sys.path) 
 
    @abc.abstractmethod 
    def find_distributions(self, context=Context()): 
        """ 
        Find distributions. 
 
        Return an iterable of all Distribution instances capable of 
        loading the metadata for packages matching the ``context``, 
        a DistributionFinder.Context instance. 
        """ 
 
 
class FastPath: 
    """ 
    Micro-optimized class for searching a path for 
    children. 
    """ 
 
    def __init__(self, root): 
        self.root = root 
        self.base = os.path.basename(self.root).lower() 
 
    def joinpath(self, child): 
        return pathlib.Path(self.root, child) 
 
    def children(self): 
        with suppress(Exception): 
            return os.listdir(self.root or '.') 
        with suppress(Exception): 
            return self.zip_children() 
        return [] 
 
    def zip_children(self): 
        zip_path = zipfile.Path(self.root) 
        names = zip_path.root.namelist() 
        self.joinpath = zip_path.joinpath 
 
        return dict.fromkeys( 
            child.split(posixpath.sep, 1)[0] 
            for child in names 
            ) 
 
    def is_egg(self, search): 
        base = self.base 
        return ( 
            base == search.versionless_egg_name 
            or base.startswith(search.prefix) 
            and base.endswith('.egg')) 
 
    def search(self, name): 
        for child in self.children(): 
            n_low = child.lower() 
            if (n_low in name.exact_matches 
                    or n_low.startswith(name.prefix) 
                    and n_low.endswith(name.suffixes) 
                    # legacy case: 
                    or self.is_egg(name) and n_low == 'egg-info'): 
                yield self.joinpath(child) 
 
 
class Prepared: 
    """ 
    A prepared search for metadata on a possibly-named package. 
    """ 
    normalized = '' 
    prefix = '' 
    suffixes = '.dist-info', '.egg-info' 
    exact_matches = [''][:0] 
    versionless_egg_name = '' 
 
    def __init__(self, name): 
        self.name = name 
        if name is None: 
            return 
        self.normalized = name.lower().replace('-', '_') 
        self.prefix = self.normalized + '-' 
        self.exact_matches = [ 
            self.normalized + suffix for suffix in self.suffixes] 
        self.versionless_egg_name = self.normalized + '.egg' 
 
 
class MetadataPathFinder(DistributionFinder): 
    @classmethod 
    def find_distributions(cls, context=DistributionFinder.Context()): 
        """ 
        Find distributions. 
 
        Return an iterable of all Distribution instances capable of 
        loading the metadata for packages matching ``context.name`` 
        (or all names if ``None`` indicated) along the paths in the list 
        of directories ``context.path``. 
        """ 
        found = cls._search_paths(context.name, context.path) 
        return map(PathDistribution, found) 
 
    @classmethod 
    def _search_paths(cls, name, paths): 
        """Find metadata directories in paths heuristically.""" 
        return itertools.chain.from_iterable( 
            path.search(Prepared(name)) 
            for path in map(FastPath, paths) 
            ) 
 
 
class PathDistribution(Distribution): 
    def __init__(self, path): 
        """Construct a distribution from a path to the metadata directory. 
 
        :param path: A pathlib.Path or similar object supporting 
                     .joinpath(), __div__, .parent, and .read_text(). 
        """ 
        self._path = path 
 
    def read_text(self, filename): 
        with suppress(FileNotFoundError, IsADirectoryError, KeyError, 
                      NotADirectoryError, PermissionError): 
            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(distribution_name): 
    """Get the ``Distribution`` instance for the named package. 
 
    :param distribution_name: The name of the distribution package as a string. 
    :return: A ``Distribution`` instance (or subclass thereof). 
    """ 
    return Distribution.from_name(distribution_name) 
 
 
def distributions(**kwargs): 
    """Get all ``Distribution`` instances in the current environment. 
 
    :return: An iterable of ``Distribution`` instances. 
    """ 
    return Distribution.discover(**kwargs) 
 
 
def metadata(distribution_name): 
    """Get the metadata for the named package. 
 
    :param distribution_name: The name of the distribution package to query. 
    :return: An email.Message containing the parsed metadata. 
    """ 
    return Distribution.from_name(distribution_name).metadata 
 
 
def version(distribution_name): 
    """Get the version string for the named package. 
 
    :param distribution_name: 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(distribution_name).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(distribution_name): 
    """Return a list of files for the named package. 
 
    :param distribution_name: The name of the distribution package to query. 
    :return: List of files composing the distribution. 
    """ 
    return distribution(distribution_name).files 
 
 
def requires(distribution_name): 
    """ 
    Return a list of requirements for the named package. 
 
    :return: An iterator of requirements, suitable for 
    packaging.requirement.Requirement. 
    """ 
    return distribution(distribution_name).requires