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bpo-43926: Cleaner metadata with PEP 566 JSON support. (GH-25565)

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* bpo-43926: Cleaner metadata with PEP 566 JSON support.

* Add blurb

* Add versionchanged and versionadded declarations for changes to metadata.

* Use descriptor for PEP 566
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Jason R. Coombs 2021-05-02 17:03:40 -04:00 • committed by GitHub
parent 0ad1e0384c
commit 37e0c7850d
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890
Lib/importlib/metadata/__init__.py Normal file
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import os
import re
import abc
import csv
import sys
import email
import pathlib
import zipfile
import operator
import textwrap
import warnings
import functools
import itertools
import posixpath
import collections
from . import _adapters, _meta
from ._collections import FreezableDefaultDict, Pair
from ._functools import method_cache
from ._itertools import unique_everseen
from contextlib import suppress
from importlib import import_module
from importlib.abc import MetaPathFinder
from itertools import starmap
from typing import List, Mapping, Optional, Union
__all__ = [
'Distribution',
'DistributionFinder',
'PackageNotFoundError',
'distribution',
'distributions',
'entry_points',
'files',
'metadata',
'packages_distributions',
'requires',
'version',
]
class PackageNotFoundError(ModuleNotFoundError):
"""The package was not found."""
def __str__(self):
tmpl = "No package metadata was found for {self.name}"
return tmpl.format(**locals())
@property
def name(self):
(name,) = self.args
return name
class Sectioned:
"""
A simple entry point config parser for performance
>>> for item in Sectioned.read(Sectioned._sample):
... print(item)
Pair(name='sec1', value='# comments ignored')
Pair(name='sec1', value='a = 1')
Pair(name='sec1', value='b = 2')
Pair(name='sec2', value='a = 2')
>>> res = Sectioned.section_pairs(Sectioned._sample)
>>> item = next(res)
>>> item.name
'sec1'
>>> item.value
Pair(name='a', value='1')
>>> item = next(res)
>>> item.value
Pair(name='b', value='2')
>>> item = next(res)
>>> item.name
'sec2'
>>> item.value
Pair(name='a', value='2')
>>> list(res)
[]
"""
_sample = textwrap.dedent(
"""
[sec1]
# comments ignored
a = 1
b = 2
[sec2]
a = 2
"""
).lstrip()
@classmethod
def section_pairs(cls, text):
return (
section._replace(value=Pair.parse(section.value))
for section in cls.read(text, filter_=cls.valid)
if section.name is not None
)
@staticmethod
def read(text, filter_=None):
lines = filter(filter_, map(str.strip, text.splitlines()))
name = None
for value in lines:
section_match = value.startswith('[') and value.endswith(']')
if section_match:
name = value.strip('[]')
continue
yield Pair(name, value)
@staticmethod
def valid(line):
return line and not line.startswith('#')
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.
"""
dist: Optional['Distribution'] = None
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 ''))
def _for(self, dist):
self.dist = dist
return self
def __iter__(self):
"""
Supply iter so one may construct dicts of EntryPoints by name.
"""
msg = (
"Construction of dict of EntryPoints is deprecated in "
"favor of EntryPoints."
)
warnings.warn(msg, DeprecationWarning)
return iter((self.name, self))
def __reduce__(self):
return (
self.__class__,
(self.name, self.value, self.group),
)
def matches(self, **params):
attrs = (getattr(self, param) for param in params)
return all(map(operator.eq, params.values(), attrs))
class EntryPoints(tuple):
"""
An immutable collection of selectable EntryPoint objects.
"""
__slots__ = ()
def __getitem__(self, name): # -> EntryPoint:
"""
Get the EntryPoint in self matching name.
"""
try:
return next(iter(self.select(name=name)))
except StopIteration:
raise KeyError(name)
def select(self, **params):
"""
Select entry points from self that match the
given parameters (typically group and/or name).
"""
return EntryPoints(ep for ep in self if ep.matches(**params))
@property
def names(self):
"""
Return the set of all names of all entry points.
"""
return set(ep.name for ep in self)
@property
def groups(self):
"""
Return the set of all groups of all entry points.
For coverage while SelectableGroups is present.
>>> EntryPoints().groups
set()
"""
return set(ep.group for ep in self)
@classmethod
def _from_text_for(cls, text, dist):
return cls(ep._for(dist) for ep in cls._from_text(text))
@classmethod
def _from_text(cls, text):
return itertools.starmap(EntryPoint, cls._parse_groups(text or ''))
@staticmethod
def _parse_groups(text):
return (
(item.value.name, item.value.value, item.name)
for item in Sectioned.section_pairs(text)
)
def flake8_bypass(func):
# defer inspect import as performance optimization.
import inspect
is_flake8 = any('flake8' in str(frame.filename) for frame in inspect.stack()[:5])
return func if not is_flake8 else lambda: None
class Deprecated:
"""
Compatibility add-in for mapping to indicate that
mapping behavior is deprecated.
>>> recwarn = getfixture('recwarn')
>>> class DeprecatedDict(Deprecated, dict): pass
>>> dd = DeprecatedDict(foo='bar')
>>> dd.get('baz', None)
>>> dd['foo']
'bar'
>>> list(dd)
['foo']
>>> list(dd.keys())
['foo']
>>> 'foo' in dd
True
>>> list(dd.values())
['bar']
>>> len(recwarn)
1
"""
_warn = functools.partial(
warnings.warn,
"SelectableGroups dict interface is deprecated. Use select.",
DeprecationWarning,
stacklevel=2,
)
def __getitem__(self, name):
self._warn()
return super().__getitem__(name)
def get(self, name, default=None):
flake8_bypass(self._warn)()
return super().get(name, default)
def __iter__(self):
self._warn()
return super().__iter__()
def __contains__(self, *args):
self._warn()
return super().__contains__(*args)
def keys(self):
self._warn()
return super().keys()
def values(self):
self._warn()
return super().values()
class SelectableGroups(Deprecated, dict):
"""
A backward- and forward-compatible result from
entry_points that fully implements the dict interface.
"""
@classmethod
def load(cls, eps):
by_group = operator.attrgetter('group')
ordered = sorted(eps, key=by_group)
grouped = itertools.groupby(ordered, by_group)
return cls((group, EntryPoints(eps)) for group, eps in grouped)
@property
def _all(self):
"""
Reconstruct a list of all entrypoints from the groups.
"""
groups = super(Deprecated, self).values()
return EntryPoints(itertools.chain.from_iterable(groups))
@property
def groups(self):
return self._all.groups
@property
def names(self):
"""
for coverage:
>>> SelectableGroups().names
set()
"""
return self._all.names
def select(self, **params):
if not params:
return self
return self._all.select(**params)
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) -> _meta.PackageMetadata:
"""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 _adapters.Message(email.message_from_string(text))
@property
def name(self):
"""Return the 'Name' metadata for the distribution package."""
return self.metadata['Name']
@property
def version(self):
"""Return the 'Version' metadata for the distribution package."""
return self.metadata['Version']
@property
def entry_points(self):
return EntryPoints._from_text_for(self.read_text('entry_points.txt'), self)
@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):
return cls._convert_egg_info_reqs_to_simple_reqs(Sectioned.read(source))
@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 in sections:
yield section.value + parse_condition(section.name)
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.
"""
@functools.lru_cache() # type: ignore
def __new__(cls, root):
return super().__new__(cls)
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 search(self, name):
return self.lookup(self.mtime).search(name)
@property
def mtime(self):
with suppress(OSError):
return os.stat(self.root).st_mtime
self.lookup.cache_clear()
@method_cache
def lookup(self, mtime):
return Lookup(self)
class Lookup:
def __init__(self, path: FastPath):
base = os.path.basename(path.root).lower()
base_is_egg = base.endswith(".egg")
self.infos = FreezableDefaultDict(list)
self.eggs = FreezableDefaultDict(list)
for child in path.children():
low = child.lower()
if low.endswith((".dist-info", ".egg-info")):
# rpartition is faster than splitext and suitable for this purpose.
name = low.rpartition(".")[0].partition("-")[0]
normalized = Prepared.normalize(name)
self.infos[normalized].append(path.joinpath(child))
elif base_is_egg and low == "egg-info":
name = base.rpartition(".")[0].partition("-")[0]
legacy_normalized = Prepared.legacy_normalize(name)
self.eggs[legacy_normalized].append(path.joinpath(child))
self.infos.freeze()
self.eggs.freeze()
def search(self, prepared):
infos = (
self.infos[prepared.normalized]
if prepared
else itertools.chain.from_iterable(self.infos.values())
)
eggs = (
self.eggs[prepared.legacy_normalized]
if prepared
else itertools.chain.from_iterable(self.eggs.values())
)
return itertools.chain(infos, eggs)
class Prepared:
"""
A prepared search for metadata on a possibly-named package.
"""
normalized = None
legacy_normalized = None
def __init__(self, name):
self.name = name
if name is None:
return
self.normalized = self.normalize(name)
self.legacy_normalized = self.legacy_normalize(name)
@staticmethod
def normalize(name):
"""
PEP 503 normalization plus dashes as underscores.
"""
return re.sub(r"[-_.]+", "-", name).lower().replace('-', '_')
@staticmethod
def legacy_normalize(name):
"""
Normalize the package name as found in the convention in
older packaging tools versions and specs.
"""
return name.lower().replace('-', '_')
def __bool__(self):
return bool(self.name)
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."""
prepared = Prepared(name)
return itertools.chain.from_iterable(
path.search(prepared) for path in map(FastPath, paths)
)
def invalidate_caches(cls):
FastPath.__new__.cache_clear()
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) -> _meta.PackageMetadata:
"""Get the metadata for the named package.
:param distribution_name: The name of the distribution package to query.
:return: A PackageMetadata 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(**params) -> Union[EntryPoints, SelectableGroups]:
"""Return EntryPoint objects for all installed packages.
Pass selection parameters (group or name) to filter the
result to entry points matching those properties (see
EntryPoints.select()).
For compatibility, returns ``SelectableGroups`` object unless
selection parameters are supplied. In the future, this function
will return ``EntryPoints`` instead of ``SelectableGroups``
even when no selection parameters are supplied.
For maximum future compatibility, pass selection parameters
or invoke ``.select`` with parameters on the result.
:return: EntryPoints or SelectableGroups for all installed packages.
"""
unique = functools.partial(unique_everseen, key=operator.attrgetter('name'))
eps = itertools.chain.from_iterable(
dist.entry_points for dist in unique(distributions())
)
return SelectableGroups.load(eps).select(**params)
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
def packages_distributions() -> Mapping[str, List[str]]:
"""
Return a mapping of top-level packages to their
distributions.
>>> import collections.abc
>>> pkgs = packages_distributions()
>>> all(isinstance(dist, collections.abc.Sequence) for dist in pkgs.values())
True
"""
pkg_to_dist = collections.defaultdict(list)
for dist in distributions():
for pkg in (dist.read_text('top_level.txt') or '').split():
pkg_to_dist[pkg].append(dist.metadata['Name'])
return dict(pkg_to_dist)

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import re
import textwrap
import email.message
from ._text import FoldedCase
class Message(email.message.Message):
multiple_use_keys = set(
map(
FoldedCase,
[
'Classifier',
'Obsoletes-Dist',
'Platform',
'Project-URL',
'Provides-Dist',
'Provides-Extra',
'Requires-Dist',
'Requires-External',
'Supported-Platform',
],
)
)
"""
Keys that may be indicated multiple times per PEP 566.
"""
def __new__(cls, orig: email.message.Message):
res = super().__new__(cls)
vars(res).update(vars(orig))
return res
def __init__(self, *args, **kwargs):
self._headers = self._repair_headers()
# suppress spurious error from mypy
def __iter__(self):
return super().__iter__()
def _repair_headers(self):
def redent(value):
"Correct for RFC822 indentation"
if not value or '\n' not in value:
return value
return textwrap.dedent(' ' * 8 + value)
headers = [(key, redent(value)) for key, value in vars(self)['_headers']]
if self._payload:
headers.append(('Description', self.get_payload()))
return headers
@property
def json(self):
"""
Convert PackageMetadata to a JSON-compatible format
per PEP 0566.
"""
def transform(key):
value = self.get_all(key) if key in self.multiple_use_keys else self[key]
if key == 'Keywords':
value = re.split(r'\s+', value)
tk = key.lower().replace('-', '_')
return tk, value
return dict(map(transform, map(FoldedCase, self)))

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Lib/importlib/metadata/_collections.py Normal file
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import collections
# from jaraco.collections 3.3
class FreezableDefaultDict(collections.defaultdict):
"""
Often it is desirable to prevent the mutation of
a default dict after its initial construction, such
as to prevent mutation during iteration.
>>> dd = FreezableDefaultDict(list)
>>> dd[0].append('1')
>>> dd.freeze()
>>> dd[1]
[]
>>> len(dd)
1
"""
def __missing__(self, key):
return getattr(self, '_frozen', super().__missing__)(key)
def freeze(self):
self._frozen = lambda key: self.default_factory()
class Pair(collections.namedtuple('Pair', 'name value')):
@classmethod
def parse(cls, text):
return cls(*map(str.strip, text.split("=", 1)))

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import types
import functools
# from jaraco.functools 3.3
def method_cache(method, cache_wrapper=None):
"""
Wrap lru_cache to support storing the cache data in the object instances.
Abstracts the common paradigm where the method explicitly saves an
underscore-prefixed protected property on first call and returns that
subsequently.
>>> class MyClass:
... calls = 0
...
... @method_cache
... def method(self, value):
... self.calls += 1
... return value
>>> a = MyClass()
>>> a.method(3)
3
>>> for x in range(75):
... res = a.method(x)
>>> a.calls
75
Note that the apparent behavior will be exactly like that of lru_cache
except that the cache is stored on each instance, so values in one
instance will not flush values from another, and when an instance is
deleted, so are the cached values for that instance.
>>> b = MyClass()
>>> for x in range(35):
... res = b.method(x)
>>> b.calls
35
>>> a.method(0)
0
>>> a.calls
75
Note that if method had been decorated with ``functools.lru_cache()``,
a.calls would have been 76 (due to the cached value of 0 having been
flushed by the 'b' instance).
Clear the cache with ``.cache_clear()``
>>> a.method.cache_clear()
Same for a method that hasn't yet been called.
>>> c = MyClass()
>>> c.method.cache_clear()
Another cache wrapper may be supplied:
>>> cache = functools.lru_cache(maxsize=2)
>>> MyClass.method2 = method_cache(lambda self: 3, cache_wrapper=cache)
>>> a = MyClass()
>>> a.method2()
3
Caution - do not subsequently wrap the method with another decorator, such
as ``@property``, which changes the semantics of the function.
See also
http://code.activestate.com/recipes/577452-a-memoize-decorator-for-instance-methods/
for another implementation and additional justification.
"""
cache_wrapper = cache_wrapper or functools.lru_cache()
def wrapper(self, *args, **kwargs):
# it's the first call, replace the method with a cached, bound method
bound_method = types.MethodType(method, self)
cached_method = cache_wrapper(bound_method)
setattr(self, method.__name__, cached_method)
return cached_method(*args, **kwargs)
# Support cache clear even before cache has been created.
wrapper.cache_clear = lambda: None
return wrapper

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from itertools import filterfalse
def unique_everseen(iterable, key=None):
"List unique elements, preserving order. Remember all elements ever seen."
# unique_everseen('AAAABBBCCDAABBB') --> A B C D
# unique_everseen('ABBCcAD', str.lower) --> A B C D
seen = set()
seen_add = seen.add
if key is None:
for element in filterfalse(seen.__contains__, iterable):
seen_add(element)
yield element
else:
for element in iterable:
k = key(element)
if k not in seen:
seen_add(k)
yield element

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from typing import Any, Dict, Iterator, List, Protocol, TypeVar, Union
_T = TypeVar("_T")
class PackageMetadata(Protocol):
def __len__(self) -> int:
... # pragma: no cover
def __contains__(self, item: str) -> bool:
... # pragma: no cover
def __getitem__(self, key: str) -> str:
... # pragma: no cover
def __iter__(self) -> Iterator[str]:
... # pragma: no cover
def get_all(self, name: str, failobj: _T = ...) -> Union[List[Any], _T]:
"""
Return all values associated with a possibly multi-valued key.
"""
@property
def json(self) -> Dict[str, Union[str, List[str]]]:
"""
A JSON-compatible form of the metadata.
"""

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import re
from ._functools import method_cache
# from jaraco.text 3.5
class FoldedCase(str):
"""
A case insensitive string class; behaves just like str
except compares equal when the only variation is case.
>>> s = FoldedCase('hello world')
>>> s == 'Hello World'
True
>>> 'Hello World' == s
True
>>> s != 'Hello World'
False
>>> s.index('O')
4
>>> s.split('O')
['hell', ' w', 'rld']
>>> sorted(map(FoldedCase, ['GAMMA', 'alpha', 'Beta']))
['alpha', 'Beta', 'GAMMA']
Sequence membership is straightforward.
>>> "Hello World" in [s]
True
>>> s in ["Hello World"]
True
You may test for set inclusion, but candidate and elements
must both be folded.
>>> FoldedCase("Hello World") in {s}
True
>>> s in {FoldedCase("Hello World")}
True
String inclusion works as long as the FoldedCase object
is on the right.
>>> "hello" in FoldedCase("Hello World")
True
But not if the FoldedCase object is on the left:
>>> FoldedCase('hello') in 'Hello World'
False
In that case, use in_:
>>> FoldedCase('hello').in_('Hello World')
True
>>> FoldedCase('hello') > FoldedCase('Hello')
False
"""
def __lt__(self, other):
return self.lower() < other.lower()
def __gt__(self, other):
return self.lower() > other.lower()
def __eq__(self, other):
return self.lower() == other.lower()
def __ne__(self, other):
return self.lower() != other.lower()
def __hash__(self):
return hash(self.lower())
def __contains__(self, other):
return super(FoldedCase, self).lower().__contains__(other.lower())
def in_(self, other):
"Does self appear in other?"
return self in FoldedCase(other)
# cache lower since it's likely to be called frequently.
@method_cache
def lower(self):
return super(FoldedCase, self).lower()
def index(self, sub):
return self.lower().index(sub.lower())
def split(self, splitter=' ', maxsplit=0):
pattern = re.compile(re.escape(splitter), re.I)
return pattern.split(self, maxsplit)