cpython/Lib/importlib/metadata/_hooks.py
2019-03-25 22:23:55 -04:00

138 lines
4.2 KiB
Python

import re
import sys
import itertools
from . import zipp
from .api import Distribution
from .abc import DistributionFinder
from contextlib import suppress
from pathlib import Path
def install(cls):
"""Class decorator for installation on sys.meta_path."""
sys.meta_path.append(cls())
return cls
class NullFinder(DistributionFinder):
"""
A "Finder" (aka "MetaClassFinder") that never finds any modules,
but may find distributions.
"""
@staticmethod
def find_spec(*args, **kwargs):
return None
@install
class MetadataPathFinder(NullFinder):
"""A degenerate finder for distribution packages on the file system.
This finder supplies only a find_distributions() method for versions
of Python that do not have a PathFinder find_distributions().
"""
search_template = r'{pattern}(-.*)?\.(dist|egg)-info'
def find_distributions(self, name=None, path=None):
"""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).
"""
if path is None:
path = sys.path
pattern = '.*' if name is None else re.escape(name)
found = self._search_paths(pattern, path)
return map(PathDistribution, found)
@classmethod
def _search_paths(cls, pattern, paths):
"""
Find metadata directories in paths heuristically.
"""
return itertools.chain.from_iterable(
cls._search_path(path, pattern)
for path in map(Path, paths)
)
@classmethod
def _search_path(cls, root, pattern):
if not root.is_dir():
return ()
normalized = pattern.replace('-', '_')
return (
item
for item in root.iterdir()
if item.is_dir()
and re.match(
cls.search_template.format(pattern=normalized),
str(item.name),
flags=re.IGNORECASE,
)
)
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):
with self._path.joinpath(filename).open(encoding='utf-8') as fp:
return fp.read()
return None
read_text.__doc__ = Distribution.read_text.__doc__
def locate_file(self, path):
return self._path.parent / path
@install
class WheelMetadataFinder(NullFinder):
"""A degenerate finder for distribution packages in wheels.
This finder supplies only a find_distributions() method for versions
of Python that do not have a PathFinder find_distributions().
"""
search_template = r'{pattern}(-.*)?\.whl'
def find_distributions(self, name=None, path=None):
"""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).
"""
if path is None:
path = sys.path
pattern = '.*' if name is None else re.escape(name)
found = self._search_paths(pattern, path)
return map(WheelDistribution, found)
@classmethod
def _search_paths(cls, pattern, paths):
return (
path
for path in map(Path, paths)
if re.match(
cls.search_template.format(pattern=pattern),
str(path.name),
flags=re.IGNORECASE,
)
)
class WheelDistribution(Distribution):
def __init__(self, archive):
self._archive = zipp.Path(archive)
name, version = archive.name.split('-')[0:2]
self._dist_info = '{}-{}.dist-info'.format(name, version)
def read_text(self, filename):
target = self._archive / self._dist_info / filename
return target.read_text() if target.exists() else None
read_text.__doc__ = Distribution.read_text.__doc__
def locate_file(self, path):
return self._archive / path