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90 lines
2.7 KiB
Python
90 lines
2.7 KiB
Python
import re
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import sys
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import zipfile
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import itertools
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from .api import Distribution
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from .abc import DistributionFinder
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from contextlib import suppress
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from pathlib import Path
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def install(cls):
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"""Class decorator for installation on sys.meta_path."""
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sys.meta_path.append(cls())
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return cls
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class NullFinder(DistributionFinder):
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"""
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A "Finder" (aka "MetaClassFinder") that never finds any modules,
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but may find distributions.
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"""
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@staticmethod
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def find_spec(*args, **kwargs):
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return None
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@install
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class MetadataPathFinder(NullFinder):
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"""A degenerate finder for distribution packages on the file system.
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This finder supplies only a find_distributions() method for versions
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of Python that do not have a PathFinder find_distributions().
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"""
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search_template = r'{pattern}(-.*)?\.(dist|egg)-info'
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def find_distributions(self, name=None, path=None):
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"""Return an iterable of all Distribution instances capable of
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loading the metadata for packages matching the name
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(or all names if not supplied) along the paths in the list
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of directories ``path`` (defaults to sys.path).
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"""
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if path is None:
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path = sys.path
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pattern = '.*' if name is None else re.escape(name)
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found = self._search_paths(pattern, path)
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return map(PathDistribution, found)
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@classmethod
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def _search_paths(cls, pattern, paths):
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"""
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Find metadata directories in paths heuristically.
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"""
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return itertools.chain.from_iterable(
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cls._search_path(path, pattern)
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for path in map(cls._switch_path, paths)
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)
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@staticmethod
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def _switch_path(path):
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with suppress(Exception):
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return zipfile.Path(path)
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return Path(path)
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@classmethod
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def _predicate(cls, pattern, root, item):
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return re.match(pattern, str(item.name), flags=re.IGNORECASE)
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@classmethod
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def _search_path(cls, root, pattern):
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if not root.is_dir():
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return ()
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normalized = pattern.replace('-', '_')
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matcher = cls.search_template.format(pattern=normalized)
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return (item for item in root.iterdir()
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if cls._predicate(matcher, root, item))
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class PathDistribution(Distribution):
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def __init__(self, path):
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"""Construct a distribution from a path to the metadata directory."""
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self._path = path
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def read_text(self, filename):
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with suppress(FileNotFoundError, NotADirectoryError, KeyError):
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return self._path.joinpath(filename).read_text(encoding='utf-8')
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read_text.__doc__ = Distribution.read_text.__doc__
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def locate_file(self, path):
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return self._path.parent / path
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