mirror of
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464a7a91d0
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Brett Cannon <brett@python.org>
477 lines
16 KiB
Python
477 lines
16 KiB
Python
"""Utilities to support packages."""
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from collections import namedtuple
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from functools import singledispatch as simplegeneric
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import importlib
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import importlib.util
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import importlib.machinery
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import os
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import os.path
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import sys
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from types import ModuleType
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import warnings
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__all__ = [
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'get_importer', 'iter_importers',
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'walk_packages', 'iter_modules', 'get_data',
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'read_code', 'extend_path',
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'ModuleInfo',
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]
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ModuleInfo = namedtuple('ModuleInfo', 'module_finder name ispkg')
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ModuleInfo.__doc__ = 'A namedtuple with minimal info about a module.'
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def read_code(stream):
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# This helper is needed in order for the PEP 302 emulation to
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# correctly handle compiled files
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import marshal
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magic = stream.read(4)
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if magic != importlib.util.MAGIC_NUMBER:
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return None
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stream.read(12) # Skip rest of the header
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return marshal.load(stream)
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def walk_packages(path=None, prefix='', onerror=None):
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"""Yields ModuleInfo for all modules recursively
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on path, or, if path is None, all accessible modules.
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'path' should be either None or a list of paths to look for
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modules in.
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'prefix' is a string to output on the front of every module name
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on output.
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Note that this function must import all *packages* (NOT all
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modules!) on the given path, in order to access the __path__
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attribute to find submodules.
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'onerror' is a function which gets called with one argument (the
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name of the package which was being imported) if any exception
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occurs while trying to import a package. If no onerror function is
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supplied, ImportErrors are caught and ignored, while all other
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exceptions are propagated, terminating the search.
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Examples:
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# list all modules python can access
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walk_packages()
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# list all submodules of ctypes
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walk_packages(ctypes.__path__, ctypes.__name__+'.')
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"""
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def seen(p, m={}):
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if p in m:
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return True
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m[p] = True
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for info in iter_modules(path, prefix):
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yield info
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if info.ispkg:
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try:
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__import__(info.name)
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except ImportError:
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if onerror is not None:
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onerror(info.name)
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except Exception:
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if onerror is not None:
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onerror(info.name)
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else:
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raise
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else:
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path = getattr(sys.modules[info.name], '__path__', None) or []
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# don't traverse path items we've seen before
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path = [p for p in path if not seen(p)]
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yield from walk_packages(path, info.name+'.', onerror)
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def iter_modules(path=None, prefix=''):
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"""Yields ModuleInfo for all submodules on path,
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or, if path is None, all top-level modules on sys.path.
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'path' should be either None or a list of paths to look for
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modules in.
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'prefix' is a string to output on the front of every module name
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on output.
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"""
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if path is None:
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importers = iter_importers()
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elif isinstance(path, str):
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raise ValueError("path must be None or list of paths to look for "
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"modules in")
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else:
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importers = map(get_importer, path)
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yielded = {}
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for i in importers:
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for name, ispkg in iter_importer_modules(i, prefix):
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if name not in yielded:
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yielded[name] = 1
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yield ModuleInfo(i, name, ispkg)
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@simplegeneric
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def iter_importer_modules(importer, prefix=''):
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if not hasattr(importer, 'iter_modules'):
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return []
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return importer.iter_modules(prefix)
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# Implement a file walker for the normal importlib path hook
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def _iter_file_finder_modules(importer, prefix=''):
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if importer.path is None or not os.path.isdir(importer.path):
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return
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yielded = {}
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import inspect
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try:
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filenames = os.listdir(importer.path)
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except OSError:
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# ignore unreadable directories like import does
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filenames = []
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filenames.sort() # handle packages before same-named modules
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for fn in filenames:
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modname = inspect.getmodulename(fn)
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if modname=='__init__' or modname in yielded:
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continue
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path = os.path.join(importer.path, fn)
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ispkg = False
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if not modname and os.path.isdir(path) and '.' not in fn:
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modname = fn
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try:
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dircontents = os.listdir(path)
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except OSError:
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# ignore unreadable directories like import does
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dircontents = []
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for fn in dircontents:
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subname = inspect.getmodulename(fn)
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if subname=='__init__':
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ispkg = True
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break
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else:
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continue # not a package
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if modname and '.' not in modname:
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yielded[modname] = 1
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yield prefix + modname, ispkg
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iter_importer_modules.register(
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importlib.machinery.FileFinder, _iter_file_finder_modules)
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try:
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import zipimport
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from zipimport import zipimporter
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def iter_zipimport_modules(importer, prefix=''):
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dirlist = sorted(zipimport._zip_directory_cache[importer.archive])
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_prefix = importer.prefix
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plen = len(_prefix)
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yielded = {}
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import inspect
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for fn in dirlist:
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if not fn.startswith(_prefix):
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continue
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fn = fn[plen:].split(os.sep)
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if len(fn)==2 and fn[1].startswith('__init__.py'):
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if fn[0] not in yielded:
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yielded[fn[0]] = 1
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yield prefix + fn[0], True
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if len(fn)!=1:
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continue
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modname = inspect.getmodulename(fn[0])
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if modname=='__init__':
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continue
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if modname and '.' not in modname and modname not in yielded:
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yielded[modname] = 1
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yield prefix + modname, False
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iter_importer_modules.register(zipimporter, iter_zipimport_modules)
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except ImportError:
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pass
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def get_importer(path_item):
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"""Retrieve a finder for the given path item
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The returned finder is cached in sys.path_importer_cache
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if it was newly created by a path hook.
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The cache (or part of it) can be cleared manually if a
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rescan of sys.path_hooks is necessary.
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"""
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path_item = os.fsdecode(path_item)
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try:
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importer = sys.path_importer_cache[path_item]
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except KeyError:
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for path_hook in sys.path_hooks:
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try:
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importer = path_hook(path_item)
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sys.path_importer_cache.setdefault(path_item, importer)
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break
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except ImportError:
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pass
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else:
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importer = None
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return importer
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def iter_importers(fullname=""):
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"""Yield finders for the given module name
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If fullname contains a '.', the finders will be for the package
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containing fullname, otherwise they will be all registered top level
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finders (i.e. those on both sys.meta_path and sys.path_hooks).
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If the named module is in a package, that package is imported as a side
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effect of invoking this function.
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If no module name is specified, all top level finders are produced.
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"""
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if fullname.startswith('.'):
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msg = "Relative module name {!r} not supported".format(fullname)
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raise ImportError(msg)
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if '.' in fullname:
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# Get the containing package's __path__
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pkg_name = fullname.rpartition(".")[0]
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pkg = importlib.import_module(pkg_name)
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path = getattr(pkg, '__path__', None)
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if path is None:
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return
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else:
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yield from sys.meta_path
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path = sys.path
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for item in path:
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yield get_importer(item)
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def extend_path(path, name):
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"""Extend a package's path.
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Intended use is to place the following code in a package's __init__.py:
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from pkgutil import extend_path
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__path__ = extend_path(__path__, __name__)
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For each directory on sys.path that has a subdirectory that
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matches the package name, add the subdirectory to the package's
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__path__. This is useful if one wants to distribute different
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parts of a single logical package as multiple directories.
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It also looks for *.pkg files beginning where * matches the name
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argument. This feature is similar to *.pth files (see site.py),
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except that it doesn't special-case lines starting with 'import'.
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A *.pkg file is trusted at face value: apart from checking for
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duplicates, all entries found in a *.pkg file are added to the
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path, regardless of whether they are exist the filesystem. (This
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is a feature.)
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If the input path is not a list (as is the case for frozen
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packages) it is returned unchanged. The input path is not
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modified; an extended copy is returned. Items are only appended
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to the copy at the end.
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It is assumed that sys.path is a sequence. Items of sys.path that
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are not (unicode or 8-bit) strings referring to existing
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directories are ignored. Unicode items of sys.path that cause
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errors when used as filenames may cause this function to raise an
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exception (in line with os.path.isdir() behavior).
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"""
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if not isinstance(path, list):
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# This could happen e.g. when this is called from inside a
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# frozen package. Return the path unchanged in that case.
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return path
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sname_pkg = name + ".pkg"
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path = path[:] # Start with a copy of the existing path
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parent_package, _, final_name = name.rpartition('.')
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if parent_package:
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try:
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search_path = sys.modules[parent_package].__path__
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except (KeyError, AttributeError):
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# We can't do anything: find_loader() returns None when
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# passed a dotted name.
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return path
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else:
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search_path = sys.path
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for dir in search_path:
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if not isinstance(dir, str):
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continue
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finder = get_importer(dir)
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if finder is not None:
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portions = []
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if hasattr(finder, 'find_spec'):
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spec = finder.find_spec(final_name)
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if spec is not None:
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portions = spec.submodule_search_locations or []
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# Is this finder PEP 420 compliant?
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elif hasattr(finder, 'find_loader'):
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_, portions = finder.find_loader(final_name)
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for portion in portions:
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# XXX This may still add duplicate entries to path on
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# case-insensitive filesystems
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if portion not in path:
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path.append(portion)
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# XXX Is this the right thing for subpackages like zope.app?
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# It looks for a file named "zope.app.pkg"
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pkgfile = os.path.join(dir, sname_pkg)
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if os.path.isfile(pkgfile):
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try:
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f = open(pkgfile)
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except OSError as msg:
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sys.stderr.write("Can't open %s: %s\n" %
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(pkgfile, msg))
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else:
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with f:
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for line in f:
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line = line.rstrip('\n')
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if not line or line.startswith('#'):
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continue
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path.append(line) # Don't check for existence!
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return path
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def get_data(package, resource):
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"""Get a resource from a package.
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This is a wrapper round the PEP 302 loader get_data API. The package
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argument should be the name of a package, in standard module format
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(foo.bar). The resource argument should be in the form of a relative
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filename, using '/' as the path separator. The parent directory name '..'
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is not allowed, and nor is a rooted name (starting with a '/').
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The function returns a binary string, which is the contents of the
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specified resource.
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For packages located in the filesystem, which have already been imported,
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this is the rough equivalent of
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d = os.path.dirname(sys.modules[package].__file__)
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data = open(os.path.join(d, resource), 'rb').read()
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If the package cannot be located or loaded, or it uses a PEP 302 loader
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which does not support get_data(), then None is returned.
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"""
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spec = importlib.util.find_spec(package)
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if spec is None:
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return None
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loader = spec.loader
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if loader is None or not hasattr(loader, 'get_data'):
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return None
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# XXX needs test
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mod = (sys.modules.get(package) or
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importlib._bootstrap._load(spec))
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if mod is None or not hasattr(mod, '__file__'):
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return None
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# Modify the resource name to be compatible with the loader.get_data
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# signature - an os.path format "filename" starting with the dirname of
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# the package's __file__
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parts = resource.split('/')
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parts.insert(0, os.path.dirname(mod.__file__))
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resource_name = os.path.join(*parts)
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return loader.get_data(resource_name)
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_NAME_PATTERN = None
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def resolve_name(name):
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"""
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Resolve a name to an object.
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It is expected that `name` will be a string in one of the following
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formats, where W is shorthand for a valid Python identifier and dot stands
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for a literal period in these pseudo-regexes:
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W(.W)*
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W(.W)*:(W(.W)*)?
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The first form is intended for backward compatibility only. It assumes that
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some part of the dotted name is a package, and the rest is an object
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somewhere within that package, possibly nested inside other objects.
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Because the place where the package stops and the object hierarchy starts
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can't be inferred by inspection, repeated attempts to import must be done
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with this form.
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In the second form, the caller makes the division point clear through the
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provision of a single colon: the dotted name to the left of the colon is a
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package to be imported, and the dotted name to the right is the object
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hierarchy within that package. Only one import is needed in this form. If
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it ends with the colon, then a module object is returned.
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The function will return an object (which might be a module), or raise one
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of the following exceptions:
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ValueError - if `name` isn't in a recognised format
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ImportError - if an import failed when it shouldn't have
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AttributeError - if a failure occurred when traversing the object hierarchy
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within the imported package to get to the desired object.
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"""
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global _NAME_PATTERN
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if _NAME_PATTERN is None:
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# Lazy import to speedup Python startup time
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import re
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dotted_words = r'(?!\d)(\w+)(\.(?!\d)(\w+))*'
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_NAME_PATTERN = re.compile(f'^(?P<pkg>{dotted_words})'
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f'(?P<cln>:(?P<obj>{dotted_words})?)?$',
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re.UNICODE)
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m = _NAME_PATTERN.match(name)
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if not m:
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raise ValueError(f'invalid format: {name!r}')
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gd = m.groupdict()
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if gd.get('cln'):
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# there is a colon - a one-step import is all that's needed
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mod = importlib.import_module(gd['pkg'])
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parts = gd.get('obj')
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parts = parts.split('.') if parts else []
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else:
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# no colon - have to iterate to find the package boundary
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parts = name.split('.')
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modname = parts.pop(0)
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# first part *must* be a module/package.
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mod = importlib.import_module(modname)
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while parts:
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p = parts[0]
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s = f'{modname}.{p}'
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try:
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mod = importlib.import_module(s)
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parts.pop(0)
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modname = s
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except ImportError:
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break
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# if we reach this point, mod is the module, already imported, and
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# parts is the list of parts in the object hierarchy to be traversed, or
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# an empty list if just the module is wanted.
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result = mod
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for p in parts:
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result = getattr(result, p)
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return result
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