mirror of https://github.com/python/cpython
997 lines
33 KiB
Python
997 lines
33 KiB
Python
"""Core implementation of import.
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This module is NOT meant to be directly imported! It has been designed such
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that it can be bootstrapped into Python as the implementation of import. As
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such it requires the injection of specific modules and attributes in order to
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work. One should use importlib as the public-facing version of this module.
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"""
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# Injected modules are '_warnings', 'imp', 'sys', 'marshal', '_io',
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# and '_os' (a.k.a. 'posix', 'nt' or 'os2').
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# Injected attribute is path_sep.
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#
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# When editing this code be aware that code executed at import time CANNOT
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# reference any injected objects! This includes not only global code but also
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# anything specified at the class level.
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# Bootstrap-related code ######################################################
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# TODO: when not on any of these platforms, replace _case_ok() w/
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# ``lambda x,y: True``.
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CASE_OK_PLATFORMS = 'win', 'cygwin', 'darwin'
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def _case_ok(directory, check):
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"""Check if the directory contains something matching 'check'
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case-sensitively when running on Windows or OS X.
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If running on Window or OS X and PYTHONCASEOK is a defined environment
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variable then no case-sensitive check is performed. No check is done to see
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if what is being checked for exists, so if the platform is not Windows or
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OS X then assume the case is fine.
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"""
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if (any(map(sys.platform.startswith, CASE_OK_PLATFORMS)) and
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b'PYTHONCASEOK' not in _os.environ):
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if not directory:
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directory = '.'
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if check in _os.listdir(directory):
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return True
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else:
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return False
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else:
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return True
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# TODO: Expose from marshal
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def _w_long(x):
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"""Convert a 32-bit integer to little-endian.
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XXX Temporary until marshal's long functions are exposed.
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"""
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x = int(x)
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int_bytes = []
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int_bytes.append(x & 0xFF)
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int_bytes.append((x >> 8) & 0xFF)
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int_bytes.append((x >> 16) & 0xFF)
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int_bytes.append((x >> 24) & 0xFF)
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return bytearray(int_bytes)
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# TODO: Expose from marshal
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def _r_long(int_bytes):
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"""Convert 4 bytes in little-endian to an integer.
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XXX Temporary until marshal's long function are exposed.
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"""
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x = int_bytes[0]
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x |= int_bytes[1] << 8
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x |= int_bytes[2] << 16
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x |= int_bytes[3] << 24
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return x
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# XXX Could also expose Modules/getpath.c:joinpath()
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def _path_join(*args):
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"""Replacement for os.path.join."""
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return path_sep.join(x[:-len(path_sep)] if x.endswith(path_sep) else x
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for x in args if x)
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def _path_exists(path):
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"""Replacement for os.path.exists."""
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try:
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_os.stat(path)
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except OSError:
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return False
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else:
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return True
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def _path_is_mode_type(path, mode):
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"""Test whether the path is the specified mode type."""
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try:
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stat_info = _os.stat(path)
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except OSError:
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return False
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return (stat_info.st_mode & 0o170000) == mode
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# XXX Could also expose Modules/getpath.c:isfile()
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def _path_isfile(path):
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"""Replacement for os.path.isfile."""
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return _path_is_mode_type(path, 0o100000)
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# XXX Could also expose Modules/getpath.c:isdir()
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def _path_isdir(path):
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"""Replacement for os.path.isdir."""
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if not path:
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path = _os.getcwd()
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return _path_is_mode_type(path, 0o040000)
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def _path_without_ext(path, ext_type):
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"""Replacement for os.path.splitext()[0]."""
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for suffix in _suffix_list(ext_type):
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if path.endswith(suffix):
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return path[:-len(suffix)]
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else:
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raise ValueError("path is not of the specified type")
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def _path_absolute(path):
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"""Replacement for os.path.abspath."""
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if not path:
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path = _os.getcwd()
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try:
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return _os._getfullpathname(path)
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except AttributeError:
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if path.startswith('/'):
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return path
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else:
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return _path_join(_os.getcwd(), path)
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def _write_atomic(path, data):
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"""Best-effort function to write data to a path atomically.
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Be prepared to handle a FileExistsError if concurrent writing of the
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temporary file is attempted."""
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# Renaming should be atomic on most platforms (including Windows).
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# Under Windows, the limitation is that we can't rename() to an existing
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# path, while POSIX will overwrite it. But here we don't really care
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# if there is a glimpse of time during which the final pyc file doesn't
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# exist.
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# id() is used to generate a pseudo-random filename.
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path_tmp = '{}.{}'.format(path, id(path))
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fd = _os.open(path_tmp, _os.O_EXCL | _os.O_CREAT | _os.O_WRONLY, 0o666)
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try:
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with _io.FileIO(fd, 'wb') as file:
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file.write(data)
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try:
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_os.rename(path_tmp, path)
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except FileExistsError:
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# Windows (if we had access to MoveFileEx, we could overwrite)
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_os.unlink(path)
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_os.rename(path_tmp, path)
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except OSError:
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try:
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_os.unlink(path_tmp)
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except OSError:
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pass
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raise
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def _wrap(new, old):
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"""Simple substitute for functools.wraps."""
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for replace in ['__module__', '__name__', '__qualname__', '__doc__']:
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setattr(new, replace, getattr(old, replace))
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new.__dict__.update(old.__dict__)
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code_type = type(_wrap.__code__)
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# Finder/loader utility code ##################################################
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def set_package(fxn):
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"""Set __package__ on the returned module."""
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def set_package_wrapper(*args, **kwargs):
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module = fxn(*args, **kwargs)
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if not hasattr(module, '__package__') or module.__package__ is None:
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module.__package__ = module.__name__
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if not hasattr(module, '__path__'):
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module.__package__ = module.__package__.rpartition('.')[0]
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return module
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_wrap(set_package_wrapper, fxn)
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return set_package_wrapper
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def set_loader(fxn):
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"""Set __loader__ on the returned module."""
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def set_loader_wrapper(self, *args, **kwargs):
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module = fxn(self, *args, **kwargs)
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if not hasattr(module, '__loader__'):
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module.__loader__ = self
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return module
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_wrap(set_loader_wrapper, fxn)
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return set_loader_wrapper
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def module_for_loader(fxn):
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"""Decorator to handle selecting the proper module for loaders.
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The decorated function is passed the module to use instead of the module
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name. The module passed in to the function is either from sys.modules if
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it already exists or is a new module which has __name__ set and is inserted
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into sys.modules. If an exception is raised and the decorator created the
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module it is subsequently removed from sys.modules.
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The decorator assumes that the decorated function takes the module name as
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the second argument.
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"""
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def module_for_loader_wrapper(self, fullname, *args, **kwargs):
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module = sys.modules.get(fullname)
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is_reload = bool(module)
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if not is_reload:
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# This must be done before open() is called as the 'io' module
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# implicitly imports 'locale' and would otherwise trigger an
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# infinite loop.
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module = imp.new_module(fullname)
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sys.modules[fullname] = module
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try:
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return fxn(self, module, *args, **kwargs)
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except:
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if not is_reload:
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del sys.modules[fullname]
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raise
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_wrap(module_for_loader_wrapper, fxn)
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return module_for_loader_wrapper
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def _check_name(method):
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"""Decorator to verify that the module being requested matches the one the
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loader can handle.
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The first argument (self) must define _name which the second argument is
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compared against. If the comparison fails then ImportError is raised.
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"""
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def _check_name_wrapper(self, name, *args, **kwargs):
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if self._name != name:
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raise ImportError("loader cannot handle %s" % name)
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return method(self, name, *args, **kwargs)
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_wrap(_check_name_wrapper, method)
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return _check_name_wrapper
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def _requires_builtin(fxn):
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"""Decorator to verify the named module is built-in."""
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def _requires_builtin_wrapper(self, fullname):
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if fullname not in sys.builtin_module_names:
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raise ImportError("{0} is not a built-in module".format(fullname))
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return fxn(self, fullname)
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_wrap(_requires_builtin_wrapper, fxn)
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return _requires_builtin_wrapper
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def _requires_frozen(fxn):
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"""Decorator to verify the named module is frozen."""
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def _requires_frozen_wrapper(self, fullname):
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if not imp.is_frozen(fullname):
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raise ImportError("{0} is not a frozen module".format(fullname))
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return fxn(self, fullname)
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_wrap(_requires_frozen_wrapper, fxn)
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return _requires_frozen_wrapper
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def _suffix_list(suffix_type):
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"""Return a list of file suffixes based on the imp file type."""
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return [suffix[0] for suffix in imp.get_suffixes()
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if suffix[2] == suffix_type]
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# Loaders #####################################################################
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class BuiltinImporter:
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"""Meta path import for built-in modules.
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All methods are either class or static methods to avoid the need to
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instantiate the class.
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"""
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@classmethod
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def find_module(cls, fullname, path=None):
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"""Find the built-in module.
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If 'path' is ever specified then the search is considered a failure.
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"""
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if path is not None:
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return None
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return cls if imp.is_builtin(fullname) else None
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@classmethod
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@set_package
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@set_loader
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@_requires_builtin
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def load_module(cls, fullname):
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"""Load a built-in module."""
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is_reload = fullname in sys.modules
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try:
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return imp.init_builtin(fullname)
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except:
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if not is_reload and fullname in sys.modules:
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del sys.modules[fullname]
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raise
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@classmethod
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@_requires_builtin
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def get_code(cls, fullname):
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"""Return None as built-in modules do not have code objects."""
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return None
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@classmethod
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@_requires_builtin
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def get_source(cls, fullname):
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"""Return None as built-in modules do not have source code."""
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return None
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@classmethod
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@_requires_builtin
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def is_package(cls, fullname):
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"""Return None as built-in modules are never packages."""
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return False
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class FrozenImporter:
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"""Meta path import for frozen modules.
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All methods are either class or static methods to avoid the need to
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instantiate the class.
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"""
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@classmethod
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def find_module(cls, fullname, path=None):
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"""Find a frozen module."""
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return cls if imp.is_frozen(fullname) else None
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@classmethod
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@set_package
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@set_loader
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@_requires_frozen
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def load_module(cls, fullname):
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"""Load a frozen module."""
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is_reload = fullname in sys.modules
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try:
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return imp.init_frozen(fullname)
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except:
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if not is_reload and fullname in sys.modules:
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del sys.modules[fullname]
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raise
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@classmethod
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@_requires_frozen
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def get_code(cls, fullname):
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"""Return the code object for the frozen module."""
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return imp.get_frozen_object(fullname)
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@classmethod
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@_requires_frozen
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def get_source(cls, fullname):
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"""Return None as frozen modules do not have source code."""
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return None
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@classmethod
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@_requires_frozen
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def is_package(cls, fullname):
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"""Return if the frozen module is a package."""
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return imp.is_frozen_package(fullname)
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class _LoaderBasics:
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"""Base class of common code needed by both SourceLoader and
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_SourcelessFileLoader."""
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def is_package(self, fullname):
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"""Concrete implementation of InspectLoader.is_package by checking if
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the path returned by get_filename has a filename of '__init__.py'."""
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filename = self.get_filename(fullname).rpartition(path_sep)[2]
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return filename.rsplit('.', 1)[0] == '__init__'
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def _bytes_from_bytecode(self, fullname, data, source_stats):
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"""Return the marshalled bytes from bytecode, verifying the magic
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number, timestamp and source size along the way.
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If source_stats is None then skip the timestamp check.
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"""
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magic = data[:4]
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raw_timestamp = data[4:8]
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raw_size = data[8:12]
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if len(magic) != 4 or magic != imp.get_magic():
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raise ImportError("bad magic number in {}".format(fullname))
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elif len(raw_timestamp) != 4:
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raise EOFError("bad timestamp in {}".format(fullname))
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elif len(raw_size) != 4:
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raise EOFError("bad size in {}".format(fullname))
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if source_stats is not None:
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try:
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source_mtime = int(source_stats['mtime'])
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except KeyError:
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pass
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else:
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if _r_long(raw_timestamp) != source_mtime:
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raise ImportError("bytecode is stale for {}".format(fullname))
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try:
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source_size = source_stats['size'] & 0xFFFFFFFF
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except KeyError:
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pass
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else:
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if _r_long(raw_size) != source_size:
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raise ImportError("bytecode is stale for {}".format(fullname))
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# Can't return the code object as errors from marshal loading need to
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# propagate even when source is available.
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return data[12:]
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@module_for_loader
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def _load_module(self, module, *, sourceless=False):
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"""Helper for load_module able to handle either source or sourceless
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loading."""
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name = module.__name__
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code_object = self.get_code(name)
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module.__file__ = self.get_filename(name)
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if not sourceless:
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module.__cached__ = imp.cache_from_source(module.__file__)
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else:
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module.__cached__ = module.__file__
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module.__package__ = name
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if self.is_package(name):
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module.__path__ = [module.__file__.rsplit(path_sep, 1)[0]]
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else:
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module.__package__ = module.__package__.rpartition('.')[0]
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module.__loader__ = self
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exec(code_object, module.__dict__)
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return module
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class SourceLoader(_LoaderBasics):
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def path_mtime(self, path):
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"""Optional method that returns the modification time (an int) for the
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specified path, where path is a str.
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"""
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raise NotImplementedError
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def path_stats(self, path):
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"""Optional method returning a metadata dict for the specified path
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to by the path (str).
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Possible keys:
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- 'mtime' (mandatory) is the numeric timestamp of last source
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code modification;
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- 'size' (optional) is the size in bytes of the source code.
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Implementing this method allows the loader to read bytecode files.
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"""
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return {'mtime': self.path_mtime(path)}
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def set_data(self, path, data):
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"""Optional method which writes data (bytes) to a file path (a str).
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Implementing this method allows for the writing of bytecode files.
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"""
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raise NotImplementedError
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def get_source(self, fullname):
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"""Concrete implementation of InspectLoader.get_source."""
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import tokenize
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path = self.get_filename(fullname)
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try:
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source_bytes = self.get_data(path)
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except IOError:
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raise ImportError("source not available through get_data()")
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encoding = tokenize.detect_encoding(_io.BytesIO(source_bytes).readline)
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newline_decoder = _io.IncrementalNewlineDecoder(None, True)
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return newline_decoder.decode(source_bytes.decode(encoding[0]))
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def get_code(self, fullname):
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"""Concrete implementation of InspectLoader.get_code.
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Reading of bytecode requires path_stats to be implemented. To write
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bytecode, set_data must also be implemented.
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"""
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source_path = self.get_filename(fullname)
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bytecode_path = imp.cache_from_source(source_path)
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source_mtime = None
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if bytecode_path is not None:
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try:
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st = self.path_stats(source_path)
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except NotImplementedError:
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pass
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else:
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source_mtime = int(st['mtime'])
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try:
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data = self.get_data(bytecode_path)
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except IOError:
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pass
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else:
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try:
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bytes_data = self._bytes_from_bytecode(fullname, data,
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st)
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except (ImportError, EOFError):
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pass
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else:
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found = marshal.loads(bytes_data)
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if isinstance(found, code_type):
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imp._fix_co_filename(found, source_path)
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return found
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else:
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msg = "Non-code object in {}"
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raise ImportError(msg.format(bytecode_path))
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source_bytes = self.get_data(source_path)
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code_object = compile(source_bytes, source_path, 'exec',
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dont_inherit=True)
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if (not sys.dont_write_bytecode and bytecode_path is not None and
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source_mtime is not None):
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# If e.g. Jython ever implements imp.cache_from_source to have
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# their own cached file format, this block of code will most likely
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# throw an exception.
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data = bytearray(imp.get_magic())
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data.extend(_w_long(source_mtime))
|
|
data.extend(_w_long(len(source_bytes)))
|
|
data.extend(marshal.dumps(code_object))
|
|
try:
|
|
self.set_data(bytecode_path, data)
|
|
except NotImplementedError:
|
|
pass
|
|
return code_object
|
|
|
|
def load_module(self, fullname):
|
|
"""Concrete implementation of Loader.load_module.
|
|
|
|
Requires ExecutionLoader.get_filename and ResourceLoader.get_data to be
|
|
implemented to load source code. Use of bytecode is dictated by whether
|
|
get_code uses/writes bytecode.
|
|
|
|
"""
|
|
return self._load_module(fullname)
|
|
|
|
|
|
class _FileLoader:
|
|
|
|
"""Base file loader class which implements the loader protocol methods that
|
|
require file system usage."""
|
|
|
|
def __init__(self, fullname, path):
|
|
"""Cache the module name and the path to the file found by the
|
|
finder."""
|
|
self._name = fullname
|
|
self._path = path
|
|
|
|
@_check_name
|
|
def get_filename(self, fullname):
|
|
"""Return the path to the source file as found by the finder."""
|
|
return self._path
|
|
|
|
def get_data(self, path):
|
|
"""Return the data from path as raw bytes."""
|
|
with _io.FileIO(path, 'r') as file:
|
|
return file.read()
|
|
|
|
|
|
class _SourceFileLoader(_FileLoader, SourceLoader):
|
|
|
|
"""Concrete implementation of SourceLoader using the file system."""
|
|
|
|
def path_stats(self, path):
|
|
"""Return the metadat for the path."""
|
|
st = _os.stat(path)
|
|
return {'mtime': st.st_mtime, 'size': st.st_size}
|
|
|
|
def set_data(self, path, data):
|
|
"""Write bytes data to a file."""
|
|
parent, _, filename = path.rpartition(path_sep)
|
|
path_parts = []
|
|
# Figure out what directories are missing.
|
|
while parent and not _path_isdir(parent):
|
|
parent, _, part = parent.rpartition(path_sep)
|
|
path_parts.append(part)
|
|
# Create needed directories.
|
|
for part in reversed(path_parts):
|
|
parent = _path_join(parent, part)
|
|
try:
|
|
_os.mkdir(parent)
|
|
except FileExistsError:
|
|
# Probably another Python process already created the dir.
|
|
continue
|
|
except PermissionError:
|
|
# If can't get proper access, then just forget about writing
|
|
# the data.
|
|
return
|
|
try:
|
|
_write_atomic(path, data)
|
|
except (PermissionError, FileExistsError):
|
|
# Don't worry if you can't write bytecode or someone is writing
|
|
# it at the same time.
|
|
pass
|
|
|
|
|
|
class _SourcelessFileLoader(_FileLoader, _LoaderBasics):
|
|
|
|
"""Loader which handles sourceless file imports."""
|
|
|
|
def load_module(self, fullname):
|
|
return self._load_module(fullname, sourceless=True)
|
|
|
|
def get_code(self, fullname):
|
|
path = self.get_filename(fullname)
|
|
data = self.get_data(path)
|
|
bytes_data = self._bytes_from_bytecode(fullname, data, None)
|
|
found = marshal.loads(bytes_data)
|
|
if isinstance(found, code_type):
|
|
return found
|
|
else:
|
|
raise ImportError("Non-code object in {}".format(path))
|
|
|
|
def get_source(self, fullname):
|
|
"""Return None as there is no source code."""
|
|
return None
|
|
|
|
|
|
class _ExtensionFileLoader:
|
|
|
|
"""Loader for extension modules.
|
|
|
|
The constructor is designed to work with FileFinder.
|
|
|
|
"""
|
|
|
|
def __init__(self, name, path):
|
|
"""Initialize the loader.
|
|
|
|
If is_pkg is True then an exception is raised as extension modules
|
|
cannot be the __init__ module for an extension module.
|
|
|
|
"""
|
|
self._name = name
|
|
self._path = path
|
|
|
|
@_check_name
|
|
@set_package
|
|
@set_loader
|
|
def load_module(self, fullname):
|
|
"""Load an extension module."""
|
|
is_reload = fullname in sys.modules
|
|
try:
|
|
return imp.load_dynamic(fullname, self._path)
|
|
except:
|
|
if not is_reload and fullname in sys.modules:
|
|
del sys.modules[fullname]
|
|
raise
|
|
|
|
@_check_name
|
|
def is_package(self, fullname):
|
|
"""Return False as an extension module can never be a package."""
|
|
return False
|
|
|
|
@_check_name
|
|
def get_code(self, fullname):
|
|
"""Return None as an extension module cannot create a code object."""
|
|
return None
|
|
|
|
@_check_name
|
|
def get_source(self, fullname):
|
|
"""Return None as extension modules have no source code."""
|
|
return None
|
|
|
|
|
|
# Finders #####################################################################
|
|
|
|
class PathFinder:
|
|
|
|
"""Meta path finder for sys.(path|path_hooks|path_importer_cache)."""
|
|
|
|
@classmethod
|
|
def _path_hooks(cls, path, hooks=None):
|
|
"""Search sequence of hooks for a finder for 'path'.
|
|
|
|
If 'hooks' is false then use sys.path_hooks.
|
|
|
|
"""
|
|
if not hooks:
|
|
hooks = sys.path_hooks
|
|
for hook in hooks:
|
|
try:
|
|
return hook(path)
|
|
except ImportError:
|
|
continue
|
|
else:
|
|
raise ImportError("no path hook found for {0}".format(path))
|
|
|
|
@classmethod
|
|
def _path_importer_cache(cls, path, default=None):
|
|
"""Get the finder for the path from sys.path_importer_cache.
|
|
|
|
If the path is not in the cache, find the appropriate finder and cache
|
|
it. If None is cached, get the default finder and cache that
|
|
(if applicable).
|
|
|
|
Because of NullImporter, some finder should be returned. The only
|
|
explicit fail case is if None is cached but the path cannot be used for
|
|
the default hook, for which ImportError is raised.
|
|
|
|
"""
|
|
try:
|
|
finder = sys.path_importer_cache[path]
|
|
except KeyError:
|
|
finder = cls._path_hooks(path)
|
|
sys.path_importer_cache[path] = finder
|
|
else:
|
|
if finder is None and default:
|
|
# Raises ImportError on failure.
|
|
finder = default(path)
|
|
sys.path_importer_cache[path] = finder
|
|
return finder
|
|
|
|
@classmethod
|
|
def find_module(cls, fullname, path=None):
|
|
"""Find the module on sys.path or 'path' based on sys.path_hooks and
|
|
sys.path_importer_cache."""
|
|
if not path:
|
|
path = sys.path
|
|
for entry in path:
|
|
try:
|
|
finder = cls._path_importer_cache(entry)
|
|
except ImportError:
|
|
continue
|
|
if finder:
|
|
loader = finder.find_module(fullname)
|
|
if loader:
|
|
return loader
|
|
else:
|
|
return None
|
|
|
|
|
|
class _FileFinder:
|
|
|
|
"""File-based finder.
|
|
|
|
Constructor takes a list of objects detailing what file extensions their
|
|
loader supports along with whether it can be used for a package.
|
|
|
|
"""
|
|
|
|
def __init__(self, path, *details):
|
|
"""Initialize with finder details."""
|
|
packages = []
|
|
modules = []
|
|
for detail in details:
|
|
modules.extend((suffix, detail.loader) for suffix in detail.suffixes)
|
|
if detail.supports_packages:
|
|
packages.extend((suffix, detail.loader)
|
|
for suffix in detail.suffixes)
|
|
self.packages = packages
|
|
self.modules = modules
|
|
self.path = path
|
|
|
|
def find_module(self, fullname):
|
|
"""Try to find a loader for the specified module."""
|
|
tail_module = fullname.rpartition('.')[2]
|
|
base_path = _path_join(self.path, tail_module)
|
|
if _path_isdir(base_path) and _case_ok(self.path, tail_module):
|
|
for suffix, loader in self.packages:
|
|
init_filename = '__init__' + suffix
|
|
full_path = _path_join(base_path, init_filename)
|
|
if (_path_isfile(full_path) and
|
|
_case_ok(base_path, init_filename)):
|
|
return loader(fullname, full_path)
|
|
else:
|
|
msg = "Not importing directory {}: missing __init__"
|
|
_warnings.warn(msg.format(base_path), ImportWarning)
|
|
for suffix, loader in self.modules:
|
|
mod_filename = tail_module + suffix
|
|
full_path = _path_join(self.path, mod_filename)
|
|
if _path_isfile(full_path) and _case_ok(self.path, mod_filename):
|
|
return loader(fullname, full_path)
|
|
return None
|
|
|
|
class _SourceFinderDetails:
|
|
|
|
loader = _SourceFileLoader
|
|
supports_packages = True
|
|
|
|
def __init__(self):
|
|
self.suffixes = _suffix_list(imp.PY_SOURCE)
|
|
|
|
class _SourcelessFinderDetails:
|
|
|
|
loader = _SourcelessFileLoader
|
|
supports_packages = True
|
|
|
|
def __init__(self):
|
|
self.suffixes = _suffix_list(imp.PY_COMPILED)
|
|
|
|
|
|
class _ExtensionFinderDetails:
|
|
|
|
loader = _ExtensionFileLoader
|
|
supports_packages = False
|
|
|
|
def __init__(self):
|
|
self.suffixes = _suffix_list(imp.C_EXTENSION)
|
|
|
|
|
|
# Import itself ###############################################################
|
|
|
|
def _file_path_hook(path):
|
|
"""If the path is a directory, return a file-based finder."""
|
|
if _path_isdir(path):
|
|
return _FileFinder(path, _ExtensionFinderDetails(),
|
|
_SourceFinderDetails(),
|
|
_SourcelessFinderDetails())
|
|
else:
|
|
raise ImportError("only directories are supported")
|
|
|
|
|
|
_DEFAULT_PATH_HOOK = _file_path_hook
|
|
|
|
class _DefaultPathFinder(PathFinder):
|
|
|
|
"""Subclass of PathFinder that implements implicit semantics for
|
|
__import__."""
|
|
|
|
@classmethod
|
|
def _path_hooks(cls, path):
|
|
"""Search sys.path_hooks as well as implicit path hooks."""
|
|
try:
|
|
return super()._path_hooks(path)
|
|
except ImportError:
|
|
implicit_hooks = [_DEFAULT_PATH_HOOK, imp.NullImporter]
|
|
return super()._path_hooks(path, implicit_hooks)
|
|
|
|
@classmethod
|
|
def _path_importer_cache(cls, path):
|
|
"""Use the default path hook when None is stored in
|
|
sys.path_importer_cache."""
|
|
return super()._path_importer_cache(path, _DEFAULT_PATH_HOOK)
|
|
|
|
|
|
class _ImportLockContext:
|
|
|
|
"""Context manager for the import lock."""
|
|
|
|
def __enter__(self):
|
|
"""Acquire the import lock."""
|
|
imp.acquire_lock()
|
|
|
|
def __exit__(self, exc_type, exc_value, exc_traceback):
|
|
"""Release the import lock regardless of any raised exceptions."""
|
|
imp.release_lock()
|
|
|
|
|
|
_IMPLICIT_META_PATH = [BuiltinImporter, FrozenImporter, _DefaultPathFinder]
|
|
|
|
_ERR_MSG = 'No module named {!r}'
|
|
|
|
def _gcd_import(name, package=None, level=0):
|
|
"""Import and return the module based on its name, the package the call is
|
|
being made from, and the level adjustment.
|
|
|
|
This function represents the greatest common denominator of functionality
|
|
between import_module and __import__. This includes setting __package__ if
|
|
the loader did not.
|
|
|
|
"""
|
|
if package:
|
|
if not hasattr(package, 'rindex'):
|
|
raise ValueError("__package__ not set to a string")
|
|
elif package not in sys.modules:
|
|
msg = ("Parent module {0!r} not loaded, cannot perform relative "
|
|
"import")
|
|
raise SystemError(msg.format(package))
|
|
if not name and level == 0:
|
|
raise ValueError("Empty module name")
|
|
if level > 0:
|
|
dot = len(package)
|
|
for x in range(level, 1, -1):
|
|
try:
|
|
dot = package.rindex('.', 0, dot)
|
|
except ValueError:
|
|
raise ValueError("attempted relative import beyond "
|
|
"top-level package")
|
|
if name:
|
|
name = "{0}.{1}".format(package[:dot], name)
|
|
else:
|
|
name = package[:dot]
|
|
with _ImportLockContext():
|
|
try:
|
|
module = sys.modules[name]
|
|
if module is None:
|
|
message = ("import of {} halted; "
|
|
"None in sys.modules".format(name))
|
|
raise ImportError(message)
|
|
return module
|
|
except KeyError:
|
|
pass
|
|
parent = name.rpartition('.')[0]
|
|
path = None
|
|
if parent:
|
|
if parent not in sys.modules:
|
|
_gcd_import(parent)
|
|
# Backwards-compatibility; be nicer to skip the dict lookup.
|
|
parent_module = sys.modules[parent]
|
|
try:
|
|
path = parent_module.__path__
|
|
except AttributeError:
|
|
msg = (_ERR_MSG + '; {} is not a package').format(name, parent)
|
|
raise ImportError(msg)
|
|
meta_path = sys.meta_path + _IMPLICIT_META_PATH
|
|
for finder in meta_path:
|
|
loader = finder.find_module(name, path)
|
|
if loader is not None:
|
|
# The parent import may have already imported this module.
|
|
if name not in sys.modules:
|
|
loader.load_module(name)
|
|
break
|
|
else:
|
|
raise ImportError(_ERR_MSG.format(name))
|
|
# Backwards-compatibility; be nicer to skip the dict lookup.
|
|
module = sys.modules[name]
|
|
if parent:
|
|
# Set the module as an attribute on its parent.
|
|
setattr(parent_module, name.rpartition('.')[2], module)
|
|
# Set __package__ if the loader did not.
|
|
if not hasattr(module, '__package__') or module.__package__ is None:
|
|
# Watch out for what comes out of sys.modules to not be a module,
|
|
# e.g. an int.
|
|
try:
|
|
module.__package__ = module.__name__
|
|
if not hasattr(module, '__path__'):
|
|
module.__package__ = module.__package__.rpartition('.')[0]
|
|
except AttributeError:
|
|
pass
|
|
return module
|
|
|
|
|
|
def __import__(name, globals={}, locals={}, fromlist=[], level=0):
|
|
"""Import a module.
|
|
|
|
The 'globals' argument is used to infer where the import is occuring from
|
|
to handle relative imports. The 'locals' argument is ignored. The
|
|
'fromlist' argument specifies what should exist as attributes on the module
|
|
being imported (e.g. ``from module import <fromlist>``). The 'level'
|
|
argument represents the package location to import from in a relative
|
|
import (e.g. ``from ..pkg import mod`` would have a 'level' of 2).
|
|
|
|
"""
|
|
if not hasattr(name, 'rpartition'):
|
|
raise TypeError("module name must be str, not {}".format(type(name)))
|
|
if level == 0:
|
|
module = _gcd_import(name)
|
|
else:
|
|
# __package__ is not guaranteed to be defined or could be set to None
|
|
# to represent that its proper value is unknown
|
|
package = globals.get('__package__')
|
|
if package is None:
|
|
package = globals['__name__']
|
|
if '__path__' not in globals:
|
|
package = package.rpartition('.')[0]
|
|
module = _gcd_import(name, package, level)
|
|
# The hell that is fromlist ...
|
|
if not fromlist:
|
|
# Return up to the first dot in 'name'. This is complicated by the fact
|
|
# that 'name' may be relative.
|
|
if level == 0:
|
|
return sys.modules[name.partition('.')[0]]
|
|
elif not name:
|
|
return module
|
|
else:
|
|
cut_off = len(name) - len(name.partition('.')[0])
|
|
return sys.modules[module.__name__[:-cut_off]]
|
|
else:
|
|
# If a package was imported, try to import stuff from fromlist.
|
|
if hasattr(module, '__path__'):
|
|
if '*' in fromlist and hasattr(module, '__all__'):
|
|
fromlist = list(fromlist)
|
|
fromlist.remove('*')
|
|
fromlist.extend(module.__all__)
|
|
for x in (y for y in fromlist if not hasattr(module,y)):
|
|
try:
|
|
_gcd_import('{0}.{1}'.format(module.__name__, x))
|
|
except ImportError:
|
|
pass
|
|
return module
|