324 lines
10 KiB
Python
324 lines
10 KiB
Python
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"""Abstract base classes related to import."""
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from . import _bootstrap
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from . import machinery
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try:
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import _frozen_importlib
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except ImportError as exc:
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if exc.name != '_frozen_importlib':
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raise
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_frozen_importlib = None
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import abc
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def _register(abstract_cls, *classes):
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for cls in classes:
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abstract_cls.register(cls)
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if _frozen_importlib is not None:
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frozen_cls = getattr(_frozen_importlib, cls.__name__)
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abstract_cls.register(frozen_cls)
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class Finder(metaclass=abc.ABCMeta):
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"""Legacy abstract base class for import finders.
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It may be subclassed for compatibility with legacy third party
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reimplementations of the import system. Otherwise, finder
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implementations should derive from the more specific MetaPathFinder
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or PathEntryFinder ABCs.
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"""
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@abc.abstractmethod
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def find_module(self, fullname, path=None):
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"""An abstract method that should find a module.
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The fullname is a str and the optional path is a str or None.
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Returns a Loader object or None.
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"""
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class MetaPathFinder(Finder):
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"""Abstract base class for import finders on sys.meta_path."""
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# We don't define find_spec() here since that would break
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# hasattr checks we do to support backward compatibility.
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def find_module(self, fullname, path):
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"""Return a loader for the module.
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If no module is found, return None. The fullname is a str and
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the path is a list of strings or None.
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This method is deprecated in favor of finder.find_spec(). If find_spec()
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exists then backwards-compatible functionality is provided for this
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method.
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"""
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if not hasattr(self, 'find_spec'):
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return None
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found = self.find_spec(fullname, path)
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return found.loader if found is not None else None
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def invalidate_caches(self):
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"""An optional method for clearing the finder's cache, if any.
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This method is used by importlib.invalidate_caches().
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"""
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_register(MetaPathFinder, machinery.BuiltinImporter, machinery.FrozenImporter,
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machinery.PathFinder, machinery.WindowsRegistryFinder)
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class PathEntryFinder(Finder):
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"""Abstract base class for path entry finders used by PathFinder."""
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# We don't define find_spec() here since that would break
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# hasattr checks we do to support backward compatibility.
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def find_loader(self, fullname):
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"""Return (loader, namespace portion) for the path entry.
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The fullname is a str. The namespace portion is a sequence of
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path entries contributing to part of a namespace package. The
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sequence may be empty. If loader is not None, the portion will
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be ignored.
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The portion will be discarded if another path entry finder
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locates the module as a normal module or package.
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This method is deprecated in favor of finder.find_spec(). If find_spec()
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is provided than backwards-compatible functionality is provided.
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"""
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if not hasattr(self, 'find_spec'):
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return None, []
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found = self.find_spec(fullname)
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if found is not None:
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if not found.submodule_search_locations:
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portions = []
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else:
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portions = found.submodule_search_locations
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return found.loader, portions
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else:
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return None, []
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find_module = _bootstrap._find_module_shim
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def invalidate_caches(self):
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"""An optional method for clearing the finder's cache, if any.
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This method is used by PathFinder.invalidate_caches().
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"""
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_register(PathEntryFinder, machinery.FileFinder)
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class Loader(metaclass=abc.ABCMeta):
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"""Abstract base class for import loaders."""
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def create_module(self, spec):
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"""Return a module to initialize and into which to load.
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This method should raise ImportError if anything prevents it
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from creating a new module. It may return None to indicate
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that the spec should create the new module.
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create_module() is optional.
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"""
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# By default, defer to _SpecMethods.create() for the new module.
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return None
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# We don't define exec_module() here since that would break
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# hasattr checks we do to support backward compatibility.
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def load_module(self, fullname):
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"""Return the loaded module.
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The module must be added to sys.modules and have import-related
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attributes set properly. The fullname is a str.
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ImportError is raised on failure.
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This method is deprecated in favor of loader.exec_module(). If
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exec_module() exists then it is used to provide a backwards-compatible
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functionality for this method.
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"""
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if not hasattr(self, 'exec_module'):
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raise ImportError
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return _bootstrap._load_module_shim(self, fullname)
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def module_repr(self, module):
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"""Return a module's repr.
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Used by the module type when the method does not raise
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NotImplementedError.
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This method is deprecated.
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"""
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# The exception will cause ModuleType.__repr__ to ignore this method.
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raise NotImplementedError
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class ResourceLoader(Loader):
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"""Abstract base class for loaders which can return data from their
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back-end storage.
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This ABC represents one of the optional protocols specified by PEP 302.
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"""
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@abc.abstractmethod
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def get_data(self, path):
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"""Abstract method which when implemented should return the bytes for
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the specified path. The path must be a str."""
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raise IOError
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class InspectLoader(Loader):
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"""Abstract base class for loaders which support inspection about the
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modules they can load.
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This ABC represents one of the optional protocols specified by PEP 302.
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"""
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def is_package(self, fullname):
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"""Optional method which when implemented should return whether the
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module is a package. The fullname is a str. Returns a bool.
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Raises ImportError if the module cannot be found.
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"""
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raise ImportError
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def get_code(self, fullname):
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"""Method which returns the code object for the module.
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The fullname is a str. Returns a types.CodeType if possible, else
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returns None if a code object does not make sense
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(e.g. built-in module). Raises ImportError if the module cannot be
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found.
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"""
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source = self.get_source(fullname)
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if source is None:
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return None
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return self.source_to_code(source)
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@abc.abstractmethod
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def get_source(self, fullname):
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"""Abstract method which should return the source code for the
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module. The fullname is a str. Returns a str.
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Raises ImportError if the module cannot be found.
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"""
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raise ImportError
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def source_to_code(self, data, path='<string>'):
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"""Compile 'data' into a code object.
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The 'data' argument can be anything that compile() can handle. The'path'
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argument should be where the data was retrieved (when applicable)."""
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return compile(data, path, 'exec', dont_inherit=True)
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exec_module = _bootstrap._LoaderBasics.exec_module
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load_module = _bootstrap._LoaderBasics.load_module
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_register(InspectLoader, machinery.BuiltinImporter, machinery.FrozenImporter)
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class ExecutionLoader(InspectLoader):
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"""Abstract base class for loaders that wish to support the execution of
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modules as scripts.
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This ABC represents one of the optional protocols specified in PEP 302.
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"""
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@abc.abstractmethod
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def get_filename(self, fullname):
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"""Abstract method which should return the value that __file__ is to be
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set to.
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Raises ImportError if the module cannot be found.
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"""
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raise ImportError
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def get_code(self, fullname):
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"""Method to return the code object for fullname.
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Should return None if not applicable (e.g. built-in module).
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Raise ImportError if the module cannot be found.
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"""
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source = self.get_source(fullname)
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if source is None:
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return None
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try:
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path = self.get_filename(fullname)
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except ImportError:
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return self.source_to_code(source)
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else:
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return self.source_to_code(source, path)
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_register(ExecutionLoader, machinery.ExtensionFileLoader)
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class FileLoader(_bootstrap.FileLoader, ResourceLoader, ExecutionLoader):
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"""Abstract base class partially implementing the ResourceLoader and
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ExecutionLoader ABCs."""
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_register(FileLoader, machinery.SourceFileLoader,
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machinery.SourcelessFileLoader)
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class SourceLoader(_bootstrap.SourceLoader, ResourceLoader, ExecutionLoader):
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"""Abstract base class for loading source code (and optionally any
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corresponding bytecode).
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To support loading from source code, the abstractmethods inherited from
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ResourceLoader and ExecutionLoader need to be implemented. To also support
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loading from bytecode, the optional methods specified directly by this ABC
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is required.
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Inherited abstractmethods not implemented in this ABC:
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* ResourceLoader.get_data
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* ExecutionLoader.get_filename
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"""
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def path_mtime(self, path):
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"""Return the (int) modification time for the path (str)."""
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if self.path_stats.__func__ is SourceLoader.path_stats:
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raise IOError
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return int(self.path_stats(path)['mtime'])
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def path_stats(self, path):
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"""Return a metadata dict for the source pointed 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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"""
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if self.path_mtime.__func__ is SourceLoader.path_mtime:
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raise IOError
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return {'mtime': self.path_mtime(path)}
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def set_data(self, path, data):
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"""Write the bytes to the path (if possible).
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Accepts a str path and data as bytes.
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Any needed intermediary directories are to be created. If for some
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reason the file cannot be written because of permissions, fail
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silently.
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"""
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_register(SourceLoader, machinery.SourceFileLoader)
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