"""Abstract base classes related to import.""" from . import _bootstrap from . import machinery try: import _frozen_importlib except ImportError as exc: if exc.name != '_frozen_importlib': raise _frozen_importlib = None import abc import imp import marshal import sys import tokenize import warnings def _register(abstract_cls, *classes): for cls in classes: abstract_cls.register(cls) if _frozen_importlib is not None: frozen_cls = getattr(_frozen_importlib, cls.__name__) abstract_cls.register(frozen_cls) class Finder(metaclass=abc.ABCMeta): """Legacy abstract base class for import finders. It may be subclassed for compatibility with legacy third party reimplementations of the import system. Otherwise, finder implementations should derive from the more specific MetaPathFinder or PathEntryFinder ABCs. """ @abc.abstractmethod def find_module(self, fullname, path=None): """An abstract method that should find a module. The fullname is a str and the optional path is a str or None. Returns a Loader object or None. """ class MetaPathFinder(Finder): """Abstract base class for import finders on sys.meta_path.""" @abc.abstractmethod def find_module(self, fullname, path): """Abstract method which, when implemented, should find a module. The fullname is a str and the path is a list of strings or None. Returns a Loader object or None. """ def invalidate_caches(self): """An optional method for clearing the finder's cache, if any. This method is used by importlib.invalidate_caches(). """ _register(MetaPathFinder, machinery.BuiltinImporter, machinery.FrozenImporter, machinery.PathFinder, machinery.WindowsRegistryFinder) class PathEntryFinder(Finder): """Abstract base class for path entry finders used by PathFinder.""" @abc.abstractmethod def find_loader(self, fullname): """Abstract method which, when implemented, returns a module loader or a possible part of a namespace. The fullname is a str. Returns a 2-tuple of (Loader, portion) where portion is a sequence of file system locations contributing to part of a namespace package. The sequence may be empty and the loader may be None. """ return None, [] find_module = _bootstrap._find_module_shim def invalidate_caches(self): """An optional method for clearing the finder's cache, if any. This method is used by PathFinder.invalidate_caches(). """ _register(PathEntryFinder, machinery.FileFinder) class Loader(metaclass=abc.ABCMeta): """Abstract base class for import loaders. The optional method module_repr(module) may be defined to provide a repr for a module when appropriate (see PEP 420). The __repr__() method on the module type will use the method as appropriate. """ @abc.abstractmethod def load_module(self, fullname): """Abstract method which when implemented should load a module. The fullname is a str. ImportError is raised on failure. """ raise ImportError def module_repr(self, module): """Return a module's repr. Used by the module type when implemented without raising an exception. """ raise NotImplementedError class ResourceLoader(Loader): """Abstract base class for loaders which can return data from their back-end storage. This ABC represents one of the optional protocols specified by PEP 302. """ @abc.abstractmethod def get_data(self, path): """Abstract method which when implemented should return the bytes for the specified path. The path must be a str.""" raise IOError class InspectLoader(Loader): """Abstract base class for loaders which support inspection about the modules they can load. This ABC represents one of the optional protocols specified by PEP 302. """ @abc.abstractmethod def is_package(self, fullname): """Abstract method which when implemented should return whether the module is a package. The fullname is a str. Returns a bool. Raises ImportError is the module cannot be found. """ raise ImportError @abc.abstractmethod def get_code(self, fullname): """Abstract method which when implemented should return the code object for the module. The fullname is a str. Returns a types.CodeType. Raises ImportError if the module cannot be found. """ raise ImportError @abc.abstractmethod def get_source(self, fullname): """Abstract method which should return the source code for the module. The fullname is a str. Returns a str. Raises ImportError if the module cannot be found. """ raise ImportError _register(InspectLoader, machinery.BuiltinImporter, machinery.FrozenImporter, machinery.ExtensionFileLoader) class ExecutionLoader(InspectLoader): """Abstract base class for loaders that wish to support the execution of modules as scripts. This ABC represents one of the optional protocols specified in PEP 302. """ @abc.abstractmethod def get_filename(self, fullname): """Abstract method which should return the value that __file__ is to be set to. Raises ImportError if the module cannot be found. """ raise ImportError class FileLoader(_bootstrap.FileLoader, ResourceLoader, ExecutionLoader): """Abstract base class partially implementing the ResourceLoader and ExecutionLoader ABCs.""" _register(FileLoader, machinery.SourceFileLoader, machinery.SourcelessFileLoader) class SourceLoader(_bootstrap.SourceLoader, ResourceLoader, ExecutionLoader): """Abstract base class for loading source code (and optionally any corresponding bytecode). To support loading from source code, the abstractmethods inherited from ResourceLoader and ExecutionLoader need to be implemented. To also support loading from bytecode, the optional methods specified directly by this ABC is required. Inherited abstractmethods not implemented in this ABC: * ResourceLoader.get_data * ExecutionLoader.get_filename """ def path_mtime(self, path): """Return the (int) modification time for the path (str).""" if self.path_stats.__func__ is SourceLoader.path_stats: raise IOError return int(self.path_stats(path)['mtime']) def path_stats(self, path): """Return a metadata dict for the source pointed to by the path (str). Possible keys: - 'mtime' (mandatory) is the numeric timestamp of last source code modification; - 'size' (optional) is the size in bytes of the source code. """ if self.path_mtime.__func__ is SourceLoader.path_mtime: raise IOError return {'mtime': self.path_mtime(path)} def set_data(self, path, data): """Write the bytes to the path (if possible). Accepts a str path and data as bytes. Any needed intermediary directories are to be created. If for some reason the file cannot be written because of permissions, fail silently. """ _register(SourceLoader, machinery.SourceFileLoader)