"""Abstract base classes related to import."""
from . import _bootstrap
from . import _bootstrap_external
from . import machinery
try:
 import _frozen_importlib
except ImportError as exc:
 if exc.name != '_frozen_importlib':
 raise
 _frozen_importlib = None
try:
 import _frozen_importlib_external
except ImportError as exc:
 _frozen_importlib_external = _bootstrap_external
import abc
import warnings


def _register(abstract_cls, *classes):
 for cls in classes:
 abstract_cls.register(cls)
 if _frozen_importlib is not None:
 try:
 frozen_cls = getattr(_frozen_importlib, cls.__name__)
 except AttributeError:
 frozen_cls = getattr(_frozen_importlib_external, 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.

 Deprecated since Python 3.3
 """

 @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."""

 # We don't define find_spec() here since that would break
 # hasattr checks we do to support backward compatibility.

 def find_module(self, fullname, path):
 """Return a loader for the module.

 If no module is found, return None. The fullname is a str and
 the path is a list of strings or None.

 This method is deprecated since Python 3.4 in favor of
 finder.find_spec(). If find_spec() exists then backwards-compatible
 functionality is provided for this method.

 """
 warnings.warn("MetaPathFinder.find_module() is deprecated since Python "
 "3.4 in favor of MetaPathFinder.find_spec() "
 "(available since 3.4)",
 DeprecationWarning,
 stacklevel=2)
 if not hasattr(self, 'find_spec'):
 return None
 found = self.find_spec(fullname, path)
 return found.loader if found is not None else 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."""

 # We don't define find_spec() here since that would break
 # hasattr checks we do to support backward compatibility.

 def find_loader(self, fullname):
 """Return (loader, namespace portion) for the path entry.

 The fullname is a str. The namespace portion is a sequence of
 path entries contributing to part of a namespace package. The
 sequence may be empty. If loader is not None, the portion will
 be ignored.

 The portion will be discarded if another path entry finder
 locates the module as a normal module or package.

 This method is deprecated since Python 3.4 in favor of
 finder.find_spec(). If find_spec() is provided than backwards-compatible
 functionality is provided.
 """
 warnings.warn("PathEntryFinder.find_loader() is deprecated since Python "
 "3.4 in favor of PathEntryFinder.find_spec() "
 "(available since 3.4)",
 DeprecationWarning,
 stacklevel=2)
 if not hasattr(self, 'find_spec'):
 return None, []
 found = self.find_spec(fullname)
 if found is not None:
 if not found.submodule_search_locations:
 portions = []
 else:
 portions = found.submodule_search_locations
 return found.loader, portions
 else:
 return None, []

 find_module = _bootstrap_external._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."""

 def create_module(self, spec):
 """Return a module to initialize and into which to load.

 This method should raise ImportError if anything prevents it
 from creating a new module. It may return None to indicate
 that the spec should create the new module.
 """
 # By default, defer to default semantics for the new module.
 return None

 # We don't define exec_module() here since that would break
 # hasattr checks we do to support backward compatibility.

 def load_module(self, fullname):
 """Return the loaded module.

 The module must be added to sys.modules and have import-related
 attributes set properly. The fullname is a str.

 ImportError is raised on failure.

 This method is deprecated in favor of loader.exec_module(). If
 exec_module() exists then it is used to provide a backwards-compatible
 functionality for this method.

 """
 if not hasattr(self, 'exec_module'):
 raise ImportError
 return _bootstrap._load_module_shim(self, fullname)

 def module_repr(self, module):
 """Return a module's repr.

 Used by the module type when the method does not raise
 NotImplementedError.

 This method is deprecated.

 """
 # The exception will cause ModuleType.__repr__ to ignore this method.
 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 OSError


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.

 """

 def is_package(self, fullname):
 """Optional method which when implemented should return whether the
 module is a package. The fullname is a str. Returns a bool.

 Raises ImportError if the module cannot be found.
 """
 raise ImportError

 def get_code(self, fullname):
 """Method which returns the code object for the module.

 The fullname is a str. Returns a types.CodeType if possible, else
 returns None if a code object does not make sense
 (e.g. built-in module). Raises ImportError if the module cannot be
 found.
 """
 source = self.get_source(fullname)
 if source is None:
 return None
 return self.source_to_code(source)

 @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

 @staticmethod
 def source_to_code(data, path='<string>'):
 """Compile 'data' into a code object.

 The 'data' argument can be anything that compile() can handle. The'path'
 argument should be where the data was retrieved (when applicable)."""
 return compile(data, path, 'exec', dont_inherit=True)

 exec_module = _bootstrap_external._LoaderBasics.exec_module
 load_module = _bootstrap_external._LoaderBasics.load_module

_register(InspectLoader, machinery.BuiltinImporter, machinery.FrozenImporter)


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

 def get_code(self, fullname):
 """Method to return the code object for fullname.

 Should return None if not applicable (e.g. built-in module).
 Raise ImportError if the module cannot be found.
 """
 source = self.get_source(fullname)
 if source is None:
 return None
 try:
 path = self.get_filename(fullname)
 except ImportError:
 return self.source_to_code(source)
 else:
 return self.source_to_code(source, path)

_register(ExecutionLoader, machinery.ExtensionFileLoader)


class FileLoader(_bootstrap_external.FileLoader, ResourceLoader, ExecutionLoader):

 """Abstract base class partially implementing the ResourceLoader and
 ExecutionLoader ABCs."""

_register(FileLoader, machinery.SourceFileLoader,
 machinery.SourcelessFileLoader)


class SourceLoader(_bootstrap_external.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 OSError
 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 OSError
 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)


class ResourceReader(metaclass=abc.ABCMeta):

 """Abstract base class to provide resource-reading support.

 Loaders that support resource reading are expected to implement
 the ``get_resource_reader(fullname)`` method and have it either return None
 or an object compatible with this ABC.
 """

 @abc.abstractmethod
 def open_resource(self, resource):
 """Return an opened, file-like object for binary reading.

 The 'resource' argument is expected to represent only a file name
 and thus not contain any subdirectory components.

 If the resource cannot be found, FileNotFoundError is raised.
 """
 raise FileNotFoundError

 @abc.abstractmethod
 def resource_path(self, resource):
 """Return the file system path to the specified resource.

 The 'resource' argument is expected to represent only a file name
 and thus not contain any subdirectory components.

 If the resource does not exist on the file system, raise
 FileNotFoundError.
 """
 raise FileNotFoundError

 @abc.abstractmethod
 def is_resource(self, name):
 """Return True if the named 'name' is consider a resource."""
 raise FileNotFoundError

 @abc.abstractmethod
 def contents(self):
 """Return an iterable of strings over the contents of the package."""
 return []


_register(ResourceReader, machinery.SourceFileLoader)