gsoc_import_engine / Lib / importlib / engine.py

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# Required built-in modules.
try:
    import posix as _os
except ImportError:
    try:
        import nt as _os
    except ImportError:
        try:
            import os2 as _os
        except ImportError:
            raise ImportError('posix, nt, or os2 module required for importlib')
import imp, sys, marshal, errno, _io, os
import _warnings
from os import sep as path_sep

# __all__ = [ ImportEngine, GlobalImportEngine, sysengine ]

# XXX Could also expose Modules/getpath.c:joinpath()
def _path_join(*args):
    """Replacement for os.path.join."""
    return path_sep.join(x[:-len(path_sep)] if x.endswith(path_sep) else x
                            for x in args if x)

def _case_ok(directory, check):
    """Check if the directory contains something matching 'check'.

    No check is done if the file/directory exists or not.

    """
    if 'PYTHONCASEOK' in os.environ:
        return True
    elif check in os.listdir(directory if directory else os.getcwd()):
        return True
    return False


def _w_long(x):
    """Convert a 32-bit integer to little-endian.

    XXX Temporary until marshal's long functions are exposed.

    """
    x = int(x)
    int_bytes = []
    int_bytes.append(x & 0xFF)
    int_bytes.append((x >> 8) & 0xFF)
    int_bytes.append((x >> 16) & 0xFF)
    int_bytes.append((x >> 24) & 0xFF)
    return bytearray(int_bytes)


def _r_long(int_bytes):
    """Convert 4 bytes in little-endian to an integer.

    XXX Temporary until marshal's long function are exposed.

    """
    x = int_bytes[0]
    x |= int_bytes[1] << 8
    x |= int_bytes[2] << 16
    x |= int_bytes[3] << 24
    return x

def _path_exists(path):
    """Replacement for os.path.exists."""
    try:
        _os.stat(path)
    except OSError:
        return False
    else:
        return True


def _path_is_mode_type(path, mode):
    """Test whether the path is the specified mode type."""
    try:
        stat_info = _os.stat(path)
    except OSError:
        return False
    return (stat_info.st_mode & 0o170000) == mode


# XXX Could also expose Modules/getpath.c:isfile()
def _path_isfile(path):
    """Replacement for os.path.isfile."""
    return _path_is_mode_type(path, 0o100000)


# XXX Could also expose Modules/getpath.c:isdir()
def _path_isdir(path):
    """Replacement for os.path.isdir."""
    if not path:
        path = _os.getcwd()
    return _path_is_mode_type(path, 0o040000)


def _path_without_ext(path, ext_type):
    """Replacement for os.path.splitext()[0]."""
    for suffix in _suffix_list(ext_type):
        if path.endswith(suffix):
            return path[:-len(suffix)]
    else:
        raise ValueError("path is not of the specified type")


def _path_absolute(path):
    """Replacement for os.path.abspath."""
    if not path:
        path = _os.getcwd()
    try:
        return _os._getfullpathname(path)
    except AttributeError:
        if path.startswith('/'):
            return path
        else:
            return _path_join(_os.getcwd(), path)


def _wrap(new, old):
    """Simple substitute for functools.wraps."""
    for replace in ['__module__', '__name__', '__doc__']:
        setattr(new, replace, getattr(old, replace))
    new.__dict__.update(old.__dict__)


code_type = type(_wrap.__code__)

# Finder/loader utility code ##################################################

def set_package(fxn):
    """Set __package__ on the returned module."""
    def wrapper(*args, **kwargs):
        module = fxn(*args, **kwargs)
        if not hasattr(module, '__package__') or module.__package__ is None:
            module.__package__ = module.__name__
            if not hasattr(module, '__path__'):
                module.__package__ = module.__package__.rpartition('.')[0]
        return module
    _wrap(wrapper, fxn)
    return wrapper


def set_loader(fxn):
    """Set __loader__ on the returned module."""
    def wrapper(self, *args, **kwargs):
        module = fxn(self, *args, **kwargs)
        if not hasattr(module, '__loader__'):
            module.__loader__ = self
        return module
    _wrap(wrapper, fxn)
    return wrapper


def module_for_loader(fxn):
    """Decorator to handle selecting the proper module for loaders.

    The decorated function is passed the module to use instead of the module
    name. The module passed in to the function is either from engine.modules if
    it already exists or is a new module which has __name__ set and is inserted
    into engine.modules. If an exception is raised and the decorator created the
    module it is subsequently removed from engine.modules.

    The decorator assumes that the decorated function takes the module name as
    the second argument and an ImportEngine object as the third.

    """
    def decorated(self, fullname, engine, *args, **kwargs):
        if engine:
            modules = engine.modules
        else:
            modules = sys.modules

        module = modules.get(fullname)

        is_reload = bool(module)
        if not is_reload:
            # This must be done before open() is called as the 'io' module
            # implicitly imports 'locale' and would otherwise trigger an
            # infinite loop.
            module = imp.new_module(fullname)
            modules[fullname] = module
        try:
            return fxn(self, module, engine, *args, **kwargs)
        except:
            if not is_reload:
                del modules[fullname]
            raise
    _wrap(decorated, fxn)
    return decorated


def _check_name(method):
    """Decorator to verify that the module being requested matches the one the
    loader can handle.

    The first argument (self) must define _name which the second argument is
    compared against. If the comparison fails then ImportError is raised.

    """
    def inner(self, name, *args, **kwargs):
        if self._name != name:
            raise ImportError("loader cannot handle %s" % name)
        return method(self, name, *args, **kwargs)
    _wrap(inner, method)
    return inner


def _requires_builtin(fxn):
    """Decorator to verify the named module is built-in."""
    def wrapper(self, fullname, engine=None):
        if fullname not in sys.builtin_module_names:
            raise ImportError("{0} is not a built-in module".format(fullname))
        return fxn(self, fullname, engine)
    _wrap(wrapper, fxn)
    return wrapper


def _requires_frozen(fxn):
    """Decorator to verify the named module is frozen."""
    def wrapper(self, fullname):
        if not imp.is_frozen(fullname):
            raise ImportError("{0} is not a frozen module".format(fullname))
        return fxn(self, fullname)
    _wrap(wrapper, fxn)
    return wrapper


def _suffix_list(suffix_type):
    """Return a list of file suffixes based on the imp file type."""
    return [suffix[0] for suffix in imp.get_suffixes()
            if suffix[2] == suffix_type]


# Loaders #####################################################################

class NullImporter:
    def __init__(self, path):
        if not len(path):
            raise ImportError("empty pathname")
        if _path_isdir(path):
            raise ImportError("existing directory")
    
    def find_module(cls, fullname, engine=None):
        return None

class BuiltinImporter:

    """Meta path import for built-in modules.

    All methods are either class or static methods to avoid the need to
    instantiate the class.

    """

    @classmethod
    def find_module(cls, fullname, path=None, engine=None):
        """Find the built-in module.

        If 'path' is ever specified then the search is considered a failure.

        """
        if path is not None:
            return None
        return cls if imp.is_builtin(fullname) else None

    @classmethod
    @set_package
    @set_loader
    @_requires_builtin
    def load_module(cls, fullname, engine=None):
        """Load a built-in module."""
        is_reload = fullname in sys.modules
        try:
            module = imp.init_builtin(fullname)
            if engine:
                engine.modules[fullname] = sys.modules[fullname]
            return module
        except:
            if not is_reload and fullname in sys.modules:
                del sys.modules[fullname]
                if engine and fullname in engine.modules:
                    del engine.modules[fullname]
            raise

    @classmethod
    @_requires_builtin
    def get_code(cls, fullname):
        """Return None as built-in modules do not have code objects."""
        return None

    @classmethod
    @_requires_builtin
    def get_source(cls, fullname):
        """Return None as built-in modules do not have source code."""
        return None

    @classmethod
    @_requires_builtin
    def is_package(cls, fullname):
        """Return None as built-in modules are never packages."""
        return False


class FrozenImporter:

    """Meta path import for frozen modules.

    All methods are either class or static methods to avoid the need to
    instantiate the class.

    """

    @classmethod
    def find_module(cls, fullname, path=None, engine=None):
        """Find a frozen module."""
        return cls if imp.is_frozen(fullname) else None

    @classmethod
    @set_package
    @set_loader
    @_requires_frozen
    def load_module(cls, fullname, engine=None):
        """Load a frozen module."""
        if not engine:
            engine = sysengine

        is_reload = fullname in engine.modules
        try:
            return imp.init_frozen(fullname)
        except:
            if not is_reload and fullname in engine.modules:
                del engine.modules[fullname]
            raise

    @classmethod
    @_requires_frozen
    def get_code(cls, fullname):
        """Return the code object for the frozen module."""
        return imp.get_frozen_object(fullname)

    @classmethod
    @_requires_frozen
    def get_source(cls, fullname):
        """Return None as frozen modules do not have source code."""
        return None

    @classmethod
    @_requires_frozen
    def is_package(cls, fullname):
        """Return if the frozen module is a package."""
        return imp.is_frozen_package(fullname)


class _LoaderBasics:
    
    """Base class of common code needed by both SourceLoader and
    _SourcelessFileLoader."""

    def is_package(self, fullname):
        """Concrete implementation of InspectLoader.is_package by checking if
        the path returned by get_filename has a filename of '__init__.py'."""
        filename = self.get_filename(fullname).rpartition(path_sep)[2]
        return filename.rsplit('.', 1)[0] == '__init__'

    def _bytes_from_bytecode(self, fullname, data, source_mtime):
        """Return the marshalled bytes from bytecode, verifying the magic
        number and timestamp along the way.

        If source_mtime is None then skip the timestamp check.

        """
        magic = data[:4]
        raw_timestamp = data[4:8]
        if len(magic) != 4 or magic != imp.get_magic():
            raise ImportError("bad magic number in {}".format(fullname))
        elif len(raw_timestamp) != 4:
            raise EOFError("bad timestamp in {}".format(fullname))
        elif source_mtime is not None:
            if marshal._r_long(raw_timestamp) != source_mtime:
                raise ImportError("bytecode is stale for {}".format(fullname))
        # Can't return the code object as errors from marshal loading need to
        # propagate even when source is available.
        return data[8:]

    @module_for_loader
    def _load_module(self, module, engine, *, sourceless=False):
        """Helper for load_module able to handle either source or sourceless
        loading."""
        name = module.__name__
        code_object = self.get_code(name)
        module.__file__ = self.get_filename(name)
        if not sourceless:
            module.__cached__ = imp.cache_from_source(module.__file__)
        else:
            module.__cached__ = module.__file__
        module.__package__ = name
        if self.is_package(name):
            module.__path__ = [module.__file__.rsplit(path_sep, 1)[0]]
        else:
            module.__package__ = module.__package__.rpartition('.')[0]
        module.__loader__ = self
        exec(code_object, module.__dict__)
        return module


class SourceLoader(_LoaderBasics):

    def path_mtime(self, path):
        """Optional method that returns the modification time (an int) for the
        specified path, where path is a str.

        Implementing this method allows the loader to read bytecode files.

        """
        raise NotImplementedError

    def set_data(self, path, data):
        """Optional method which writes data (bytes) to a file path (a str).

        Implementing this method allows for the writing of bytecode files.

        """
        raise NotImplementedError


    def get_source(self, fullname):
        """Concrete implementation of InspectLoader.get_source."""
        import tokenize
        path = self.get_filename(fullname)
        try:
            source_bytes = self.get_data(path)
        except IOError:
            raise ImportError("source not available through get_data()")
        encoding = tokenize.detect_encoding(_io.BytesIO(source_bytes).readline)
        newline_decoder = _io.IncrementalNewlineDecoder(None, True)
        return newline_decoder.decode(source_bytes.decode(encoding[0]))

    def get_code(self, fullname):
        """Concrete implementation of InspectLoader.get_code.

        Reading of bytecode requires path_mtime to be implemented. To write
        bytecode, set_data must also be implemented.

        """
        source_path = self.get_filename(fullname)
        bytecode_path = imp.cache_from_source(source_path)
        source_mtime = None
        if bytecode_path is not None:
            try:
                source_mtime = self.path_mtime(source_path)
            except NotImplementedError:
                pass
            else:
                try:
                    data = self.get_data(bytecode_path)
                except IOError:
                    pass
                else:
                    try:
                        bytes_data = self._bytes_from_bytecode(fullname, data,
                                                               source_mtime)
                    except (ImportError, EOFError):
                        pass
                    else:
                        found = marshal.loads(bytes_data)
                        if isinstance(found, code_type):
                            imp._fix_co_filename(found, source_path)
                            return found
                        else:
                            msg = "Non-code object in {}"
                            raise ImportError(msg.format(bytecode_path))
        source_bytes = self.get_data(source_path)
        code_object = compile(source_bytes, source_path, 'exec',
                                dont_inherit=True)
        if (not sys.dont_write_bytecode and bytecode_path is not None and
                source_mtime is not None):
            # If e.g. Jython ever implements imp.cache_from_source to have
            # their own cached file format, this block of code will most likely
            # throw an exception.
            data = bytearray(imp.get_magic())
            data.extend(marshal._w_long(source_mtime))
            data.extend(marshal.dumps(code_object))
            try:
                self.set_data(bytecode_path, data)
            except NotImplementedError:
                pass
        return code_object

    def load_module(self, fullname, engine=None):
        """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, engine=engine)


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_mtime(self, path):
        """Return the modification time for the path."""
        return int(_os.stat(path).st_mtime)

    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 OSError as exc:
                # Probably another Python process already created the dir.
                if exc.errno == errno.EEXIST:
                    continue
                else:
                    raise
            except IOError as exc:
                # If can't get proper access, then just forget about writing
                # the data.
                if exc.errno == errno.EACCES:
                    return
                else:
                    raise
        try:
            with _io.FileIO(path, 'wb') as file:
                file.write(data)
        except IOError as exc:
            # Don't worry if you can't write bytecode.
            if exc.errno == errno.EACCES:
                return
            else:
                raise


class _SourcelessFileLoader(_FileLoader, _LoaderBasics):

    """Loader which handles sourceless file imports."""

    def load_module(self, fullname, engine=None):
        return self._load_module(fullname, sourceless=True, engine=engine)

    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, engine=None):
        """Load an extension module."""
        is_reload = fullname in sys.modules
        try:
            module = imp.load_dynamic(fullname, self._path)
            if engine:
                engine.modules[fullname] = sys.modules[fullname]
            return module
        except:
            if not is_reload and fullname in sys.modules:
                del sys.modules[fullname]
                if engine and fullname in engine.modules:
                    del engine.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 ImportEngine.(path|path_hooks|path_importer_cache)."""

    @classmethod
    def _path_hooks(cls, path, hooks=None, engine=None):
        """Search sequence of hooks for a finder for 'path'.

        If 'hooks' is false then use ImportEngine.path_hooks.

        """
        if not hooks:
            if engine:
                hooks = engine.path_hooks
            else:
                hooks = sysengine.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, engine=None, default=None):
        """Get the finder for the path from ImportEngine.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.

        """
        if not engine:
            engine = sysengine

        try:
            finder = engine.path_importer_cache[path]
        except KeyError:
            finder = cls._path_hooks(path, engine=engine)
            engine.path_importer_cache[path] = finder
        else:
            if finder is None and default:
                # Raises ImportError on failure.
                finder = default(path)
                engine.path_importer_cache[path] = finder
        return finder

    @classmethod
    def find_module(cls, fullname, path=None, engine=None):
        """Find the module on sys.path or 'path' based on ImportEngine.path_hooks and
        sys.path_importer_cache."""
        if not path:
            if engine:
                path = engine.path
            else:
                path = sysengine.path
        for entry in path:
            try:
                finder = cls._path_importer_cache(entry, engine=engine)
            except ImportError:
                continue
            if finder:
                print(type(finder))
                loader = finder.find_module(fullname, engine=engine)
                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, engine=None):
        """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, engine=None):
        """Search ImportEngine.path_hooks as well as implicit path hooks."""
        try:
            return super()._path_hooks(path, engine=engine)
        except ImportError:
            implicit_hooks = [_DEFAULT_PATH_HOOK, NullImporter]
            return super()._path_hooks(path, implicit_hooks, engine=engine)

    @classmethod
    def _path_importer_cache(cls, path, engine=None):
        """Use the default path hook when None is stored in
        sys.path_importer_cache."""
        return super()._path_importer_cache(path, default=_DEFAULT_PATH_HOOK, engine=engine)


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}'

class ImportEngine(object):
    def __init__(self):
        self.modules = {}
        self.path = []
        self.path_hooks = []
        self.meta_path = []
        self.path_importer_cache = {}

    def _gcd_import(self, name, package=None, level=0):
        if package:
            if not hasattr(package, 'rindex'):
                raise ValueError("__package__ not set to a string")
            elif package not in self.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 = self.modules[name]
            except KeyError:
                pass
            else:
                if module is None:
                    message = ("import of {} halted; "
                                "None in engine.modules".format(name))
                    raise ImportError(message)
                return module

            parent = name.rpartition('.')[0]
            path = None
            if parent:
                if parent not in self.modules:
                    self._gcd_import(parent)
                # Backwards-compatibility; be nicer to skip the dict lookup.
                parent_module = self.modules[parent]
                try:
                    path = parent_module.__path__
                except AttributeError:
                    msg = (_ERR_MSG + '; {} is not a package').format(name, parent)
                    raise ImportError(msg)
            meta_path = self.meta_path + _IMPLICIT_META_PATH
            for finder in meta_path:
                print(finder)
                loader = finder.find_module(name, path, self)
                if loader is not None:
                    loader.load_module(name, self)
                    break
            else:
                raise ImportError(_ERR_MSG.format(name))
            # Backwards-compatibility; be nicer to skip the dict lookup.
            module = self.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 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_module(self, name, package=None):
        level = 0
        if name.startswith('.'):
            if not package:
                raise TypeError("relative imports require the 'package' argument")
            for character in name:
                if character != '.':
                    break
                level += 1
        return self._gcd_import(name[level:], package, level)

    def __import__(self, name, globals={}, locals={}, fromlist=[], level=0):
        if not hasattr(name, 'rpartition'):
            raise TypeError("module name must be str, not {}".format(type(name)))
        if level == 0:
            module = self._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 = self._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 self.modules[name.partition('.')[0]]
            elif not name:
                return module
            else:
                cut_off = len(name) - len(name.partition('.')[0])
                return self.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:
                        self._gcd_import('{0}.{1}'.format(module.__name__, x))
                    except ImportError:
                        pass
            return module

    @classmethod
    def from_engine(cls, other):
        """
        Return an ImportEngine with a copy of the global import state.
        """
        import copy
        engine = ImportEngine()

        engine.modules = copy.copy(other.modules)
        engine.path = copy.copy(other.path)
        engine.path_hooks = copy.copy(other.path_hooks)
        engine.meta_path = copy.copy(other.meta_path)
        engine.path_importer_cache = copy.copy(other.path_importer_cache)

        return engine

class GlobalImportEngine(ImportEngine):
    """
    Subclass of ImportEngine which uses and writes to the global import-related
    state in sys.
    """
    def __init__(self):
        # Don't want to call super().__init__() since it would overwrite
        # global state.
        pass

    def getmodules(self):
        return sys.modules

    def setmodules(self, value):
        sys.modules = value

    modules = property(getmodules, setmodules)

    def getpath(self):
        return sys.path

    def setpath(self, value):
        sys.path = value

    path = property(getpath, setpath)

    def getpathhooks(self):
        return sys.path_hooks

    def setpathhooks(self, value):
        sys.path_hooks = value

    path_hooks = property(getpathhooks, setpathhooks)

    def getmetapath(self):
        return sys.meta_path

    def setmetapath(self, value):
        sys.meta_path = value

    meta_path = property(getmetapath, setmetapath)

    def getpathimportercache(self):
        return sys.path_importer_cache

    def setpathimportercache(self, value):
        sys.path_importer_cache = value

    path_importer_cache = property(getpathimportercache, setpathimportercache)

sysengine = GlobalImportEngine()
Tip: Filter by directory path e.g. /media app.js to search for public/media/app.js.
Tip: Use camelCasing e.g. ProjME to search for ProjectModifiedEvent.java.
Tip: Filter by extension type e.g. /repo .js to search for all .js files in the /repo directory.
Tip: Separate your search with spaces e.g. /ssh pom.xml to search for src/ssh/pom.xml.
Tip: Use ↑ and ↓ arrow keys to navigate and return to view the file.
Tip: You can also navigate files with Ctrl+j (next) and Ctrl+k (previous) and view the file with Ctrl+o.
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