_compatibility.py

"""
To ensure compatibility from Python ``2.7`` - ``3.x``, a module has been
created. Clearly there is huge need to use conforming syntax.
"""
from __future__ import print_function
import atexit
import errno
import functools
import sys
import os
import re
import pkgutil
import warnings
import subprocess
import weakref
try:
    import importlib
except ImportError:
    pass
from zipimport import zipimporter

from jedi.file_io import KnownContentFileIO, ZipFileIO

is_py3 = sys.version_info[0] >= 3
is_py35 = is_py3 and sys.version_info[1] >= 5
py_version = int(str(sys.version_info[0]) + str(sys.version_info[1]))


if sys.version_info[:2] < (3, 5):
    """
    A super-minimal shim around listdir that behave like
    scandir for the information we need.
    """
    class _DirEntry:

        def __init__(self, name, basepath):
            self.name = name
            self.basepath = basepath

        def is_dir(self):
            path_for_name = os.path.join(self.basepath, self.name)
            return os.path.isdir(path_for_name)

    def scandir(dir):
        return [_DirEntry(name, dir) for name in os.listdir(dir)]
else:
    from os import scandir


class DummyFile(object):
    def __init__(self, loader, string):
        self.loader = loader
        self.string = string

    def read(self):
        return self.loader.get_source(self.string)

    def close(self):
        del self.loader


def find_module_py34(string, path=None, full_name=None, is_global_search=True):
    spec = None
    loader = None

    for finder in sys.meta_path:
        if is_global_search and finder != importlib.machinery.PathFinder:
            p = None
        else:
            p = path
        try:
            find_spec = finder.find_spec
        except AttributeError:
            # These are old-school clases that still have a different API, just
            # ignore those.
            continue

        spec = find_spec(string, p)
        if spec is not None:
            loader = spec.loader
            if loader is None and not spec.has_location:
                # This is a namespace package.
                full_name = string if not path else full_name
                implicit_ns_info = ImplicitNSInfo(full_name, spec.submodule_search_locations._path)
                return implicit_ns_info, True
            break

    return find_module_py33(string, path, loader)


def find_module_py33(string, path=None, loader=None, full_name=None, is_global_search=True):
    loader = loader or importlib.machinery.PathFinder.find_module(string, path)

    if loader is None and path is None:  # Fallback to find builtins
        try:
            with warnings.catch_warnings(record=True):
                # Mute "DeprecationWarning: Use importlib.util.find_spec()
                # instead." While we should replace that in the future, it's
                # probably good to wait until we deprecate Python 3.3, since
                # it was added in Python 3.4 and find_loader hasn't been
                # removed in 3.6.
                loader = importlib.find_loader(string)
        except ValueError as e:
            # See #491. Importlib might raise a ValueError, to avoid this, we
            # just raise an ImportError to fix the issue.
            raise ImportError("Originally  " + repr(e))

    if loader is None:
        raise ImportError("Couldn't find a loader for {}".format(string))

    return _from_loader(loader, string)


def _from_loader(loader, string):
    try:
        is_package_method = loader.is_package
    except AttributeError:
        is_package = False
    else:
        is_package = is_package_method(string)
    try:
        get_filename = loader.get_filename
    except AttributeError:
        return None, is_package
    else:
        module_path = cast_path(get_filename(string))

    # To avoid unicode and read bytes, "overwrite" loader.get_source if
    # possible.
    try:
        f = type(loader).get_source
    except AttributeError:
        raise ImportError("get_source was not defined on loader")

    if is_py3 and f is not importlib.machinery.SourceFileLoader.get_source:
        # Unfortunately we are reading unicode here, not bytes.
        # It seems hard to get bytes, because the zip importer
        # logic just unpacks the zip file and returns a file descriptor
        # that we cannot as easily access. Therefore we just read it as
        # a string in the cases where get_source was overwritten.
        code = loader.get_source(string)
    else:
        code = _get_source(loader, string)

    if code is None:
        return None, is_package
    if isinstance(loader, zipimporter):
        return ZipFileIO(module_path, code, cast_path(loader.archive)), is_package

    return KnownContentFileIO(module_path, code), is_package


def _get_source(loader, fullname):
    """
    This method is here as a replacement for SourceLoader.get_source. That
    method returns unicode, but we prefer bytes.
    """
    path = loader.get_filename(fullname)
    try:
        return loader.get_data(path)
    except OSError:
        raise ImportError('source not available through get_data()',
                          name=fullname)


def find_module_pre_py3(string, path=None, full_name=None, is_global_search=True):
    # This import is here, because in other places it will raise a
    # DeprecationWarning.
    import imp
    try:
        module_file, module_path, description = imp.find_module(string, path)
        module_type = description[2]
        is_package = module_type is imp.PKG_DIRECTORY
        if is_package:
            # In Python 2 directory package imports are returned as folder
            # paths, not __init__.py paths.
            p = os.path.join(module_path, '__init__.py')
            try:
                module_file = open(p)
                module_path = p
            except FileNotFoundError:
                pass
        elif module_type != imp.PY_SOURCE:
            if module_file is not None:
                module_file.close()
            module_file = None

        if module_file is None:
            return None, is_package

        with module_file:
            code = module_file.read()
        return KnownContentFileIO(cast_path(module_path), code), is_package
    except ImportError:
        pass

    if path is None:
        path = sys.path
    for item in path:
        loader = pkgutil.get_importer(item)
        if loader:
            loader = loader.find_module(string)
            if loader is not None:
                return _from_loader(loader, string)
    raise ImportError("No module named {}".format(string))


find_module = find_module_py34 if is_py3 else find_module_pre_py3
find_module.__doc__ = """
Provides information about a module.

This function isolates the differences in importing libraries introduced with
python 3.3 on; it gets a module name and optionally a path. It will return a
tuple containin an open file for the module (if not builtin), the filename
or the name of the module if it is a builtin one and a boolean indicating
if the module is contained in a package.
"""


class ImplicitNSInfo(object):
    """Stores information returned from an implicit namespace spec"""
    def __init__(self, name, paths):
        self.name = name
        self.paths = paths


if is_py3:
    all_suffixes = importlib.machinery.all_suffixes
else:
    def all_suffixes():
        # Is deprecated and raises a warning in Python 3.6.
        import imp
        return [suffix for suffix, _, _ in imp.get_suffixes()]


# unicode function
try:
    unicode = unicode
except NameError:
    unicode = str


# re-raise function
if is_py3:
    def reraise(exception, traceback):
        raise exception.with_traceback(traceback)
else:
    eval(compile("""
def reraise(exception, traceback):
    raise exception, None, traceback
""", 'blub', 'exec'))

reraise.__doc__ = """
Re-raise `exception` with a `traceback` object.

Usage::

    reraise(Exception, sys.exc_info()[2])

"""


def use_metaclass(meta, *bases):
    """ Create a class with a metaclass. """
    if not bases:
        bases = (object,)
    return meta("Py2CompatibilityMetaClass", bases, {})


try:
    encoding = sys.stdout.encoding
    if encoding is None:
        encoding = 'utf-8'
except AttributeError:
    encoding = 'ascii'


def u(string, errors='strict'):
    """Cast to unicode DAMMIT!
    Written because Python2 repr always implicitly casts to a string, so we
    have to cast back to a unicode (and we now that we always deal with valid
    unicode, because we check that in the beginning).
    """
    if isinstance(string, bytes):
        return unicode(string, encoding='UTF-8', errors=errors)
    return string


def cast_path(obj):
    """
    Take a bytes or str path and cast it to unicode.

    Apparently it is perfectly fine to pass both byte and unicode objects into
    the sys.path. This probably means that byte paths are normal at other
    places as well.

    Since this just really complicates everything and Python 2.7 will be EOL
    soon anyway, just go with always strings.
    """
    return u(obj, errors='replace')


def force_unicode(obj):
    # Intentionally don't mix those two up, because those two code paths might
    # be different in the future (maybe windows?).
    return cast_path(obj)


try:
    import builtins  # module name in python 3
except ImportError:
    import __builtin__ as builtins  # noqa: F401


import ast  # noqa: F401


def literal_eval(string):
    return ast.literal_eval(string)


try:
    from itertools import zip_longest
except ImportError:
    from itertools import izip_longest as zip_longest  # Python 2  # noqa: F401

try:
    FileNotFoundError = FileNotFoundError
except NameError:
    FileNotFoundError = IOError

try:
    IsADirectoryError = IsADirectoryError
except NameError:
    IsADirectoryError = IOError

try:
    PermissionError = PermissionError
except NameError:
    PermissionError = IOError


def no_unicode_pprint(dct):
    """
    Python 2/3 dict __repr__ may be different, because of unicode differens
    (with or without a `u` prefix). Normally in doctests we could use `pprint`
    to sort dicts and check for equality, but here we have to write a separate
    function to do that.
    """
    import pprint
    s = pprint.pformat(dct)
    print(re.sub("u'", "'", s))


def utf8_repr(func):
    """
    ``__repr__`` methods in Python 2 don't allow unicode objects to be
    returned. Therefore cast them to utf-8 bytes in this decorator.
    """
    def wrapper(self):
        result = func(self)
        if isinstance(result, unicode):
            return result.encode('utf-8')
        else:
            return result

    if is_py3:
        return func
    else:
        return wrapper


if is_py3:
    import queue
else:
    import Queue as queue  # noqa: F401

try:
    # Attempt to load the C implementation of pickle on Python 2 as it is way
    # faster.
    import cPickle as pickle
except ImportError:
    import pickle


def pickle_load(file):
    try:
        if is_py3:
            return pickle.load(file, encoding='bytes')
        return pickle.load(file)
    # Python on Windows don't throw EOF errors for pipes. So reraise them with
    # the correct type, which is caught upwards.
    except OSError:
        if sys.platform == 'win32':
            raise EOFError()
        raise


def _python2_dct_keys_to_unicode(data):
    """
    Python 2 stores object __dict__ entries as bytes, not unicode, correct it
    here. Python 2 can deal with both, Python 3 expects unicode.
    """
    if isinstance(data, tuple):
        return tuple(_python2_dct_keys_to_unicode(x) for x in data)
    elif isinstance(data, list):
        return list(_python2_dct_keys_to_unicode(x) for x in data)
    elif hasattr(data, '__dict__') and type(data.__dict__) == dict:
        data.__dict__ = {unicode(k): v for k, v in data.__dict__.items()}
    return data


def pickle_dump(data, file, protocol):
    try:
        if not is_py3:
            data = _python2_dct_keys_to_unicode(data)
        pickle.dump(data, file, protocol)
        # On Python 3.3 flush throws sometimes an error even though the writing
        # operation should be completed.
        file.flush()
    # Python on Windows don't throw EPIPE errors for pipes. So reraise them with
    # the correct type and error number.
    except OSError:
        if sys.platform == 'win32':
            raise IOError(errno.EPIPE, "Broken pipe")
        raise


# Determine the highest protocol version compatible for a given list of Python
# versions.
def highest_pickle_protocol(python_versions):
    protocol = 4
    for version in python_versions:
        if version[0] == 2:
            # The minimum protocol version for the versions of Python that we
            # support (2.7 and 3.3+) is 2.
            return 2
        if version[1] < 4:
            protocol = 3
    return protocol


try:
    from inspect import Parameter
except ImportError:
    class Parameter(object):
        POSITIONAL_ONLY = object()
        POSITIONAL_OR_KEYWORD = object()
        VAR_POSITIONAL = object()
        KEYWORD_ONLY = object()
        VAR_KEYWORD = object()


class GeneralizedPopen(subprocess.Popen):
    def __init__(self, *args, **kwargs):
        if os.name == 'nt':
            try:
                # Was introduced in Python 3.7.
                CREATE_NO_WINDOW = subprocess.CREATE_NO_WINDOW
            except AttributeError:
                CREATE_NO_WINDOW = 0x08000000
            kwargs['creationflags'] = CREATE_NO_WINDOW
        # The child process doesn't need file descriptors except 0, 1, 2.
        # This is unix only.
        kwargs['close_fds'] = 'posix' in sys.builtin_module_names
        super(GeneralizedPopen, self).__init__(*args, **kwargs)


# shutil.which is not available on Python 2.7.
def which(cmd, mode=os.F_OK | os.X_OK, path=None):
    """Given a command, mode, and a PATH string, return the path which
    conforms to the given mode on the PATH, or None if there is no such
    file.

    `mode` defaults to os.F_OK | os.X_OK. `path` defaults to the result
    of os.environ.get("PATH"), or can be overridden with a custom search
    path.

    """
    # Check that a given file can be accessed with the correct mode.
    # Additionally check that `file` is not a directory, as on Windows
    # directories pass the os.access check.
    def _access_check(fn, mode):
        return (os.path.exists(fn) and os.access(fn, mode)
                and not os.path.isdir(fn))

    # If we're given a path with a directory part, look it up directly rather
    # than referring to PATH directories. This includes checking relative to the
    # current directory, e.g. ./script
    if os.path.dirname(cmd):
        if _access_check(cmd, mode):
            return cmd
        return None

    if path is None:
        path = os.environ.get("PATH", os.defpath)
    if not path:
        return None
    path = path.split(os.pathsep)

    if sys.platform == "win32":
        # The current directory takes precedence on Windows.
        if os.curdir not in path:
            path.insert(0, os.curdir)

        # PATHEXT is necessary to check on Windows.
        pathext = os.environ.get("PATHEXT", "").split(os.pathsep)
        # See if the given file matches any of the expected path extensions.
        # This will allow us to short circuit when given "python.exe".
        # If it does match, only test that one, otherwise we have to try
        # others.
        if any(cmd.lower().endswith(ext.lower()) for ext in pathext):
            files = [cmd]
        else:
            files = [cmd + ext for ext in pathext]
    else:
        # On other platforms you don't have things like PATHEXT to tell you
        # what file suffixes are executable, so just pass on cmd as-is.
        files = [cmd]

    seen = set()
    for dir in path:
        normdir = os.path.normcase(dir)
        if normdir not in seen:
            seen.add(normdir)
            for thefile in files:
                name = os.path.join(dir, thefile)
                if _access_check(name, mode):
                    return name
    return None


if not is_py3:
    # Simplified backport of Python 3 weakref.finalize:
    # https://github.com/python/cpython/blob/ded4737989316653469763230036b04513cb62b3/Lib/weakref.py#L502-L662
    class finalize(object):
        """Class for finalization of weakrefable objects.

        finalize(obj, func, *args, **kwargs) returns a callable finalizer
        object which will be called when obj is garbage collected. The
        first time the finalizer is called it evaluates func(*arg, **kwargs)
        and returns the result. After this the finalizer is dead, and
        calling it just returns None.

        When the program exits any remaining finalizers will be run.
        """

        # Finalizer objects don't have any state of their own.
        # This ensures that they cannot be part of a ref-cycle.
        __slots__ = ()
        _registry = {}

        def __init__(self, obj, func, *args, **kwargs):
            info = functools.partial(func, *args, **kwargs)
            info.weakref = weakref.ref(obj, self)
            self._registry[self] = info

        # To me it's an absolute mystery why in Python 2 we need _=None. It
        # makes really no sense since it's never really called. Then again it
        # might be called by Python 2.7 itself, but weakref.finalize is not
        # documented in Python 2 and therefore shouldn't be randomly called.
        # We never call this stuff with a parameter and therefore this
        # parameter should not be needed. But it is. ~dave
        def __call__(self, _=None):
            """Return func(*args, **kwargs) if alive."""
            info = self._registry.pop(self, None)
            if info:
                return info()

        @classmethod
        def _exitfunc(cls):
            if not cls._registry:
                return
            for finalizer in list(cls._registry):
                try:
                    finalizer()
                except Exception:
                    sys.excepthook(*sys.exc_info())
                assert finalizer not in cls._registry

    atexit.register(finalize._exitfunc)
    weakref.finalize = finalize


if is_py3 and sys.version_info[1] > 5:
    from inspect import unwrap
else:
    # Only Python >=3.6 does properly limit the amount of unwraps. This is very
    # relevant in the case of unittest.mock.patch.
    # Below is the implementation of Python 3.7.
    def unwrap(func, stop=None):
        """Get the object wrapped by *func*.

       Follows the chain of :attr:`__wrapped__` attributes returning the last
       object in the chain.

       *stop* is an optional callback accepting an object in the wrapper chain
       as its sole argument that allows the unwrapping to be terminated early if
       the callback returns a true value. If the callback never returns a true
       value, the last object in the chain is returned as usual. For example,
       :func:`signature` uses this to stop unwrapping if any object in the
       chain has a ``__signature__`` attribute defined.

       :exc:`ValueError` is raised if a cycle is encountered.

        """
        if stop is None:
            def _is_wrapper(f):
                return hasattr(f, '__wrapped__')
        else:
            def _is_wrapper(f):
                return hasattr(f, '__wrapped__') and not stop(f)
        f = func  # remember the original func for error reporting
        # Memoise by id to tolerate non-hashable objects, but store objects to
        # ensure they aren't destroyed, which would allow their IDs to be reused.
        memo = {id(f): f}
        recursion_limit = sys.getrecursionlimit()
        while _is_wrapper(func):
            func = func.__wrapped__
            id_func = id(func)
            if (id_func in memo) or (len(memo) >= recursion_limit):
                raise ValueError('wrapper loop when unwrapping {!r}'.format(f))
            memo[id_func] = func
        return func