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# util/compat.py
# Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Handle Python version/platform incompatibilities."""
import collections
import contextlib
import inspect
import operator
import platform
import sys
py36 = sys.version_info >= (3, 6)
py33 = sys.version_info >= (3, 3)
py35 = sys.version_info >= (3, 5)
py32 = sys.version_info >= (3, 2)
py3k = sys.version_info >= (3, 0)
py2k = sys.version_info < (3, 0)
py265 = sys.version_info >= (2, 6, 5)
jython = sys.platform.startswith("java")
pypy = hasattr(sys, "pypy_version_info")
win32 = sys.platform.startswith("win")
osx = sys.platform.startswith("darwin")
cpython = not pypy and not jython # TODO: something better for this ?
arm = "aarch" in platform.machine().lower()
contextmanager = contextlib.contextmanager
dottedgetter = operator.attrgetter
namedtuple = collections.namedtuple
next = next # noqa
FullArgSpec = collections.namedtuple(
"FullArgSpec",
[
"args",
"varargs",
"varkw",
"defaults",
"kwonlyargs",
"kwonlydefaults",
"annotations",
],
)
try:
import threading
except ImportError:
import dummy_threading as threading # noqa
# work around http://bugs.python.org/issue2646
if py265:
safe_kwarg = lambda arg: arg # noqa
else:
safe_kwarg = str
def inspect_getfullargspec(func):
"""Fully vendored version of getfullargspec from Python 3.3."""
if inspect.ismethod(func):
func = func.__func__
if not inspect.isfunction(func):
raise TypeError("{!r} is not a Python function".format(func))
co = func.__code__
if not inspect.iscode(co):
raise TypeError("{!r} is not a code object".format(co))
nargs = co.co_argcount
names = co.co_varnames
nkwargs = co.co_kwonlyargcount if py3k else 0
args = list(names[:nargs])
kwonlyargs = list(names[nargs : nargs + nkwargs])
nargs += nkwargs
varargs = None
if co.co_flags & inspect.CO_VARARGS:
varargs = co.co_varnames[nargs]
nargs = nargs + 1
varkw = None
if co.co_flags & inspect.CO_VARKEYWORDS:
varkw = co.co_varnames[nargs]
return FullArgSpec(
args,
varargs,
varkw,
func.__defaults__,
kwonlyargs,
func.__kwdefaults__ if py3k else None,
func.__annotations__ if py3k else {},
)
if py3k:
import base64
import builtins
import configparser
import itertools
import pickle
from functools import reduce
from io import BytesIO as byte_buffer
from io import StringIO
from itertools import zip_longest
from urllib.parse import (
quote_plus,
unquote_plus,
parse_qsl,
quote,
unquote,
)
string_types = (str,)
binary_types = (bytes,)
binary_type = bytes
text_type = str
int_types = (int,)
iterbytes = iter
itertools_filterfalse = itertools.filterfalse
itertools_filter = filter
itertools_imap = map
exec_ = getattr(builtins, "exec")
import_ = getattr(builtins, "__import__")
print_ = getattr(builtins, "print")
def b(s):
return s.encode("latin-1")
def b64decode(x):
return base64.b64decode(x.encode("ascii"))
def b64encode(x):
return base64.b64encode(x).decode("ascii")
def decode_backslashreplace(text, encoding):
return text.decode(encoding, errors="backslashreplace")
def cmp(a, b):
return (a > b) - (a < b)
def raise_(
exception, with_traceback=None, replace_context=None, from_=False
):
r"""implement "raise" with cause support.
:param exception: exception to raise
:param with_traceback: will call exception.with_traceback()
:param replace_context: an as-yet-unsupported feature. This is
an exception object which we are "replacing", e.g., it's our
"cause" but we don't want it printed. Basically just what
``__suppress_context__`` does but we don't want to suppress
the enclosing context, if any. So for now we make it the
cause.
:param from\_: the cause. this actually sets the cause and doesn't
hope to hide it someday.
"""
if with_traceback is not None:
exception = exception.with_traceback(with_traceback)
if from_ is not False:
exception.__cause__ = from_
elif replace_context is not None:
# no good solution here, we would like to have the exception
# have only the context of replace_context.__context__ so that the
# intermediary exception does not change, but we can't figure
# that out.
exception.__cause__ = replace_context
try:
raise exception
finally:
# credit to
# https://cosmicpercolator.com/2016/01/13/exception-leaks-in-python-2-and-3/
# as the __traceback__ object creates a cycle
del exception, replace_context, from_, with_traceback
from typing import TYPE_CHECKING
def u(s):
return s
def ue(s):
return s
if py32:
callable = callable # noqa
else:
def callable(fn): # noqa
return hasattr(fn, "__call__")
else:
import base64
import ConfigParser as configparser # noqa
import itertools
from StringIO import StringIO # noqa
from cStringIO import StringIO as byte_buffer # noqa
from itertools import izip_longest as zip_longest # noqa
from urllib import quote # noqa
from urllib import quote_plus # noqa
from urllib import unquote # noqa
from urllib import unquote_plus # noqa
from urlparse import parse_qsl # noqa
try:
import cPickle as pickle
except ImportError:
import pickle # noqa
string_types = (basestring,) # noqa
binary_types = (bytes,)
binary_type = str
text_type = unicode # noqa
int_types = int, long # noqa
callable = callable # noqa
cmp = cmp # noqa
reduce = reduce # noqa
b64encode = base64.b64encode
b64decode = base64.b64decode
itertools_filterfalse = itertools.ifilterfalse
itertools_filter = itertools.ifilter
itertools_imap = itertools.imap
def b(s):
return s
def exec_(func_text, globals_, lcl=None):
if lcl is None:
exec("exec func_text in globals_")
else:
exec("exec func_text in globals_, lcl")
def iterbytes(buf):
return (ord(byte) for byte in buf)
def import_(*args):
if len(args) == 4:
args = args[0:3] + ([str(arg) for arg in args[3]],)
return __import__(*args)
def print_(*args, **kwargs):
fp = kwargs.pop("file", sys.stdout)
if fp is None:
return
for arg in enumerate(args):
if not isinstance(arg, basestring): # noqa
arg = str(arg)
fp.write(arg)
def u(s):
# this differs from what six does, which doesn't support non-ASCII
# strings - we only use u() with
# literal source strings, and all our source files with non-ascii
# in them (all are tests) are utf-8 encoded.
return unicode(s, "utf-8") # noqa
def ue(s):
return unicode(s, "unicode_escape") # noqa
def decode_backslashreplace(text, encoding):
try:
return text.decode(encoding)
except UnicodeDecodeError:
# regular "backslashreplace" for an incompatible encoding raises:
# "TypeError: don't know how to handle UnicodeDecodeError in
# error callback"
return repr(text)[1:-1].decode()
def safe_bytestring(text):
# py2k only
if not isinstance(text, string_types):
return unicode(text).encode("ascii", errors="backslashreplace")
elif isinstance(text, unicode):
return text.encode("ascii", errors="backslashreplace")
else:
return text
exec(
"def raise_(exception, with_traceback=None, replace_context=None, "
"from_=False):\n"
" if with_traceback:\n"
" raise type(exception), exception, with_traceback\n"
" else:\n"
" raise exception\n"
)
TYPE_CHECKING = False
if py35:
def _formatannotation(annotation, base_module=None):
"""vendored from python 3.7"""
if getattr(annotation, "__module__", None) == "typing":
return repr(annotation).replace("typing.", "")
if isinstance(annotation, type):
if annotation.__module__ in ("builtins", base_module):
return annotation.__qualname__
return annotation.__module__ + "." + annotation.__qualname__
return repr(annotation)
def inspect_formatargspec(
args,
varargs=None,
varkw=None,
defaults=None,
kwonlyargs=(),
kwonlydefaults={},
annotations={},
formatarg=str,
formatvarargs=lambda name: "*" + name,
formatvarkw=lambda name: "**" + name,
formatvalue=lambda value: "=" + repr(value),
formatreturns=lambda text: " -> " + text,
formatannotation=_formatannotation,
):
"""Copy formatargspec from python 3.7 standard library.
Python 3 has deprecated formatargspec and requested that Signature
be used instead, however this requires a full reimplementation
of formatargspec() in terms of creating Parameter objects and such.
Instead of introducing all the object-creation overhead and having
to reinvent from scratch, just copy their compatibility routine.
Utimately we would need to rewrite our "decorator" routine completely
which is not really worth it right now, until all Python 2.x support
is dropped.
"""
def formatargandannotation(arg):
result = formatarg(arg)
if arg in annotations:
result += ": " + formatannotation(annotations[arg])
return result
specs = []
if defaults:
firstdefault = len(args) - len(defaults)
for i, arg in enumerate(args):
spec = formatargandannotation(arg)
if defaults and i >= firstdefault:
spec = spec + formatvalue(defaults[i - firstdefault])
specs.append(spec)
if varargs is not None:
specs.append(formatvarargs(formatargandannotation(varargs)))
else:
if kwonlyargs:
specs.append("*")
if kwonlyargs:
for kwonlyarg in kwonlyargs:
spec = formatargandannotation(kwonlyarg)
if kwonlydefaults and kwonlyarg in kwonlydefaults:
spec += formatvalue(kwonlydefaults[kwonlyarg])
specs.append(spec)
if varkw is not None:
specs.append(formatvarkw(formatargandannotation(varkw)))
result = "(" + ", ".join(specs) + ")"
if "return" in annotations:
result += formatreturns(formatannotation(annotations["return"]))
return result
elif py2k:
from inspect import formatargspec as _inspect_formatargspec
def inspect_formatargspec(*spec, **kw):
# convert for a potential FullArgSpec from compat.getfullargspec()
return _inspect_formatargspec(*spec[0:4], **kw) # noqa
else:
from inspect import formatargspec as inspect_formatargspec # noqa
# Fix deprecation of accessing ABCs straight from collections module
# (which will stop working in 3.8).
if py33:
import collections.abc as collections_abc
else:
import collections as collections_abc # noqa
@contextlib.contextmanager
def nested(*managers):
"""Implement contextlib.nested, mostly for unit tests.
As tests still need to run on py2.6 we can't use multiple-with yet.
Function is removed in py3k but also emits deprecation warning in 2.7
so just roll it here for everyone.
"""
exits = []
vars_ = []
exc = (None, None, None)
try:
for mgr in managers:
exit_ = mgr.__exit__
enter = mgr.__enter__
vars_.append(enter())
exits.append(exit_)
yield vars_
except:
exc = sys.exc_info()
finally:
while exits:
exit_ = exits.pop() # noqa
try:
if exit_(*exc):
exc = (None, None, None)
except:
exc = sys.exc_info()
if exc != (None, None, None):
reraise(exc[0], exc[1], exc[2])
def raise_from_cause(exception, exc_info=None):
r"""legacy. use raise\_()"""
if exc_info is None:
exc_info = sys.exc_info()
exc_type, exc_value, exc_tb = exc_info
cause = exc_value if exc_value is not exception else None
reraise(type(exception), exception, tb=exc_tb, cause=cause)
def reraise(tp, value, tb=None, cause=None):
r"""legacy. use raise\_()"""
raise_(value, with_traceback=tb, from_=cause)
def with_metaclass(meta, *bases):
"""Create a base class with a metaclass.
Drops the middle class upon creation.
Source: http://lucumr.pocoo.org/2013/5/21/porting-to-python-3-redux/
"""
class metaclass(meta):
__call__ = type.__call__
__init__ = type.__init__
def __new__(cls, name, this_bases, d):
if this_bases is None:
return type.__new__(cls, name, (), d)
return meta(name, bases, d)
return metaclass("temporary_class", None, {})
if py3k:
from datetime import timezone
else:
from datetime import datetime
from datetime import timedelta
from datetime import tzinfo
class timezone(tzinfo):
"""Minimal port of python 3 timezone object"""
__slots__ = "_offset"
def __init__(self, offset):
if not isinstance(offset, timedelta):
raise TypeError("offset must be a timedelta")
if not self._minoffset <= offset <= self._maxoffset:
raise ValueError(
"offset must be a timedelta "
"strictly between -timedelta(hours=24) and "
"timedelta(hours=24)."
)
self._offset = offset
def __eq__(self, other):
if type(other) != timezone:
return False
return self._offset == other._offset
def __hash__(self):
return hash(self._offset)
def __repr__(self):
return "sqlalchemy.util.%s(%r)" % (
self.__class__.__name__,
self._offset,
)
def __str__(self):
return self.tzname(None)
def utcoffset(self, dt):
return self._offset
def tzname(self, dt):
return self._name_from_offset(self._offset)
def dst(self, dt):
return None
def fromutc(self, dt):
if isinstance(dt, datetime):
if dt.tzinfo is not self:
raise ValueError("fromutc: dt.tzinfo " "is not self")
return dt + self._offset
raise TypeError(
"fromutc() argument must be a datetime instance" " or None"
)
@staticmethod
def _timedelta_to_microseconds(timedelta):
"""backport of timedelta._to_microseconds()"""
return (
timedelta.days * (24 * 3600) + timedelta.seconds
) * 1000000 + timedelta.microseconds
@staticmethod
def _divmod_timedeltas(a, b):
"""backport of timedelta.__divmod__"""
q, r = divmod(
timezone._timedelta_to_microseconds(a),
timezone._timedelta_to_microseconds(b),
)
return q, timedelta(0, 0, r)
@staticmethod
def _name_from_offset(delta):
if not delta:
return "UTC"
if delta < timedelta(0):
sign = "-"
delta = -delta
else:
sign = "+"
hours, rest = timezone._divmod_timedeltas(
delta, timedelta(hours=1)
)
minutes, rest = timezone._divmod_timedeltas(
rest, timedelta(minutes=1)
)
result = "UTC%s%02d:%02d" % (sign, hours, minutes)
if rest.seconds:
result += ":%02d" % (rest.seconds,)
if rest.microseconds:
result += ".%06d" % (rest.microseconds,)
return result
_maxoffset = timedelta(hours=23, minutes=59)
_minoffset = -_maxoffset
timezone.utc = timezone(timedelta(0))
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