diff --git a/lib/contextlib2.py b/lib/contextlib2.py deleted file mode 100644 index 3aae8f41..00000000 --- a/lib/contextlib2.py +++ /dev/null @@ -1,518 +0,0 @@ -"""contextlib2 - backports and enhancements to the contextlib module""" - -import abc -import sys -import warnings -from collections import deque -from functools import wraps - -__all__ = ["contextmanager", "closing", "nullcontext", - "AbstractContextManager", - "ContextDecorator", "ExitStack", - "redirect_stdout", "redirect_stderr", "suppress"] - -# Backwards compatibility -__all__ += ["ContextStack"] - - -# Backport abc.ABC -if sys.version_info[:2] >= (3, 4): - _abc_ABC = abc.ABC -else: - _abc_ABC = abc.ABCMeta('ABC', (object,), {'__slots__': ()}) - - -# Backport classic class MRO -def _classic_mro(C, result): - if C in result: - return - result.append(C) - for B in C.__bases__: - _classic_mro(B, result) - return result - - -# Backport _collections_abc._check_methods -def _check_methods(C, *methods): - try: - mro = C.__mro__ - except AttributeError: - mro = tuple(_classic_mro(C, [])) - - for method in methods: - for B in mro: - if method in B.__dict__: - if B.__dict__[method] is None: - return NotImplemented - break - else: - return NotImplemented - return True - - -class AbstractContextManager(_abc_ABC): - """An abstract base class for context managers.""" - - def __enter__(self): - """Return `self` upon entering the runtime context.""" - return self - - @abc.abstractmethod - def __exit__(self, exc_type, exc_value, traceback): - """Raise any exception triggered within the runtime context.""" - return None - - @classmethod - def __subclasshook__(cls, C): - """Check whether subclass is considered a subclass of this ABC.""" - if cls is AbstractContextManager: - return _check_methods(C, "__enter__", "__exit__") - return NotImplemented - - -class ContextDecorator(object): - """A base class or mixin that enables context managers to work as decorators.""" - - def refresh_cm(self): - """Returns the context manager used to actually wrap the call to the - decorated function. - - The default implementation just returns *self*. - - Overriding this method allows otherwise one-shot context managers - like _GeneratorContextManager to support use as decorators via - implicit recreation. - - DEPRECATED: refresh_cm was never added to the standard library's - ContextDecorator API - """ - warnings.warn("refresh_cm was never added to the standard library", - DeprecationWarning) - return self._recreate_cm() - - def _recreate_cm(self): - """Return a recreated instance of self. - - Allows an otherwise one-shot context manager like - _GeneratorContextManager to support use as - a decorator via implicit recreation. - - This is a private interface just for _GeneratorContextManager. - See issue #11647 for details. - """ - return self - - def __call__(self, func): - @wraps(func) - def inner(*args, **kwds): - with self._recreate_cm(): - return func(*args, **kwds) - return inner - - -class _GeneratorContextManager(ContextDecorator): - """Helper for @contextmanager decorator.""" - - def __init__(self, func, args, kwds): - self.gen = func(*args, **kwds) - self.func, self.args, self.kwds = func, args, kwds - # Issue 19330: ensure context manager instances have good docstrings - doc = getattr(func, "__doc__", None) - if doc is None: - doc = type(self).__doc__ - self.__doc__ = doc - # Unfortunately, this still doesn't provide good help output when - # inspecting the created context manager instances, since pydoc - # currently bypasses the instance docstring and shows the docstring - # for the class instead. - # See http://bugs.python.org/issue19404 for more details. - - def _recreate_cm(self): - # _GCM instances are one-shot context managers, so the - # CM must be recreated each time a decorated function is - # called - return self.__class__(self.func, self.args, self.kwds) - - def __enter__(self): - try: - return next(self.gen) - except StopIteration: - raise RuntimeError("generator didn't yield") - - def __exit__(self, type, value, traceback): - if type is None: - try: - next(self.gen) - except StopIteration: - return - else: - raise RuntimeError("generator didn't stop") - else: - if value is None: - # Need to force instantiation so we can reliably - # tell if we get the same exception back - value = type() - try: - self.gen.throw(type, value, traceback) - raise RuntimeError("generator didn't stop after throw()") - except StopIteration as exc: - # Suppress StopIteration *unless* it's the same exception that - # was passed to throw(). This prevents a StopIteration - # raised inside the "with" statement from being suppressed. - return exc is not value - except RuntimeError as exc: - # Don't re-raise the passed in exception - if exc is value: - return False - # Likewise, avoid suppressing if a StopIteration exception - # was passed to throw() and later wrapped into a RuntimeError - # (see PEP 479). - if _HAVE_EXCEPTION_CHAINING and exc.__cause__ is value: - return False - raise - except: - # only re-raise if it's *not* the exception that was - # passed to throw(), because __exit__() must not raise - # an exception unless __exit__() itself failed. But throw() - # has to raise the exception to signal propagation, so this - # fixes the impedance mismatch between the throw() protocol - # and the __exit__() protocol. - # - if sys.exc_info()[1] is not value: - raise - - -def contextmanager(func): - """@contextmanager decorator. - - Typical usage: - - @contextmanager - def some_generator(): - - try: - yield - finally: - - - This makes this: - - with some_generator() as : - - - equivalent to this: - - - try: - = - - finally: - - - """ - @wraps(func) - def helper(*args, **kwds): - return _GeneratorContextManager(func, args, kwds) - return helper - - -class closing(object): - """Context to automatically close something at the end of a block. - - Code like this: - - with closing(.open()) as f: - - - is equivalent to this: - - f = .open() - try: - - finally: - f.close() - - """ - def __init__(self, thing): - self.thing = thing - - def __enter__(self): - return self.thing - - def __exit__(self, *exc_info): - self.thing.close() - - -class _RedirectStream(object): - - _stream = None - - def __init__(self, new_target): - self._new_target = new_target - # We use a list of old targets to make this CM re-entrant - self._old_targets = [] - - def __enter__(self): - self._old_targets.append(getattr(sys, self._stream)) - setattr(sys, self._stream, self._new_target) - return self._new_target - - def __exit__(self, exctype, excinst, exctb): - setattr(sys, self._stream, self._old_targets.pop()) - - -class redirect_stdout(_RedirectStream): - """Context manager for temporarily redirecting stdout to another file. - - # How to send help() to stderr - with redirect_stdout(sys.stderr): - help(dir) - - # How to write help() to a file - with open('help.txt', 'w') as f: - with redirect_stdout(f): - help(pow) - """ - - _stream = "stdout" - - -class redirect_stderr(_RedirectStream): - """Context manager for temporarily redirecting stderr to another file.""" - - _stream = "stderr" - - -class suppress(object): - """Context manager to suppress specified exceptions - - After the exception is suppressed, execution proceeds with the next - statement following the with statement. - - with suppress(FileNotFoundError): - os.remove(somefile) - # Execution still resumes here if the file was already removed - """ - - def __init__(self, *exceptions): - self._exceptions = exceptions - - def __enter__(self): - pass - - def __exit__(self, exctype, excinst, exctb): - # Unlike isinstance and issubclass, CPython exception handling - # currently only looks at the concrete type hierarchy (ignoring - # the instance and subclass checking hooks). While Guido considers - # that a bug rather than a feature, it's a fairly hard one to fix - # due to various internal implementation details. suppress provides - # the simpler issubclass based semantics, rather than trying to - # exactly reproduce the limitations of the CPython interpreter. - # - # See http://bugs.python.org/issue12029 for more details - return exctype is not None and issubclass(exctype, self._exceptions) - - -# Context manipulation is Python 3 only -_HAVE_EXCEPTION_CHAINING = sys.version_info[0] >= 3 -if _HAVE_EXCEPTION_CHAINING: - def _make_context_fixer(frame_exc): - def _fix_exception_context(new_exc, old_exc): - # Context may not be correct, so find the end of the chain - while 1: - exc_context = new_exc.__context__ - if exc_context is old_exc: - # Context is already set correctly (see issue 20317) - return - if exc_context is None or exc_context is frame_exc: - break - new_exc = exc_context - # Change the end of the chain to point to the exception - # we expect it to reference - new_exc.__context__ = old_exc - return _fix_exception_context - - def _reraise_with_existing_context(exc_details): - try: - # bare "raise exc_details[1]" replaces our carefully - # set-up context - fixed_ctx = exc_details[1].__context__ - raise exc_details[1] - except BaseException: - exc_details[1].__context__ = fixed_ctx - raise -else: - # No exception context in Python 2 - def _make_context_fixer(frame_exc): - return lambda new_exc, old_exc: None - - # Use 3 argument raise in Python 2, - # but use exec to avoid SyntaxError in Python 3 - def _reraise_with_existing_context(exc_details): - exc_type, exc_value, exc_tb = exc_details - exec("raise exc_type, exc_value, exc_tb") - -# Handle old-style classes if they exist -try: - from types import InstanceType -except ImportError: - # Python 3 doesn't have old-style classes - _get_type = type -else: - # Need to handle old-style context managers on Python 2 - def _get_type(obj): - obj_type = type(obj) - if obj_type is InstanceType: - return obj.__class__ # Old-style class - return obj_type # New-style class - - -# Inspired by discussions on http://bugs.python.org/issue13585 -class ExitStack(object): - """Context manager for dynamic management of a stack of exit callbacks - - For example: - - with ExitStack() as stack: - files = [stack.enter_context(open(fname)) for fname in filenames] - # All opened files will automatically be closed at the end of - # the with statement, even if attempts to open files later - # in the list raise an exception - - """ - def __init__(self): - self._exit_callbacks = deque() - - def pop_all(self): - """Preserve the context stack by transferring it to a new instance""" - new_stack = type(self)() - new_stack._exit_callbacks = self._exit_callbacks - self._exit_callbacks = deque() - return new_stack - - def _push_cm_exit(self, cm, cm_exit): - """Helper to correctly register callbacks to __exit__ methods""" - def _exit_wrapper(*exc_details): - return cm_exit(cm, *exc_details) - _exit_wrapper.__self__ = cm - self.push(_exit_wrapper) - - def push(self, exit): - """Registers a callback with the standard __exit__ method signature - - Can suppress exceptions the same way __exit__ methods can. - - Also accepts any object with an __exit__ method (registering a call - to the method instead of the object itself) - """ - # We use an unbound method rather than a bound method to follow - # the standard lookup behaviour for special methods - _cb_type = _get_type(exit) - try: - exit_method = _cb_type.__exit__ - except AttributeError: - # Not a context manager, so assume its a callable - self._exit_callbacks.append(exit) - else: - self._push_cm_exit(exit, exit_method) - return exit # Allow use as a decorator - - def callback(self, callback, *args, **kwds): - """Registers an arbitrary callback and arguments. - - Cannot suppress exceptions. - """ - def _exit_wrapper(exc_type, exc, tb): - callback(*args, **kwds) - # We changed the signature, so using @wraps is not appropriate, but - # setting __wrapped__ may still help with introspection - _exit_wrapper.__wrapped__ = callback - self.push(_exit_wrapper) - return callback # Allow use as a decorator - - def enter_context(self, cm): - """Enters the supplied context manager - - If successful, also pushes its __exit__ method as a callback and - returns the result of the __enter__ method. - """ - # We look up the special methods on the type to match the with statement - _cm_type = _get_type(cm) - _exit = _cm_type.__exit__ - result = _cm_type.__enter__(cm) - self._push_cm_exit(cm, _exit) - return result - - def close(self): - """Immediately unwind the context stack""" - self.__exit__(None, None, None) - - def __enter__(self): - return self - - def __exit__(self, *exc_details): - received_exc = exc_details[0] is not None - - # We manipulate the exception state so it behaves as though - # we were actually nesting multiple with statements - frame_exc = sys.exc_info()[1] - _fix_exception_context = _make_context_fixer(frame_exc) - - # Callbacks are invoked in LIFO order to match the behaviour of - # nested context managers - suppressed_exc = False - pending_raise = False - while self._exit_callbacks: - cb = self._exit_callbacks.pop() - try: - if cb(*exc_details): - suppressed_exc = True - pending_raise = False - exc_details = (None, None, None) - except: - new_exc_details = sys.exc_info() - # simulate the stack of exceptions by setting the context - _fix_exception_context(new_exc_details[1], exc_details[1]) - pending_raise = True - exc_details = new_exc_details - if pending_raise: - _reraise_with_existing_context(exc_details) - return received_exc and suppressed_exc - - -# Preserve backwards compatibility -class ContextStack(ExitStack): - """Backwards compatibility alias for ExitStack""" - - def __init__(self): - warnings.warn("ContextStack has been renamed to ExitStack", - DeprecationWarning) - super(ContextStack, self).__init__() - - def register_exit(self, callback): - return self.push(callback) - - def register(self, callback, *args, **kwds): - return self.callback(callback, *args, **kwds) - - def preserve(self): - return self.pop_all() - - -class nullcontext(AbstractContextManager): - """Context manager that does no additional processing. - Used as a stand-in for a normal context manager, when a particular - block of code is only sometimes used with a normal context manager: - cm = optional_cm if condition else nullcontext() - with cm: - # Perform operation, using optional_cm if condition is True - """ - - def __init__(self, enter_result=None): - self.enter_result = enter_result - - def __enter__(self): - return self.enter_result - - def __exit__(self, *excinfo): - pass diff --git a/lib/contextlib2/__init__.py b/lib/contextlib2/__init__.py new file mode 100644 index 00000000..d6c0c4ac --- /dev/null +++ b/lib/contextlib2/__init__.py @@ -0,0 +1,798 @@ +"""contextlib2 - backports and enhancements to the contextlib module""" + +import abc +import sys +import warnings +import _collections_abc +from collections import deque +from functools import wraps +from types import MethodType + +# Python 3.6/3.7/3.8 compatibility: GenericAlias may not be defined +try: + from types import GenericAlias +except ImportError: + # If the real GenericAlias type doesn't exist, __class_getitem__ won't be used, + # so the fallback placeholder doesn't need to provide any meaningful behaviour + class GenericAlias: + pass + + +__all__ = ["asynccontextmanager", "contextmanager", "closing", "nullcontext", + "AbstractContextManager", "AbstractAsyncContextManager", + "AsyncExitStack", "ContextDecorator", "ExitStack", + "redirect_stdout", "redirect_stderr", "suppress", "aclosing"] + +# Backwards compatibility +__all__ += ["ContextStack"] + +class AbstractContextManager(abc.ABC): + """An abstract base class for context managers.""" + + __class_getitem__ = classmethod(GenericAlias) + + def __enter__(self): + """Return `self` upon entering the runtime context.""" + return self + + @abc.abstractmethod + def __exit__(self, exc_type, exc_value, traceback): + """Raise any exception triggered within the runtime context.""" + return None + + @classmethod + def __subclasshook__(cls, C): + if cls is AbstractContextManager: + return _collections_abc._check_methods(C, "__enter__", "__exit__") + return NotImplemented + + +class AbstractAsyncContextManager(abc.ABC): + + """An abstract base class for asynchronous context managers.""" + + __class_getitem__ = classmethod(GenericAlias) + + async def __aenter__(self): + """Return `self` upon entering the runtime context.""" + return self + + @abc.abstractmethod + async def __aexit__(self, exc_type, exc_value, traceback): + """Raise any exception triggered within the runtime context.""" + return None + + @classmethod + def __subclasshook__(cls, C): + if cls is AbstractAsyncContextManager: + return _collections_abc._check_methods(C, "__aenter__", + "__aexit__") + return NotImplemented + + +class ContextDecorator(object): + "A base class or mixin that enables context managers to work as decorators." + + def refresh_cm(self): + """Returns the context manager used to actually wrap the call to the + decorated function. + + The default implementation just returns *self*. + + Overriding this method allows otherwise one-shot context managers + like _GeneratorContextManager to support use as decorators via + implicit recreation. + + DEPRECATED: refresh_cm was never added to the standard library's + ContextDecorator API + """ + warnings.warn("refresh_cm was never added to the standard library", + DeprecationWarning) + return self._recreate_cm() + + def _recreate_cm(self): + """Return a recreated instance of self. + + Allows an otherwise one-shot context manager like + _GeneratorContextManager to support use as + a decorator via implicit recreation. + + This is a private interface just for _GeneratorContextManager. + See issue #11647 for details. + """ + return self + + def __call__(self, func): + @wraps(func) + def inner(*args, **kwds): + with self._recreate_cm(): + return func(*args, **kwds) + return inner + + +class AsyncContextDecorator(object): + "A base class or mixin that enables async context managers to work as decorators." + + def _recreate_cm(self): + """Return a recreated instance of self. + """ + return self + + def __call__(self, func): + @wraps(func) + async def inner(*args, **kwds): + async with self._recreate_cm(): + return await func(*args, **kwds) + return inner + + +class _GeneratorContextManagerBase: + """Shared functionality for @contextmanager and @asynccontextmanager.""" + + def __init__(self, func, args, kwds): + self.gen = func(*args, **kwds) + self.func, self.args, self.kwds = func, args, kwds + # Issue 19330: ensure context manager instances have good docstrings + doc = getattr(func, "__doc__", None) + if doc is None: + doc = type(self).__doc__ + self.__doc__ = doc + # Unfortunately, this still doesn't provide good help output when + # inspecting the created context manager instances, since pydoc + # currently bypasses the instance docstring and shows the docstring + # for the class instead. + # See http://bugs.python.org/issue19404 for more details. + + +class _GeneratorContextManager(_GeneratorContextManagerBase, + AbstractContextManager, + ContextDecorator): + """Helper for @contextmanager decorator.""" + + def _recreate_cm(self): + # _GCM instances are one-shot context managers, so the + # CM must be recreated each time a decorated function is + # called + return self.__class__(self.func, self.args, self.kwds) + + def __enter__(self): + # do not keep args and kwds alive unnecessarily + # they are only needed for recreation, which is not possible anymore + del self.args, self.kwds, self.func + try: + return next(self.gen) + except StopIteration: + raise RuntimeError("generator didn't yield") from None + + def __exit__(self, type, value, traceback): + if type is None: + try: + next(self.gen) + except StopIteration: + return False + else: + raise RuntimeError("generator didn't stop") + else: + if value is None: + # Need to force instantiation so we can reliably + # tell if we get the same exception back + value = type() + try: + self.gen.throw(type, value, traceback) + except StopIteration as exc: + # Suppress StopIteration *unless* it's the same exception that + # was passed to throw(). This prevents a StopIteration + # raised inside the "with" statement from being suppressed. + return exc is not value + except RuntimeError as exc: + # Don't re-raise the passed in exception. (issue27122) + if exc is value: + return False + # Likewise, avoid suppressing if a StopIteration exception + # was passed to throw() and later wrapped into a RuntimeError + # (see PEP 479). + if type is StopIteration and exc.__cause__ is value: + return False + raise + except: + # only re-raise if it's *not* the exception that was + # passed to throw(), because __exit__() must not raise + # an exception unless __exit__() itself failed. But throw() + # has to raise the exception to signal propagation, so this + # fixes the impedance mismatch between the throw() protocol + # and the __exit__() protocol. + # + # This cannot use 'except BaseException as exc' (as in the + # async implementation) to maintain compatibility with + # Python 2, where old-style class exceptions are not caught + # by 'except BaseException'. + if sys.exc_info()[1] is value: + return False + raise + raise RuntimeError("generator didn't stop after throw()") + + +class _AsyncGeneratorContextManager(_GeneratorContextManagerBase, + AbstractAsyncContextManager, + AsyncContextDecorator): + """Helper for @asynccontextmanager.""" + + def _recreate_cm(self): + # _AGCM instances are one-shot context managers, so the + # ACM must be recreated each time a decorated function is + # called + return self.__class__(self.func, self.args, self.kwds) + + async def __aenter__(self): + try: + return await self.gen.__anext__() + except StopAsyncIteration: + raise RuntimeError("generator didn't yield") from None + + async def __aexit__(self, typ, value, traceback): + if typ is None: + try: + await self.gen.__anext__() + except StopAsyncIteration: + return + else: + raise RuntimeError("generator didn't stop") + else: + if value is None: + value = typ() + # See _GeneratorContextManager.__exit__ for comments on subtleties + # in this implementation + try: + await self.gen.athrow(typ, value, traceback) + raise RuntimeError("generator didn't stop after athrow()") + except StopAsyncIteration as exc: + return exc is not value + except RuntimeError as exc: + if exc is value: + return False + # Avoid suppressing if a StopIteration exception + # was passed to throw() and later wrapped into a RuntimeError + # (see PEP 479 for sync generators; async generators also + # have this behavior). But do this only if the exception wrapped + # by the RuntimeError is actually Stop(Async)Iteration (see + # issue29692). + if isinstance(value, (StopIteration, StopAsyncIteration)): + if exc.__cause__ is value: + return False + raise + except BaseException as exc: + if exc is not value: + raise + + +def contextmanager(func): + """@contextmanager decorator. + + Typical usage: + + @contextmanager + def some_generator(): + + try: + yield + finally: + + + This makes this: + + with some_generator() as : + + + equivalent to this: + + + try: + = + + finally: + + """ + @wraps(func) + def helper(*args, **kwds): + return _GeneratorContextManager(func, args, kwds) + return helper + + +def asynccontextmanager(func): + """@asynccontextmanager decorator. + + Typical usage: + + @asynccontextmanager + async def some_async_generator(): + + try: + yield + finally: + + + This makes this: + + async with some_async_generator() as : + + + equivalent to this: + + + try: + = + + finally: + + """ + @wraps(func) + def helper(*args, **kwds): + return _AsyncGeneratorContextManager(func, args, kwds) + return helper + + +class closing(AbstractContextManager): + """Context to automatically close something at the end of a block. + + Code like this: + + with closing(.open()) as f: + + + is equivalent to this: + + f = .open() + try: + + finally: + f.close() + + """ + def __init__(self, thing): + self.thing = thing + def __enter__(self): + return self.thing + def __exit__(self, *exc_info): + self.thing.close() + + +class aclosing(AbstractAsyncContextManager): + """Async context manager for safely finalizing an asynchronously cleaned-up + resource such as an async generator, calling its ``aclose()`` method. + + Code like this: + + async with aclosing(.fetch()) as agen: + + + is equivalent to this: + + agen = .fetch() + try: + + finally: + await agen.aclose() + + """ + def __init__(self, thing): + self.thing = thing + async def __aenter__(self): + return self.thing + async def __aexit__(self, *exc_info): + await self.thing.aclose() + + +class _RedirectStream(AbstractContextManager): + + _stream = None + + def __init__(self, new_target): + self._new_target = new_target + # We use a list of old targets to make this CM re-entrant + self._old_targets = [] + + def __enter__(self): + self._old_targets.append(getattr(sys, self._stream)) + setattr(sys, self._stream, self._new_target) + return self._new_target + + def __exit__(self, exctype, excinst, exctb): + setattr(sys, self._stream, self._old_targets.pop()) + + +class redirect_stdout(_RedirectStream): + """Context manager for temporarily redirecting stdout to another file. + + # How to send help() to stderr + with redirect_stdout(sys.stderr): + help(dir) + + # How to write help() to a file + with open('help.txt', 'w') as f: + with redirect_stdout(f): + help(pow) + """ + + _stream = "stdout" + + +class redirect_stderr(_RedirectStream): + """Context manager for temporarily redirecting stderr to another file.""" + + _stream = "stderr" + + +class suppress(AbstractContextManager): + """Context manager to suppress specified exceptions + + After the exception is suppressed, execution proceeds with the next + statement following the with statement. + + with suppress(FileNotFoundError): + os.remove(somefile) + # Execution still resumes here if the file was already removed + """ + + def __init__(self, *exceptions): + self._exceptions = exceptions + + def __enter__(self): + pass + + def __exit__(self, exctype, excinst, exctb): + # Unlike isinstance and issubclass, CPython exception handling + # currently only looks at the concrete type hierarchy (ignoring + # the instance and subclass checking hooks). While Guido considers + # that a bug rather than a feature, it's a fairly hard one to fix + # due to various internal implementation details. suppress provides + # the simpler issubclass based semantics, rather than trying to + # exactly reproduce the limitations of the CPython interpreter. + # + # See http://bugs.python.org/issue12029 for more details + return exctype is not None and issubclass(exctype, self._exceptions) + + +class _BaseExitStack: + """A base class for ExitStack and AsyncExitStack.""" + + @staticmethod + def _create_exit_wrapper(cm, cm_exit): + return MethodType(cm_exit, cm) + + @staticmethod + def _create_cb_wrapper(*args, **kwds): + # Python 3.6/3.7 compatibility: no native positional-only args syntax + callback, *args = args + def _exit_wrapper(exc_type, exc, tb): + callback(*args, **kwds) + return _exit_wrapper + + def __init__(self): + self._exit_callbacks = deque() + + def pop_all(self): + """Preserve the context stack by transferring it to a new instance.""" + new_stack = type(self)() + new_stack._exit_callbacks = self._exit_callbacks + self._exit_callbacks = deque() + return new_stack + + def push(self, exit): + """Registers a callback with the standard __exit__ method signature. + + Can suppress exceptions the same way __exit__ method can. + Also accepts any object with an __exit__ method (registering a call + to the method instead of the object itself). + """ + # We use an unbound method rather than a bound method to follow + # the standard lookup behaviour for special methods. + _cb_type = type(exit) + + try: + exit_method = _cb_type.__exit__ + except AttributeError: + # Not a context manager, so assume it's a callable. + self._push_exit_callback(exit) + else: + self._push_cm_exit(exit, exit_method) + return exit # Allow use as a decorator. + + def enter_context(self, cm): + """Enters the supplied context manager. + + If successful, also pushes its __exit__ method as a callback and + returns the result of the __enter__ method. + """ + # We look up the special methods on the type to match the with + # statement. + _cm_type = type(cm) + _exit = _cm_type.__exit__ + result = _cm_type.__enter__(cm) + self._push_cm_exit(cm, _exit) + return result + + def callback(*args, **kwds): + """Registers an arbitrary callback and arguments. + + Cannot suppress exceptions. + """ + # Python 3.6/3.7 compatibility: no native positional-only args syntax + try: + self, callback, *args = args + except ValueError as exc: + exc_details = str(exc).partition("(")[2] + msg = "Not enough positional arguments {}".format(exc_details) + raise TypeError(msg) from None + _exit_wrapper = self._create_cb_wrapper(callback, *args, **kwds) + + # We changed the signature, so using @wraps is not appropriate, but + # setting __wrapped__ may still help with introspection. + _exit_wrapper.__wrapped__ = callback + self._push_exit_callback(_exit_wrapper) + return callback # Allow use as a decorator + + def _push_cm_exit(self, cm, cm_exit): + """Helper to correctly register callbacks to __exit__ methods.""" + _exit_wrapper = self._create_exit_wrapper(cm, cm_exit) + self._push_exit_callback(_exit_wrapper, True) + + def _push_exit_callback(self, callback, is_sync=True): + self._exit_callbacks.append((is_sync, callback)) + + +# Inspired by discussions on http://bugs.python.org/issue13585 +class ExitStack(_BaseExitStack, AbstractContextManager): + """Context manager for dynamic management of a stack of exit callbacks. + + For example: + with ExitStack() as stack: + files = [stack.enter_context(open(fname)) for fname in filenames] + # All opened files will automatically be closed at the end of + # the with statement, even if attempts to open files later + # in the list raise an exception. + """ + + def __enter__(self): + return self + + def __exit__(self, *exc_details): + received_exc = exc_details[0] is not None + + # We manipulate the exception state so it behaves as though + # we were actually nesting multiple with statements + frame_exc = sys.exc_info()[1] + def _fix_exception_context(new_exc, old_exc): + # Context may not be correct, so find the end of the chain + while 1: + exc_context = new_exc.__context__ + if exc_context is old_exc: + # Context is already set correctly (see issue 20317) + return + if exc_context is None or exc_context is frame_exc: + break + new_exc = exc_context + # Change the end of the chain to point to the exception + # we expect it to reference + new_exc.__context__ = old_exc + + # Callbacks are invoked in LIFO order to match the behaviour of + # nested context managers + suppressed_exc = False + pending_raise = False + while self._exit_callbacks: + is_sync, cb = self._exit_callbacks.pop() + assert is_sync + try: + if cb(*exc_details): + suppressed_exc = True + pending_raise = False + exc_details = (None, None, None) + except: + new_exc_details = sys.exc_info() + # simulate the stack of exceptions by setting the context + _fix_exception_context(new_exc_details[1], exc_details[1]) + pending_raise = True + exc_details = new_exc_details + if pending_raise: + try: + # bare "raise exc_details[1]" replaces our carefully + # set-up context + fixed_ctx = exc_details[1].__context__ + raise exc_details[1] + except BaseException: + exc_details[1].__context__ = fixed_ctx + raise + return received_exc and suppressed_exc + + def close(self): + """Immediately unwind the context stack.""" + self.__exit__(None, None, None) + + +# Inspired by discussions on https://bugs.python.org/issue29302 +class AsyncExitStack(_BaseExitStack, AbstractAsyncContextManager): + """Async context manager for dynamic management of a stack of exit + callbacks. + + For example: + async with AsyncExitStack() as stack: + connections = [await stack.enter_async_context(get_connection()) + for i in range(5)] + # All opened connections will automatically be released at the + # end of the async with statement, even if attempts to open a + # connection later in the list raise an exception. + """ + + @staticmethod + def _create_async_exit_wrapper(cm, cm_exit): + return MethodType(cm_exit, cm) + + @staticmethod + def _create_async_cb_wrapper(*args, **kwds): + # Python 3.6/3.7 compatibility: no native positional-only args syntax + callback, *args = args + async def _exit_wrapper(exc_type, exc, tb): + await callback(*args, **kwds) + return _exit_wrapper + + async def enter_async_context(self, cm): + """Enters the supplied async context manager. + + If successful, also pushes its __aexit__ method as a callback and + returns the result of the __aenter__ method. + """ + _cm_type = type(cm) + _exit = _cm_type.__aexit__ + result = await _cm_type.__aenter__(cm) + self._push_async_cm_exit(cm, _exit) + return result + + def push_async_exit(self, exit): + """Registers a coroutine function with the standard __aexit__ method + signature. + + Can suppress exceptions the same way __aexit__ method can. + Also accepts any object with an __aexit__ method (registering a call + to the method instead of the object itself). + """ + _cb_type = type(exit) + try: + exit_method = _cb_type.__aexit__ + except AttributeError: + # Not an async context manager, so assume it's a coroutine function + self._push_exit_callback(exit, False) + else: + self._push_async_cm_exit(exit, exit_method) + return exit # Allow use as a decorator + + def push_async_callback(*args, **kwds): + """Registers an arbitrary coroutine function and arguments. + + Cannot suppress exceptions. + """ + # Python 3.6/3.7 compatibility: no native positional-only args syntax + try: + self, callback, *args = args + except ValueError as exc: + exc_details = str(exc).partition("(")[2] + msg = "Not enough positional arguments {}".format(exc_details) + raise TypeError(msg) from None + _exit_wrapper = self._create_async_cb_wrapper(callback, *args, **kwds) + + # We changed the signature, so using @wraps is not appropriate, but + # setting __wrapped__ may still help with introspection. + _exit_wrapper.__wrapped__ = callback + self._push_exit_callback(_exit_wrapper, False) + return callback # Allow use as a decorator + + async def aclose(self): + """Immediately unwind the context stack.""" + await self.__aexit__(None, None, None) + + def _push_async_cm_exit(self, cm, cm_exit): + """Helper to correctly register coroutine function to __aexit__ + method.""" + _exit_wrapper = self._create_async_exit_wrapper(cm, cm_exit) + self._push_exit_callback(_exit_wrapper, False) + + async def __aenter__(self): + return self + + async def __aexit__(self, *exc_details): + received_exc = exc_details[0] is not None + + # We manipulate the exception state so it behaves as though + # we were actually nesting multiple with statements + frame_exc = sys.exc_info()[1] + def _fix_exception_context(new_exc, old_exc): + # Context may not be correct, so find the end of the chain + while 1: + exc_context = new_exc.__context__ + if exc_context is old_exc: + # Context is already set correctly (see issue 20317) + return + if exc_context is None or exc_context is frame_exc: + break + new_exc = exc_context + # Change the end of the chain to point to the exception + # we expect it to reference + new_exc.__context__ = old_exc + + # Callbacks are invoked in LIFO order to match the behaviour of + # nested context managers + suppressed_exc = False + pending_raise = False + while self._exit_callbacks: + is_sync, cb = self._exit_callbacks.pop() + try: + if is_sync: + cb_suppress = cb(*exc_details) + else: + cb_suppress = await cb(*exc_details) + + if cb_suppress: + suppressed_exc = True + pending_raise = False + exc_details = (None, None, None) + except: + new_exc_details = sys.exc_info() + # simulate the stack of exceptions by setting the context + _fix_exception_context(new_exc_details[1], exc_details[1]) + pending_raise = True + exc_details = new_exc_details + if pending_raise: + try: + # bare "raise exc_details[1]" replaces our carefully + # set-up context + fixed_ctx = exc_details[1].__context__ + raise exc_details[1] + except BaseException: + exc_details[1].__context__ = fixed_ctx + raise + return received_exc and suppressed_exc + + +class nullcontext(AbstractContextManager, AbstractAsyncContextManager): + """Context manager that does no additional processing. + + Used as a stand-in for a normal context manager, when a particular + block of code is only sometimes used with a normal context manager: + + cm = optional_cm if condition else nullcontext() + with cm: + # Perform operation, using optional_cm if condition is True + """ + + def __init__(self, enter_result=None): + self.enter_result = enter_result + + def __enter__(self): + return self.enter_result + + def __exit__(self, *excinfo): + pass + + async def __aenter__(self): + return self.enter_result + + async def __aexit__(self, *excinfo): + pass + + +# Preserve backwards compatibility +class ContextStack(ExitStack): + """Backwards compatibility alias for ExitStack""" + + def __init__(self): + warnings.warn("ContextStack has been renamed to ExitStack", + DeprecationWarning) + super(ContextStack, self).__init__() + + def register_exit(self, callback): + return self.push(callback) + + def register(self, callback, *args, **kwds): + return self.callback(callback, *args, **kwds) + + def preserve(self): + return self.pop_all() diff --git a/lib/contextlib2/__init__.pyi b/lib/contextlib2/__init__.pyi new file mode 100644 index 00000000..d42c6b05 --- /dev/null +++ b/lib/contextlib2/__init__.pyi @@ -0,0 +1,132 @@ +# Type hints copied from the typeshed project under the Apache License 2.0 +# https://github.com/python/typeshed/blob/64c85cdd449ccaff90b546676220c9ecfa6e697f/LICENSE + +import sys +from types import TracebackType +from typing import ( + IO, + Any, + AsyncContextManager, + AsyncIterator, + Awaitable, + Callable, + ContextManager, + Iterator, + Optional, + Type, + TypeVar, + overload, +) +from typing_extensions import ParamSpec, Protocol + +# contextlib2 API adaptation notes: +# * the various 'if True:' guards replace sys.version checks in the original +# typeshed file (those APIs are available on all supported versions) +# * deliberately omitted APIs are listed in `dev/mypy.allowlist` +# (e.g. deprecated experimental APIs that never graduated to the stdlib) + +AbstractContextManager = ContextManager +if True: + AbstractAsyncContextManager = AsyncContextManager + +_T = TypeVar("_T") +_T_co = TypeVar("_T_co", covariant=True) +_T_io = TypeVar("_T_io", bound=Optional[IO[str]]) +_F = TypeVar("_F", bound=Callable[..., Any]) +_P = ParamSpec("_P") + +_ExitFunc = Callable[[Optional[Type[BaseException]], Optional[BaseException], Optional[TracebackType]], bool] +_CM_EF = TypeVar("_CM_EF", ContextManager[Any], _ExitFunc) + +class _GeneratorContextManager(ContextManager[_T_co]): + def __call__(self, func: _F) -> _F: ... + +# type ignore to deal with incomplete ParamSpec support in mypy +def contextmanager(func: Callable[_P, Iterator[_T]]) -> Callable[_P, _GeneratorContextManager[_T]]: ... # type: ignore + +if True: + def asynccontextmanager(func: Callable[_P, AsyncIterator[_T]]) -> Callable[_P, AsyncContextManager[_T]]: ... # type: ignore + +class _SupportsClose(Protocol): + def close(self) -> object: ... + +_SupportsCloseT = TypeVar("_SupportsCloseT", bound=_SupportsClose) + +class closing(ContextManager[_SupportsCloseT]): + def __init__(self, thing: _SupportsCloseT) -> None: ... + +if True: + class _SupportsAclose(Protocol): + async def aclose(self) -> object: ... + _SupportsAcloseT = TypeVar("_SupportsAcloseT", bound=_SupportsAclose) + class aclosing(AsyncContextManager[_SupportsAcloseT]): + def __init__(self, thing: _SupportsAcloseT) -> None: ... + _AF = TypeVar("_AF", bound=Callable[..., Awaitable[Any]]) + class AsyncContextDecorator: + def __call__(self, func: _AF) -> _AF: ... + +class suppress(ContextManager[None]): + def __init__(self, *exceptions: Type[BaseException]) -> None: ... + def __exit__( + self, exctype: Optional[Type[BaseException]], excinst: Optional[BaseException], exctb: Optional[TracebackType] + ) -> bool: ... + +class redirect_stdout(ContextManager[_T_io]): + def __init__(self, new_target: _T_io) -> None: ... + +class redirect_stderr(ContextManager[_T_io]): + def __init__(self, new_target: _T_io) -> None: ... + +class ContextDecorator: + def __call__(self, func: _F) -> _F: ... + +_U = TypeVar("_U", bound=ExitStack) + +class ExitStack(ContextManager[ExitStack]): + def __init__(self) -> None: ... + def enter_context(self, cm: ContextManager[_T]) -> _T: ... + def push(self, exit: _CM_EF) -> _CM_EF: ... + def callback(self, callback: Callable[..., Any], *args: Any, **kwds: Any) -> Callable[..., Any]: ... + def pop_all(self: _U) -> _U: ... + def close(self) -> None: ... + def __enter__(self: _U) -> _U: ... + def __exit__( + self, + __exc_type: Optional[Type[BaseException]], + __exc_value: Optional[BaseException], + __traceback: Optional[TracebackType], + ) -> bool: ... + +if True: + _S = TypeVar("_S", bound=AsyncExitStack) + + _ExitCoroFunc = Callable[[Optional[Type[BaseException]], Optional[BaseException], Optional[TracebackType]], Awaitable[bool]] + _CallbackCoroFunc = Callable[..., Awaitable[Any]] + _ACM_EF = TypeVar("_ACM_EF", AsyncContextManager[Any], _ExitCoroFunc) + class AsyncExitStack(AsyncContextManager[AsyncExitStack]): + def __init__(self) -> None: ... + def enter_context(self, cm: ContextManager[_T]) -> _T: ... + def enter_async_context(self, cm: AsyncContextManager[_T]) -> Awaitable[_T]: ... + def push(self, exit: _CM_EF) -> _CM_EF: ... + def push_async_exit(self, exit: _ACM_EF) -> _ACM_EF: ... + def callback(self, callback: Callable[..., Any], *args: Any, **kwds: Any) -> Callable[..., Any]: ... + def push_async_callback(self, callback: _CallbackCoroFunc, *args: Any, **kwds: Any) -> _CallbackCoroFunc: ... + def pop_all(self: _S) -> _S: ... + def aclose(self) -> Awaitable[None]: ... + def __aenter__(self: _S) -> Awaitable[_S]: ... + def __aexit__( + self, + __exc_type: Optional[Type[BaseException]], + __exc_value: Optional[BaseException], + __traceback: Optional[TracebackType], + ) -> Awaitable[bool]: ... + +if True: + class nullcontext(AbstractContextManager[_T]): + enter_result: _T + @overload + def __init__(self: nullcontext[None], enter_result: None = ...) -> None: ... + @overload + def __init__(self: nullcontext[_T], enter_result: _T) -> None: ... + def __enter__(self) -> _T: ... + def __exit__(self, *exctype: Any) -> bool: ... diff --git a/lib/contextlib2/py.typed b/lib/contextlib2/py.typed new file mode 100644 index 00000000..e69de29b