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Diffstat (limited to 'tests/bytecode/pylib-tests/contextlib.py')
| -rw-r--r-- | tests/bytecode/pylib-tests/contextlib.py | 255 |
1 files changed, 0 insertions, 255 deletions
diff --git a/tests/bytecode/pylib-tests/contextlib.py b/tests/bytecode/pylib-tests/contextlib.py deleted file mode 100644 index 0b6bf71b08..0000000000 --- a/tests/bytecode/pylib-tests/contextlib.py +++ /dev/null @@ -1,255 +0,0 @@ -"""Utilities for with-statement contexts. See PEP 343.""" - -import sys -from collections import deque -from functools import wraps - -__all__ = ["contextmanager", "closing", "ContextDecorator", "ExitStack"] - - -class ContextDecorator(object): - "A base class or mixin that enables context managers to work as decorators." - - 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 - - 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 the exception *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: - # 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(<arguments>): - <setup> - try: - yield <value> - finally: - <cleanup> - - This makes this: - - with some_generator(<arguments>) as <variable>: - <body> - - equivalent to this: - - <setup> - try: - <variable> = <value> - <body> - finally: - <cleanup> - - """ - @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(<module>.open(<arguments>)) as f: - <block> - - is equivalent to this: - - f = <module>.open(<arguments>) - try: - <block> - finally: - f.close() - - """ - def __init__(self, thing): - self.thing = thing - def __enter__(self): - return self.thing - def __exit__(self, *exc_info): - self.thing.close() - - -# 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 = 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 = 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): - # 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): - while 1: - exc_context = new_exc.__context__ - if exc_context in (None, frame_exc): - break - new_exc = exc_context - new_exc.__context__ = old_exc - - # Callbacks are invoked in LIFO order to match the behaviour of - # nested context managers - suppressed_exc = False - while self._exit_callbacks: - cb = self._exit_callbacks.pop() - try: - if cb(*exc_details): - suppressed_exc = True - 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]) - if not self._exit_callbacks: - raise - exc_details = new_exc_details - return suppressed_exc |