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__all__ = ['coroutine',
'iscoroutinefunction', 'iscoroutine']
import functools
import inspect
import opcode
import os
import sys
import traceback
import types
from . import compat
from . import events
from . import futures
from .log import logger
# Opcode of "yield from" instruction
_YIELD_FROM = opcode.opmap.get('YIELD_FROM', None)
# If you set _DEBUG to true, @coroutine will wrap the resulting
# generator objects in a CoroWrapper instance (defined below). That
# instance will log a message when the generator is never iterated
# over, which may happen when you forget to use "yield" with a
# coroutine call. Note that the value of the _DEBUG flag is taken
# when the decorator is used, so to be of any use it must be set
# before you define your coroutines. A downside of using this feature
# is that tracebacks show entries for the CoroWrapper.__next__ method
# when _DEBUG is true.
_DEBUG = bool(os.environ.get('TROLLIUSDEBUG'))
if _YIELD_FROM is not None:
# Check for CPython issue #21209
exec('''if 1:
def has_yield_from_bug():
class MyGen:
def __init__(self):
self.send_args = None
def __iter__(self):
return self
def __next__(self):
return 42
def send(self, *what):
self.send_args = what
return None
def yield_from_gen(gen):
yield from gen
value = (1, 2, 3)
gen = MyGen()
coro = yield_from_gen(gen)
next(coro)
coro.send(value)
return gen.send_args != (value,)
''')
_YIELD_FROM_BUG = has_yield_from_bug()
del has_yield_from_bug
else:
_YIELD_FROM_BUG = False
if compat.PY33:
# Don't use the Return class on Python 3.3 and later to support asyncio
# coroutines (to avoid the warning emited in Return destructor).
#
# The problem is that Return inherits from StopIteration. "yield from
# trollius_coroutine". Task._step() does not receive the Return exception,
# because "yield from" handles it internally. So it's not possible to set
# the raised attribute to True to avoid the warning in Return destructor.
def Return(*args):
if not args:
value = None
elif len(args) == 1:
value = args[0]
else:
value = args
return StopIteration(value)
else:
class Return(StopIteration):
def __init__(self, *args):
StopIteration.__init__(self)
if not args:
self.value = None
elif len(args) == 1:
self.value = args[0]
else:
self.value = args
self.raised = False
if _DEBUG:
frame = sys._getframe(1)
self._source_traceback = traceback.extract_stack(frame)
# explicitly clear the reference to avoid reference cycles
frame = None
else:
self._source_traceback = None
def __del__(self):
if self.raised:
return
fmt = 'Return(%r) used without raise'
if self._source_traceback:
fmt += '\nReturn created at (most recent call last):\n'
tb = ''.join(traceback.format_list(self._source_traceback))
fmt += tb.rstrip()
logger.error(fmt, self.value)
def _coroutine_at_yield_from(coro):
"""Test if the last instruction of a coroutine is "yield from".
Return False if the coroutine completed.
"""
frame = coro.gi_frame
if frame is None:
return False
code = coro.gi_code
assert frame.f_lasti >= 0
offset = frame.f_lasti + 1
instr = code.co_code[offset]
return (instr == _YIELD_FROM)
class CoroWrapper(object):
# Wrapper for coroutine object in _DEBUG mode.
def __init__(self, gen, func):
assert inspect.isgenerator(gen), gen
self.gen = gen
self.func = func
self._source_traceback = traceback.extract_stack(sys._getframe(1))
# __name__, __qualname__, __doc__ attributes are set by the coroutine()
# decorator
def __repr__(self):
coro_repr = _format_coroutine(self)
if self._source_traceback:
frame = self._source_traceback[-1]
coro_repr += ', created at %s:%s' % (frame[0], frame[1])
return '<%s %s>' % (self.__class__.__name__, coro_repr)
def __iter__(self):
return self
def __next__(self):
return next(self.gen)
next = __next__
if _YIELD_FROM_BUG:
# For for CPython issue #21209: using "yield from" and a custom
# generator, generator.send(tuple) unpacks the tuple instead of passing
# the tuple unchanged. Check if the caller is a generator using "yield
# from" to decide if the parameter should be unpacked or not.
def send(self, *value):
frame = sys._getframe()
caller = frame.f_back
assert caller.f_lasti >= 0
if caller.f_code.co_code[caller.f_lasti] != _YIELD_FROM:
value = value[0]
return self.gen.send(value)
else:
def send(self, value):
return self.gen.send(value)
def throw(self, exc):
return self.gen.throw(exc)
def close(self):
return self.gen.close()
@property
def gi_frame(self):
return self.gen.gi_frame
@property
def gi_running(self):
return self.gen.gi_running
@property
def gi_code(self):
return self.gen.gi_code
def __del__(self):
# Be careful accessing self.gen.frame -- self.gen might not exist.
gen = getattr(self, 'gen', None)
frame = getattr(gen, 'gi_frame', None)
if frame is not None and frame.f_lasti == -1:
msg = '%r was never yielded from' % self
tb = getattr(self, '_source_traceback', ())
if tb:
tb = ''.join(traceback.format_list(tb))
msg += ('\nCoroutine object created at '
'(most recent call last):\n')
msg += tb.rstrip()
logger.error(msg)
if not compat.PY34:
# Backport functools.update_wrapper() from Python 3.4:
# - Python 2.7 fails if assigned attributes don't exist
# - Python 2.7 and 3.1 don't set the __wrapped__ attribute
# - Python 3.2 and 3.3 set __wrapped__ before updating __dict__
def _update_wrapper(wrapper,
wrapped,
assigned = functools.WRAPPER_ASSIGNMENTS,
updated = functools.WRAPPER_UPDATES):
"""Update a wrapper function to look like the wrapped function
wrapper is the function to be updated
wrapped is the original function
assigned is a tuple naming the attributes assigned directly
from the wrapped function to the wrapper function (defaults to
functools.WRAPPER_ASSIGNMENTS)
updated is a tuple naming the attributes of the wrapper that
are updated with the corresponding attribute from the wrapped
function (defaults to functools.WRAPPER_UPDATES)
"""
for attr in assigned:
try:
value = getattr(wrapped, attr)
except AttributeError:
pass
else:
setattr(wrapper, attr, value)
for attr in updated:
getattr(wrapper, attr).update(getattr(wrapped, attr, {}))
# Issue #17482: set __wrapped__ last so we don't inadvertently copy it
# from the wrapped function when updating __dict__
wrapper.__wrapped__ = wrapped
# Return the wrapper so this can be used as a decorator via partial()
return wrapper
def _wraps(wrapped,
assigned = functools.WRAPPER_ASSIGNMENTS,
updated = functools.WRAPPER_UPDATES):
"""Decorator factory to apply update_wrapper() to a wrapper function
Returns a decorator that invokes update_wrapper() with the decorated
function as the wrapper argument and the arguments to wraps() as the
remaining arguments. Default arguments are as for update_wrapper().
This is a convenience function to simplify applying partial() to
update_wrapper().
"""
return functools.partial(_update_wrapper, wrapped=wrapped,
assigned=assigned, updated=updated)
else:
_wraps = functools.wraps
def coroutine(func):
"""Decorator to mark coroutines.
If the coroutine is not yielded from before it is destroyed,
an error message is logged.
"""
if inspect.isgeneratorfunction(func):
coro = func
else:
@_wraps(func)
def coro(*args, **kw):
res = func(*args, **kw)
if (isinstance(res, futures._FUTURE_CLASSES)
or inspect.isgenerator(res)):
res = yield From(res)
raise Return(res)
if not _DEBUG:
wrapper = coro
else:
@_wraps(func)
def wrapper(*args, **kwds):
coro_wrapper = CoroWrapper(coro(*args, **kwds), func)
if coro_wrapper._source_traceback:
del coro_wrapper._source_traceback[-1]
for attr in ('__name__', '__qualname__', '__doc__'):
try:
value = getattr(func, attr)
except AttributeError:
pass
else:
setattr(coro_wrapper, attr, value)
return coro_wrapper
if not compat.PY3:
wrapper.__wrapped__ = func
wrapper._is_coroutine = True # For iscoroutinefunction().
return wrapper
def iscoroutinefunction(func):
"""Return True if func is a decorated coroutine function."""
return getattr(func, '_is_coroutine', False)
_COROUTINE_TYPES = (types.GeneratorType, CoroWrapper)
if events.asyncio is not None:
# Accept also asyncio CoroWrapper for interoperability
if hasattr(events.asyncio, 'coroutines'):
_COROUTINE_TYPES += (events.asyncio.coroutines.CoroWrapper,)
else:
# old Tulip/Python versions
_COROUTINE_TYPES += (events.asyncio.tasks.CoroWrapper,)
def iscoroutine(obj):
"""Return True if obj is a coroutine object."""
return isinstance(obj, _COROUTINE_TYPES)
def _format_coroutine(coro):
assert iscoroutine(coro)
coro_name = getattr(coro, '__qualname__', coro.__name__)
filename = coro.gi_code.co_filename
if (isinstance(coro, CoroWrapper)
and not inspect.isgeneratorfunction(coro.func)):
filename, lineno = events._get_function_source(coro.func)
if coro.gi_frame is None:
coro_repr = '%s() done, defined at %s:%s' % (coro_name, filename, lineno)
else:
coro_repr = '%s() running, defined at %s:%s' % (coro_name, filename, lineno)
elif coro.gi_frame is not None:
lineno = coro.gi_frame.f_lineno
coro_repr = '%s() running at %s:%s' % (coro_name, filename, lineno)
else:
lineno = coro.gi_code.co_firstlineno
coro_repr = '%s() done, defined at %s:%s' % (coro_name, filename, lineno)
return coro_repr
class FromWrapper(object):
__slots__ = ('obj',)
def __init__(self, obj):
if isinstance(obj, FromWrapper):
obj = obj.obj
assert not isinstance(obj, FromWrapper)
self.obj = obj
def From(obj):
if not _DEBUG:
return obj
else:
return FromWrapper(obj)
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