from compat.functools import wraps as _wraps
from sys import exc_info as _exc_info
class _from(object):
def __init__(self, EXPR):
self.iterator = iter(EXPR)
def supergenerator(genfunct):
"""Implements PEP 380. Use as:
@supergenerator
def genfunct(*args):
try:
sent1 = (yield val1)
,,,
retval = yield _from(iterator)
...
except Exception, e:
# caller did generator.throw
pass
finally:
pass # closing
"""
@_wraps(genfunct)
def wrapper(*args, **kwargs):
gen = genfunct(*args, **kwargs)
try:
# if first poll of gen raises StopIteration
# or any other Exception, we propagate
item = gen.next()
# OUTER loop
while True:
# yield _from(EXPR)
# semantics based on PEP 380, Revised**12, 19 April
if isinstance(item, _from):
_i = item.iterator
try:
# first poll of the subiterator
_y = _i.next()
except StopIteration, _e:
# subiterator exhausted on first poll
# extract return value
_r = _e.args if _e.args else (None,)
else:
# INNER loop
while True:
try:
# yield what the subiterator did
_s = (yield _y)
except GeneratorExit, _e:
# close the subiterator if possible
try:
_close = _i.close
except AttributeError:
pass
else:
_close()
# finally clause will gen.close()
raise _e
except BaseException:
# caller did wrapper.throw
_x = _exc_info()
# throw to the subiterator if possible
try:
_throw = _i.throw
except AttributeError:
# doesn't attempt to close _i?
# if gen raises StopIteration
# or any other Exception, we propagate
item = gen.throw(*_x)
_r = None
# fall through to INTERSECTION A
# then to OUTER loop
pass
else:
try:
_y = _throw(*_x)
except StopIteration, _e:
_r = _e.args if _e.args else (None,)
# fall through to INTERSECTION A
# then to INTERSECTION B
pass
else:
# restart INNER loop
continue
# INTERSECTION A
# restart OUTER loop or proceed to B?
if _r is None: break
else:
try:
# re-poll the subiterator
if _s is None:
_y = _i.next()
else:
_y = _i.send(_s)
except StopIteration, _e:
# subiterator is exhausted
# extract return value
_r = _e.args if _e.args else (None,)
# fall through to INTERSECTION B
pass
else:
# restart INNER loop
continue
# INTERSECTION B
# done yielding from subiterator
# send retvalue to gen
# if gen raises StopIteration
# or any other Exception, we propagate
item = gen.send(_r[0])
# restart OUTER loop
break
# traditional yield from gen
else:
try:
sent = (yield item)
except Exception:
# caller did wrapper.throw
_x = _exc_info()
# if gen raises StopIteration
# or any other Exception, we propagate
item = gen.throw(*_x)
else:
# if gen raises StopIteration
# or any other Exception, we propagate
item = gen.send(sent)
# end of OUTER loop, restart it
pass
finally:
# gen raised Exception
# or caller did wrapper.close()
# or wrapper was garbage collected
gen.close()
return wrapper
