from rpython.tool.uid import uid

# Support for explicit specialization: in code using global constants

# that are instances of SpecTag, code paths are not merged when

# the same variable holds a different SpecTag instance.

class SpecTag(object):

__slots__ = ()

def __repr__(self):

return '%s(0x%x)' % (self.__class__.__name__, uid(self))

def _freeze_(self):

return True

# 'for' iteration over iterables wrapped in an instance

# of unrolling_iterable will be unrolled by the flow space,

# like in:

# names = unrolling_iterable(['a', 'b', 'c'])

# def f(x):

# for name in names:

# setattr(x, name, 0)

class unrolling_iterable(SpecTag):

def __init__(self, iterable):

self._items = list(iterable)

self._head = _unroller(self._items)

def __iter__(self):

return iter(self._items)

def get_unroller(self):

return self._head

class _unroller(SpecTag):

def __init__(self, items, i=0):

self._items = items

self._i = i

self._next = None

def step(self):

v = self._items[self._i]

if self._next is None:

self._next = _unroller(self._items, self._i+1)

return v, self._next