38 lines
981 B
Python
38 lines
981 B
Python
from __future__ import generators
|
|
try:
|
|
reversed = reversed
|
|
except NameError:
|
|
|
|
def reversed(sequence):
|
|
"""reversed(sequence) -> reverse iterator over values of the sequence
|
|
|
|
Return a reverse iterator
|
|
"""
|
|
if hasattr(sequence, '__reversed__'):
|
|
return sequence.__reversed__()
|
|
if not hasattr(sequence, '__getitem__'):
|
|
raise TypeError("argument to reversed() must be a sequence")
|
|
return reversed_iterator(sequence)
|
|
|
|
|
|
class reversed_iterator(object):
|
|
|
|
def __init__(self, seq):
|
|
self.seq = seq
|
|
self.remaining = len(seq)
|
|
|
|
def __iter__(self):
|
|
return self
|
|
|
|
def next(self):
|
|
i = self.remaining
|
|
if i > 0:
|
|
i -= 1
|
|
item = self.seq[i]
|
|
self.remaining = i
|
|
return item
|
|
raise StopIteration
|
|
|
|
def __length_hint__(self):
|
|
return self.remaining
|