|
| 1 | +class xrange(object): |
| 2 | + """ |
| 3 | + Advanced implementation of xrange (supports slice/copy/etc.) |
| 4 | + Reference: http://code.activestate.com/recipes/521885-a-pythonic-implementation-of-xrange/ |
| 5 | + """ |
| 6 | + |
| 7 | + __slots__ = ['_slice'] |
| 8 | + |
| 9 | + def __init__(self, *args): |
| 10 | + if args and isinstance(args[0], xrange): |
| 11 | + self._slice = slice(args[0].start, args[0].stop, args[0].step) |
| 12 | + else: |
| 13 | + self._slice = slice(*args) |
| 14 | + if self._slice.stop is None: |
| 15 | + # slice(*args) will never put None in stop unless it was |
| 16 | + # given as None explicitly. |
| 17 | + raise TypeError("xrange stop must not be None") |
| 18 | + |
| 19 | + @property |
| 20 | + def start(self): |
| 21 | + if self._slice.start is not None: |
| 22 | + return self._slice.start |
| 23 | + return 0 |
| 24 | + |
| 25 | + @property |
| 26 | + def stop(self): |
| 27 | + return self._slice.stop |
| 28 | + |
| 29 | + @property |
| 30 | + def step(self): |
| 31 | + if self._slice.step is not None: |
| 32 | + return self._slice.step |
| 33 | + return 1 |
| 34 | + |
| 35 | + def __hash__(self): |
| 36 | + return hash(self._slice) |
| 37 | + |
| 38 | + def __cmp__(self, other): |
| 39 | + return (cmp(type(self), type(other)) or |
| 40 | + cmp(self._slice, other._slice)) |
| 41 | + |
| 42 | + def __repr__(self): |
| 43 | + return '%s(%r, %r, %r)' % (self.__class__.__name__, |
| 44 | + self.start, self.stop, self.step) |
| 45 | + |
| 46 | + def __len__(self): |
| 47 | + return self._len() |
| 48 | + |
| 49 | + def _len(self): |
| 50 | + try: |
| 51 | + return max(0, int((self.stop - self.start) / self.step)) |
| 52 | + except Exception, ex: |
| 53 | + import pdb |
| 54 | + pdb.set_trace() |
| 55 | + |
| 56 | + def __getitem__(self, index): |
| 57 | + if isinstance(index, slice): |
| 58 | + start, stop, step = index.indices(self._len()) |
| 59 | + return xrange(self._index(start), |
| 60 | + self._index(stop), step*self.step) |
| 61 | + elif isinstance(index, (int, long)): |
| 62 | + if index < 0: |
| 63 | + fixed_index = index + self._len() |
| 64 | + else: |
| 65 | + fixed_index = index |
| 66 | + |
| 67 | + if not 0 <= fixed_index < self._len(): |
| 68 | + raise IndexError("Index %d out of %r" % (index, self)) |
| 69 | + |
| 70 | + return self._index(fixed_index) |
| 71 | + else: |
| 72 | + raise TypeError("xrange indices must be slices or integers") |
| 73 | + |
| 74 | + def _index(self, i): |
| 75 | + return self.start + self.step * i |
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