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  1. import collections
  2.  
  3. class SliceView(collections.abc.Sequence):
  4.     def __init__(self, seq, start=None, stop=None, step=None):
  5.         self.seq = seq
  6.         sl = slice(start, stop, step)
  7.         self.start, self.stop, self.step = sl.indices(len(seq))
  8.     def __len__(self):
  9.         return len(range(self.start, self.stop, self.step))
  10.     def __getitem__(self, idx):
  11.         if isinstance(idx, slice):
  12.             start, stop, step = idx.indices(len(self))
  13.             return type(self)(self.seq, start, stop, step)
  14.         if idx < 0:
  15.             idx += self.stop
  16.             if idx < self.start:
  17.                 raise IndexError
  18.         else:
  19.             idx += self.start
  20.             if idx >= self.stop:
  21.                 raise IndexError
  22.         return self.seq[idx]
  23.     def __str__(self):
  24.         return str(list(self))
  25.  
  26. base = SliceView([1, 2, 3])
  27. print(list(base))
  28. print(list(base[1:]))
  29. print(list(base[1:][1:]))
Success #stdin #stdout 0.04s 9400KB
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Standard input is empty
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[1, 2, 3]
[2, 3]
[2]
https://ideone.com/5yKfUP
language:
Python 3 (python  3.12)
created:
7 years ago
visibility:
public

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