grammer.py

$ python
Python 3.4.3 (default, Jul 28 2015, 18:20:59) 
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from collections import deque
>>> 
>>> def grammer(tokens, grams=[(0,)]):
...     buffer_length = max(max(indexes) for indexes in grams)
...     buffer = deque(maxlen=buffer_length+1)
...     for token in tokens:
...         buffer.append(token)
...         for gram in grams:
...             if len(buffer) > max(gram):
...                 # Emit gram
...                 yield [buffer[i] for i in gram]
... 
>>> 
>>> print(list(grammer([1,2,3,4,5,6,7,8,9,0], grams=[(0,), (0,2)])))
[[1], [1], [1], [1, 3], [2], [2, 4], [3], [3, 5], [4], [4, 6], [5], [5, 7], [6], [6, 8], [7], [7, 9], [8], [8, 0]]
>>> print(list(grammer([1,2,3,4,5,6,7,8,9,0], grams=[(0,), (0,1), (0,1,2), (0,2)])))
[[1], [1], [1, 2], [1], [1, 2], [1, 2, 3], [1, 3], [2], [2, 3], [2, 3, 4], [2, 4], [3], [3, 4], [3, 4, 5], [3, 5], [4], [4, 5], [4, 5, 6], [4, 6], [5], [5, 6], [5, 6, 7], [5, 7], [6], [6, 7], [6, 7, 8], [6, 8], [7], [7, 8], [7, 8, 9], [7, 9], [8], [8, 9], [8, 9, 0], [8, 0]]