Source code for circuits.bitstring

'''
bitstring
~~~~~~~~~

Utilities for dealing with bit strings.
'''


def increment(bs):
    '''
    Increments the given bit string.

    :param bs: a bit string (list of integers)

    >>> increment([1, 0, 1])
    [1, 1, 0]
    >>> increment([0, 0, 0])
    [0, 0, 1]
    >>> increment([1, 1, 1])
    [1, 0, 0, 0]
    '''
    c = 1
    obs = []
    for b in reversed(bs):
        if b == c:
            obs.append(0)
        else:
            obs.append(1)
            c = 0
    if c == 1:
        obs = obs + [1]
    return list(reversed(obs))


def bitrange(length):
    '''
    Produces all possible bit strings up to the given length.

    :param length: the maximum length bit string to produce

    >>> list(bitrange(1))
    [[0], [1]]
    >>> list(bitrange(2))
    [[0, 0], [0, 1], [1, 0], [1, 1]]
    '''
    bs = [0] * length
    while len(bs) == length:
        yield bs
        bs = increment(bs)