Iterate lines of the string from its tail to its top.

iterlines_backward.py

def iterlines_backword(s):

    """ Iterate lines of `s` from its tail to its top.

    >>> list(iterlines_backword('a'))
    ['a']
    >>> list(iterlines_backword('a\\n'))
    ['a\\n']
    >>> list(iterlines_backword('a\\nb'))
    ['b', 'a\\n']
    >>> list(iterlines_backword('a\\nb\\n'))
    ['b\\n', 'a\\n']
    >>> list(iterlines_backword('a\\nb\\nc'))
    ['c', 'b\\n', 'a\\n']
    >>> list(iterlines_backword('a\\nb\\nc\\n'))
    ['c\\n', 'b\\n', 'a\\n']
    >>> list(iterlines_backword('a\\n\\nb\\n'))
    ['b\\n', '\\n', 'a\\n']
    >>> list(iterlines_backword('\\n'))
    ['\\n']
    >>> list(iterlines_backword('\\na'))
    ['a', '\\n']
    >>> list(iterlines_backword(''))
    []

    """
    p = q = len(s)
    while 1:
        try:
            p = s.rindex('\n', 0, q-1)+1
        except ValueError:
            break
        yield s[p:q]
        q = p
    if q:
        yield s[:q]


if __name__ == '__main__':
    import doctest
    doctest.testmod()