header_utils.py

def extract_line(line):
    """
    >>> extract_line("* hello world")
    ('hello world', 1)
    >>> extract_line("** this  is a ** test!!")
    ('this  is a ** test!!', 2)
    """
    depth = 0
    l = len(line)
    while (depth < l) and (line[depth] == '*'):
        depth += 1
    return (line[depth+1:], depth)


def parse_header(header):
    """
    >>> parse_header("* a\\n* b\\n* c")
    [['a', []], ['b', []], ['c', []]]
    >>> parse_header("* a\\n** b\\n* c")
    [['a', [['b', []]]], ['c', []]]
    >>> parse_header("* a\\n** b\\n** c\\n*** d\\n* e")
    [['a', [['b', []], ['c', [['d', []]]]]], ['e', []]]
    """
    nodes = []
    current_nodes = []
    for line in header.split("\n"):
        title,depth = extract_line(line)
        this_node = [title,[]]
        if depth == 1:
            nodes.append(this_node)
            current_nodes = [this_node]
        else:
            current_nodes[depth-2][1].append(this_node)
            current_nodes = current_nodes[:depth-1]
            current_nodes.append(this_node)

    return nodes