Convert `ls -UR1` output (fastest way to get recursive listing) to plain file listing

ls_recursive_to_plain_listing.py

#!/usr/bin/env python
import sys
import argparse


def self_check():
    from subprocess import check_output, check_call
    from StringIO import StringIO

    ls_r = StringIO(check_output(['ls', '-1RU']))
    parse(ls_r, open('self_check_output.txt', 'w'))
    check_call(['sort', 'self_check_output.txt', '-o', 'self_check_output.txt'])

    find_output = check_output(r'find . -mindepth 1 | sort > self_check_reference.txt', shell=True)
    check_call(['diff', '-u', 'self_check_reference.txt', 'self_check_output.txt'])
    print 'passed'


def parse(input, output):
    lines = iter(input)

    root = './'
    try:
        while True:
            line = next(lines).rstrip()
            if len(line):
                output.write(root + line + '\n')
            else:
                line = next(lines).rstrip()
                assert line[-1] == ':'
                root = line[:-1] + '/'
    except StopIteration:
        pass


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('--self-check', action='store_true')
    args = parser.parse_args()

    if args.self_check:
        self_check()
    else:
        parse(sys.stdin, sys.stdout)