match: strengthen visit_children_set invariant, Recursive means "all files" My previous interpretation of "Recursive" was too relaxed: I thought it instructed the caller to do something like this: > you can stop calling `visit_children_set` because you'll need to descend into > every directory recursively, but you should still check every file if it > matches or not Whereas the real instruction seems to be: > I guarantee that everything in this subtree matches, you can stop > querying the matcher for all files and dirs altogether. The evidence to support this: - the test actually passes with the stronger invariant, revealing no exceptions from this rule - the implementation of `visit_children_set` for `DifferenceMatcher` clearly relies on this requirement, so it must hold for that not to lead to bugs.

     1

import argparse

     2

import os

     3

     4

ap = argparse.ArgumentParser()

     5

ap.add_argument('path', nargs='+')

     6

opts = ap.parse_args()

     7

     8

     9

def gather():

    10

    for p in opts.path:

    11

        if not os.path.exists(p):

    12

            return

    13

        if os.path.isdir(p):

    14

            yield p + os.path.sep

    15

            for dirpath, dirs, files in os.walk(p):

    16

                for d in dirs:

    17

                    yield os.path.join(dirpath, d) + os.path.sep

    18

                for f in files:

    19

                    yield os.path.join(dirpath, f)

    20

        else:

    21

            yield p

    22

    23

    24

print('\n'.join(sorted(gather(), key=lambda x: x.replace(os.path.sep, '/'))))