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.

import argparse
import os

ap = argparse.ArgumentParser()
ap.add_argument('path', nargs='+')
opts = ap.parse_args()


def gather():
    for p in opts.path:
        if not os.path.exists(p):
            return
        if os.path.isdir(p):
            yield p + os.path.sep
            for dirpath, dirs, files in os.walk(p):
                for d in dirs:
                    yield os.path.join(dirpath, d) + os.path.sep
                for f in files:
                    yield os.path.join(dirpath, f)
        else:
            yield p


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