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# Convert a list of strings to a regex that matches everything but those strings
# ... and it had to be a POSIX regex; no negative lookahead :(
# This is a workaround for erofs supporting only exclude regex, not an include list
import sys
import re
from collections import defaultdict
# We can configure this script to match in different ways if we need to.
# The regex got too long for the argument list, so we had to truncate the
# hashes and use MATCH_STRING_PREFIX. That's less accurate, and might pick up some
# garbage like .lock files, but only if the sandbox doesn't hide those. Even
# then it should be harmless.
# Produce the negation of ^a$
MATCH_EXACTLY = ".+"
# Produce the negation of ^a
MATCH_STRING_PREFIX = "//X" # //X should be epsilon regex instead. Not supported??
# Produce the negation of ^a/?
MATCH_SUBPATHS = "[^/].*$"
# match_end = MATCH_SUBPATHS
match_end = MATCH_STRING_PREFIX
# match_end = MATCH_EXACTLY
def chars_to_inverted_class(letters):
assert len(letters) > 0
letters = list(letters)
s = "[^"
if "]" in letters:
s += "]"
letters.remove("]")
final = ""
if "-" in letters:
final = "-"
letters.remove("-")
s += "".join(letters)
s += final
s += "]"
return s
# There's probably at least one bug in here, but it seems to works well enough
# for filtering store paths.
def strings_to_inverted_regex(strings):
s = "("
# Match anything that starts with the wrong character
chars = defaultdict(list)
for item in strings:
if item != "":
chars[item[0]].append(item[1:])
if len(chars) == 0:
s += match_end
else:
s += chars_to_inverted_class(chars)
# Now match anything that starts with the right char, but then goes wrong
for char, sub in chars.items():
s += "|(" + re.escape(char) + strings_to_inverted_regex(sub) + ")"
s += ")"
return s
if __name__ == "__main__":
stdin_lines = []
for line in sys.stdin:
if line.strip() != "":
stdin_lines.append(line.strip())
print("^" + strings_to_inverted_regex(stdin_lines))
# Test:
# (echo foo; echo fo/; echo foo/; echo foo/ba/r; echo b; echo az; echo az/; echo az/a; echo ab; echo ab/a; echo ab/; echo abc; echo abcde; echo abb; echo ac; echo b) | grep -vE "$((echo ab; echo az; echo foo;) | python includes-to-excludes.py | tee /dev/stderr )"
# should print ab, az, foo and their subpaths
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