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